draft-ietf-ace-key-groupcomm-oscore-02.txt   draft-ietf-ace-key-groupcomm-oscore-03.txt 
ACE Working Group M. Tiloca ACE Working Group M. Tiloca
Internet-Draft RISE AB Internet-Draft RISE AB
Intended status: Standards Track J. Park Intended status: Standards Track J. Park
Expires: January 6, 2020 Universitaet Duisburg-Essen Expires: May 7, 2020 Universitaet Duisburg-Essen
F. Palombini F. Palombini
Ericsson AB Ericsson AB
July 05, 2019 November 04, 2019
Key Management for OSCORE Groups in ACE Key Management for OSCORE Groups in ACE
draft-ietf-ace-key-groupcomm-oscore-02 draft-ietf-ace-key-groupcomm-oscore-03
Abstract Abstract
This document describes a method to request and provision keying This document describes a method to request and provision keying
material in group communication scenarios where the group material in group communication scenarios where the group
communication is based on CoAP and secured with Object Security for communication is based on CoAP and secured with Object Security for
Constrained RESTful Environments (OSCORE). The proposed method Constrained RESTful Environments (OSCORE). The proposed method
delegates the authentication and authorization of new client nodes delegates the authentication and authorization of new client nodes
that join an OSCORE group through a Group Manager server. This that join an OSCORE group through a Group Manager server. This
approach builds on the ACE framework for Authentication and approach builds on the ACE framework for Authentication and
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on January 6, 2020. This Internet-Draft will expire on May 7, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Relation to Other Documents . . . . . . . . . . . . . . . 5 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 5
2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 6 2.1. Overview of the Joining Process . . . . . . . . . . . . . 7
2.1. Overview of the Join Process . . . . . . . . . . . . . . 7
2.2. Overview of the Group Rekeying Process . . . . . . . . . 8 2.2. Overview of the Group Rekeying Process . . . . . . . . . 8
3. Joining Node to Authorization Server . . . . . . . . . . . . 9 3. Joining Node to Authorization Server . . . . . . . . . . . . 8
3.1. Authorization Request . . . . . . . . . . . . . . . . . . 9 3.1. Authorization Request . . . . . . . . . . . . . . . . . . 9
3.2. Authorization Response . . . . . . . . . . . . . . . . . 10 3.2. Authorization Response . . . . . . . . . . . . . . . . . 9
4. Joining Node to Group Manager . . . . . . . . . . . . . . . . 11 4. Joining Node to Group Manager . . . . . . . . . . . . . . . . 10
4.1. Token Post . . . . . . . . . . . . . . . . . . . . . . . 11 4.1. Token Post . . . . . . . . . . . . . . . . . . . . . . . 10
4.2. Join Request . . . . . . . . . . . . . . . . . . . . . . 12 4.2. Joining Request . . . . . . . . . . . . . . . . . . . . . 12
4.3. Join Response . . . . . . . . . . . . . . . . . . . . . . 13 4.3. Joining Response . . . . . . . . . . . . . . . . . . . . 13
5. Leaving of a Group Member . . . . . . . . . . . . . . . . . . 17 5. Public Keys of Joining Nodes . . . . . . . . . . . . . . . . 17
6. Public Keys of Joining Nodes . . . . . . . . . . . . . . . . 18 6. Retrieval of Updated Keying Material . . . . . . . . . . . . 19
7. Group Rekeying Process . . . . . . . . . . . . . . . . . . . 20 7. Retrieval of New Keying Material . . . . . . . . . . . . . . 19
8. Security Considerations . . . . . . . . . . . . . . . . . . . 21 8. Retrieval of Public Keys of Group Members . . . . . . . . . . 20
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 9. Retrieval of Group Policies . . . . . . . . . . . . . . . . . 20
9.1. ACE Groupcomm Key Registry . . . . . . . . . . . . . . . 22 10. Retrieval of Keying Material Version . . . . . . . . . . . . 21
9.2. OSCORE Security Context Parameters Registry . . . . . . . 23 11. Request to Leave the Group . . . . . . . . . . . . . . . . . 21
9.3. ACE Groupcomm Profile Registry . . . . . . . . . . . . . 24 12. Removal of a Group Member . . . . . . . . . . . . . . . . . . 21
9.4. Sequence Number Synchronization Method Registry . . . . . 24 13. Group Rekeying Process . . . . . . . . . . . . . . . . . . . 22
9.5. ACE Public Key Encoding Registry . . . . . . . . . . . . 25 14. Security Considerations . . . . . . . . . . . . . . . . . . . 23
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
10.1. Normative References . . . . . . . . . . . . . . . . . . 25 15.1. ACE Groupcomm Key Registry . . . . . . . . . . . . . . . 24
10.2. Informative References . . . . . . . . . . . . . . . . . 26 15.2. OSCORE Security Context Parameters Registry . . . . . . 24
Appendix A. Profile Requirements . . . . . . . . . . . . . . . . 27 15.3. ACE Groupcomm Profile Registry . . . . . . . . . . . . . 26
Appendix B. Document Updates . . . . . . . . . . . . . . . . . . 28 15.4. Sequence Number Synchronization Method Registry . . . . 26
B.1. Version -01 to -02 . . . . . . . . . . . . . . . . . . . 28 15.5. ACE Groupcomm Parameters Registry . . . . . . . . . . . 27
B.2. Version -00 to -01 . . . . . . . . . . . . . . . . . . . 29 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 29 16.1. Normative References . . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29 16.2. Informative References . . . . . . . . . . . . . . . . . 28
Appendix A. Profile Requirements . . . . . . . . . . . . . . . . 29
Appendix B. Document Updates . . . . . . . . . . . . . . . . . . 31
B.1. Version -02 to -03 . . . . . . . . . . . . . . . . . . . 31
B.2. Version -01 to -02 . . . . . . . . . . . . . . . . . . . 32
B.3. Version -00 to -01 . . . . . . . . . . . . . . . . . . . 32
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
1. Introduction 1. Introduction
Object Security for Constrained RESTful Environments (OSCORE) Object Security for Constrained RESTful Environments (OSCORE)
[I-D.ietf-core-object-security] is a method for application-layer [RFC8613] is a method for application-layer protection of the
protection of the Constrained Application Protocol (CoAP) [RFC7252], Constrained Application Protocol (CoAP) [RFC7252], using CBOR Object
using CBOR Object Signing and Encryption (COSE) [RFC8152] and Signing and Encryption (COSE) [RFC8152] and enabling end-to-end
enabling end-to-end security of CoAP payload and options. security of CoAP payload and options.
