draft-ietf-rtcweb-security-arch-20.txt   rfc8827.txt 
RTCWEB E. Rescorla Internet Engineering Task Force (IETF) E. Rescorla
Internet-Draft RTFM, Inc. Request for Comments: 8827 Mozilla
Intended status: Standards Track July 21, 2019 Category: Standards Track January 2021
Expires: January 22, 2020 ISSN: 2070-1721
WebRTC Security Architecture WebRTC Security Architecture
draft-ietf-rtcweb-security-arch-20
Abstract Abstract
This document defines the security architecture for WebRTC, a This document defines the security architecture for WebRTC, a
protocol suite intended for use with real-time applications that can protocol suite intended for use with real-time applications that can
be deployed in browsers - "real time communication on the Web". be deployed in browsers -- "real-time communication on the Web".
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on January 22, 2020. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8827.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 2, line 19 skipping to change at line 58
modifications of such material outside the IETF Standards Process. modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other it for publication as an RFC or to translate it into languages other
than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology
3. Trust Model . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Trust Model
3.1. Authenticated Entities . . . . . . . . . . . . . . . . . 5 3.1. Authenticated Entities
3.2. Unauthenticated Entities . . . . . . . . . . . . . . . . 6 3.2. Unauthenticated Entities
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Overview
4.1. Initial Signaling . . . . . . . . . . . . . . . . . . . . 8 4.1. Initial Signaling
4.2. Media Consent Verification . . . . . . . . . . . . . . . 10 4.2. Media Consent Verification
4.3. DTLS Handshake . . . . . . . . . . . . . . . . . . . . . 11 4.3. DTLS Handshake
4.4. Communications and Consent Freshness . . . . . . . . . . 11 4.4. Communications and Consent Freshness
5. SDP Identity Attribute . . . . . . . . . . . . . . . . . . . 12 5. SDP Identity Attribute
5.1. Offer/Answer Considerations . . . . . . . . . . . . . . . 13 5.1. Offer/Answer Considerations
5.1.1. Generating the Initial SDP Offer . . . . . . . . . . 13 5.1.1. Generating the Initial SDP Offer
5.1.2. Generating of SDP Answer . . . . . . . . . . . . . . 14 5.1.2. Generating an SDP Answer
5.1.3. Processing an SDP Offer or Answer . . . . . . . . . . 14 5.1.3. Processing an SDP Offer or Answer
5.1.4. Modifying the Session . . . . . . . . . . . . . . . . 14 5.1.4. Modifying the Session
6. Detailed Technical Description . . . . . . . . . . . . . . . 14 6. Detailed Technical Description
6.1. Origin and Web Security Issues . . . . . . . . . . . . . 14 6.1. Origin and Web Security Issues
6.2. Device Permissions Model . . . . . . . . . . . . . . . . 15 6.2. Device Permissions Model
6.3. Communications Consent . . . . . . . . . . . . . . . . . 17 6.3. Communications Consent
6.4. IP Location Privacy . . . . . . . . . . . . . . . . . . . 17 6.4. IP Location Privacy
6.5. Communications Security . . . . . . . . . . . . . . . . . 18 6.5. Communications Security
7. Web-Based Peer Authentication . . . . . . . . . . . . . . . . 20 7. Web-Based Peer Authentication
7.1. Trust Relationships: IdPs, APs, and RPs . . . . . . . . . 21 7.1. Trust Relationships: IdPs, APs, and RPs
7.2. Overview of Operation . . . . . . . . . . . . . . . . . . 23 7.2. Overview of Operation
7.3. Items for Standardization . . . . . . . . . . . . . . . . 24 7.3. Items for Standardization
7.4. Binding Identity Assertions to JSEP Offer/Answer 7.4. Binding Identity Assertions to JSEP Offer/Answer
Transactions . . . . . . . . . . . . . . . . . . . . . . 24 Transactions
7.4.1. Carrying Identity Assertions . . . . . . . . . . . . 25 7.4.1. Carrying Identity Assertions
7.5. Determining the IdP URI . . . . . . . . . . . . . . . . . 26 7.5. Determining the IdP URI
7.5.1. Authenticating Party . . . . . . . . . . . . . . . . 27 7.5.1. Authenticating Party
7.5.2. Relying Party . . . . . . . . . . . . . . . . . . . . 28 7.5.2. Relying Party
7.6. Requesting Assertions . . . . . . . . . . . . . . . . . . 28 7.6. Requesting Assertions
7.7. Managing User Login . . . . . . . . . . . . . . . . . . . 29 7.7. Managing User Login
8. Verifying Assertions
8. Verifying Assertions . . . . . . . . . . . . . . . . . . . . 29 8.1. Identity Formats
8.1. Identity Formats . . . . . . . . . . . . . . . . . . . . 30 9. Security Considerations
9. Security Considerations . . . . . . . . . . . . . . . . . . . 31 9.1. Communications Security
9.1. Communications Security . . . . . . . . . . . . . . . . . 31 9.2. Privacy
9.2. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 32 9.3. Denial of Service
9.3. Denial of Service . . . . . . . . . . . . . . . . . . . . 33 9.4. IdP Authentication Mechanism
9.4. IdP Authentication Mechanism . . . . . . . . . . . . . . 34 9.4.1. PeerConnection Origin Check
9.4.1. PeerConnection Origin Check . . . . . . . . . . . . . 34 9.4.2. IdP Well-Known URI
9.4.2. IdP Well-known URI . . . . . . . . . . . . . . . . . 34 9.4.3. Privacy of IdP-Generated Identities and the Hosting
9.4.3. Privacy of IdP-generated identities and the hosting Site
site . . . . . . . . . . . . . . . . . . . . . . . . 35 9.4.4. Security of Third-Party IdPs
9.4.4. Security of Third-Party IdPs . . . . . . . . . . . . 35 9.4.4.1. Confusable Characters
9.4.4.1. Confusable Characters . . . . . . . . . . . . . . 35 9.4.5. Web Security Feature Interactions
9.4.5. Web Security Feature Interactions . . . . . . . . . . 35 9.4.5.1. Popup Blocking
9.4.5.1. Popup Blocking . . . . . . . . . . . . . . . . . 36 9.4.5.2. Third Party Cookies
9.4.5.2. Third Party Cookies . . . . . . . . . . . . . . . 36 10. IANA Considerations
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36 11. References
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 37 11.1. Normative References
12. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 11.2. Informative References
12.1. Changes since -15 . . . . . . . . . . . . . . . . . . . 37 Acknowledgements
12.2. Changes since -11 . . . . . . . . . . . . . . . . . . . 37 Author's Address
12.3. Changes since -10 . . . . . . . . . . . . . . . . . . . 37
12.4. Changes since -06 . . . . . . . . . . . . . . . . . . . 37
12.5. Changes since -05 . . . . . . . . . . . . . . . . . . . 38
12.6. Changes since -03 . . . . . . . . . . . . . . . . . . . 38
12.7. Changes since -03 . . . . . . . . . . . . . . . . . . . 38
12.8. Changes since -02 . . . . . . . . . . . . . . . . . . . 38
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 39
13.1. Normative References . . . . . . . . . . . . . . . . . . 39
13.2. Informative References . . . . . . . . . . . . . . . . . 42
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 43
1. Introduction 1. Introduction
The Real-Time Communications on the Web (RTCWEB) working group The Real-Time Communications on the Web (RTCWEB) Working Group
standardized protocols for real-time communications between Web standardized protocols for real-time communications between Web
browsers, generally called "WebRTC" [I-D.ietf-rtcweb-overview]. The browsers, generally called "WebRTC" [RFC8825]. The major use cases
major use cases for WebRTC technology are real-time audio and/or for WebRTC technology are real-time audio and/or video calls, Web
video calls, Web conferencing, and direct data transfer. Unlike most conferencing, and direct data transfer. Unlike most conventional
conventional real-time systems, (e.g., SIP-based [RFC3261] soft real-time systems (e.g., SIP-based [RFC3261] soft phones), WebRTC
phones) WebRTC communications are directly controlled by some Web communications are directly controlled by some Web server, via a
server, via a JavaScript (JS) API as shown in Figure 1. JavaScript (JS) API as shown in Figure 1.
+----------------+ +----------------+
| | | |
| Web Server | | Web Server |
| | | |
+----------------+ +----------------+
^ ^ ^ ^
/ \ / \
HTTP / \ HTTP HTTP / \ HTTP
/ \ / \
/ \ / \
v v v v
JS API JS API JS API JS API
+-----------+ +-----------+ +-----------+ +-----------+
| | Media | | | | Media | |
| Browser |<---------->| Browser | | Browser |<---------->| Browser |
| | | | | | | |
+-----------+ +-----------+ +-----------+ +-----------+
Figure 1: A simple WebRTC system Figure 1: A Simple WebRTC System
A more complicated system might allow for interdomain calling, as A more complicated system might allow for inter-domain calling, as
shown in Figure 2. The protocol to be used between the domains is shown in Figure 2. The protocol to be used between the domains is
not standardized by WebRTC, but given the installed base and the form not standardized by WebRTC, but given the installed base and the form
of the WebRTC API is likely to be something SDP-based like SIP or of the WebRTC API is likely to be something SDP-based like SIP or
something like Extensible Messaging and Presence Protocol (XMPP) something like the Extensible Messaging and Presence Protocol (XMPP)
[RFC6120]. [RFC6120].
+--------------+ +--------------+ +--------------+ +--------------+
| | SIP,XMPP,...| | | | SIP, XMPP, ... | |
| Web Server |<----------->| Web Server | | Web Server |<-------------->| Web Server |
| | | | | | | |
+--------------+ +--------------+ +--------------+ +--------------+
^ ^ ^ ^
| | | |
HTTP | | HTTP HTTP | | HTTP
| | | |
v v v v
JS API JS API JS API JS API
+-----------+ +-----------+ +-----------+ +-----------+
| | Media | | | | Media | |
| Browser |<---------------->| Browser | | Browser |<------------------->| Browser |
| | | | | | | |
+-----------+ +-----------+ +-----------+ +-----------+
Figure 2: A multidomain WebRTC system Figure 2: A Multidomain WebRTC System
This system presents a number of new security challenges, which are This system presents a number of new security challenges, which are
analyzed in [I-D.ietf-rtcweb-security]. This document describes a analyzed in [RFC8826]. This document describes a security
security architecture for WebRTC which addresses the threats and architecture for WebRTC which addresses the threats and requirements
requirements described in that document. described in that document.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Trust Model 3. Trust Model
The basic assumption of this architecture is that network resources The basic assumption of this architecture is that network resources
exist in a hierarchy of trust, rooted in the browser, which serves as exist in a hierarchy of trust, rooted in the browser, which serves as
the user's Trusted Computing Base (TCB). Any security property which the user's Trusted Computing Base (TCB). Any security property which
the user wishes to have enforced must be ultimately guaranteed by the the user wishes to have enforced must be ultimately guaranteed by the
browser (or transitively by some property the browser verifies). browser (or transitively by some property the browser verifies).
Conversely, if the browser is compromised, then no security Conversely, if the browser is compromised, then no security
skipping to change at page 5, line 39 skipping to change at line 209
browser. However, this is unfortunately not possible if we wish to browser. However, this is unfortunately not possible if we wish to
have a functional system. Other network elements fall into two have a functional system. Other network elements fall into two
categories: those which can be authenticated by the browser and thus categories: those which can be authenticated by the browser and thus
can be granted permissions to access sensitive resources, and those can be granted permissions to access sensitive resources, and those
which cannot be authenticated and thus are untrusted. which cannot be authenticated and thus are untrusted.
3.1. Authenticated Entities 3.1. Authenticated Entities
There are two major classes of authenticated entities in the system: There are two major classes of authenticated entities in the system:
o Calling services: Web sites whose origin we can verify (optimally Calling services: Web sites whose origin we can verify (optimally
via HTTPS, but in some cases because we are on a topologically via HTTPS, but in some cases because we are on a topologically
restricted network, such as behind a firewall, and can infer restricted network, such as behind a firewall, and can infer
authentication from firewall behavior). authentication from firewall behavior).
o Other users: WebRTC peers whose origin we can verify Other users: WebRTC peers whose origin we can verify
cryptographically (optimally via DTLS-SRTP). cryptographically (optimally via DTLS-SRTP).
Note that merely being authenticated does not make these entities Note that merely being authenticated does not make these entities
trusted. For instance, just because we can verify that trusted. For instance, just because we can verify that
https://www.example.org/ is owned by Dr. Evil does not mean that we <https://www.example.org/> is owned by Dr. Evil does not mean that we
can trust Dr. Evil to access our camera and microphone. However, it can trust Dr. Evil to access our camera and microphone. However, it
gives the user an opportunity to determine whether he wishes to trust gives the user an opportunity to determine whether they wish to trust
Dr. Evil or not; after all, if he desires to contact Dr. Evil Dr. Evil or not; after all, if they desire to contact Dr. Evil
(perhaps to arrange for ransom payment), it's safe to temporarily (perhaps to arrange for ransom payment), it's safe to temporarily
give him access to the camera and microphone for the purpose of the give them access to the camera and microphone for the purpose of the
call, but he doesn't want Dr. Evil to be able to access his camera call, but they don't want Dr. Evil to be able to access their camera
and microphone other than during the call. The point here is that we and microphone other than during the call. The point here is that we
must first identify other elements before we can determine whether must first identify other elements before we can determine whether
and how much to trust them. Additionally, sometimes we need to and how much to trust them. Additionally, sometimes we need to
identify the communicating peer before we know what policies to identify the communicating peer before we know what policies to
apply. apply.
3.2. Unauthenticated Entities 3.2. Unauthenticated Entities
Other than the above entities, we are not generally able to identify Other than the above entities, we are not generally able to identify
other network elements, thus we cannot trust them. This does not other network elements; thus, we cannot trust them. This does not
mean that it is not possible to have any interaction with them, but mean that it is not possible to have any interaction with them, but
it means that we must assume that they will behave maliciously and it means that we must assume that they will behave maliciously and
design a system which is secure even if they do so. design a system which is secure even if they do so.
4. Overview 4. Overview
This section describes a typical WebRTC session and shows how the This section describes a typical WebRTC session and shows how the
various security elements interact and what guarantees are provided various security elements interact and what guarantees are provided
to the user. The example in this section is a "best case" scenario to the user. The example in this section is a "best case" scenario
in which we provide the maximal amount of user authentication and in which we provide the maximal amount of user authentication and
media privacy with the minimal level of trust in the calling service. media privacy with the minimal level of trust in the calling service.
Simpler versions with lower levels of security are also possible and Simpler versions with lower levels of security are also possible and
are noted in the text where applicable. It's also important to are noted in the text where applicable. It's also important to
recognize the tension between security (or performance) and privacy. recognize the tension between security (or performance) and privacy.
The example shown here is aimed towards settings where we are more The example shown here is aimed towards settings where we are more
concerned about secure calling than about privacy, but as we shall concerned about secure calling than about privacy, but as we shall
see, there are settings where one might wish to make different see, there are settings where one might wish to make different
tradeoffs--this architecture is still compatible with those settings. tradeoffs -- this architecture is still compatible with those
settings.
For the purposes of this example, we assume the topology shown in the For the purposes of this example, we assume the topology shown in the
figures below. This topology is derived from the topology shown in figures below. This topology is derived from the topology shown in
Figure 1, but separates Alice and Bob's identities from the process Figure 1, but separates Alice's and Bob's identities from the process
of signaling. Specifically, Alice and Bob have relationships with of signaling. Specifically, Alice and Bob have relationships with
some Identity Provider (IdP) that supports a protocol (such as OpenID some Identity Provider (IdP) that supports a protocol (such as OpenID
Connect) that can be used to demonstrate their identity to other Connect) that can be used to demonstrate their identity to other
parties. For instance, Alice might have an account with a social parties. For instance, Alice might have an account with a social
network which she can then use to authenticate to other web sites network which she can then use to authenticate to other Web sites
without explicitly having an account with those sites; this is a without explicitly having an account with those sites; this is a
fairly conventional pattern on the Web. Section 7.1 provides an fairly conventional pattern on the Web. Section 7.1 provides an
overview of Identity Providers and the relevant terminology. Alice overview of IdPs and the relevant terminology. Alice and Bob might
and Bob might have relationships with different IdPs as well. have relationships with different IdPs as well. Note: The IdP
mechanism described here has not seen wide adoption. See Section 7
for more on the status of IdP-based authentication.