As described in [I-D.ietf-core-oscore-groupcomm], OSCORE may be used As described in [I-D.ietf-core-oscore-groupcomm], Group OSCORE is
to protect CoAP group communication over IP multicast used to protect CoAP group communication over IP multicast
[RFC7390][I-D.dijk-core-groupcomm-bis]. This relies on a Group [RFC7390][I-D.dijk-core-groupcomm-bis]. This relies on a Group
Manager, which is responsible for managing an OSCORE group, where Manager, which is responsible for managing an OSCORE group, where
members exchange CoAP messages secured with OSCORE. The Group members exchange CoAP messages secured with Group OSCORE. The Group
Manager can be responsible for multiple groups, coordinates the join Manager can be responsible for multiple groups, coordinates the
process of new group members, and is entrusted with the distribution joining process of new group members, and is entrusted with the
and renewal of group keying material. distribution and renewal of group keying material.
This specification builds on the ACE framework for Authentication and This specification builds on the ACE framework for Authentication and
Authorization [I-D.ietf-ace-oauth-authz] and defines a method to: Authorization [I-D.ietf-ace-oauth-authz] and defines a method to:
o Authorize a node to join an OSCORE group, and provide it with the o Authorize a node to join an OSCORE group, and provide it with the
group keying material to communicate with other group members. group keying material to communicate with other group members.
o Provide updated keying material to group members upon request. o Provide updated keying material to group members upon request.
o Renew the group keying material and distribute it to the OSCORE o Renew the group keying material and distribute it to the OSCORE
group (rekeying) upon changes in the group membership. group (rekeying) upon changes in the group membership.
A client node joins an OSCORE group through a resource server acting A client node joins an OSCORE group through a resource server acting
as Group Manager for that group. The join process relies on an as Group Manager for that group. The joining process relies on an
Access Token, which is bound to a proof-of-possession key and Access Token, which is bound to a proof-of-possession key and
authorizes the client to access a specific join resource at the Group authorizes the client to access a specific group-membership resource
Manager. at the Group Manager.
Messages exchanged among the participants follow the formats defined Message exchanges among the participants as well as message formats
in [I-D.ietf-ace-key-groupcomm] for provisioning and renewing keying and processing follow what specified in [I-D.ietf-ace-key-groupcomm]
material in group communication scenarios. for provisioning and renewing keying material in group communication
scenarios.
In order to achieve communication security, proof-of-possession and In order to achieve communication security, proof-of-possession and
server authentication, the client and the Group Manager leverage server authentication, the client and the Group Manager leverage
protocol-specific transport profiles of ACE. These include also protocol-specific transport profiles of ACE. These include also
possible forthcoming transport profiles that comply with the possible forthcoming transport profiles that comply with the
requirements in Appendix C of [I-D.ietf-ace-oauth-authz]. requirements in Appendix C of [I-D.ietf-ace-oauth-authz].
1.1. Terminology 1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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Readers are expected to be familiar with the terms and concepts Readers are expected to be familiar with the terms and concepts
related to the CoAP protocol described in related to the CoAP protocol described in
[RFC7252][RFC7390][I-D.dijk-core-groupcomm-bis]. Note that, unless [RFC7252][RFC7390][I-D.dijk-core-groupcomm-bis]. Note that, unless
otherwise indicated, the term "endpoint" is used here following its otherwise indicated, the term "endpoint" is used here following its
OAuth definition, aimed at denoting resources such as /token and OAuth definition, aimed at denoting resources such as /token and
/introspect at the AS and /authz-info at the RS. This document does /introspect at the AS and /authz-info at the RS. This document does
not use the CoAP definition of "endpoint", which is "An entity not use the CoAP definition of "endpoint", which is "An entity
participating in the CoAP protocol". participating in the CoAP protocol".
Readers are expected to be familiar with the terms and concepts for Readers are expected to be familiar with the terms and concepts for
protection and processing of CoAP messages through OSCORE protection and processing of CoAP messages through OSCORE [RFC8613]
[I-D.ietf-core-object-security] also in group communication scenarios and through Group OSCORE [I-D.ietf-core-oscore-groupcomm] in group
[I-D.ietf-core-oscore-groupcomm]. These include the concept of Group communication scenarios. These include the concept of Group Manager,
Manager, as the entity responsible for a set of groups where as the entity responsible for a set of groups where communications
communications are secured with OSCORE. In this specification, the are secured with Group OSCORE. In this specification, the Group
Group Manager acts as Resource Server. Manager acts as Resource Server.
This document refers also to the following terminology. This document refers also to the following terminology.
o Joining node: a network node intending to join an OSCORE group, o Joining node: a network node intending to join an OSCORE group,
where communication is based on CoAP where communication is based on CoAP
[RFC7390][I-D.dijk-core-groupcomm-bis] and secured with OSCORE as [RFC7390][I-D.dijk-core-groupcomm-bis] and secured with Group
described in [I-D.ietf-core-oscore-groupcomm]. OSCORE as described in [I-D.ietf-core-oscore-groupcomm].
o Join process: the process through which a joining node becomes a o Joining process: the process through which a joining node becomes
member of an OSCORE group. The join process is enforced and a member of an OSCORE group. The joining process is enforced and
assisted by the Group Manager responsible for that group. assisted by the Group Manager responsible for that group.
o Join resource: a resource hosted by the Group Manager, associated o Group name: stable and invariant identifier of an OSCORE group.
to an OSCORE group under that Group Manager. A join resource is The group name MUST be unique under the same Group Manager, and
identifiable with the Group Identifier (Gid) of the respective MUST include only characters that are valid for a url-path
group. A joining node accesses a join resource to start the join segment, namely unreserved and pct-encoded characters [RFC3986].
process and become a member of that group. The URI of a join
resource is fixed.
o Join endpoint: an endpoint at the Group Manager associated to a o Group-membership resource: a resource hosted by the Group Manager,
join resource. associated to an OSCORE group under that Group Manager. A group-
membership resource is identifiable with the name of the
respective OSCORE group. A joining node accesses a group-
membership resource to start the joining process and become a
member of that group. The url-path of a group-membership resource
is fixed, and ends with the segments /group-oscore/NAME , where
"NAME" is the name of the associated OSCORE group. This replaces
the url-path /ace-group/gid at the KDC used in
[I-D.ietf-ace-key-groupcomm], with "gid" indicating the group
identifier. The url-path /group-oscore/NAME is a default name:
implementations are not required to use this name, and can define
their own instead.
o Group-membership endpoint: an endpoint at the Group Manager
associated to a group-membership resource.
o Requester: member of an OSCORE group that sends request messages o Requester: member of an OSCORE group that sends request messages
to other members of the group. to other members of the group.
o Responder: member of an OSCORE group that receives request o Responder: member of an OSCORE group that receives request
messages from other members of the group. A responder may reply messages from other members of the group. A responder may reply
back, by sending a response message to the requester which has back, by sending a response message to the requester which has
sent the request message. sent the request message.
o Monitor: member of a group that is configured as responder and o Monitor: member of an OSCORE group that is configured as responder
never replies back to requesters after receiving request messages. and never replies back to requesters after receiving request
This corresponds to the term "silent server" used in messages. This corresponds to the term "silent server" used in
[I-D.ietf-core-oscore-groupcomm]. [I-D.ietf-core-oscore-groupcomm].
o Group rekeying process: the process through which the Group o Group rekeying process: the process through which the Group
Manager renews the security parameters and group keying material, Manager renews the security parameters and group keying material,
and (re-)distributes them to the OSCORE group members. and (re-)distributes them to the OSCORE group members.
1.2. Relation to Other Documents
Figure 1 overviews the main documents related to this specification.
Arrows and asterisk-arrows denote normative references and
informative refences, respectively.
+---------------------------------------+
| |
+----------------|--------------+ |
| | | |
| v v Key Management
Pub-sub ---> Key Groupcomm ---> ACE Framework <--- for OSCORE Groups
profile * [[WG]] [[WG]] [[This document]]
| * * ^ ^ | |
| * * * * | |
| * * * *************** | |
| *********** * * * | |
| * * * * +--------------+ |
ACE | * * * * | |
-----|-*--------------*--------------*-*-|--------------------|-------
CoRE | * * * * | |
v v v * * v v
CoRE CoRE OSCORE -------------> OSCORE
Pubsub Groupcomm <*** Groupcomm <************* [[WG]]
[[WG]] [[RFC7390]] [[WG]]
Figure 1: Related Documents
2. Protocol Overview 2. Protocol Overview
Group communication for CoAP over IP multicast has been enabled in Group communication for CoAP over IP multicast has been enabled in
[RFC7390][I-D.dijk-core-groupcomm-bis] and can be secured with Object [RFC7390][I-D.dijk-core-groupcomm-bis] and can be secured with Group
Security for Constrained RESTful Environments (OSCORE) Object Security for Constrained RESTful Environments (OSCORE)
[I-D.ietf-core-object-security] as described in [RFC8613] as described in [I-D.ietf-core-oscore-groupcomm]. A
[I-D.ietf-core-oscore-groupcomm]. A network node joins an OSCORE network node joins an OSCORE group by interacting with the
group by interacting with the responsible Group Manager. Once responsible Group Manager. Once registered in the group, the new
registered in the group, the new node can securely exchange messages node can securely exchange messages with other group members.
with other group members.
This specification describes how to use the ACE framework for This specification describes how to use the ACE framework for
authentication and authorization [I-D.ietf-ace-oauth-authz] to: authentication and authorization [I-D.ietf-ace-oauth-authz] to:
o Enable a node to join an OSCORE group through the Group Manager o Enable a node to join an OSCORE group through the Group Manager
and receive the security parameters and keying material to and receive the security parameters and keying material to
communicate with the other members of the gorup. communicate with the other members of the group.
o Enable members of OSCORE groups to retrieve updated group keying o Enable members of OSCORE groups to retrieve updated group keying
material from the Group Manager. material and public key of other group members, from the Group
Manager.
o Enable the Group Manager to renew the security parameters and o Enable the Group Manager to renew the security parameters and
group keying material, and to (re-)distribute them to the members group keying material, and to (re-)distribute them to the members
of the OSCORE group (rekeying). of the OSCORE group (rekeying).
With reference to the ACE framework and the terminology defined in With reference to the ACE framework and the terminology defined in
OAuth 2.0 [RFC6749]: OAuth 2.0 [RFC6749]:
o The Group Manager acts as Resource Server (RS), and hosts one join o The Group Manager acts as Resource Server (RS), and hosts one
resource for each OSCORE group it manages. Each join resource is group-membership resource for each OSCORE group it manages. Each
exported by a distinct join endpoint. During the join process, group-membership resource is exported by a distinct group-
the Group Manager provides joining nodes with the parameters and membership endpoint. During the joining process, the Group
keying material for taking part to secure communications in the Manager provides joining nodes with the parameters and keying
OSCORE group. The Group Manager also maintains the group keying material for taking part to secure communications in the OSCORE
material and performs the group rekeying process to distribute group. The Group Manager also maintains the group keying material
updated keying material to the group members. and performs the group rekeying process to distribute updated
keying material to the group members.
o The joining node acts as Client (C), and requests to join an o The joining node acts as Client (C), and requests to join an
OSCORE group by accessing the related join endpoint at the Group OSCORE group by accessing the related group-membership endpoint at
Manager. the Group Manager.
o The Authorization Server (AS) authorizes joining nodes to join o The Authorization Server (AS) authorizes joining nodes to join
OSCORE groups under their respective Group Manager. Multiple OSCORE groups under their respective Group Manager. Multiple
Group Managers can be associated to the same AS. The AS MAY Group Managers can be associated to the same AS. The AS MAY
release Access Tokens for other purposes than joining OSCORE release Access Tokens for other purposes than joining OSCORE
groups under registered Group Managers. For example, the AS may groups under registered Group Managers. For example, the AS may
also release Access Tokens for accessing resources hosted by also release Access Tokens for accessing resources hosted by
members of OSCORE groups. members of OSCORE groups.
All communications between the involved entities rely on the CoAP All communications between the involved entities rely on the CoAP
protocol and MUST be secured. protocol and MUST be secured.
In particular, communications between the joining node and the Group In particular, communications between the joining node and the Group
Manager leverage protocol-specific transport profiles of ACE to Manager leverage protocol-specific transport profiles of ACE to
achieve communication security, proof-of-possession and server achieve communication security, proof-of-possession and server
authentication. To this end, the AS must signal the specific authentication. To this end, the AS MAY signal the specific
transport profile to use, consistently with requirements and transport profile to use, consistently with requirements and
assumptions defined in the ACE framework [I-D.ietf-ace-oauth-authz]. assumptions defined in the ACE framework [I-D.ietf-ace-oauth-authz].
Note that in the commonly referred base-case the transport profile to
use is pre-configured and well-known to nodes participating in
constrained applications.
With reference to the AS, communications between the joining node and With reference to the AS, communications between the joining node and
the AS (/token endpoint) as well as between the Group Manager and the the AS (/token endpoint) as well as between the Group Manager and the
AS (/introspect endpoint) can be secured by different means, for AS (/introspect endpoint) can be secured by different means, for
instance using DTLS [RFC6347] or OSCORE instance using DTLS [RFC6347] or OSCORE [RFC8613]. Further details
[I-D.ietf-core-object-security]. Further details on how the AS on how the AS secures communications (with the joining node and the
secures communications (with the joining node and the Group Manager) Group Manager) depend on the specifically used transport profile of
depend on the specifically used transport profile of ACE, and are out ACE, and are out of the scope of this specification.
of the scope of this specification.
2.1. Overview of the Join Process 2.1. Overview of the Joining Process
A node performs the following steps in order to join an OSCORE group. A node performs the following steps in order to join an OSCORE group.
Messages exchanged among the participants follow the formats defined The format and processing of messages exchanged among the
in [I-D.ietf-ace-key-groupcomm], and are further specified in participants follow what is defined in [I-D.ietf-ace-key-groupcomm],
Section 3 and Section 4 of this document. The Group Manager acts as and are further specified in Section 3 and Section 4 of this
the Key Distribution Center (KDC) defined in document. The Group Manager acts as the Key Distribution Center
[I-D.ietf-ace-key-groupcomm]. (KDC) defined in [I-D.ietf-ace-key-groupcomm].