This separation of identity provision and signaling isn't This separation of identity provision and signaling isn't
particularly important in "closed world" cases where Alice and Bob particularly important in "closed world" cases where Alice and Bob
are users on the same social network and have identities based on are users on the same social network and have identities based on
that domain (Figure 3). However, there are important settings where that domain (Figure 3). However, there are important settings where
that is not the case, such as federation (calls from one domain to that is not the case, such as federation (calls from one domain to
another; Figure 4) and calling on untrusted sites, such as where two another; see Figure 4) and calling on untrusted sites, such as where
users who have a relationship via a given social network want to call two users who have a relationship via a given social network want to
each other on another, untrusted, site, such as a poker site. call each other on another, untrusted, site, such as a poker site.
Note that the servers themselves are also authenticated by an Note that the servers themselves are also authenticated by an
external identity service, the SSL/TLS certificate infrastructure external identity service, the SSL/TLS certificate infrastructure
(not shown). As is conventional in the Web, all identities are (not shown). As is conventional in the Web, all identities are
ultimately rooted in that system. For instance, when an IdP makes an ultimately rooted in that system. For instance, when an IdP makes an
identity assertion, the Relying Party consuming that assertion is identity assertion, the Relying Party consuming that assertion is
able to verify because it is able to connect to the IdP via HTTPS. able to verify because it is able to connect to the IdP via HTTPS.
+----------------+ +----------------+
| | | |
skipping to change at page 7, line 45 skipping to change at line 314
+-----------+ +-----------+ +-----------+ +-----------+
^ ^--+ +--^ ^ ^ ^--+ +--^ ^
| | | | | | | |
v | | v v | | v
+-----------+ | | +-----------+ +-----------+ | | +-----------+
| |<--------+ | | | |<--------+ | |
| IdP1 | | | IdP2 | | IdP1 | | | IdP2 |
| | +------->| | | | +------->| |
+-----------+ +-----------+ +-----------+ +-----------+
Figure 3: A call with IdP-based identity Figure 3: A Call with IdP-Based Identity
Figure 4 shows essentially the same calling scenario but with a call Figure 4 shows essentially the same calling scenario but with a call
between two separate domains (i.e., a federated case), as in between two separate domains (i.e., a federated case), as in
Figure 2. As mentioned above, the domains communicate by some Figure 2. As mentioned above, the domains communicate by some
unspecified protocol and providing separate signaling and identity unspecified protocol, and providing separate signaling and identity
allows for calls to be authenticated regardless of the details of the allows for calls to be authenticated regardless of the details of the
inter-domain protocol. inter-domain protocol.
+----------------+ Unspecified +----------------+ +----------------+ Unspecified +----------------+
| | protocol | | | | protocol | |
| Signaling |<----------------->| Signaling | | Signaling |<----------------->| Signaling |
| Server | (SIP, XMPP, ...) | Server | | Server | (SIP, XMPP, ...) | Server |
| | | | | | | |
+----------------+ +----------------+ +----------------+ +----------------+
^ ^ ^ ^
skipping to change at page 8, line 34 skipping to change at line 350
+-----------+ +-----------+ +-----------+ +-----------+
^ ^--+ +--^ ^ ^ ^--+ +--^ ^
| | | | | | | |
v | | v v | | v
+-----------+ | | +-----------+ +-----------+ | | +-----------+
| |<-------------------------+ | | | |<-------------------------+ | |
| IdP1 | | | IdP2 | | IdP1 | | | IdP2 |
| | +------------------------>| | | | +------------------------>| |
+-----------+ +-----------+ +-----------+ +-----------+
Figure 4: A federated call with IdP-based identity Figure 4: A Federated Call with IdP-Based Identity
4.1. Initial Signaling 4.1. Initial Signaling
For simplicity, assume the topology in Figure 3. Alice and Bob are For simplicity, assume the topology in Figure 3. Alice and Bob are
both users of a common calling service; they both have approved the both users of a common calling service; they both have approved the
calling service to make calls (we defer the discussion of device calling service to make calls (we defer the discussion of device
access permissions until later). They are both connected to the access permissions until later). They are both connected to the
calling service via HTTPS and so know the origin with some level of calling service via HTTPS and so know the origin with some level of
confidence. They also have accounts with some identity provider. confidence. They also have accounts with some IdP. This sort of
This sort of identity service is becoming increasingly common in the identity service is becoming increasingly common in the Web
Web environment (with technologies such as Federated Google Login, environment (with technologies such as Federated Google Login,
Facebook Connect, OAuth, OpenID, WebFinger), and is often provided as Facebook Connect, OAuth, OpenID, WebFinger), and is often provided as
a side effect service of a user's ordinary accounts with some a side effect service of a user's ordinary accounts with some
service. In this example, we show Alice and Bob using a separate service. In this example, we show Alice and Bob using a separate
identity service, though the identity service may be the same entity identity service, though the identity service may be the same entity
as the calling service or there may be no identity service at all. as the calling service or there may be no identity service at all.
Alice is logged onto the calling service and decides to call Bob. Alice is logged onto the calling service and decides to call Bob. She
She can see from the calling service that he is online and the can see from the calling service that he is online and the calling
calling service presents a JS UI in the form of a button next to service presents a JS UI in the form of a button next to Bob's name
Bob's name which says "Call". Alice clicks the button, which which says "Call". Alice clicks the button, which initiates a JS
initiates a JS callback that instantiates a PeerConnection object. callback that instantiates a PeerConnection object. This does not
This does not require a security check: JS from any origin is allowed require a security check: JS from any origin is allowed to get this
to get this far. far.
Once the PeerConnection is created, the calling service JS needs to Once the PeerConnection is created, the calling service JS needs to
set up some media. Because this is an audio/video call, it creates a set up some media. Because this is an audio/video call, it creates a
MediaStream with two MediaStreamTracks, one connected to an audio MediaStream with two MediaStreamTracks, one connected to an audio
input and one connected to a video input. At this point the first input and one connected to a video input. At this point, the first
security check is required: untrusted origins are not allowed to security check is required: untrusted origins are not allowed to
access the camera and microphone, so the browser prompts Alice for access the camera and microphone, so the browser prompts Alice for
permission. permission.
In the current W3C API, once some streams have been added, Alice's In the current W3C API, once some streams have been added, Alice's
browser + JS generates a signaling message [I-D.ietf-rtcweb-jsep] browser + JS generates a signaling message [RFC8829] containing:
containing:
o Media channel information * Media channel information
o Interactive Connectivity Establishment (ICE) [RFC8445] candidates * Interactive Connectivity Establishment (ICE) [RFC8445] candidates
o A fingerprint attribute binding the communication to a key pair * A "fingerprint" attribute binding the communication to a key pair
[RFC5763]. Note that this key may simply be ephemerally generated [RFC5763]. Note that this key may simply be ephemerally generated
for this call or specific to this domain, and Alice may have a for this call or specific to this domain, and Alice may have a
large number of such keys. large number of such keys.
Prior to sending out the signaling message, the PeerConnection code Prior to sending out the signaling message, the PeerConnection code
contacts the identity service and obtains an assertion binding contacts the identity service and obtains an assertion binding
Alice's identity to her fingerprint. The exact details depend on the Alice's identity to her fingerprint. The exact details depend on the
identity service (though as discussed in Section 7 PeerConnection can identity service (though as discussed in Section 7 PeerConnection can
be agnostic to them), but for now it's easiest to think of as an be agnostic to them), but for now it's easiest to think of as an
OAuth token. The assertion may bind other information to the OAuth token. The assertion may bind other information to the
identity besides the fingerprint, but at minimum it needs to bind the identity besides the fingerprint, but at minimum it needs to bind the
fingerprint. fingerprint.
This message is sent to the signaling server, e.g., by XMLHttpRequest This message is sent to the signaling server, e.g., by fetch()
[XmlHttpRequest] or by WebSockets [RFC6455], over TLS [RFC5246]. The [fetch] or by WebSockets [RFC6455], over TLS [RFC8446]. The
signaling server processes the message from Alice's browser, signaling server processes the message from Alice's browser,
determines that this is a call to Bob and sends a signaling message determines that this is a call to Bob, and sends a signaling message
to Bob's browser (again, the format is currently undefined). The JS to Bob's browser (again, the format is currently undefined). The JS
on Bob's browser processes it, and alerts Bob to the incoming call on Bob's browser processes it, and alerts Bob to the incoming call
and to Alice's identity. In this case, Alice has provided an and to Alice's identity. In this case, Alice has provided an
identity assertion and so Bob's browser contacts Alice's identity identity assertion and so Bob's browser contacts Alice's IdP (again,
provider (again, this is done in a generic way so the browser has no this is done in a generic way so the browser has no specific
specific knowledge of the IdP) to verify the assertion. It is also knowledge of the IdP) to verify the assertion. It is also possible
possible to have IdPs with which the browser has a specific to have IdPs with which the browser has a specific trust
trustrelationship, as described in Section 7.1. This allows the relationship, as described in Section 7.1. This allows the browser
browser to display a trusted element in the browser chrome indicating to display a trusted element in the browser chrome indicating that a
that a call is coming in from Alice. If Alice is in Bob's address call is coming in from Alice. If Alice is in Bob's address book,
book, then this interface might also include her real name, a then this interface might also include her real name, a picture, etc.
picture, etc. The calling site will also provide some user interface The calling site will also provide some user interface element (e.g.,
element (e.g., a button) to allow Bob to answer the call, though this a button) to allow Bob to answer the call, though this is most likely
is most likely not part of the trusted UI. not part of the trusted UI.
If Bob agrees a PeerConnection is instantiated with the message from If Bob agrees, a PeerConnection is instantiated with the message from
Alice's side. Then, a similar process occurs as on Alice's browser: Alice's side. Then, a similar process occurs as on Alice's browser:
Bob's browser prompts him for device permission, the media streams Bob's browser prompts him for device permission, the media streams
are created, and a return signaling message containing media are created, and a return signaling message containing media
information, ICE candidates, and a fingerprint is sent back to Alice information, ICE candidates, and a fingerprint is sent back to Alice
via the signaling service. If Bob has a relationship with an IdP, via the signaling service. If Bob has a relationship with an IdP,
the message will also come with an identity assertion. the message will also come with an identity assertion.
At this point, Alice and Bob each know that the other party wants to At this point, Alice and Bob each know that the other party wants to
have a secure call with them. Based purely on the interface provided have a secure call with them. Based purely on the interface provided
by the signaling server, they know that the signaling server claims by the signaling server, they know that the signaling server claims
that the call is from Alice to Bob. This level of security is that the call is from Alice to Bob. This level of security is
provided merely by having the fingerprint in the message and having provided merely by having the fingerprint in the message and having
that message received securely from the signaling server. Because that message received securely from the signaling server. Because
the far end sent an identity assertion along with their message, they the far end sent an identity assertion along with their message, they
know that this is verifiable from the IdP as well. Note that if the know that this is verifiable from the IdP as well. Note that if the
call is federated, as shown in Figure 4 then Alice is able to verify call is federated, as shown in Figure 4, then Alice is able to verify
Bob's identity in a way that is not mediated by either her signaling Bob's identity in a way that is not mediated by either her signaling
server or Bob's. Rather, she verifies it directly with Bob's IdP. server or Bob's. Rather, she verifies it directly with Bob's IdP.
Of course, the call works perfectly well if either Alice or Bob Of course, the call works perfectly well if either Alice or Bob
doesn't have a relationship with an IdP; they just get a lower level doesn't have a relationship with an IdP; they just get a lower level
of assurance. I.e., they simply have whatever information their of assurance. I.e., they simply have whatever information their
calling site claims about the caller/callee's identity. Moreover, calling site claims about the caller/callee's identity. Moreover,
Alice might wish to make an anonymous call through an anonymous Alice might wish to make an anonymous call through an anonymous
calling site, in which case she would of course just not provide any calling site, in which case she would of course just not provide any
identity assertion and the calling site would mask her identity from identity assertion and the calling site would mask her identity from
Bob. Bob.
4.2. Media Consent Verification 4.2. Media Consent Verification
As described in ([I-D.ietf-rtcweb-security]; Section 4.2) media As described in [RFC8826], Section 4.2, media consent verification is
consent verification is provided via ICE. Thus, Alice and Bob provided via ICE. Thus, Alice and Bob perform ICE checks with each
perform ICE checks with each other. At the completion of these other. At the completion of these checks, they are ready to send
checks, they are ready to send non-ICE data. non-ICE data.
At this point, Alice knows that (a) Bob (assuming he is verified via At this point, Alice knows that (a) Bob (assuming he is verified via
his IdP) or someone else who the signaling service is claiming is Bob his IdP) or someone else who the signaling service is claiming is Bob
is willing to exchange traffic with her and (b) that either Bob is at is willing to exchange traffic with her and (b) either Bob is at the
the IP address which she has verified via ICE or there is an attacker IP address which she has verified via ICE or there is an attacker who
who is on-path to that IP address detouring the traffic. Note that is on-path to that IP address detouring the traffic. Note that it is
it is not possible for an attacker who is on-path between Alice and not possible for an attacker who is on-path between Alice and Bob but
Bob but not attached to the signaling service to spoof these checks not attached to the signaling service to spoof these checks because
because they do not have the ICE credentials. Bob has the same they do not have the ICE credentials. Bob has the same security
security guarantees with respect to Alice. guarantees with respect to Alice.
4.3. DTLS Handshake 4.3. DTLS Handshake
Once the requisite ICE checks have completed, Alice and Bob can set Once the requisite ICE checks have completed, Alice and Bob can set
up a secure channel or channels. This is performed via DTLS up a secure channel or channels. This is performed via DTLS
[RFC6347] and DTLS-SRTP [RFC5763] keying for SRTP [RFC3711] for the [RFC6347] and DTLS-SRTP [RFC5763] keying for SRTP [RFC3711] for the
media channel and SCTP over DTLS [RFC8261] for data channels. media channel and the Stream Control Transmission Protocol (SCTP)
Specifically, Alice and Bob perform a DTLS handshake on every over DTLS [RFC8261] for data channels. Specifically, Alice and Bob
component which has been established by ICE. The total number of perform a DTLS handshake on every component which has been
channels depends on the amount of muxing; in the most likely case we established by ICE. The total number of channels depends on the
are using both RTP/RTCP mux and muxing multiple media streams on the amount of muxing; in the most likely case, we are using both RTP/RTCP
same channel, in which case there is only one DTLS handshake. Once mux and muxing multiple media streams on the same channel, in which
the DTLS handshake has completed, the keys are exported [RFC5705] and case there is only one DTLS handshake. Once the DTLS handshake has
used to key SRTP for the media channels. completed, the keys are exported [RFC5705] and used to key SRTP for
the media channels.