1. The joining node requests an Access Token from the AS, in order 1. The joining node requests an Access Token from the AS, in order
to access a join resource on the Group Manager and hence join the to access a group-membership resource on the Group Manager and
associated OSCORE group (see Section 3). The joining node will hence join the associated OSCORE group (see Section 3). The
start or continue using a secure communication channel with the joining node will start or continue using a secure communication
Group Manager, according to the response from the AS. association with the Group Manager, according to the response
from the AS.
2. The joining node transfers authentication and authorization 2. The joining node transfers authentication and authorization
information to the Group Manager by posting the obtained Access information to the Group Manager, by posting the obtained Access
Token (see Section 4). After that, a joining node must have a Token to the /authz-info endpoint at the Group Manager (see
secure communication channel established with the Group Manager, Section 4). After that, a joining node MUST have a secure
communication association established with the Group Manager,
before starting to join an OSCORE group under that Group Manager before starting to join an OSCORE group under that Group Manager
(see Section 4). Possible ways to provide a secure communication (see Section 4). Possible ways to provide a secure communication
channel are DTLS [RFC6347] and OSCORE association are DTLS [RFC6347] and OSCORE [RFC8613].
[I-D.ietf-core-object-security].
3. The joining node starts the join process to become a member of 3. The joining node starts the joining process to become a member of
the OSCORE group, by accessing the related join resource hosted the OSCORE group, by accessing the related group-membership
by the Group Manager (see Section 4). resource hosted by the Group Manager (see Section 4).
4. At the end of the join process, the joining node has received 4. At the end of the joining process, the joining node has received
from the Group Manager the parameters and keying material to from the Group Manager the parameters and keying material to
securely communicate with the other members of the OSCORE group. securely communicate with the other members of the OSCORE group.
5. The joining node and the Group Manager maintain the secure 5. The joining node and the Group Manager maintain the secure
channel, to support possible future communications. association, to support possible future communications. These
especially include key management operations, such as retrieval
of updated keying material from the Group Manager or
participation to a group rekeying process (see Section 2.2).
All further communications between the joining node and the Group All further communications between the joining node and the Group
Manager MUST be secured, for instance with the same secure channel Manager MUST be secured, for instance with the same secure
mentioned in step 2. association mentioned in step 2.
2.2. Overview of the Group Rekeying Process 2.2. Overview of the Group Rekeying Process
If the application requires backward and forward security, the Group If the application requires backward and forward security, the Group
Manager MUST generate new security parameters and group keying Manager MUST generate new security parameters and group keying
material, and distribute them to the group (rekeying) upon membership material, and distribute them to the group (rekeying) upon membership
changes. changes.
That is, the group is rekeyed when a node joins the group as a new That is, the group is rekeyed when a node joins the group as a new
member, or after a current member leaves the group. By doing so, a member, or after a current member leaves the group. By doing so, a
joining node cannot access communications in the group prior its joining node cannot access communications in the group prior its
joining, while a leaving node cannot access communications in the joining, while a leaving node cannot access communications in the
group after its leaving. group after its leaving.
Parameters and keying material include a new Group Identifier (Gid) Parameters and group keying material include a new Group Identifier
for the group and a new Master Secret for the OSCORE Common Security (Gid) for the group and a new Master Secret for the OSCORE Common
Context of that group (see Section 2 of Security Context of that group (see Section 2 of
[I-D.ietf-core-oscore-groupcomm]). [I-D.ietf-core-oscore-groupcomm]). Once completed a group rekeying,
the GM MUST increment the version number of the group keying
material.
The Group Manager MUST support the Group Rekeying Process described The Group Manager MUST support the Group Rekeying Process described
in Section 7. Future application profiles may define alternative in Section 13. Future application profiles may define alternative
message formats and distribution schemes to perform group rekeying. message formats and distribution schemes to perform group rekeying.
3. Joining Node to Authorization Server 3. Joining Node to Authorization Server
This section describes how the joining node interacts with the AS in This section describes how the joining node interacts with the AS in
order to be authorized to join an OSCORE group under a given Group order to be authorized to join an OSCORE group under a given Group
Manager. In particular, it considers a joining node that intends to Manager. In particular, it considers a joining node that intends to
contact that Group Manager for the first time. contact that Group Manager for the first time.
The message exchange between the joining node and the AS consists of The message exchange between the joining node and the AS consists of
skipping to change at page 9, line 33 skipping to change at page 9, line 8
in Section 3 of [I-D.ietf-ace-key-groupcomm]. in Section 3 of [I-D.ietf-ace-key-groupcomm].
In case the specific AS associated to the Group Manager is unknown to In case the specific AS associated to the Group Manager is unknown to
the joining node, the latter can rely on mechanisms like the the joining node, the latter can rely on mechanisms like the
Unauthorized Resource Request message described in Section 5.1.1 of Unauthorized Resource Request message described in Section 5.1.1 of
[I-D.ietf-ace-oauth-authz] to discover the correct AS to contact. [I-D.ietf-ace-oauth-authz] to discover the correct AS to contact.
3.1. Authorization Request 3.1. Authorization Request
The joining node contacts the AS, in order to request an Access Token The joining node contacts the AS, in order to request an Access Token
for accessing the join resource hosted by the Group Manager and for accessing the group-membership resource hosted by the Group
associated to the OSCORE group. The Access Token request sent to the Manager and associated to the OSCORE group. The Access Token request
/token endpoint follows the format of the Authorization Request sent to the /token endpoint follows the format of the Authorization
message defined in Section 3.1 of [I-D.ietf-ace-key-groupcomm]. In Request message defined in Section 3.1 of
particular: [I-D.ietf-ace-key-groupcomm]. In particular:
o The 'scope' parameter MUST be present and MUST include: o The 'scope' parameter MUST be present and MUST include:
* in the first element, either the Group Identifier (Gid) of the * in the first element, the name of the OSCORE group to join
group to join under the Group Manager, or a value from which under the Group Manager, encoded as a CBOR text string.
the Group Manager can derive the Gid of the group to join. It
is up to the application to define how the Group Manager
possibly performs the derivation of the full Gid. Appendix C of
[I-D.ietf-core-oscore-groupcomm] provides an example of
structured Gid, composed of a fixed part, namely Group Prefix,
and a variable part, namely Group Epoch.
* in the second element, the role (encoded as a text string) or * in the second element, the role (encoded as a text string) or
CBOR array of roles that the joining node intends to have in CBOR array of roles that the joining node intends to have in
the group it intends to join. Accepted values of roles are: the group it intends to join. Accepted values of roles are:
"requester", "responder", and "monitor". Possible combinations "requester", "responder", and "monitor". Possible combinations
are: ["requester" , "responder"]; ["requester" , "monitor"]. are: ["requester" , "responder"]; ["requester" , "monitor"].
o The 'audience' parameter MUST be present and is set to the o The 'audience' parameter MUST be present and is set to the
identifier of the Group Manager. identifier of the Group Manager.
3.2. Authorization Response 3.2. Authorization Response
The AS is responsible for authorizing the joining node to join The AS is responsible for authorizing the joining node to join
specific OSCORE groups, according to join policies enforced on behalf specific OSCORE groups, according to join policies enforced on behalf
skipping to change at page 10, line 25 skipping to change at page 9, line 42
of the respective Group Manager. of the respective Group Manager.
In case of successful authorization, the AS releases an Access Token In case of successful authorization, the AS releases an Access Token
bound to a proof-of-possession key associated to the joining node. bound to a proof-of-possession key associated to the joining node.
Then, the AS provides the joining node with the Access Token as part Then, the AS provides the joining node with the Access Token as part
of an Access Token response, which follows the format of the of an Access Token response, which follows the format of the
Authorization Response message defined in Section 3.2 of Authorization Response message defined in Section 3.2 of
[I-D.ietf-ace-key-groupcomm]. [I-D.ietf-ace-key-groupcomm].
The 'exp' parameter MUST be present. Other means for the AS to The AS MUST include the 'exp' parameter in the response to the
specify the lifetime of Access Tokens are out of the scope of this joining node. Other means for the AS to specify the lifetime of
specification. Access Tokens are out of the scope of this specification.
The AS must include the 'scope' parameter in the response when the The AS must include the 'scope' parameter in the response to the
value included in the Access Token differs from the one specified by joining node, when the value included in the Access Token differs
the joining node in the request. In such a case, the second element from the one specified by the joining node in the request. In such a
of 'scope' MUST be present and includes the role or CBOR array of case, the second element of 'scope' MUST be present and includes the
roles that the joining node is actually authorized to take in the role or CBOR array of roles that the joining node is actually
group, encoded as specified in Section 3.1 of this document. authorized to take in the group, encoded as specified in Section 3.1
of this document.
Also, the 'profile' parameter indicates the specific transport The AS MAY also include the 'profile' parameter in the response to
profile of ACE to use for securing communications between the joining the joining node, in order to indicate the specific transport profile
node and the Group Manager (see Section 5.6.4.3 of of ACE to use for securing communications between the joining node
and the Group Manager (see Section 5.6.4.3 of
[I-D.ietf-ace-oauth-authz]). [I-D.ietf-ace-oauth-authz]).
In particular, if symmetric keys are used, the AS generates a proof- In particular, if symmetric keys are used, the AS generates a proof-
of-possession key, binds it to the Access Token, and provides it to of-possession key, binds it to the Access Token, and provides it to
the joining node in the 'cnf' parameter of the Access Token response. the joining node in the 'cnf' parameter of the Access Token response.
Instead, if asymmetric keys are used, the joining node provides its Instead, if asymmetric keys are used, the joining node provides its
own public key to the AS in the 'req_cnf' parameter of the Access own public key to the AS in the 'req_cnf' parameter of the Access
Token request. Then, the AS uses it as proof-of-possession key bound Token request. Then, the AS uses it as proof-of-possession key bound
to the Access Token, and provides the joining node with the Group to the Access Token, and provides the joining node with the Group
Manager's public key in the 'rs_cnf' parameter of the Access Token Manager's public key in the 'rs_cnf' parameter of the Access Token
response. response.
4. Joining Node to Group Manager 4. Joining Node to Group Manager
The following subsections describe the interactions between the The following subsections describe the interactions between the
joining node and the Group Manager, i.e. the Access Token post and joining node and the Group Manager, i.e. the sending of the Access
the Request-Response exchange to join the OSCORE group. Token and the Request-Response exchange to join the OSCORE group.
4.1. Token Post 4.1. Token Post
The joining node posts the Access Token to the /authz-info endpoint The joining node posts the Access Token to the /authz-info endpoint
at the Group Manager, according to the Token post defined in at the Group Manager, according to the Token post defined in
Section 3.3 of [I-D.ietf-ace-key-groupcomm]. Section 3.3 of [I-D.ietf-ace-key-groupcomm].
At this point in time, the joining node might not have all the At this point in time, the joining node might not have all the
necessary information concerning the public keys in the OSCORE group, necessary information concerning the public keys in the OSCORE group,
as well as concerning the algorithm and related parameters for as well as concerning the algorithm and related parameters for
skipping to change at page 11, line 36 skipping to change at page 10, line 52
other means, e.g. by using the approach described in other means, e.g. by using the approach described in
[I-D.tiloca-core-oscore-discovery]. [I-D.tiloca-core-oscore-discovery].
If the Access Token is valid, the Group Manager responds to the POST If the Access Token is valid, the Group Manager responds to the POST
request with a 2.01 (Created) response, according to what is request with a 2.01 (Created) response, according to what is
specified in the signalled transport profile of ACE. The Group specified in the signalled transport profile of ACE. The Group
Manager MUST use the Content-Format "application/ace+cbor" defined in Manager MUST use the Content-Format "application/ace+cbor" defined in
Section 8.14 of [I-D.ietf-ace-oauth-authz]. Section 8.14 of [I-D.ietf-ace-oauth-authz].
The payload of the 2.01 (Created) response is a CBOR map, which MUST The payload of the 2.01 (Created) response is a CBOR map, which MUST
include the 'cnonce' parameter defined in section 5.1.2 of include the 'rsnonce' parameter defined in Section 3.3.3 of
[I-D.ietf-ace-oauth-authz], and MAY include the 'sign_info' parameter
as well as the 'pub_key_enc' parameter.
The 'cnonce' parameter includes a nonce N generated by the Group [I-D.ietf-ace-key-groupcomm], and MAY include the 'sign_info'
Manager. The joining node may use this nonce in order to prove the parameter as well as the 'pub_key_enc' parameter, defined in its
possession of its own private key, upon joining the group (see Sections 3.3.1 and 3.3.2, respectively. Note that this deviates from
Section 4.2). the default payload format for this response message as defined in
the ACE framework (see Section 5.8.1 of [I-D.ietf-ace-oauth-authz]).
The 'rsnonce' parameter includes a dedicated nonce N_S generated by
the Group Manager. The joining node may use this nonce in order to
prove the possession of its own private key, upon joining the group
(see Section 4.2).
If present in the response: If present in the response:
o 'sign_alg', i.e. the first element of the 'sign_info' parameter, o 'sign_alg', i.e. the first element of the 'sign_info' parameter,
takes value from Tables 5 and 6 of [RFC8152]. takes value from Tables 5 and 6 of [RFC8152].
o 'sign_parameters', i.e. the second element of the 'sign_info' o 'sign_parameters', i.e. the second element of the 'sign_info'
parameter, takes values from the "Counter Signature Parameters" parameter, takes values from the "Counter Signature Parameters"
Registry (see Section 9.1 of [I-D.ietf-core-oscore-groupcomm]). Registry (see Section 9.1 of [I-D.ietf-core-oscore-groupcomm]).