At this point, Alice and Bob know that they share a set of secure At this point, Alice and Bob know that they share a set of secure
data and/or media channels with keys which are not known to any data and/or media channels with keys which are not known to any
third-party attacker. If Alice and Bob authenticated via their IdPs, third-party attacker. If Alice and Bob authenticated via their IdPs,
then they also know that the signaling service is not mounting a man- then they also know that the signaling service is not mounting a man-
in-the-middle attack on their traffic. Even if they do not use an in-the-middle attack on their traffic. Even if they do not use an
IdP, as long as they have minimal trust in the signaling service not IdP, as long as they have minimal trust in the signaling service not
to perform a man-in-the-middle attack, they know that their to perform a man-in-the-middle attack, they know that their
communications are secure against the signaling service as well communications are secure against the signaling service as well
(i.e., that the signaling service cannot mount a passive attack on (i.e., that the signaling service cannot mount a passive attack on
skipping to change at page 11, line 48 skipping to change at line 508
From a security perspective, everything from here on in is a little From a security perspective, everything from here on in is a little
anticlimactic: Alice and Bob exchange data protected by the keys anticlimactic: Alice and Bob exchange data protected by the keys
negotiated by DTLS. Because of the security guarantees discussed in negotiated by DTLS. Because of the security guarantees discussed in
the previous sections, they know that the communications are the previous sections, they know that the communications are
encrypted and authenticated. encrypted and authenticated.
The one remaining security property we need to establish is "consent The one remaining security property we need to establish is "consent
freshness", i.e., allowing Alice to verify that Bob is still prepared freshness", i.e., allowing Alice to verify that Bob is still prepared
to receive her communications so that Alice does not continue to send to receive her communications so that Alice does not continue to send
large traffic volumes to entities which went abruptly offline. ICE large traffic volumes to entities which went abruptly offline. ICE
specifies periodic STUN keepalives but only if media is not flowing. specifies periodic Session Traversal Utilities for NAT (STUN)
Because the consent issue is more difficult here, we require WebRTC keepalives but only if media is not flowing. Because the consent
implementations to periodically send keepalives. As described in issue is more difficult here, we require WebRTC implementations to
Section 5.3, these keepalives MUST be based on the consent freshness periodically send keepalives using the consent freshness mechanism
mechanism specified in [RFC7675]. If a keepalive fails and no new specified in [RFC7675]. If a keepalive fails and no new ICE channels
ICE channels can be established, then the session is terminated. can be established, then the session is terminated.
5. SDP Identity Attribute 5. SDP Identity Attribute
The SDP 'identity' attribute is a session-level attribute that is The SDP "identity" attribute is a session-level attribute that is
used by an endpoint to convey its identity assertion to its peer. used by an endpoint to convey its identity assertion to its peer.
The identity assertion value is encoded as Base-64, as described in The identity-assertion value is encoded as base64, as described in
Section 4 of [RFC4648]. Section 4 of [RFC4648].
The procedures in this section are based on the assumption that the The procedures in this section are based on the assumption that the
identity assertion of an endpoint is bound to the fingerprints of the identity assertion of an endpoint is bound to the fingerprints of the
endpoint. This does not preclude the definition of alternative means endpoint. This does not preclude the definition of alternative means
of binding an assertion to the endpoint, but such means are outside of binding an assertion to the endpoint, but such means are outside
the scope of this specification. the scope of this specification.
The semantics of multiple 'identity' attributes within an offer or The semantics of multiple "identity" attributes within an offer or
answer are undefined. Implementations SHOULD only include a single answer are undefined. Implementations SHOULD only include a single
'identity' attribute in an offer or answer and relying parties MAY "identity" attribute in an offer or answer, and Relying Parties MAY
elect to ignore all but the first 'identity' attribute. elect to ignore all but the first "identity" attribute.
Name: identity Name: identity
Value: identity-assertion Value: identity-assertion
Usage Level: session Usage Level: session
Charset Dependent: no Charset Dependent: no
Default Value: N/A Default Value: N/A
Name: identity Syntax:
Syntax:
identity-assertion = identity-assertion-value identity-assertion = identity-assertion-value
*(SP identity-extension) *(SP identity-extension)
identity-assertion-value = base64 identity-assertion-value = base64
identity-extension = extension-name [ "=" extension-value ] identity-extension = extension-name [ "=" extension-value ]
extension-name = token extension-name = token
extension-value = 1*(%x01-09 / %x0b-0c / %x0e-3a / %x3c-ff) extension-value = 1*(%x01-09 / %x0b-0c / %x0e-3a / %x3c-ff)
; byte-string from [RFC4566] ; byte-string from [RFC4566]
<ALPHA and DIGIT as defined in [RFC4566]> <ALPHA and DIGIT as defined in [RFC4566]>
<base64 as defined in [RFC4566]> <base64 as defined in [RFC4566]>
Example: Example:
a=identity:\ a=identity:\
eyJpZHAiOnsiZG9tYWluIjoiZXhhbXBsZS5vcmciLCJwcm90b2NvbCI6ImJvZ3Vz\ eyJpZHAiOnsiZG9tYWluIjoiZXhhbXBsZS5vcmciLCJwcm90b2NvbCI6ImJvZ3Vz\
In0sImFzc2VydGlvbiI6IntcImlkZW50aXR5XCI6XCJib2JAZXhhbXBsZS5vcmdc\ In0sImFzc2VydGlvbiI6IntcImlkZW50aXR5XCI6XCJib2JAZXhhbXBsZS5vcmdc\
IixcImNvbnRlbnRzXCI6XCJhYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3l6XCIsXCJz\ IixcImNvbnRlbnRzXCI6XCJhYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3l6XCIsXCJz\
aWduYXR1cmVcIjpcIjAxMDIwMzA0MDUwNlwifSJ9 aWduYXR1cmVcIjpcIjAxMDIwMzA0MDUwNlwifSJ9
Note that long lines in the example are folded to meet the column | Note that long lines in the example are folded to meet the
width constraints of this document; the backslash ("\") at the end of | column width constraints of this document; the backslash ("\")
a line, the carriage return that follows, and whitespace shall be ignored. | at the end of a line, the carriage return that follows, and
| whitespace shall be ignored.
This specification does not define any extensions for the attribute. This specification does not define any extensions for the attribute.
The identity-assertion value is a JSON [RFC8259] encoded string. The The identity-assertion value is a JSON encoded string [RFC8259]. The
JSON object contains two keys: "assertion" and "idp". The JSON object contains two keys: "assertion" and "idp". The
"assertion" key value contains an opaque string that is consumed by "assertion" key value contains an opaque string that is consumed by
the IdP. The "idp" key value contains a dictionary with one or two the IdP. The "idp" key value contains a dictionary with one or two
further values that identify the IdP. See Section 7.6 for more further values that identify the IdP. See Section 7.6 for more
details. details.
5.1. Offer/Answer Considerations 5.1. Offer/Answer Considerations
This section defines the SDP Offer/Answer [RFC3264] considerations This section defines the SDP offer/answer [RFC3264] considerations
for the SDP 'identity' attribute. for the SDP "identity" attribute.
Within this section, 'initial offer' refers to the first offer in the Within this section, 'initial offer' refers to the first offer in the
SDP session that contains an SDP "identity" attribute. SDP session that contains an SDP "identity" attribute.
5.1.1. Generating the Initial SDP Offer 5.1.1. Generating the Initial SDP Offer
When an offerer sends an offer, in order to provide its identity When an offerer sends an offer, in order to provide its identity
assertion to the peer, it includes an 'identity' attribute in the assertion to the peer, it includes an "identity" attribute in the
offer. In addition, the offerer includes one or more SDP offer. In addition, the offerer includes one or more SDP
'fingerprint' attributes. The 'identity' attribute MUST be bound to "fingerprint" attributes. The "identity" attribute MUST be bound to
all the 'fingerprint' attributes in the session description. all the "fingerprint" attributes in the session description.
5.1.2. Generating of SDP Answer 5.1.2. Generating an SDP Answer
If the answerer elects to include an 'identity' attribute, it follows If the answerer elects to include an "identity" attribute, it follows
the same steps as those in Section 5.1.1. The answerer can choose to the same steps as those in Section 5.1.1. The answerer can choose to
include or omit an 'identity' attribute independently, regardless of include or omit an "identity" attribute independently, regardless of
whether the offerer did so. whether the offerer did so.
5.1.3. Processing an SDP Offer or Answer 5.1.3. Processing an SDP Offer or Answer
When an endpoint receives an offer or answer that contains an When an endpoint receives an offer or answer that contains an
'identity' attribute, the answerer can use the the attribute "identity" attribute, the answerer can use the attribute information
information to contact the IdP and verify the identity of the peer. to contact the IdP and verify the identity of the peer. If the
If the identity requires a third-party IdP as described in identity requires a third-party IdP as described in Section 7.1, then
Section 7.1 then that IdP will need to have been specifically that IdP will need to have been specifically configured. If the
configured. If the identity verification fails, the answerer MUST identity verification fails, the answerer MUST discard the offer or
discard the offer or answer as malformed. answer as malformed.
5.1.4. Modifying the Session 5.1.4. Modifying the Session
When modifying a session, if the set of fingerprints is unchanged, When modifying a session, if the set of fingerprints is unchanged,
then the sender MAY send the same 'identity' attribute. In this then the sender MAY send the same "identity" attribute. In this
case, the established identity MUST be applied to existing DTLS case, the established identity MUST be applied to existing DTLS
connections as well as new connections established using one of those connections as well as new connections established using one of those
fingerprints. Note that [I-D.ietf-rtcweb-jsep], Section 5.2.1 fingerprints. Note that [RFC8829], Section 5.2.1 requires that each
requires that each media section use the same set of fingerprints for media section use the same set of fingerprints. If a new "identity"
every media section. If a new identity attribute is received, then attribute is received, then the receiver MUST apply that identity to
the receiver MUST apply that identity to all existing connections. all existing connections.
If the set of fingerprints changes, then the sender MUST either send If the set of fingerprints changes, then the sender MUST either send
a new 'identity' attribute or none at all. Because a change in a new "identity" attribute or none at all. Because a change in
fingerprints also causes a new DTLS connection to be established, the fingerprints also causes a new DTLS connection to be established, the
receiver MUST discard all previously established identities. receiver MUST discard all previously established identities.
6. Detailed Technical Description 6. Detailed Technical Description
6.1. Origin and Web Security Issues 6.1. Origin and Web Security Issues
The basic unit of permissions for WebRTC is the origin [RFC6454]. The basic unit of permissions for WebRTC is the origin [RFC6454].
Because the security of the origin depends on being able to Because the security of the origin depends on being able to
authenticate content from that origin, the origin can only be authenticate content from that origin, the origin can only be
securely established if data is transferred over HTTPS [RFC2818]. securely established if data is transferred over HTTPS [RFC2818].
Thus, clients MUST treat HTTP and HTTPS origins as different Thus, clients MUST treat HTTP and HTTPS origins as different
permissions domains. Note: this follows directly from the origin permissions domains. Note: This follows directly from the origin
security model and is stated here merely for clarity. security model and is stated here merely for clarity.
Many web browsers currently forbid by default any active mixed Many Web browsers currently forbid by default any active mixed
content on HTTPS pages. That is, when JavaScript is loaded from an content on HTTPS pages. That is, when JavaScript is loaded from an
HTTP origin onto an HTTPS page, an error is displayed and the HTTP HTTP origin onto an HTTPS page, an error is displayed and the HTTP
content is not executed unless the user overrides the error. Any content is not executed unless the user overrides the error. Any
browser which enforces such a policy will also not permit access to browser which enforces such a policy will also not permit access to
WebRTC functionality from mixed content pages (because they never WebRTC functionality from mixed content pages (because they never
display mixed content). Browsers which allow active mixed content display mixed content). Browsers which allow active mixed content
MUST nevertheless disable WebRTC functionality in mixed content MUST nevertheless disable WebRTC functionality in mixed content
settings. settings.
Note that it is possible for a page which was not mixed content to Note that it is possible for a page which was not mixed content to
become mixed content during the duration of the call. The major risk become mixed content during the duration of the call. The major risk
here is that the newly arrived insecure JS might redirect media to a here is that the newly arrived insecure JS might redirect media to a
location controlled by the attacker. Implementations MUST either location controlled by the attacker. Implementations MUST either
choose to terminate the call or display a warning at that point. choose to terminate the call or display a warning at that point.
Also note that the security architecture depends on the keying Also note that the security architecture depends on the keying
material not being available to move between origins. But, it is material not being available to move between origins. However, it is
assumed that the identity assertion can be passed to anyone that the assumed that the identity assertion can be passed to anyone that the
page cares to. page cares to.
6.2. Device Permissions Model 6.2. Device Permissions Model
Implementations MUST obtain explicit user consent prior to providing Implementations MUST obtain explicit user consent prior to providing
access to the camera and/or microphone. Implementations MUST at access to the camera and/or microphone. Implementations MUST at
minimum support the following two permissions models for HTTPS minimum support the following two permissions models for HTTPS
origins. origins.
o Requests for one-time camera/microphone access. * Requests for one-time camera/microphone access.
o Requests for permanent access. * Requests for permanent access.
Because HTTP origins cannot be securely established against network Because HTTP origins cannot be securely established against network
attackers, implementations MUST refuse all permissions grants for attackers, implementations MUST refuse all permissions grants for
HTTP origins. HTTP origins.
In addition, they SHOULD support requests for access that promise In addition, they SHOULD support requests for access that promise
that media from this grant will be sent to a single communicating that media from this grant will be sent to a single communicating
peer (obviously there could be other requests for other peers), peer (obviously there could be other requests for other peers), e.g.,
eE.g., "Call customerservice@example.org". The semantics of this "Call customerservice@example.org". The semantics of this request
request are that the media stream from the camera and microphone will are that the media stream from the camera and microphone will only be
only be routed through a connection which has been cryptographically routed through a connection which has been cryptographically verified
verified (through the IdP mechanism or an X.509 certificate in the (through the IdP mechanism or an X.509 certificate in the DTLS-SRTP
DTLS-SRTP handshake) as being associated with the stated identity. handshake) as being associated with the stated identity. Note that
Note that it is unlikely that browsers would have X.509 certificates, it is unlikely that browsers would have X.509 certificates, but
but servers might. Browsers servicing such requests SHOULD clearly servers might. Browsers servicing such requests SHOULD clearly
indicate that identity to the user when asking for permission. The indicate that identity to the user when asking for permission. The
idea behind this type of permissions is that a user might have a idea behind this type of permissions is that a user might have a
fairly narrow list of peers he is willing to communicate with, e.g., fairly narrow list of peers they are willing to communicate with,
"my mother" rather than "anyone on Facebook". Narrow permissions e.g., "my mother" rather than "anyone on Facebook". Narrow
grants allow the browser to do that enforcement. permissions grants allow the browser to do that enforcement.
API Requirement: The API MUST provide a mechanism for the requesting API Requirement: The API MUST provide a mechanism for the requesting
JS to relinquish the ability to see or modify the media (e.g., via JS to relinquish the ability to see or modify the media (e.g., via
MediaStream.record()). Combined with secure authentication of the MediaStream.record()). Combined with secure authentication of the
communicating peer, this allows a user to be sure that the calling communicating peer, this allows a user to be sure that the calling
site is not accessing or modifying their conversion. site is not accessing or modifying their conversion.
UI Requirement: The UI MUST clearly indicate when the user's camera UI Requirement: The UI MUST clearly indicate when the user's camera
and microphone are in use. This indication MUST NOT be and microphone are in use. This indication MUST NOT be
suppressable by the JS and MUST clearly indicate how to terminate suppressible by the JS and MUST clearly indicate how to terminate
device access, and provide a UI means to immediately stop camera/ device access, and provide a UI means to immediately stop camera/
microphone input without the JS being able to prevent it. microphone input without the JS being able to prevent it.
UI Requirement: If the UI indication of camera/microphone use are UI Requirement: If the UI indication of camera/microphone use is
displayed in the browser such that minimizing the browser window displayed in the browser such that minimizing the browser window
would hide the indication, or the JS creating an overlapping would hide the indication, or the JS creating an overlapping
window would hide the indication, then the browser SHOULD stop window would hide the indication, then the browser SHOULD stop
camera and microphone input when the indication is hidden. [Note: camera and microphone input when the indication is hidden. (Note:
this may not be necessary in systems that are non-windows-based This may not be necessary in systems that are non-windows-based
but that have good notifications support, such as phones.] but that have good notifications support, such as phones.)
o Browsers MUST NOT permit permanent screen or application sharing * Browsers MUST NOT permit permanent screen or application sharing
permissions to be installed as a response to a JS request for permissions to be installed as a response to a JS request for
permissions. Instead, they must require some other user action permissions. Instead, they must require some other user action
such as a permissions setting or an application install experience such as a permissions setting or an application install experience
to grant permission to a site. to grant permission to a site.
o Browsers MUST provide a separate dialog request for screen/ * Browsers MUST provide a separate dialog request for screen/
application sharing permissions even if the media request is made application sharing permissions even if the media request is made
at the same time as camera and microphone. at the same time as the request for camera and microphone
permissions.
o The browser MUST indicate any windows which are currently being * The browser MUST indicate any windows which are currently being
shared in some unambiguous way. Windows which are not visible shared in some unambiguous way. Windows which are not visible
MUST NOT be shared even if the application is being shared. If MUST NOT be shared even if the application is being shared. If
the screen is being shared, then that MUST be indicated. the screen is being shared, then that MUST be indicated.
Browsers MAY permit the formation of data channels without any direct Browsers MAY permit the formation of data channels without any direct
user approval. Because sites can always tunnel data through the user approval. Because sites can always tunnel data through the
server, further restrictions on the data channel do not provide any server, further restrictions on the data channel do not provide any
additional security. (See Section 6.3 for a related issue). additional security. (See Section 6.3 for a related issue.)
Implementations which support some form of direct user authentication Implementations which support some form of direct user authentication
SHOULD also provide a policy by which a user can authorize calls only SHOULD also provide a policy by which a user can authorize calls only
to specific communicating peers. Specifically, the implementation to specific communicating peers. Specifically, the implementation
SHOULD provide the following interfaces/controls: SHOULD provide the following interfaces/controls:
o Allow future calls to this verified user. * Allow future calls to this verified user.
o Allow future calls to any verified user who is in my system * Allow future calls to any verified user who is in my system
address book (this only works with address book integration, of address book (this only works with address book integration, of
course). course).
Implementations SHOULD also provide a different user interface Implementations SHOULD also provide a different user interface
indication when calls are in progress to users whose identities are indication when calls are in progress to users whose identities are
directly verifiable. Section 6.5 provides more on this. directly verifiable. Section 6.5 provides more on this.
6.3. Communications Consent 6.3. Communications Consent
Browser client implementations of WebRTC MUST implement ICE. Server Browser client implementations of WebRTC MUST implement ICE. Server
skipping to change at page 17, line 29 skipping to change at line 761
MUST implement either full ICE or ICE-Lite [RFC8445]. MUST implement either full ICE or ICE-Lite [RFC8445].
Browser implementations MUST verify reachability via ICE prior to Browser implementations MUST verify reachability via ICE prior to
sending any non-ICE packets to a given destination. Implementations sending any non-ICE packets to a given destination. Implementations
MUST NOT provide the ICE transaction ID to JavaScript during the MUST NOT provide the ICE transaction ID to JavaScript during the
lifetime of the transaction (i.e., during the period when the ICE lifetime of the transaction (i.e., during the period when the ICE
stack would accept a new response for that transaction). The JS MUST stack would accept a new response for that transaction). The JS MUST
NOT be permitted to control the local ufrag and password, though it NOT be permitted to control the local ufrag and password, though it
of course knows it. of course knows it.
While continuing consent is required, the ICE [RFC8445]; Section 10 While continuing consent is required, the ICE [RFC8445], Section 11
keepalives use STUN Binding Indications which are one-way and keepalives use STUN Binding Indications, which are one-way and
therefore not sufficient. The current WG consensus is to use ICE therefore not sufficient. The current WG consensus is to use ICE
Binding Requests for continuing consent freshness. ICE already Binding Requests for continuing consent freshness. ICE already
requires that implementations respond to such requests, so this requires that implementations respond to such requests, so this
approach is maximally compatible. A separate document will profile approach is maximally compatible. A separate document will profile
the ICE timers to be used; see [RFC7675]. the ICE timers to be used; see [RFC7675].
6.4. IP Location Privacy 6.4. IP Location Privacy
A side effect of the default ICE behavior is that the peer learns A side effect of the default ICE behavior is that the peer learns
one's IP address, which leaks large amounts of location information. one's IP address, which leaks large amounts of location information.
This has negative privacy consequences in some circumstances. The This has negative privacy consequences in some circumstances. The
API requirements in this section are intended to mitigate this issue. API requirements in this section are intended to mitigate this issue.
Note that these requirements are not intended to protect the user's Note that these requirements are not intended to protect the user's
IP address from a malicious site. In general, the site will learn at IP address from a malicious site. In general, the site will learn at
least a user's server reflexive address from any HTTP transaction. least a user's server-reflexive address from any HTTP transaction.
Rather, these requirements are intended to allow a site to cooperate Rather, these requirements are intended to allow a site to cooperate
with the user to hide the user's IP address from the other side of with the user to hide the user's IP address from the other side of
the call. Hiding the user's IP address from the server requires some the call. Hiding the user's IP address from the server requires some
sort of explicit privacy preserving mechanism on the client (e.g., sort of explicit privacy-preserving mechanism on the client (e.g.,
Tor Browser [https://www.torproject.org/projects/torbrowser.html.en]) Tor Browser <https://www.torproject.org/projects/torbrowser.html.en>)
and is out of scope for this specification. and is out of scope for this specification.
API Requirement: The API MUST provide a mechanism to allow the JS to API Requirement: The API MUST provide a mechanism to allow the JS to
suppress ICE negotiation (though perhaps to allow candidate suppress ICE negotiation (though perhaps to allow candidate
gathering) until the user has decided to answer the call [note: gathering) until the user has decided to answer the call. (Note:
determining when the call has been answered is a question for the Determining when the call has been answered is a question for the
JS.] This enables a user to prevent a peer from learning their IP JS.) This enables a user to prevent a peer from learning their IP
address if they elect not to answer a call and also from learning address if they elect not to answer a call and also from learning
whether the user is online. whether the user is online.
API Requirement: The API MUST provide a mechanism for the calling API Requirement: The API MUST provide a mechanism for the calling
application JS to indicate that only TURN candidates are to be application JS to indicate that only TURN candidates are to be
used. This prevents the peer from learning one's IP address at used. This prevents the peer from learning one's IP address at
all. This mechanism MUST also permit suppression of the related all. This mechanism MUST also permit suppression of the related
address field, since that leaks local addresses. address field, since that leaks local addresses.
API Requirement: The API MUST provide a mechanism for the calling API Requirement: The API MUST provide a mechanism for the calling
application to reconfigure an existing call to add non-TURN application to reconfigure an existing call to add non-TURN
candidates. Taken together, this and the previous requirement candidates. Taken together, this and the previous requirement
allow ICE negotiation to start immediately on incoming call allow ICE negotiation to start immediately on incoming call
notification, thus reducing post-dial delay, but also to avoid notification, thus reducing post-dial delay, but also to avoid
disclosing the user's IP address until they have decided to disclosing the user's IP address until they have decided to
answer. They also allow users to completely hide their IP address answer. They also allow users to completely hide their IP address
for the duration of the call. Finally, they allow a mechanism for for the duration of the call. Finally, they allow a mechanism for
the user to optimize performance by reconfiguring to allow non- the user to optimize performance by reconfiguring to allow non-
TURN candidates during an active call if the user decides they no TURN candidates during an active call if the user decides they no
longer need to hide their IP address longer need to hide their IP address.
Note that some enterprises may operate proxies and/or NATs designed Note that some enterprises may operate proxies and/or NATs designed
to hide internal IP addresses from the outside world. WebRTC to hide internal IP addresses from the outside world. WebRTC
provides no explicit mechanism to allow this function. Either such provides no explicit mechanism to allow this function. Either such
enterprises need to proxy the HTTP/HTTPS and modify the SDP and/or enterprises need to proxy the HTTP/HTTPS and modify the SDP and/or
the JS, or there needs to be browser support to set the "TURN-only" the JS, or there needs to be browser support to set the "TURN-only"
policy regardless of the site's preferences. policy regardless of the site's preferences.
Note: These requirements are intended to allow sites to conceal the
user's IP address from the peer. For guidance on concealing the
user's IP address from the calling site see [RFC8828].
6.5. Communications Security 6.5. Communications Security
Implementations MUST support SRTP [RFC3711]. Implementations MUST Implementations MUST support SRTP [RFC3711]. Implementations MUST
support DTLS [RFC6347] and DTLS-SRTP [RFC5763][RFC5764] for SRTP support DTLS [RFC6347] and DTLS-SRTP [RFC5763] [RFC5764] for SRTP
keying. Implementations MUST support SCTP over DTLS [RFC8261]. keying. Implementations MUST support SCTP over DTLS [RFC8261].
All media channels MUST be secured via SRTP and SRTCP. Media traffic All media channels MUST be secured via SRTP and the Secure Real-time
MUST NOT be sent over plain (unencrypted) RTP or RTCP; that is, Transport Control Protocol (SRTCP). Media traffic MUST NOT be sent
implementations MUST NOT negotiate cipher suites with NULL encryption over plain (unencrypted) RTP or RTCP; that is, implementations MUST
modes. DTLS-SRTP MUST be offered for every media channel. WebRTC NOT negotiate cipher suites with NULL encryption modes. DTLS-SRTP
implementations MUST NOT offer SDP Security Descriptions [RFC4568] or MUST be offered for every media channel. WebRTC implementations MUST
select it if offered. A SRTP MKI MUST NOT be used. NOT offer SDP security descriptions [RFC4568] or select it if
offered. An SRTP Master Key Identifier (MKI) MUST NOT be used.
All data channels MUST be secured via DTLS. All data channels MUST be secured via DTLS.
All Implementations MUST support DTLS 1.2 with the All implementations MUST support DTLS 1.2 with the
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 cipher suite and the P-256 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 cipher suite and the P-256
curve [FIPS186]. Earlier drafts of this specification required DTLS curve [FIPS186]. Earlier drafts of this specification required DTLS
1.0 with the cipher suite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, and 1.0 with the cipher suite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, and
at the time of this writing some implementations do not support DTLS at the time of this writing some implementations do not support DTLS
1.2; endpoints which support only DTLS 1.2 might encounter 1.2; endpoints which support only DTLS 1.2 might encounter
interoperability issues. The DTLS-SRTP protection profile interoperability issues. The DTLS-SRTP protection profile
SRTP_AES128_CM_HMAC_SHA1_80 MUST be supported for SRTP. SRTP_AES128_CM_HMAC_SHA1_80 MUST be supported for SRTP.
Implementations MUST favor cipher suites which support (Perfect Implementations MUST favor cipher suites which support Forward
Forward Secrecy) PFS over non-PFS cipher suites and SHOULD favor AEAD Secrecy (FS) over non-FS cipher suites and SHOULD favor Authenticated
over non-AEAD cipher suites. Encryption with Associated Data (AEAD) over non-AEAD cipher suites.
Note: the IETF is in the process of standardizing DTLS 1.3
[TLS-DTLS13].
Implementations MUST NOT implement DTLS renegotiation and MUST reject Implementations MUST NOT implement DTLS renegotiation and MUST reject
it with a "no_renegotiation" alert if offered. it with a "no_renegotiation" alert if offered.
Endpoints MUST NOT implement TLS False Start [RFC7918]. Endpoints MUST NOT implement TLS False Start [RFC7918].
API Requirement: The API MUST generate a new authentication key pair API Requirement: The API MUST generate a new authentication key pair
for every new call by default. This is intended to allow for for every new call by default. This is intended to allow for
unlinkability. unlinkability.
skipping to change at page 19, line 39 skipping to change at line 874
costs. costs.
API Requirement: Unless the user specifically configures an external API Requirement: Unless the user specifically configures an external
key pair, different key pairs MUST be used for each origin. (This key pair, different key pairs MUST be used for each origin. (This
avoids creating a super-cookie.) avoids creating a super-cookie.)
API Requirement: When DTLS-SRTP is used, the API MUST NOT permit the API Requirement: When DTLS-SRTP is used, the API MUST NOT permit the
JS to obtain the negotiated keying material. This requirement JS to obtain the negotiated keying material. This requirement
preserves the end-to-end security of the media. preserves the end-to-end security of the media.
UI Requirements: A user-oriented client MUST provide an "inspector" UI Requirements: A user-oriented client MUST provide an "inspector"
interface which allows the user to determine the security interface which allows the user to determine the "security
characteristics of the media. characteristics" of the media.
The following properties SHOULD be displayed "up-front" in the The following properties SHOULD be displayed "up-front" in the
browser chrome, i.e., without requiring the user to ask for them: browser chrome, i.e., without requiring the user to ask for them:
* A client MUST provide a user interface through which a user may * A client MUST provide a user interface through which a user may
determine the security characteristics for currently-displayed determine the "security characteristics" for currently
audio and video stream(s) displayed audio and video stream(s).
* A client MUST provide a user interface through which a user may * A client MUST provide a user interface through which a user may
determine the security characteristics for transmissions of determine the "security characteristics" for transmissions of
their microphone audio and camera video. their microphone audio and camera video.
* If the far endpoint was directly verified, either via a third- * If the far endpoint was directly verified, either via a third-
party verifiable X.509 certificate or via a Web IdP mechanism party verifiable X.509 certificate or via a Web IdP mechanism
(see Section 7) the "security characteristics" MUST include the (see Section 7), the "security characteristics" MUST include
verified information. X.509 identities and Web IdP identities the verified information. X.509 identities and Web IdP
have similar semantics and should be displayed in a similar identities have similar semantics and should be displayed in a
way. similar way.
The following properties are more likely to require some "drill- The following properties are more likely to require some "drill-
down" from the user: down" from the user:
* The "security characteristics" MUST indicate the cryptographic * The "security characteristics" MUST indicate the cryptographic
algorithms in use (For example: "AES-CBC".) algorithms in use (for example, "AES-CBC").
* The "security characteristics" MUST indicate whether PFS is * The "security characteristics" MUST indicate whether FS is
provided. provided.
* The "security characteristics" MUST include some mechanism to * The "security characteristics" MUST include some mechanism to
allow an out-of-band verification of the peer, such as a allow an out-of-band verification of the peer, such as a
certificate fingerprint or a Short Authentication String (SAS). certificate fingerprint or a Short Authentication String (SAS).
These are compared by the peers to authenticate one another. These are compared by the peers to authenticate one another.
7. Web-Based Peer Authentication 7. Web-Based Peer Authentication
NOTE: The mechanism described in this section was designed relatively
early in the RTCWEB process. In retrospect, the WG was too
optimistic about the enthusiasm for this kind of mechanism. At the
time of publication, it has not been widely adopted or implemented.
It appears in this document as a description of the state of the art
as of this writing.
In a number of cases, it is desirable for the endpoint (i.e., the In a number of cases, it is desirable for the endpoint (i.e., the
browser) to be able to directly identify the endpoint on the other browser) to be able to directly identify the endpoint on the other
side without trusting the signaling service to which they are side without trusting the signaling service to which they are
connected. For instance, users may be making a call via a federated connected. For instance, users may be making a call via a federated
system where they wish to get direct authentication of the other system where they wish to get direct authentication of the other
side. Alternately, they may be making a call on a site which they side. Alternately, they may be making a call on a site which they
minimally trust (such as a poker site) but to someone who has an minimally trust (such as a poker site) but to someone who has an
identity on a site they do trust (such as a social network.) identity on a site they do trust (such as a social network).