Its structure depends on the value of 'sign_alg'. If no Its structure depends on the value of 'sign_alg'. If no
parameters of the counter signature algorithm are specified, parameters of the counter signature algorithm are specified,
'sign_parameters' MUST be encoding the CBOR simple value Null. 'sign_parameters' MUST be encoding the CBOR simple value Null.
o 'sign_key_parameters', i.e. the third element of the 'sign_info' o 'sign_key_parameters', i.e. the third element of the 'sign_info'
parameter, takes values from the "Counter Signature Key parameter, takes values from the "Counter Signature Key
Parameters" Registry (see Section 9.2 of Parameters" Registry (see Section 9.2 of
[I-D.ietf-core-oscore-groupcomm]). Its structure depends on the [I-D.ietf-core-oscore-groupcomm]). Its structure depends on the
value of 'sign_alg'. If no parameters of the key used with the value of 'sign_alg'. If no parameters of the key used with the
counter signature algorithm are specified, 'sign_key_parameters' counter signature algorithm are specified, 'sign_key_parameters'
skipping to change at page 12, line 17 skipping to change at page 11, line 36
'sign_parameters' MUST be encoding the CBOR simple value Null. 'sign_parameters' MUST be encoding the CBOR simple value Null.
o 'sign_key_parameters', i.e. the third element of the 'sign_info' o 'sign_key_parameters', i.e. the third element of the 'sign_info'
parameter, takes values from the "Counter Signature Key parameter, takes values from the "Counter Signature Key
Parameters" Registry (see Section 9.2 of Parameters" Registry (see Section 9.2 of
[I-D.ietf-core-oscore-groupcomm]). Its structure depends on the [I-D.ietf-core-oscore-groupcomm]). Its structure depends on the
value of 'sign_alg'. If no parameters of the key used with the value of 'sign_alg'. If no parameters of the key used with the
counter signature algorithm are specified, 'sign_key_parameters' counter signature algorithm are specified, 'sign_key_parameters'
MUST be encoding the CBOR simple value Null. MUST be encoding the CBOR simple value Null.
o 'pub_key_enc' takes value from Figure 2, as a public key encoding o 'pub_key_enc' takes value 1 ("COSE_Key") from the 'Confirmation
in the "ACE Public Key Encoding" Registry (see Section 11.2 of Key' column of the "CWT Confirmation Method" Registry defined in
[I-D.ietf-ace-key-groupcomm]). [I-D.ietf-ace-cwt-proof-of-possession], so indicating that public
keys in the OSCORE group are encoded as COSE Keys [RFC8152].
+----------+-------+--------------------------------+-------------+ Future specifications may define additional values for this
| Name | Value | Description | Reference | parameter.
+----------+-------+--------------------------------+-------------+
| COSE_Key | 1 | Public key encoded as COSE Key | {{RFC8152}} |
+----------+-------+--------------------------------+-------------+
Figure 2: ACE Public Key Encoding Values
Note that the CBOR map specified as payload of the 2.01 (Created) The CBOR map specified as payload of the 2.01 (Created) response may
response may include further parameters, e.g. according to the include further parameters, e.g. according to the signalled transport
signalled transport profile of ACE. profile of ACE.
Finally, the joining node establishes a secure channel with the Group Finally, the joining node establishes a secure channel with the Group
Manager, according to what is specified in the Access Token response Manager, according to what is specified in the Access Token response
and the signalled transport profile of ACE. and the signalled transport profile of ACE.
4.2. Join Request 4.2. Joining Request
Once a secure communication channel with the Group Manager has been Once a secure communication channel with the Group Manager has been
established, the joining node requests to join the OSCORE group, by established, the joining node requests to join the OSCORE group, by
accessing the related join resource at the Group Manager. sending a Joining Request message to the related group-membership
resource at the Group Manager, as per Section 4.2 of
[I-D.ietf-ace-key-groupcomm].
In particular, the joining node sends to the Group Manager a In particular, the joining node sends a CoAP POST request to the
confirmable CoAP request, using the method POST and targeting the endpoint /group-oscore/NAME at the Group Manager, where NAME is the
join endpoint associated to that group. This Join Request follows name of the OSCORE group to join. This Joining Request is formatted
the format and processing of the Key Distribution Request message as defined in Section 4.1.2.1 of [I-D.ietf-ace-key-groupcomm].
defined in Section 4.1 of [I-D.ietf-ace-key-groupcomm]. In Specifically:
particular:
o The 'type' parameter is set to 1 ("key distribution"). o The 'scope' parameter MUST be present.
o The 'get_pub_keys' parameter is present only if the joining node o The 'get_pub_keys' parameter is present only if the joining node
wants to retrieve the public keys of the group members from the wants to retrieve the public keys of the group members from the
Group Manager during the join process (see Section 6). Otherwise, Group Manager during the joining process (see Section 5).
this parameter MUST NOT be present. Otherwise, this parameter MUST NOT be present.
o The 'client_cred' parameter, if present, includes the public key o The 'client_cred' parameter, if present, includes the public key
of the joining node. In case the joining node knows the encoding of the joining node. In case the joining node knows the encoding
of public keys in the OSCORE group, as well as the of public keys in the OSCORE group, as well as the
countersignature algorithm and possible associated parameters used countersignature algorithm and possible associated parameters used
in the OSCORE group, the included public key MUST be in a in the OSCORE group, the included public key MUST be compatible
consistent format. This parameter MAY be omitted if: i) the with those criteria. That is, the public key MUST be encoded
joining node is asking to access the group exclusively as monitor; according to the encoding of public keys in the OSCORE group, and
or ii) the Group Manager already acquired this information, for MUST be compatible with the countersignature algorithm and
instance during a past join process. In any other case, this possible associated parameters used in the OSCORE group. This
parameter MUST be present. parameter MAY be omitted if: i) the joining node is asking to
access the group exclusively as monitor; or ii) the Group Manager
already acquired this information, for instance during a past
joining process. In any other case, this parameter MUST be
present.
Furthermore, the CBOR map specified as payload of the Join Request Furthermore, if the 'client_cred' parameter is present, the CBOR map
MAY also include the following additional parameter, which MUST be specified as payload of the Joining Request MUST also include the
present if the 'client_cred' parameter is present. following parameters.
o The 'client_cred_verify' parameter, which is encoded as a CBOR o 'cnonce', as defined in Section 5.1.2 of
byte string and contains a signature computed by the joining node, [I-D.ietf-ace-oauth-authz], and including a dedicated nonce N_C
in order to prove possession of its own private key. The generated by the Client.
signature is computed over the nonce N received in the 2.01
(Created) response to the Token POST (see Section 4.1). In
particular, the joining node MUST use the COSE_CounterSignature0
object [RFC8152], with the Sig_structure containing the nonce N as
payload; and an empty external_aad. The joining node computes the
signature by using the same private key and countersignature
algorithm it intends to use for signing messages in the OSCORE
group.