Recently, a number of Web-based identity technologies (OAuth, Recently, a number of Web-based identity technologies (OAuth,
Facebook Connect etc.) have been developed. While the details vary, Facebook Connect, etc.) have been developed. While the details vary,
what these technologies share is that they have a Web-based (i.e., what these technologies share is that they have a Web-based (i.e.,
HTTP/HTTPS) identity provider which attests to Alice's identity. For HTTP/HTTPS) IdP which attests to Alice's identity. For instance, if
instance, if Alice has an account at example.org, Alice could use the Alice has an account at example.org, Alice could use the example.org
example.org identity provider to prove to others that Alice is IdP to prove to others that Alice is alice@example.org. The
alice@example.org. The development of these technologies allows us development of these technologies allows us to separate calling from
to separate calling from identity provision: Alice could call you on identity provision: Alice could call you on a poker site but identify
a poker site but identify herself as alice@example.org. herself as alice@example.org.
Whatever the underlying technology, the general principle is that the Whatever the underlying technology, the general principle is that the
party which is being authenticated is NOT the signaling site but party which is being authenticated is NOT the signaling site but
rather the user (and their browser). Similarly, the relying party is rather the user (and their browser). Similarly, the Relying Party is
the browser and not the signaling site. Thus, the browser MUST the browser and not the signaling site. Thus, the browser MUST
generate the input to the IdP assertion process and display the generate the input to the IdP assertion process and display the
results of the verification process to the user in a way which cannot results of the verification process to the user in a way which cannot
be imitated by the calling site. be imitated by the calling site.
The mechanisms defined in this document do not require the browser to The mechanisms defined in this document do not require the browser to
implement any particular identity protocol or to support any implement any particular identity protocol or to support any
particular IdP. Instead, this document provides a generic interface particular IdP. Instead, this document provides a generic interface
which any IdP can implement. Thus, new IdPs and protocols can be which any IdP can implement. Thus, new IdPs and protocols can be
introduced without change to either the browser or the calling introduced without change to either the browser or the calling
skipping to change at page 22, line 4 skipping to change at line 979
The AP and the IdP have an account relationship of some kind: the AP The AP and the IdP have an account relationship of some kind: the AP
registers with the IdP and is able to subsequently authenticate registers with the IdP and is able to subsequently authenticate
directly to the IdP (e.g., with a password). This means that the directly to the IdP (e.g., with a password). This means that the
browser must somehow know which IdP(s) the user has an account browser must somehow know which IdP(s) the user has an account
relationship with. This can either be something that the user relationship with. This can either be something that the user
configures into the browser or that is configured at the calling site configures into the browser or that is configured at the calling site
and then provided to the PeerConnection by the Web application at the and then provided to the PeerConnection by the Web application at the
calling site. The use case for having this information configured calling site. The use case for having this information configured
into the browser is that the user may "log into" the browser to bind into the browser is that the user may "log into" the browser to bind
it to some identity. This is becoming common in new browsers. it to some identity. This is becoming common in new browsers.
However, it should also be possible for the IdP information to simply However, it should also be possible for the IdP information to simply
be provided by the calling application. be provided by the calling application.
At a high level there are two kinds of IdPs: At a high level, there are two kinds of IdPs:
Authoritative: IdPs which have verifiable control of some section Authoritative: IdPs which have verifiable control of some section of
of the identity space. For instance, in the realm of e-mail, the the identity space. For instance, in the realm of email, the
operator of "example.com" has complete control of the namespace operator of "example.com" has complete control of the namespace
ending in "@example.com". Thus, "alice@example.com" is whoever ending in "@example.com". Thus, "alice@example.com" is whoever
the operator says it is. Examples of systems with authoritative the operator says it is. Examples of systems with authoritative
identity providers include DNSSEC, RFC 4474, and Facebook Connect IdPs include DNSSEC, an identity system for SIP (see [RFC8224]),
(Facebook identities only make sense within the context of the and Facebook Connect (Facebook identities only make sense within
Facebook system). the context of the Facebook system).
Third-Party: IdPs which don't have control of their section of the Third-Party: IdPs which don't have control of their section of the
identity space but instead verify user's identities via some identity space but instead verify users' identities via some
unspecified mechanism and then attest to it. Because the IdP unspecified mechanism and then attest to it. Because the IdP
doesn't actually control the namespace, RPs need to trust that the doesn't actually control the namespace, RPs need to trust that the
IdP is correctly verifying AP identities, and there can IdP is correctly verifying AP identities, and there can
potentially be multiple IdPs attesting to the same section of the potentially be multiple IdPs attesting to the same section of the
identity space. Probably the best-known example of a third-party identity space. Probably the best-known example of a third-party
identity provider is SSL/TLS certificates, where there are a large IdP is SSL/TLS certificates, where there are a large number of
number of CAs all of whom can attest to any domain name. certificate authorities (CAs) all of whom can attest to any domain
name.
If an AP is authenticating via an authoritative IdP, then the RP does If an AP is authenticating via an authoritative IdP, then the RP does
not need to explicitly configure trust in the IdP at all. The not need to explicitly configure trust in the IdP at all. The
identity mechanism can directly verify that the IdP indeed made the identity mechanism can directly verify that the IdP indeed made the
relevant identity assertion (a function provided by the mechanisms in relevant identity assertion (a function provided by the mechanisms in
this document), and any assertion it makes about an identity for this document), and any assertion it makes about an identity for
which it is authoritative is directly verifiable. Note that this which it is authoritative is directly verifiable. Note that this
does not mean that the IdP might not lie, but that is a does not mean that the IdP might not lie, but that is a
trustworthiness judgement that the user can make at the time he looks trustworthiness judgement that the user can make at the time they
at the identity. look at the identity.
By contrast, if an AP is authenticating via a third-party IdP, the RP By contrast, if an AP is authenticating via a third-party IdP, the RP
needs to explicitly trust that IdP (hence the need for an explicit needs to explicitly trust that IdP (hence the need for an explicit
trust anchor list in PKI-based SSL/TLS clients). The list of trust anchor list in PKI-based SSL/TLS clients). The list of
trustable IdPs needs to be configured directly into the browser, trustable IdPs needs to be configured directly into the browser,
either by the user or potentially by the browser manufacturer. This either by the user or potentially by the browser manufacturer. This
is a significant advantage of authoritative IdPs and implies that if is a significant advantage of authoritative IdPs and implies that if
third-party IdPs are to be supported, the potential number needs to third-party IdPs are to be supported, the potential number needs to
be fairly small. be fairly small.
7.2. Overview of Operation 7.2. Overview of Operation
In order to provide security without trusting the calling site, the In order to provide security without trusting the calling site, the
PeerConnection component of the browser must interact directly with PeerConnection component of the browser must interact directly with
the IdP. The details of the mechanism are described in the W3C API the IdP. The details of the mechanism are described in the W3C API
specification, but the general idea is that the PeerConnection specification, but the general idea is that the PeerConnection
component downloads JS from a specific location on the IdP dictated component downloads JS from a specific location on the IdP dictated
by the IdP domain name. That JS (the "IdP proxy") runs in an by the IdP domain name. That JS (the "IdP proxy") runs in an
isolated security context within the browser and the PeerConnection isolated security context within the browser, and the PeerConnection
talks to it via a secure message passing channel. talks to it via a secure message passing channel.
Note that there are two logically separate functions here: Note that there are two logically separate functions here:
o Identity assertion generation. * Identity assertion generation.
o Identity assertion verification. * Identity assertion verification.
The same IdP JS "endpoint" is used for both functions but of course a The same IdP JS "endpoint" is used for both functions, but of course
given IdP might behave differently and load new JS to perform one a given IdP might behave differently and load new JS to perform one
function or the other. function or the other.
+--------------------------------------+ +--------------------------------------+
| Browser | | Browser |
| | | |
| +----------------------------------+ | | +----------------------------------+ |
| | https://calling-site.example.com | | | | https://calling-site.example.com | |
| | | | | | | |
| | Calling JS Code | | | | Calling JS Code | |
| | ^ | | | | ^ | |
skipping to change at page 24, line 17 skipping to change at line 1082
the proxy. The resulting code runs in the IdP's security the proxy. The resulting code runs in the IdP's security
context. context.
2. The IdP registers an object with the browser that conforms to the 2. The IdP registers an object with the browser that conforms to the
API defined in [webrtc-api]. API defined in [webrtc-api].
3. The browser invokes methods on the object registered by the IdP 3. The browser invokes methods on the object registered by the IdP
proxy to create or verify identity assertions. proxy to create or verify identity assertions.
This approach allows us to decouple the browser from any particular This approach allows us to decouple the browser from any particular
identity provider; the browser need only know how to load the IdP's IdP; the browser need only know how to load the IdP's JavaScript --
JavaScript--the location of which is determined based on the IdP's the location of which is determined based on the IdP's identity --
identity--and to call the generic API for requesting and verifying and to call the generic API for requesting and verifying identity
identity assertions. The IdP provides whatever logic is necessary to assertions. The IdP provides whatever logic is necessary to bridge
bridge the generic protocol to the IdP's specific requirements. the generic protocol to the IdP's specific requirements. Thus, a
Thus, a single browser can support any number of identity protocols, single browser can support any number of identity protocols,
including being forward compatible with IdPs which did not exist at including being forward compatible with IdPs which did not exist at
the time the browser was written. the time the browser was written.
7.3. Items for Standardization 7.3. Items for Standardization
There are two parts to this work: There are two parts to this work:
o The precise information from the signaling message that must be * The precise information from the signaling message that must be
cryptographically bound to the user's identity and a mechanism for cryptographically bound to the user's identity and a mechanism for
carrying assertions in JSEP messages. This is specified in carrying assertions in JavaScript Session Establishment Protocol
Section 7.4. (JSEP) messages. This is specified in Section 7.4.
o The interface to the IdP, which is defined in the companion W3C * The interface to the IdP, which is defined in the companion W3C
WebRTC API specification [webrtc-api]. WebRTC API specification [webrtc-api].
The WebRTC API specification also defines JavaScript interfaces that The WebRTC API specification also defines JavaScript interfaces that
the calling application can use to specify which IdP to use. That the calling application can use to specify which IdP to use. That
API also provides access to the assertion-generation capability and API also provides access to the assertion-generation capability and
the status of the validation process. the status of the validation process.
7.4. Binding Identity Assertions to JSEP Offer/Answer Transactions 7.4. Binding Identity Assertions to JSEP Offer/Answer Transactions
An identity assertion binds the user's identity (as asserted by the An identity assertion binds the user's identity (as asserted by the
IdP) to the SDP offer/answer exchange and specifically to the media. IdP) to the SDP offer/answer exchange and specifically to the media.
In order to achieve this, the PeerConnection must provide the DTLS- In order to achieve this, the PeerConnection must provide the DTLS-
SRTP fingerprint to be bound to the identity. This is provided as a SRTP fingerprint to be bound to the identity. This is provided as a
JavaScript object (also known as a dictionary or hash) with a single JavaScript object (also known as a dictionary or hash) with a single
"fingerprint" key, as shown below: "fingerprint" key, as shown below:
{ {
"fingerprint": "fingerprint":
[ [
{ "algorithm": "sha-256", { "algorithm": "sha-256",
"digest": "4A:AD:B9:B1:3F:...:E5:7C:AB" }, "digest": "4A:AD:B9:B1:3F:...:E5:7C:AB" },
{ "algorithm": "sha-1", { "algorithm": "sha-1",
"digest": "74:E9:76:C8:19:...:F4:45:6B" } "digest": "74:E9:76:C8:19:...:F4:45:6B" }
] ]
} }
The "fingerprint" value is an array of objects. Each object in the The "fingerprint" value is an array of objects. Each object in the
array contains "algorithm" and "digest" values, which correspond array contains "algorithm" and "digest" values, which correspond
directly to the algorithm and digest values in the "fingerprint" directly to the algorithm and digest values in the "fingerprint"
attribute of the SDP [RFC8122]. attribute of the SDP [RFC8122].
This object is encoded in a JSON [RFC8259] string for passing to the This object is encoded in a JSON [RFC8259] string for passing to the
IdP. The identity assertion returned by the IdP, which is encoded in IdP. The identity assertion returned by the IdP, which is encoded in
the "identity" attribute, is a JSON object that is encoded as the "identity" attribute, is a JSON object that is encoded as
described in Section 7.4.1. described in Section 7.4.1.
This structure does not need to be interpreted by the IdP or the IdP This structure does not need to be interpreted by the IdP or the IdP
proxy. It is consumed solely by the RP's browser. The IdP merely proxy. It is consumed solely by the RP's browser. The IdP merely
treats it as an opaque value to be attested to. Thus, new parameters treats it as an opaque value to be attested to. Thus, new parameters
can be added to the assertion without modifying the IdP. can be added to the assertion without modifying the IdP.
7.4.1. Carrying Identity Assertions 7.4.1. Carrying Identity Assertions
Once an IdP has generated an assertion (see Section 7.6), it is Once an IdP has generated an assertion (see Section 7.6), it is
attached to the SDP offer/answer message. This is done by adding a attached to the SDP offer/answer message. This is done by adding a
new 'identity' attribute to the SDP. The sole contents of this value new "identity" attribute to the SDP. The sole contents of this value
is the identity assertion. The identity assertion produced by the is the identity assertion. The identity assertion produced by the
IdP is encoded into a UTF-8 JSON text, then Base64-encoded [RFC4648] IdP is encoded into a UTF-8 JSON text, then base64-encoded [RFC4648]
to produce this string. For example: to produce this string. For example:
v=0 v=0
o=- 1181923068 1181923196 IN IP4 ua1.example.com o=- 1181923068 1181923196 IN IP4 ua1.example.com
s=example1 s=example1
c=IN IP4 ua1.example.com c=IN IP4 ua1.example.com
a=fingerprint:sha-1 \ a=fingerprint:sha-1 \
4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB
a=identity:\ a=identity:\
eyJpZHAiOnsiZG9tYWluIjoiZXhhbXBsZS5vcmciLCJwcm90b2NvbCI6ImJvZ3Vz\ eyJpZHAiOnsiZG9tYWluIjoiZXhhbXBsZS5vcmciLCJwcm90b2NvbCI6ImJvZ3Vz\
In0sImFzc2VydGlvbiI6IntcImlkZW50aXR5XCI6XCJib2JAZXhhbXBsZS5vcmdc\ In0sImFzc2VydGlvbiI6IntcImlkZW50aXR5XCI6XCJib2JAZXhhbXBsZS5vcmdc\
IixcImNvbnRlbnRzXCI6XCJhYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3l6XCIsXCJz\ IixcImNvbnRlbnRzXCI6XCJhYmNkZWZnaGlqa2xtbm9wcXJzdHV2d3l6XCIsXCJz\
aWduYXR1cmVcIjpcIjAxMDIwMzA0MDUwNlwifSJ9 aWduYXR1cmVcIjpcIjAxMDIwMzA0MDUwNlwifSJ9
a=... a=...
t=0 0 t=0 0
m=audio 6056 RTP/SAVP 0 m=audio 6056 RTP/SAVP 0
a=sendrecv a=sendrecv
... ...
Note that long lines in the example are folded to meet the column | Note that long lines in the example are folded to meet the
width constraints of this document; the backslash ("\") at the end of | column width constraints of this document; the backslash ("\")
a line, the carriage return that follows, and whitespace shall be ignored. | at the end of a line, the carriage return that follows, and
| whitespace shall be ignored.
The 'identity' attribute attests to all "fingerprint" attributes in The "identity" attribute attests to all "fingerprint" attributes in
the session description. It is therefore a session-level attribute. the session description. It is therefore a session-level attribute.
Multiple "fingerprint" values can be used to offer alternative Multiple "fingerprint" values can be used to offer alternative
certificates for a peer. The "identity" attribute MUST include all certificates for a peer. The "identity" attribute MUST include all
fingerprint values that are included in "fingerprint" attributes of "fingerprint" values that are included in "fingerprint" attributes of
the session description. the session description.
The RP browser MUST verify that the in-use certificate for a DTLS The RP browser MUST verify that the in-use certificate for a DTLS
connection is in the set of fingerprints returned from the IdP when connection is in the set of fingerprints returned from the IdP when
verifying an assertion. verifying an assertion.
7.5. Determining the IdP URI 7.5. Determining the IdP URI
In order to ensure that the IdP is under control of the domain owner In order to ensure that the IdP is under control of the domain owner
rather than someone who merely has an account on the domain owner's rather than someone who merely has an account on the domain owner's
server (e.g., in shared hosting scenarios), the IdP JavaScript is server (e.g., in shared hosting scenarios), the IdP JavaScript is
hosted at a deterministic location based on the IdP's domain name. hosted at a deterministic location based on the IdP's domain name.
Each IdP proxy instance is associated with two values: Each IdP proxy instance is associated with two values:
Authority: The authority [RFC3986] at which the IdP's service is authority: The authority [RFC3986] at which the IdP's service is
hosted. hosted.
protocol: The specific IdP protocol which the IdP is using. This is protocol: The specific IdP protocol which the IdP is using. This is
a completely opaque IdP-specific string, but allows an IdP to a completely opaque IdP-specific string, but allows an IdP to
implement two protocols in parallel. This value may be the empty implement two protocols in parallel. This value may be the empty
string. If no value for protocol is provided, a value of string. If no value for protocol is provided, a value of
"default" is used. "default" is used.
Each IdP MUST serve its initial entry page (i.e., the one loaded by Each IdP MUST serve its initial entry page (i.e., the one loaded by
the IdP proxy) from a well-known URI [RFC5785]. The well-known URI the IdP proxy) from a well-known URI [RFC8615]. The well-known URI
for an IdP proxy is formed from the following URI components: for an IdP proxy is formed from the following URI components:
1. The scheme, "https:". An IdP MUST be loaded using HTTPS 1. The scheme, "https:". An IdP MUST be loaded using HTTPS
[RFC2818]. [RFC2818].
2. The authority [RFC3986]. As noted above, the authority MAY 2. The authority [RFC3986]. As noted above, the authority MAY
contain a non-default port number or userinfo sub-component. contain a non-default port number or userinfo sub-component.
Both are removed when determining if an asserted identity matches Both are removed when determining if an asserted identity matches
the name of the IdP. the name of the IdP.
3. The path, starting with "/.well-known/idp-proxy/" and appended 3. The path, starting with "/.well-known/idp-proxy/" and appended
with the IdP protocol. Note that the separator characters '/' with the IdP protocol. Note that the separator characters '/'
(%2F) and '\' (%5C) MUST NOT be permitted in the protocol field, (%2F) and '\' (%5C) MUST NOT be permitted in the protocol field,
lest an attacker be able to direct requests outside of the lest an attacker be able to direct requests outside of the
controlled "/.well-known/" prefix. Query and fragment values MAY controlled "/.well-known/" prefix. Query and fragment values MAY
be used by including '?' or '#' characters. be used by including '?' or '#' characters.
For example, for the IdP "identity.example.com" and the protocol For example, for the IdP "identity.example.com" and the protocol
"example", the URL would be: "example", the URL would be:
https://identity.example.com/.well-known/idp-proxy/example https://identity.example.com/.well-known/idp-proxy/example
The IdP MAY redirect requests to this URL, but they MUST retain the The IdP MAY redirect requests to this URL, but they MUST retain the
"https" scheme. This changes the effective origin of the IdP, but "https:" scheme. This changes the effective origin of the IdP, but
not the domain of the identities that the IdP is permitted to assert not the domain of the identities that the IdP is permitted to assert
and validate. I.e., the IdP is still regarded as authoritative for and validate. I.e., the IdP is still regarded as authoritative for
the original domain. the original domain.
7.5.1. Authenticating Party 7.5.1. Authenticating Party
How an AP determines the appropriate IdP domain is out of scope of How an AP determines the appropriate IdP domain is out of scope of
this specification. In general, however, the AP has some actual this specification. In general, however, the AP has some actual
account relationship with the IdP, as this identity is what the IdP account relationship with the IdP, as this identity is what the IdP
is attesting to. Thus, the AP somehow supplies the IdP information is attesting to. Thus, the AP somehow supplies the IdP information
to the browser. Some potential mechanisms include: to the browser. Some potential mechanisms include:
o Provided by the user directly. * Provided by the user directly.
o Selected from some set of IdPs known to the calling site. E.g., a * Selected from some set of IdPs known to the calling site (e.g., a
button that shows "Authenticate via Facebook Connect" button that shows "Authenticate via Facebook Connect").
7.5.2. Relying Party 7.5.2. Relying Party
Unlike the AP, the RP need not have any particular relationship with Unlike the AP, the RP need not have any particular relationship with
the IdP. Rather, it needs to be able to process whatever assertion the IdP. Rather, it needs to be able to process whatever assertion
is provided by the AP. As the assertion contains the IdP's identity is provided by the AP. As the assertion contains the IdP's identity
in the "idp" field of the JSON-encoded object (see Section 7.6), the in the "idp" field of the JSON-encoded object (see Section 7.6), the
URI can be constructed directly from the assertion, and thus the RP URI can be constructed directly from the assertion, and thus the RP
can directly verify the technical validity of the assertion with no can directly verify the technical validity of the assertion with no
user interaction. Authoritative assertions need only be verifiable. user interaction. Authoritative assertions need only be verifiable.
Third-party assertions also MUST be verified against local policy, as Third-party assertions also MUST be verified against local policy, as
described in Section 8.1. described in Section 8.1.
7.6. Requesting Assertions 7.6. Requesting Assertions
The input to identity assertion is the JSON-encoded object described The input to the identity assertion generation process is the JSON-
in Section 7.4 that contains the set of certificate fingerprints the encoded object described in Section 7.4 that contains the set of
browser intends to use. This string is treated as opaque from the certificate fingerprints the browser intends to use. This string is
perspective of the IdP. treated as opaque from the perspective of the IdP.
The browser also identifies the origin that the PeerConnection is run The browser also identifies the origin that the PeerConnection is run
in, which allows the IdP to make decisions based on who is requesting in, which allows the IdP to make decisions based on who is requesting
the assertion. the assertion.
An application can optionally provide a user identifier hint when An application can optionally provide a user identifier hint when
specifying an IdP. This value is a hint that the IdP can use to specifying an IdP. This value is a hint that the IdP can use to
select amongst multiple identities, or to avoid providing assertions select amongst multiple identities, or to avoid providing assertions
for unwanted identities. The "username" is a string that has no for unwanted identities. The "username" is a string that has no
meaning to any entity other than the IdP, it can contain any data the meaning to any entity other than the IdP; it can contain any data the
IdP needs in order to correctly generate an assertion. IdP needs in order to correctly generate an assertion.
An identity assertion that is successfully provided by the IdP An identity assertion that is successfully provided by the IdP
consists of the following information: consists of the following information:
idp: The domain name of an IdP and the protocol string. This MAY idp: The domain name of an IdP and the protocol string. This MAY
identify a different IdP or protocol from the one that generated identify a different IdP or protocol from the one that generated
the assertion. the assertion.
assertion: An opaque value containing the assertion itself. This is assertion: An opaque value containing the assertion itself. This is
skipping to change at page 29, line 15 skipping to change at line 1301
{ {
"idp":{ "idp":{
"domain": "example.org", "domain": "example.org",
"protocol": "bogus" "protocol": "bogus"
}, },
"assertion": "{\"identity\":\"bob@example.org\", "assertion": "{\"identity\":\"bob@example.org\",
\"contents\":\"abcdefghijklmnopqrstuvwyz\", \"contents\":\"abcdefghijklmnopqrstuvwyz\",
\"signature\":\"010203040506\"}" \"signature\":\"010203040506\"}"
} }
Figure 5: Example assertion Figure 5: Example Assertion
For use in signaling, the assertion is serialized into JSON, For use in signaling, the assertion is serialized into JSON,
Base64-encoded [RFC4648], and used as the value of the "identity" base64-encoded [RFC4648], and used as the value of the "identity"
attribute. IdPs SHOULD ensure that any assertions they generate attribute. IdPs SHOULD ensure that any assertions they generate
cannot be interpreted in a different context. E.g., they should use cannot be interpreted in a different context. E.g., they should use
a distinct format or have separate cryptographic keys for assertion a distinct format or have separate cryptographic keys for assertion
generation and other purposes. Line breaks are inserted solely for generation and other purposes. Line breaks are inserted solely for
readability. readability.
7.7. Managing User Login 7.7. Managing User Login
In order to generate an identity assertion, the IdP needs proof of In order to generate an identity assertion, the IdP needs proof of
the user's identity. It is common practice to authenticate users the user's identity. It is common practice to authenticate users
(using passwords or multi-factor authentication), then use Cookies (using passwords or multi-factor authentication), then use cookies
[RFC6265] or HTTP authentication [RFC7617] for subsequent exchanges. [RFC6265] or HTTP authentication [RFC7617] for subsequent exchanges.
The IdP proxy is able to access cookies, HTTP authentication or other The IdP proxy is able to access cookies, HTTP authentication data, or
persistent session data because it operates in the security context other persistent session data because it operates in the security
of the IdP origin. Therefore, if a user is logged in, the IdP could context of the IdP origin. Therefore, if a user is logged in, the
have all the information needed to generate an assertion. IdP could have all the information needed to generate an assertion.
An IdP proxy is unable to generate an assertion if the user is not An IdP proxy is unable to generate an assertion if the user is not
logged in, or the IdP wants to interact with the user to acquire more logged in, or the IdP wants to interact with the user to acquire more
information before generating the assertion. If the IdP wants to information before generating the assertion. If the IdP wants to
interact with the user before generating an assertion, the IdP proxy interact with the user before generating an assertion, the IdP proxy
can fail to generate an assertion and instead indicate a URL where can fail to generate an assertion and instead indicate a URL where
login should proceed. login should proceed.
The application can then load the provided URL to enable the user to The application can then load the provided URL to enable the user to
enter credentials. The communication between the application and the enter credentials. The communication between the application and the
IdP is described in [webrtc-api]. IdP is described in [webrtc-api].
8. Verifying Assertions 8. Verifying Assertions
The input to identity validation is the assertion string taken from a The input to identity validation is the assertion string taken from a
decoded 'identity' attribute. decoded "identity" attribute.
The IdP proxy verifies the assertion. Depending on the identity The IdP proxy verifies the assertion. Depending on the identity
protocol, the proxy might contact the IdP server or other servers. protocol, the proxy might contact the IdP server or other servers.
For instance, an OAuth-based protocol will likely require using the For instance, an OAuth-based protocol will likely require using the
IdP as an oracle, whereas with a signature-based scheme might be able IdP as an oracle, whereas with a signature-based scheme it might be
to verify the assertion without contacting the IdP, provided that it able to verify the assertion without contacting the IdP, provided
has cached the relevant public key. that it has cached the relevant public key.
Regardless of the mechanism, if verification succeeds, a successful Regardless of the mechanism, if verification succeeds, a successful
response from the IdP proxy consists of the following information: response from the IdP proxy consists of the following information:
identity: The identity of the AP from the IdP's perspective. identity: The identity of the AP from the IdP's perspective.
Details of this are provided in Section 8.1. Details of this are provided in Section 8.1.
contents: The original unmodified string provided by the AP as input contents: The original unmodified string provided by the AP as input
to the assertion generation process. to the assertion generation process.
Figure 6 shows an example response, which is JSON-formatted. Figure 6 shows an example response, which is JSON-formatted.
{ {
"identity": "bob@example.org", "identity": "bob@example.org",
"contents": "{\"fingerprint\":[ ... ]}" "contents": "{\"fingerprint\":[ ... ]}"
} }
Figure 6: Example verification result Figure 6: Example Verification Result
8.1. Identity Formats 8.1. Identity Formats
The identity provided from the IdP to the RP browser MUST consist of The identity provided from the IdP to the RP browser MUST consist of
a string representing the user's identity. This string is in the a string representing the user's identity. This string is in the
form "<user>@<domain>", where "user" consists of any character, and form "<user>@<domain>", where "user" consists of any character, and
domain is aninternationalized domain name [RFC5890] encoded as a domain is an internationalized domain name [RFC5890] encoded as a
sequence of U-labels. sequence of U-labels.
The PeerConnection API MUST check this string as follows: The PeerConnection API MUST check this string as follows:
1. If the "domain" portion of the string is equal to the domain name 1. If the "domain" portion of the string is equal to the domain name
of the IdP proxy, then the assertion is valid, as the IdP is of the IdP proxy, then the assertion is valid, as the IdP is
authoritative for this domain. Comparison of domain names is authoritative for this domain. Comparison of domain names is
done using the label equivalence rule defined in Section 2.3.2.4 done using the label equivalence rule defined in Section 2.3.2.4
of [RFC5890]. of [RFC5890].
2. If the "domain" portion of the string is not equal to the domain 2. If the "domain" portion of the string is not equal to the domain
name of the IdP proxy, then the PeerConnection object MUST reject name of the IdP proxy, then the PeerConnection object MUST reject
the assertion unless both: the assertion unless both:
1. the IdP domain is trusted as an acceptable third-party IdP; 1. the IdP domain is trusted as an acceptable third-party IdP;
and and
2. local policy is configured to trust this IdP domain for the 2. local policy is configured to trust this IdP domain for the
domain portion of the identity string. domain portion of the identity string.
Any "@" or "%" characters in the "user" portion of the identity MUST Any '@' or '%' characters in the "user" portion of the identity MUST
be escaped according to the "Percent-Encoding" rules defined in be escaped according to the "percent-encoding" rules defined in
Section 2.1 of [RFC3986]. Characters other than "@" and "%" MUST NOT Section 2.1 of [RFC3986]. Characters other than '@' and '%' MUST NOT
be percent-encoded. For example, with a "user" of "user@133" and a be percent-encoded. For example, with a "user" of "user@133" and a
"domain" of "identity.example.com", the resulting string will be "domain" of "identity.example.com", the resulting string will be
encoded as "user%40133@identity.example.com". encoded as "user%40133@identity.example.com".
Implementations are cautioned to take care when displaying user Implementations are cautioned to take care when displaying user
identities containing escaped "@" characters. If such characters are identities containing escaped '@' characters. If such characters are
unescaped prior to display, implementations MUST distinguish between unescaped prior to display, implementations MUST distinguish between
the domain of the IdP proxy and any domain that might be implied by the domain of the IdP proxy and any domain that might be implied by
the portion of the "<user>" portion that appears after the escaped the portion of the "<user>" portion that appears after the escaped
"@" sign. "@" sign.
9. Security Considerations 9. Security Considerations
Much of the security analysis of this problem is contained in Much of the security analysis of RTCWEB is contained in [RFC8826] or
[I-D.ietf-rtcweb-security] or in the discussion of the particular in the discussion of the particular issues above. In order to avoid
issues above. In order to avoid repetition, this section focuses on repetition, this section focuses on (a) residual threats that are not
(a) residual threats that are not addressed by this document and (b) addressed by this document and (b) threats produced by failure/
threats produced by failure/misbehavior of one of the components in misbehavior of one of the components in the system.
the system.
9.1. Communications Security 9.1. Communications Security
IF HTTPS is not used to secure communications to the signaling If HTTPS is not used to secure communications to the signaling
server, and the identity mechanism used in Section 7 is not used, server, and the identity mechanism used in Section 7 is not used,
then any on-path attacker can replace the DTLS-SRTP fingerprints in then any on-path attacker can replace the DTLS-SRTP fingerprints in
the handshake and thus substitute its own identity for that of either the handshake and thus substitute its own identity for that of either
endpoint. endpoint.