4.3. Join Response o The 'client_cred_verify' parameter, including a signature encoded
as a CBOR byte string, computed by the joining node to prove
possession of its own private key. The signature is computed over
N_S concatenated with N_C, where N_S is the nonce received in the
'rsnonce' parameter of the 2.01 (Created) response to the Token
POST (see Section 4.1), while N_C is the nonce generated by the
Client and specified in the 'cnonce' parameter above. The joining
node computes the signature by using the same private key and
countersignature algorithm it intends to use for signing messages
in the OSCORE group.
The Group Manager processes the Join Request according to 4.3. Joining Response
[I-D.ietf-ace-oauth-authz] and Section 4.2 of
[I-D.ietf-ace-key-groupcomm]. Also, the Group Manager MUST return a The Group Manager processes the Joining Request as defined in
4.00 (Bad Request) response in case the Join Request includes the Section 4.1.2.1 of [I-D.ietf-ace-key-groupcomm]. Also, the Group
'client_cred' parameter but does not include the 'client_cred_verify' Manager MUST return a 4.00 (Bad Request) response in case the Joining
parameter. Request includes the 'client_cred' parameter but does not include
both the 'cnonce' and 'client_cred_verify' parameters.
If the request processing yields a positive outcome, the Group If the request processing yields a positive outcome, the Group
Manager performs the further following checks. Manager performs the further following checks.
o In case the Join Request includes the 'client_cred' parameter, the o In case the Joining Request includes the 'client_cred' parameter,
Group Manager checks that the public key of the joining node has the Group Manager checks that the public key of the joining node
an accepted format. That is, the public key has to be encoded as has an accepted format. That is, the public key has to be encoded
expected in the OSCORE group, and has to be consistent with the as expected in the OSCORE group, and has to be compatible with the
counter signature algorithm and possible associated parameters counter signature algorithm and possible associated parameters
used in the OSCORE group. The join process fails if the public used in the OSCORE group. The joining process fails if the public
key of the joining node does not have an accepted format. key of the joining node does not have an accepted format.
o In case the Join Request does not include the 'client_cred' o In case the Joining Request does not include the 'client_cred'
parameter, the Group Manager checks whether it is storing a public parameter, the Group Manager checks whether it is storing a public
key for the joining node, which is consistent with the encoding, key for the joining node, which is compatible with the encoding,
counter signature algorithm and possible associated parameters counter signature algorithm and possible associated parameters
used in the OSCORE group. The join process fails if the Group used in the OSCORE group. The joining process fails if the Group
Manager either: i) does not store a public key with an accepted Manager either: i) does not store a public key with an accepted
format for the joining node; or ii) stores multiple public keys format for the joining node; or ii) stores multiple public keys
with an accepted format for the joining node. with an accepted format for the joining node.
o In case the Join Request includes the 'client_cred_verify' o In case the Joining Request includes the 'client_cred_verify'
parameter, the Group Manager verifies the signature contained in parameter, the Group Manager verifies the signature contained in
the parameter. To this end, it considers: i) as signed value, the the parameter. To this end, it considers: i) as signed value, N_S
nonce N previously provided in the 2.01 (Created) response to the concatenated with N_C, where N_S is the nonce previously provided
Token POST (see Section 4.1); ii) the countersignature algorithm in the 'rsnonce' parameter of the 2.01 (Created) response to the
used in the OSCORE group; and iii) the public key of the joining Token POST (see Section 4.1), while N_C is the nonce provided in
node, either retrieved from the 'client_cred' parameter, or as the 'cnonce' parameter of the Joining Request; ii) the
stored from a past join process. The join process fails if the countersignature algorithm used in the OSCORE group, and possible
Group Manager does not successfully verify the signature. correponding parameters; and iii) the public key of the joining
node, either retrieved from the 'client_cred' parameter, or
already stored as acquired from previous interactions with the
joining node. The joining process fails if the Group Manager does
not successfully verify the signature.
If the join process has failed, the Group Manager MUST reply to the If the joining process has failed, the Group Manager MUST reply to
joining node with a 4.00 (Bad Request) response. The payload of this the joining node with a 4.00 (Bad Request) response. The payload of
response is a CBOR map, which includes a 'sign_info' parameter and a this response is a CBOR map, which includes a 'sign_info' parameter
'pub_key_enc' parameter, formatted as in the Token POST response in and a 'pub_key_enc' parameter, formatted as in the Token POST
Section 4.1. response in Section 4.1.
Upon receiving this response, the joining node SHOULD send a new Join Upon receiving this response, the joining node SHOULD send a new
Request to the Group Manager, which contains: Joining Request to the Group Manager, which contains:
o The 'client_cred' parameter, including a public key in a format o The 'client_cred' parameter, including a public key compatible
consistent with the encoding, countersignature algorithm and with the encoding, countersignature algorithm and possible
possible associated parameters indicated by the Group Manager. associated parameters indicated by the Group Manager.
o The 'client_cred_verify' parameter, including a signature computed o The 'client_cred_verify' parameter, including a signature computed
as described in Section 4.2, by using the public key indicated in as described in Section 4.2, by using the public key indicated in
the current 'client_cred' parameter, with the countersignature the current 'client_cred' parameter, with the countersignature
algorithm and possible associated parameters indicated by the algorithm and possible associated parameters indicated by the
Group Manager. Group Manager.
Otherwise, in case of success, the Group Manager updates the group Otherwise, in case of success, the Group Manager updates the group
membership by registering the joining node as a new member of the membership by registering the joining node as a new member of the
OSCORE group. OSCORE group. If the joining node is not exclusively configured as
monitor, the Group Manager performs also the following actions.
o The Group Manager selects an available OSCORE Sender ID in the
OSCORE group, and exclusively assigns it to the joining node.
o If the 'client_cred' parameter was present in the request, the
Group Manager adds the specified public key of the joining node to
the list of public keys of the current group members.
o If the 'client_cred' parameter was not present in the request, the
Group Manager retrieves the already stored public key of the
joining node, as acquired from previous interactions (see also
Section 5). Then, the Group Manager adds the retrieved public key
to the list of public keys of the current group members.
o The Group Manager stores the association between i) the public key
of the joining node; and ii) the Group Identifier (Gid) associated
to the OSCORE group together with the OSCORE Sender ID assigned to
the joining node in the group. The Group Manager MUST keep this
association updated over time.