Even if HTTPS is used, the signaling server can potentially mount a Even if HTTPS is used, the signaling server can potentially mount a
man-in-the-middle attack unless implementations have some mechanism man-in-the-middle attack unless implementations have some mechanism
for independently verifying keys. The UI requirements in Section 6.5 for independently verifying keys. The UI requirements in Section 6.5
are designed to provide such a mechanism for motivated/security are designed to provide such a mechanism for motivated/security
conscious users, but are not suitable for general use. The identity conscious users, but are not suitable for general use. The identity
service mechanisms in Section 7 are more suitable for general use. service mechanisms in Section 7 are more suitable for general use.
Note, however, that a malicious signaling service can strip off any Note, however, that a malicious signaling service can strip off any
such identity assertions, though it cannot forge new ones. Note that such identity assertions, though it cannot forge new ones. Note that
all of the third-party security mechanisms available (whether X.509 all of the third-party security mechanisms available (whether X.509
certificates or a third-party IdP) rely on the security of the third certificates or a third-party IdP) rely on the security of the third
party--this is of course also true of the user's connection to the party -- this is of course also true of the user's connection to the
Web site itself. Users who wish to assure themselves of security Web site itself. Users who wish to assure themselves of security
against a malicious identity provider can only do so by verifying against a malicious IdP can only do so by verifying peer credentials
peer credentials directly, e.g., by checking the peer's fingerprint directly, e.g., by checking the peer's fingerprint against a value
against a value delivered out of band. delivered out of band.
In order to protect against malicious content JavaScript, that In order to protect against malicious content JavaScript, that
JavaScript MUST NOT be allowed to have direct access to---or perform JavaScript MUST NOT be allowed to have direct access to -- or perform
computations with---DTLS keys. For instance, if content JS were able computations with -- DTLS keys. For instance, if content JS were
to compute digital signatures, then it would be possible for content able to compute digital signatures, then it would be possible for
JS to get an identity assertion for a browser's generated key and content JS to get an identity assertion for a browser's generated key
then use that assertion plus a signature by the key to authenticate a and then use that assertion plus a signature by the key to
call protected under an ephemeral Diffie-Hellman (DH) key controlled authenticate a call protected under an ephemeral Diffie-Hellman (DH)
by the content JS, thus violating the security guarantees otherwise key controlled by the content JS, thus violating the security
provided by the IdP mechanism. Note that it is not sufficient merely guarantees otherwise provided by the IdP mechanism. Note that it is
to deny the content JS direct access to the keys, as some have not sufficient merely to deny the content JS direct access to the
suggested doing with the WebCrypto API [webcrypto]. The JS must also keys, as some have suggested doing with the WebCrypto API
not be allowed to perform operations that would be valid for a DTLS [webcrypto]. The JS must also not be allowed to perform operations
endpoint. By far the safest approach is simply to deny the ability that would be valid for a DTLS endpoint. By far the safest approach
to perform any operations that depend on secret information is simply to deny the ability to perform any operations that depend
associated with the key. Operations that depend on public on secret information associated with the key. Operations that
information, such as exporting the public key are of course safe. depend on public information, such as exporting the public key, are
of course safe.
9.2. Privacy 9.2. Privacy
The requirements in this document are intended to allow: The requirements in this document are intended to allow:
o Users to participate in calls without revealing their location. * Users to participate in calls without revealing their location.
o Potential callees to avoid revealing their location and even * Potential callees to avoid revealing their location and even
presence status prior to agreeing to answer a call. presence status prior to agreeing to answer a call.
However, these privacy protections come at a performance cost in However, these privacy protections come at a performance cost in
terms of using TURN relays and, in the latter case, delaying ICE. terms of using TURN relays and, in the latter case, delaying ICE.
Sites SHOULD make users aware of these tradeoffs. Sites SHOULD make users aware of these tradeoffs.
Note that the protections provided here assume a non-malicious Note that the protections provided here assume a non-malicious
calling service. As the calling service always knows the users calling service. As the calling service always knows the user's
status and (absent the use of a technology like Tor) their IP status and (absent the use of a technology like Tor) their IP
address, they can violate the users privacy at will. Users who wish address, they can violate the user's privacy at will. Users who wish
privacy against the calling sites they are using must use separate privacy against the calling sites they are using must use separate
privacy enhancing technologies such as Tor. Combined WebRTC/Tor privacy-enhancing technologies such as Tor. Combined WebRTC/Tor
implementations SHOULD arrange to route the media as well as the implementations SHOULD arrange to route the media as well as the
signaling through Tor. Currently this will produce very suboptimal signaling through Tor. Currently this will produce very suboptimal
performance. performance.
Additionally, any identifier which persists across multiple calls is Additionally, any identifier which persists across multiple calls is
potentially a problem for privacy, especially for anonymous calling potentially a problem for privacy, especially for anonymous calling
services. Such services SHOULD instruct the browser to use separate services. Such services SHOULD instruct the browser to use separate
DTLS keys for each call and also to use TURN throughout the call. DTLS keys for each call and also to use TURN throughout the call.
Otherwise, the other side will learn linkable information that would Otherwise, the other side will learn linkable information that would
allow them to correlate the browser across multiple calls. allow them to correlate the browser across multiple calls.
Additionally, browsers SHOULD implement the privacy-preserving CNAME Additionally, browsers SHOULD implement the privacy-preserving CNAME
generation mode of [RFC7022]. generation mode of [RFC7022].
9.3. Denial of Service 9.3. Denial of Service
The consent mechanisms described in this document are intended to The consent mechanisms described in this document are intended to
mitigate denial of service attacks in which an attacker uses clients mitigate denial-of-service (DoS) attacks in which an attacker uses
to send large amounts of traffic to a victim without the consent of clients to send large amounts of traffic to a victim without the
the victim. While these mechanisms are sufficient to protect victims consent of the victim. While these mechanisms are sufficient to
who have not implemented WebRTC at all, WebRTC implementations need protect victims who have not implemented WebRTC at all, WebRTC
to be more careful. implementations need to be more careful.
Consider the case of a call center which accepts calls via WebRTC. Consider the case of a call center which accepts calls via WebRTC.
An attacker proxies the call center's front-end and arranges for An attacker proxies the call center's front-end and arranges for
multiple clients to initiate calls to the call center. Note that multiple clients to initiate calls to the call center. Note that
this requires user consent in many cases but because the data channel this requires user consent in many cases, but because the data
does not need consent, he can use that directly. Since ICE will channel does not need consent, they can use that directly. Since ICE
complete, browsers can then be induced to send large amounts of data will complete, browsers can then be induced to send large amounts of
to the victim call center if it supports the data channel at all. data to the victim call center if it supports the data channel at
Preventing this attack requires that automated WebRTC implementations all. Preventing this attack requires that automated WebRTC
implement sensible flow control and have the ability to triage out implementations implement sensible flow control and have the ability
(i.e., stop responding to ICE probes on) calls which are behaving to triage out (i.e., stop responding to ICE probes on) calls which
badly, and especially to be prepared to remotely throttle the data are behaving badly, and especially to be prepared to remotely
channel in the absence of plausible audio and video (which the throttle the data channel in the absence of plausible audio and video
attacker cannot control). (which the attacker cannot control).
Another related attack is for the signaling service to swap the ICE Another related attack is for the signaling service to swap the ICE
candidates for the audio and video streams, thus forcing a browser to candidates for the audio and video streams, thus forcing a browser to
send video to the sink that the other victim expects will contain send video to the sink that the other victim expects will contain
audio (perhaps it is only expecting audio!) potentially causing audio (perhaps it is only expecting audio!), potentially causing
overload. Muxing multiple media flows over a single transport makes overload. Muxing multiple media flows over a single transport makes
it harder to individually suppress a single flow by denying ICE it harder to individually suppress a single flow by denying ICE
keepalives. Either media-level (RTCP) mechanisms must be used or the keepalives. Either media-level (RTCP) mechanisms must be used or the
implementation must deny responses entirely, thus terminating the implementation must deny responses entirely, thus terminating the
call. call.
Yet another attack, suggested by Magnus Westerlund, is for the Yet another attack, suggested by Magnus Westerlund, is for the
attacker to cross-connect offers and answers as follows. It induces attacker to cross-connect offers and answers as follows. It induces
the victim to make a call and then uses its control of other users the victim to make a call and then uses its control of other users'
browsers to get them to attempt a call to someone. It then browsers to get them to attempt a call to someone. It then
translates their offers into apparent answers to the victim, which translates their offers into apparent answers to the victim, which
looks like large-scale parallel forking. The victim still responds looks like large-scale parallel forking. The victim still responds
to ICE responses and now the browsers all try to send media to the to ICE responses, and now the browsers all try to send media to the
victim. Implementations can defend themselves from this attack by victim. Implementations can defend themselves from this attack by
only responding to ICE Binding Requests for a limited number of only responding to ICE Binding Requests for a limited number of
remote ufrags (this is the reason for the requirement that the JS not remote ufrags (this is the reason for the requirement that the JS not
be able to control the ufrag and password). be able to control the ufrag and password). [RFC8834], Section 13
documents a number of potential RTCP-based DoS attacks and
[I-D.ietf-rtcweb-rtp-usage] Section 13 documents a number of countermeasures.
potential RTCP-based DoS attacks and countermeasures.
Note that attacks based on confusing one end or the other about Note that attacks based on confusing one end or the other about
consent are possible even in the face of the third-party identity consent are possible even in the face of the third-party identity
mechanism as long as major parts of the signaling messages are not mechanism as long as major parts of the signaling messages are not
signed. On the other hand, signing the entire message severely signed. On the other hand, signing the entire message severely
restricts the capabilities of the calling application, so there are restricts the capabilities of the calling application, so there are
difficult tradeoffs here. difficult tradeoffs here.
9.4. IdP Authentication Mechanism 9.4. IdP Authentication Mechanism
skipping to change at page 34, line 30 skipping to change at line 1555
identified in the assertion wishes to be associated with the identified in the assertion wishes to be associated with the
assertion. Thus, it must not be possible for arbitrary third parties assertion. Thus, it must not be possible for arbitrary third parties
to get assertions tied to a user or to produce assertions that RPs to get assertions tied to a user or to produce assertions that RPs
will accept. will accept.
9.4.1. PeerConnection Origin Check 9.4.1. PeerConnection Origin Check
Fundamentally, the IdP proxy is just a piece of HTML and JS loaded by Fundamentally, the IdP proxy is just a piece of HTML and JS loaded by
the browser, so nothing stops a Web attacker from creating their own the browser, so nothing stops a Web attacker from creating their own
IFRAME, loading the IdP proxy HTML/JS, and requesting a signature IFRAME, loading the IdP proxy HTML/JS, and requesting a signature
over his own keys rather than those generated in the browser. over their own keys rather than those generated in the browser.
However, that proxy would be in the attacker's origin, not the IdP's However, that proxy would be in the attacker's origin, not the IdP's
origin. Only the browser itself can instantiate a context that (a) origin. Only the browser itself can instantiate a context that
is in the IdP's origin and (b) exposes the correct API surface. (a) is in the IdP's origin and (b) exposes the correct API surface.
Thus, the IdP proxy on the sender's side MUST ensure that it is Thus, the IdP proxy on the sender's side MUST ensure that it is
running in the IdP's origin prior to issuing assertions. running in the IdP's origin prior to issuing assertions.
Note that this check only asserts that the browser (or some other Note that this check only asserts that the browser (or some other
entity with access to the user's authentication data) attests to the entity with access to the user's authentication data) attests to the
request and hence to the fingerprint. It does not demonstrate that request and hence to the fingerprint. It does not demonstrate that
the browser has access to the associated private key, and therefore the browser has access to the associated private key, and therefore
an attacker can attach their own identity to another party's keying an attacker can attach their own identity to another party's keying
material, thus making a call which comes from Alice appear to come material, thus making a call which comes from Alice appear to come
from the attacker. See [I-D.ietf-mmusic-sdp-uks] for defenses from the attacker. See [RFC8844] for defenses against this form of
against this form of attack. attack.
9.4.2. IdP Well-known URI 9.4.2. IdP Well-Known URI
As described in Section 7.5 the IdP proxy HTML/JS landing page is As described in Section 7.5, the IdP proxy HTML/JS landing page is
located at a well-known URI based on the IdP's domain name. This located at a well-known URI based on the IdP's domain name. This
requirement prevents an attacker who can write some resources at the requirement prevents an attacker who can write some resources at the
IdP (e.g., on one's Facebook wall) from being able to impersonate the IdP (e.g., on one's Facebook wall) from being able to impersonate the
IdP. IdP.
9.4.3. Privacy of IdP-generated identities and the hosting site 9.4.3. Privacy of IdP-Generated Identities and the Hosting Site
Depending on the structure of the IdP's assertions, the calling site Depending on the structure of the IdP's assertions, the calling site
may learn the user's identity from the perspective of the IdP. In may learn the user's identity from the perspective of the IdP. In
many cases this is not an issue because the user is authenticating to many cases, this is not an issue because the user is authenticating
the site via the IdP in any case, for instance when the user has to the site via the IdP in any case -- for instance, when the user
logged in with Facebook Connect and is then authenticating their call has logged in with Facebook Connect and is then authenticating their
with a Facebook identity. However, in other case, the user may not call with a Facebook identity. However, in other cases, the user may
have already revealed their identity to the site. In general, IdPs not have already revealed their identity to the site. In general,
SHOULD either verify that the user is willing to have their identity IdPs SHOULD either verify that the user is willing to have their
revealed to the site (e.g., through the usual IdP permissions dialog) identity revealed to the site (e.g., through the usual IdP
or arrange that the identity information is only available to known permissions dialog) or arrange that the identity information is only
RPs (e.g., social graph adjacencies) but not to the calling site. available to known RPs (e.g., social graph adjacencies) but not to
The "domain" field of the assertion request can be used to check that the calling site. The "domain" field of the assertion request can be
the user has agreed to disclose their identity to the calling site; used to check that the user has agreed to disclose their identity to
because it is supplied by the PeerConnection it can be trusted to be the calling site; because it is supplied by the PeerConnection it can
correct. be trusted to be correct.
9.4.4. Security of Third-Party IdPs 9.4.4. Security of Third-Party IdPs
As discussed above, each third-party IdP represents a new universal As discussed above, each third-party IdP represents a new universal
trust point and therefore the number of these IdPs needs to be quite trust point and therefore the number of these IdPs needs to be quite
limited. Most IdPs, even those which issue unqualified identities limited. Most IdPs, even those which issue unqualified identities
such as Facebook, can be recast as authoritative IdPs (e.g., such as Facebook, can be recast as authoritative IdPs (e.g.,
123456@facebook.com). However, in such cases, the user interface 123456@facebook.com). However, in such cases, the user interface
implications are not entirely desirable. One intermediate approach implications are not entirely desirable. One intermediate approach
is to have special (potentially user configurable) UI for large is to have special (potentially user configurable) UI for large
authoritative IdPs, thus allowing the user to instantly grasp that authoritative IdPs, thus allowing the user to instantly grasp that
the call is being authenticated by Facebook, Google, etc. the call is being authenticated by Facebook, Google, etc.
9.4.4.1. Confusable Characters 9.4.4.1. Confusable Characters
Because a broad range of characters are permitted in identity Because a broad range of characters are permitted in identity
strings, it may be possible for attackers to craft identities which strings, it may be possible for attackers to craft identities which
are confusable with other identities (see [RFC6943] for more on this are confusable with other identities (see [RFC6943] for more on this
topic). This is a problem with any identifier space of this type topic). This is a problem with any identifier space of this type
(e.g., e-mail addresses). Those minting identifers should avoid (e.g., email addresses). Those minting identifiers should avoid
mixed scripts and similar confusable characters. Those presenting mixed scripts and similar confusable characters. Those presenting
these identifiers to a user should consider highlighting cases of these identifiers to a user should consider highlighting cases of
mixed script usage (see [RFC5890], section 4.4). Other best mixed script usage (see [RFC5890], Section 4.4). Other best
practices are still in development. practices are still in development.
9.4.5. Web Security Feature Interactions 9.4.5. Web Security Feature Interactions
A number of optional Web security features have the potential to A number of optional Web security features have the potential to
cause issues for this mechanism, as discussed below. cause issues for this mechanism, as discussed below.
9.4.5.1. Popup Blocking 9.4.5.1. Popup Blocking
When popup blocking is in use, the IdP proxy is unable to generate When popup blocking is in use, the IdP proxy is unable to generate
popup windows, dialogs or any other form of user interactions. This popup windows, dialogs, or any other form of user interactions. This
prevents the IdP proxy from being used to circumvent user prevents the IdP proxy from being used to circumvent user
interaction. The "LOGINNEEDED" message allows the IdP proxy to interaction. The "LOGINNEEDED" message allows the IdP proxy to
inform the calling site of a need for user login, providing the inform the calling site of a need for user login, providing the
information necessary to satisfy this requirement without resorting information necessary to satisfy this requirement without resorting
to direct user interaction from the IdP proxy itself. to direct user interaction from the IdP proxy itself.
9.4.5.2. Third Party Cookies 9.4.5.2. Third Party Cookies
Some browsers allow users to block third party cookies (cookies Some browsers allow users to block third party cookies (cookies
associated with origins other than the top level page) for privacy associated with origins other than the top-level page) for privacy
reasons. Any IdP which uses cookies to persist logins will be broken reasons. Any IdP which uses cookies to persist logins will be broken
by third-party cookie blocking. One option is to accept this as a by third-party cookie blocking. One option is to accept this as a
limitation; another is to have the PeerConnection object disable limitation; another is to have the PeerConnection object disable
third-party cookie blocking for the IdP proxy. third-party cookie blocking for the IdP proxy.
10. IANA Considerations 10. IANA Considerations
This specification defines the "identity" SDP attribute per the This specification defines the "identity" SDP attribute per the
procedures of Section 8.2.4 of [RFC4566]. The required information procedures of Section 8.2.4 of [RFC4566]. The required information
for the registration is included here: for the registration is included here:
Contact Name: IESG (iesg@ietf.org) Contact Name: IESG (iesg@ietf.org)
Attribute Name: identity Attribute Name: identity
Long Form: identity Long Form: identity
Type of Attribute: session-level Type of Attribute: session
Charset Considerations: This attribute is not subject to the charset Charset Considerations: This attribute is not subject to the charset
attribute. attribute.
Purpose: This attribute carries an identity assertion, binding an Purpose: This attribute carries an identity assertion, binding an
identity to the transport-level security session. identity to the transport-level security session.
Appropriate Values: See Section 5 of RFCXXXX [[Editor Note: This Appropriate Values: See Section 5 of RFC 8827.
document.]]
Mux Category: NORMAL. Mux Category: NORMAL
This section reqisters the "idp-proxy" well-known URI from [RFC5785]. This section registers the "idp-proxy" well-known URI from [RFC8615].
URI suffix: idp-proxy URI suffix: idp-proxy
Change controller: IETF
11. Acknowledgements
Bernard Aboba, Harald Alvestrand, Richard Barnes, Dan Druta, Cullen
Jennings, Hadriel Kaplan, Matthew Kaufman, Jim McEachern, Martin
Thomson, Magnus Westerland. Matthew Kaufman provided the UI material
in Section 6.5. Christer Holmberg provided the initial version of
Section 5.1.
12. Changes
[RFC Editor: Please remove this section prior to publication.]
12.1. Changes since -15
Rewrite the Identity section in more conventional offer/answer
format.
Clarify rules on changing identities.
12.2. Changes since -11
Update discussion of IdP security model
Replace "domain name" with RFC 3986 Authority
Clean up discussion of how to generate IdP URI.
Remove obsolete text about null cipher suites.
Remove obsolete appendixes about older IdP systems
Require support for ECDSA, PFS, and AEAD
12.3. Changes since -10
Update cipher suite profiles.
Rework IdP interaction based on implementation experience in Firefox.
12.4. Changes since -06
Replaced RTCWEB and RTC-Web with WebRTC, except when referring to the
IETF WG
Forbade use in mixed content as discussed in Orlando.
Added a requirement to surface NULL ciphers to the top-level.
Tried to clarify SRTP versus DTLS-SRTP.
Added a section on screen sharing permissions.
Assorted editorial work.
12.5. Changes since -05
The following changes have been made since the -05 draft.
o Response to comments from Richard Barnes
o More explanation of the IdP security properties and the federation
use case.
o Editorial cleanup.
12.6. Changes since -03
Version -04 was a version control mistake. Please ignore.
The following changes have been made since the -04 draft. Change controller: IETF
o Move origin check from IdP to RP per discussion in YVR.
o Clarified treatment of X.509-level identities.
o Editorial cleanup.
12.7. Changes since -03
12.8. Changes since -02
The following changes have been made since the -02 draft.
o Forbid persistent HTTP permissions.
o Clarified the text in S 5.4 to clearly refer to requirements on
the API to provide functionality to the site.
o Fold in the IETF portion of draft-rescorla-rtcweb-generic-idp
o Retarget the continuing consent section to assume Binding Requests
o Added some more privacy and linkage text in various places.
o Editorial improvements
13. References 11. References
13.1. Normative References 11.1. Normative References
[FIPS186] National Institute of Standards and Technology (NIST), [FIPS186] National Institute of Standards and Technology (NIST),
"Digital Signature Standard (DSS)", NIST PUB 186-4 , July "Digital Signature Standard (DSS)", NIST PUB 186-4,
2013. DOI 10.6028/NIST.FIPS.186-4, July 2013,
<https://doi.org/10.6028/NIST.FIPS.186-4>.
[I-D.ietf-mmusic-sdp-uks]
Thomson, M. and E. Rescorla, "Unknown Key Share Attacks on
uses of TLS with the Session Description Protocol (SDP)",
draft-ietf-mmusic-sdp-uks-06 (work in progress), July
2019.
[I-D.ietf-rtcweb-jsep]
Uberti, J., Jennings, C., and E. Rescorla, "JavaScript
Session Establishment Protocol", draft-ietf-rtcweb-jsep-26
(work in progress), February 2019.
[I-D.ietf-rtcweb-overview]
Alvestrand, H., "Overview: Real Time Protocols for
Browser-based Applications", draft-ietf-rtcweb-overview-19
(work in progress), November 2017.
[I-D.ietf-rtcweb-rtp-usage]
Perkins, C., Westerlund, M., and J. Ott, "Web Real-Time
Communication (WebRTC): Media Transport and Use of RTP",
draft-ietf-rtcweb-rtp-usage-26 (work in progress), March
2016.
[I-D.ietf-rtcweb-security]
Rescorla, E., "Security Considerations for WebRTC", draft-
ietf-rtcweb-security-12 (work in progress), July 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000, DOI 10.17487/RFC2818, May 2000,
<https://www.rfc-editor.org/info/rfc2818>. <https://www.rfc-editor.org/info/rfc2818>.
skipping to change at page 40, line 33 skipping to change at line 1721
[RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session [RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session
Description Protocol (SDP) Security Descriptions for Media Description Protocol (SDP) Security Descriptions for Media
Streams", RFC 4568, DOI 10.17487/RFC4568, July 2006, Streams", RFC 4568, DOI 10.17487/RFC4568, July 2006,
<https://www.rfc-editor.org/info/rfc4568>. <https://www.rfc-editor.org/info/rfc4568>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>. <https://www.rfc-editor.org/info/rfc4648>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[RFC5763] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework [RFC5763] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework
for Establishing a Secure Real-time Transport Protocol for Establishing a Secure Real-time Transport Protocol
(SRTP) Security Context Using Datagram Transport Layer (SRTP) Security Context Using Datagram Transport Layer
Security (DTLS)", RFC 5763, DOI 10.17487/RFC5763, May Security (DTLS)", RFC 5763, DOI 10.17487/RFC5763, May
2010, <https://www.rfc-editor.org/info/rfc5763>. 2010, <https://www.rfc-editor.org/info/rfc5763>.
[RFC5764] McGrew, D. and E. Rescorla, "Datagram Transport Layer [RFC5764] McGrew, D. and E. Rescorla, "Datagram Transport Layer
Security (DTLS) Extension to Establish Keys for the Secure Security (DTLS) Extension to Establish Keys for the Secure
Real-time Transport Protocol (SRTP)", RFC 5764, Real-time Transport Protocol (SRTP)", RFC 5764,
DOI 10.17487/RFC5764, May 2010, DOI 10.17487/RFC5764, May 2010,
<https://www.rfc-editor.org/info/rfc5764>. <https://www.rfc-editor.org/info/rfc5764>.
[RFC5785] Nottingham, M. and E. Hammer-Lahav, "Defining Well-Known
Uniform Resource Identifiers (URIs)", RFC 5785,
DOI 10.17487/RFC5785, April 2010,
<https://www.rfc-editor.org/info/rfc5785>.
[RFC5890] Klensin, J., "Internationalized Domain Names for [RFC5890] Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Definitions and Document Framework", Applications (IDNA): Definitions and Document Framework",
RFC 5890, DOI 10.17487/RFC5890, August 2010, RFC 5890, DOI 10.17487/RFC5890, August 2010,
<https://www.rfc-editor.org/info/rfc5890>. <https://www.rfc-editor.org/info/rfc5890>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/info/rfc6347>. January 2012, <https://www.rfc-editor.org/info/rfc6347>.
[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, [RFC6454] Barth, A., "The Web Origin Concept", RFC 6454,
skipping to change at page 42, line 16 skipping to change at line 1787
"Datagram Transport Layer Security (DTLS) Encapsulation of "Datagram Transport Layer Security (DTLS) Encapsulation of
SCTP Packets", RFC 8261, DOI 10.17487/RFC8261, November SCTP Packets", RFC 8261, DOI 10.17487/RFC8261, November
2017, <https://www.rfc-editor.org/info/rfc8261>. 2017, <https://www.rfc-editor.org/info/rfc8261>.
[RFC8445] Keranen, A., Holmberg, C., and J. Rosenberg, "Interactive [RFC8445] Keranen, A., Holmberg, C., and J. Rosenberg, "Interactive
Connectivity Establishment (ICE): A Protocol for Network Connectivity Establishment (ICE): A Protocol for Network
Address Translator (NAT) Traversal", RFC 8445, Address Translator (NAT) Traversal", RFC 8445,
DOI 10.17487/RFC8445, July 2018, DOI 10.17487/RFC8445, July 2018,
<https://www.rfc-editor.org/info/rfc8445>. <https://www.rfc-editor.org/info/rfc8445>.
[webcrypto] [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
editors, W., "Web Cryptography API", June 2013. Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
Available at http://www.w3.org/TR/WebCryptoAPI/ [RFC8615] Nottingham, M., "Well-Known Uniform Resource Identifiers
(URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019,
<https://www.rfc-editor.org/info/rfc8615>.
[RFC8825] Alvestrand, H., "Overview: Real-Time Protocols for
Browser-Based Applications", RFC 8825,
DOI 10.17487/RFC8825, January 2021,
<https://www.rfc-editor.org/info/rfc8825>.
[RFC8826] Rescorla, E., "Security Considerations for WebRTC",
RFC 8826, DOI 10.17487/RFC8826, January 2021,
<https://www.rfc-editor.org/info/rfc8826>.
[RFC8829] Uberti, J., Jennings, C., and E. Rescorla, Ed.,
"JavaScript Session Establishment Protocol (JSEP)",
RFC 8829, DOI 10.17487/RFC8829, January 2021,
<https://www.rfc-editor.org/info/rfc8829>.
[RFC8834] Perkins, C., Westerlund, M., and J. Ott, "Media Transport
and Use of RTP in WebRTC", RFC 8834, DOI 10.17487/RFC8834,
January 2021, <https://www.rfc-editor.org/info/rfc8834>.
[RFC8844] Thomson, M. and E. Rescorla, "Unknown Key-Share Attacks on
Uses of TLS with the Session Description Protocol (SDP)",
RFC 8844, DOI 10.17487/RFC8844, January 2021,
<https://www.rfc-editor.org/info/rfc8844>.
[webcrypto]
Watson, M., "Web Cryptography API", W3C Recommendation, 26
January 2017,
<https://www.w3.org/TR/2017/REC-WebCryptoAPI-20170126/>.
[webrtc-api] [webrtc-api]
editors, W., "WebRTC 1.0: Real-time Communication Between Jennings, C., Boström, H., and J-I. Bruaroey, "WebRTC 1.0:
Browsers", October 2011. Real-time Communication Between Browsers", W3C Proposed
Recommendation, <https://www.w3.org/TR/webrtc/>.
Available at http://dev.w3.org/2011/webrtc/editor/ 11.2. Informative References
webrtc.html
13.2. Informative References [fetch] van Kesteren, A., "Fetch",
<https://fetch.spec.whatwg.org/>.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002, DOI 10.17487/RFC3261, June 2002,
<https://www.rfc-editor.org/info/rfc3261>. <https://www.rfc-editor.org/info/rfc3261>.
[RFC5705] Rescorla, E., "Keying Material Exporters for Transport [RFC5705] Rescorla, E., "Keying Material Exporters for Transport
Layer Security (TLS)", RFC 5705, DOI 10.17487/RFC5705, Layer Security (TLS)", RFC 5705, DOI 10.17487/RFC5705,
March 2010, <https://www.rfc-editor.org/info/rfc5705>. March 2010, <https://www.rfc-editor.org/info/rfc5705>.
skipping to change at page 43, line 13 skipping to change at line 1863
<https://www.rfc-editor.org/info/rfc6455>. <https://www.rfc-editor.org/info/rfc6455>.
[RFC6943] Thaler, D., Ed., "Issues in Identifier Comparison for [RFC6943] Thaler, D., Ed., "Issues in Identifier Comparison for
Security Purposes", RFC 6943, DOI 10.17487/RFC6943, May Security Purposes", RFC 6943, DOI 10.17487/RFC6943, May
2013, <https://www.rfc-editor.org/info/rfc6943>. 2013, <https://www.rfc-editor.org/info/rfc6943>.
[RFC7617] Reschke, J., "The 'Basic' HTTP Authentication Scheme", [RFC7617] Reschke, J., "The 'Basic' HTTP Authentication Scheme",
RFC 7617, DOI 10.17487/RFC7617, September 2015, RFC 7617, DOI 10.17487/RFC7617, September 2015,
<https://www.rfc-editor.org/info/rfc7617>. <https://www.rfc-editor.org/info/rfc7617>.
[XmlHttpRequest] [RFC8224] Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,
van Kesteren, A., "XMLHttpRequest Level 2", January 2012. "Authenticated Identity Management in the Session
Initiation Protocol (SIP)", RFC 8224,
DOI 10.17487/RFC8224, February 2018,
<https://www.rfc-editor.org/info/rfc8224>.
[RFC8828] Uberti, J. and G. Shieh, "WebRTC IP Address Handling
Requirements", RFC 8828, DOI 10.17487/RFC8828, January
2021, <https://www.rfc-editor.org/info/rfc8828>.
[TLS-DTLS13]
Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version
1.3", Work in Progress, Internet-Draft, draft-ietf-tls-
dtls13-39, 2 November 2020,
<https://tools.ietf.org/html/draft-ietf-tls-dtls13-39>.
Acknowledgements
Bernard Aboba, Harald Alvestrand, Richard Barnes, Dan Druta, Cullen
Jennings, Hadriel Kaplan, Matthew Kaufman, Jim McEachern, Martin
Thomson, Magnus Westerlund. Matthew Kaufman provided the UI material
in Section 6.5. Christer Holmberg provided the initial version of
Section 5.1.
Author's Address Author's Address
Eric Rescorla Eric Rescorla
RTFM, Inc. Mozilla
2064 Edgewood Drive
Palo Alto, CA 94303
USA
Phone: +1 650 678 2350
Email: ekr@rtfm.com Email: ekr@rtfm.com
 End of changes. 194 change blocks. 
648 lines changed or deleted 570 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/