Then, the Group Manager replies to the joining node providing the Then, the Group Manager replies to the joining node providing the
updated security parameters and keying meterial necessary to updated security parameters and keying meterial necessary to
participate in the group communication. This Join Response follows participate in the group communication. This success Joining
the format and processing of the Key Distribution success Response Response is formatted as defined in Section 4.1.2.1 of
message defined in Section 4.2 of [I-D.ietf-ace-key-groupcomm]. In [I-D.ietf-ace-key-groupcomm]. In particular:
particular:
o The 'kty' parameter identifies a key of type o The 'kty' parameter identifies a key of type
"Group_OSCORE_Security_Context object", defined in Section 9.1 of "Group_OSCORE_Security_Context object", defined in Section 15.1 of
this specification. this specification.
o The 'key' parameter includes what the joining node needs in order o The 'key' parameter includes what the joining node needs in order
to set up the OSCORE Security Context as per Section 2 of to set up the OSCORE Security Context as per Section 2 of
[I-D.ietf-core-oscore-groupcomm]. This parameter has as value a [I-D.ietf-core-oscore-groupcomm]. This parameter has as value a
Group_OSCORE_Security_Context object, which is defined in this Group_OSCORE_Security_Context object, which is defined in this
specification and extends the OSCORE_Security_Context object specification and extends the OSCORE_Security_Context object
encoded in CBOR as defined in Section 3.2.1 of encoded in CBOR as defined in Section 3.2.1 of
[I-D.ietf-ace-oscore-profile]. In particular, it contains the [I-D.ietf-ace-oscore-profile]. In particular, it contains the
additional parameters 'cs_alg', 'cs_params', 'cs_key_params' and additional parameters 'cs_alg', 'cs_params', 'cs_key_params' and
'cs_key_enc' defined in Section 9.2 of this specification. More 'cs_key_enc' defined in Section 15.2 of this specification. More
specifically, the 'key' parameter is composed as follows. specifically, the 'key' parameter is composed as follows.
* The 'ms' parameter MUST be present and includes the OSCORE * The 'ms' parameter MUST be present and includes the OSCORE
Master Secret value. Master Secret value.
* The 'clientId' parameter, if present, has as value the OSCORE * The 'clientId' parameter, if present, has as value the OSCORE
Sender ID assigned to the joining node by the Group Manager. Sender ID assigned to the joining node by the Group Manager, as
This parameter is not present if the node joins the group described above. This parameter is not present if the node
exclusively as monitor, according to what specified in the joins the group exclusively as monitor, according to what
Access Token (see Section 3.2). In any other case, this specified in the Access Token (see Section 3.2). In any other
parameter MUST be present. case, this parameter MUST be present.
* The 'hkdf' parameter, if present, has as value the KDF * The 'hkdf' parameter, if present, has as value the KDF
algorithm used in the group. algorithm used in the group.
* The 'alg' parameter, if present, has as value the AEAD * The 'alg' parameter, if present, has as value the AEAD
algorithm used in the group. algorithm used in the group.
* The 'salt' parameter, if present, has as value the OSCORE * The 'salt' parameter, if present, has as value the OSCORE
Master Salt. Master Salt.
skipping to change at page 16, line 20 skipping to change at page 16, line 16
* The 'cs_key_params' parameter MAY be present and specifies the * The 'cs_key_params' parameter MAY be present and specifies the
additional parameters for the key used with the counter additional parameters for the key used with the counter
signature algorithm. This parameter is a CBOR map whose signature algorithm. This parameter is a CBOR map whose
content depends on the counter signature algorithm, as content depends on the counter signature algorithm, as
specified in Section 2 and Section 9.2 of specified in Section 2 and Section 9.2 of
[I-D.ietf-core-oscore-groupcomm]. [I-D.ietf-core-oscore-groupcomm].
* The 'cs_key_enc' parameter MAY be present and specifies the * The 'cs_key_enc' parameter MAY be present and specifies the
encoding of the public keys of the group members. This encoding of the public keys of the group members. This
parameter is a CBOR integer, whose value is taken from parameter is a CBOR integer, whose value is 1 ("COSE_Key")
Figure 2, as a public key encoding in the "ACE Public Key taken from the 'Confirmation Key' column of the "CWT
Encoding" Registry (see Section 11.2 of Confirmation Method" Registry defined in
[I-D.ietf-ace-key-groupcomm]). If this parameter is not [I-D.ietf-ace-cwt-proof-of-possession], so indicating that
present, COSE_Key (1) MUST be assumed as default value. public keys in the OSCORE group are encoded as COSE Keys
[RFC8152]. Future specifications may define additional values
for this parameter. If this parameter is not present, 1
("COSE_Key") MUST be assumed as default value.
o The 'num' parameter MUST be present and specifies the current
version number of the group keying material.
o The 'profile' parameter MUST be present and has value o The 'profile' parameter MUST be present and has value
coap_group_oscore_app (TBD), which is defined in Section 9.3 of coap_group_oscore_app (TBD), which is defined in Section 15.3 of
this specification. this specification.
o The 'exp' parameter MUST be present and specifies the expiration o The 'exp' parameter MUST be present and specifies the expiration
time in seconds after which the OSCORE Security Context derived time in seconds after which the OSCORE Security Context derived
from the 'key' parameter is not valid anymore. from the 'key' parameter is not valid anymore.
o The 'pub_keys' parameter is present only if the 'get_pub_keys' o The 'pub_keys' parameter is present only if the 'get_pub_keys'
parameter was present in the Join Request. If present, this parameter was present in the Joining Request. If present, this
parameter includes the public keys of the group members that are parameter includes the public keys of the group members that are
relevant to the joining node. That is, it includes: i) the public relevant to the joining node. That is, it includes: i) the public
keys of the responders currently in the group, in case the joining keys of the responders currently in the group, in case the joining
node is configured (also) as requester; and ii) the public keys of node is configured (also) as requester; and ii) the public keys of
the requesters currently in the group, in case the joining node is the requesters currently in the group, in case the joining node is
configured (also) as responder or monitor. configured (also) as responder or monitor. If public keys are
encoded as COSE_Keys, each of them has as 'kid' the Sender ID that
the corresponding owner has in the group, thus used as group
member identifier.
o The 'group_policies' parameter SHOULD be present and includes a o The 'group_policies' parameter SHOULD be present and includes a
list of parameters indicating particular policies enforced in the list of parameters indicating particular policies enforced in the
group. For instance, its field "Sequence Number Synchronization group. In particular, if the field "Sequence Number
Method" can indicate the method to achieve synchronization of Synchronization Method" is present, it indicates the method to
sequence numbers among group members (see Appendix E of achieve synchronization of sequence numbers among group members
[I-D.ietf-core-oscore-groupcomm]), as indicated by the (see Appendix E of [I-D.ietf-core-oscore-groupcomm]), by
corresponding value from the "Sequence Number Synchronization specifying the corresponding value from the "Sequence Number
Method" Registry defined in Section 11.8 of Synchronization Method" Registry defined in Section 8.6 of
[I-D.ietf-ace-key-groupcomm]. [I-D.ietf-ace-key-groupcomm].
Finally, the joining node uses the information received in the Join Finally, the joining node uses the information received in the
Response to set up the OSCORE Security Context, as described in Joining Response to set up the OSCORE Security Context, as described
Section 2 of [I-D.ietf-core-oscore-groupcomm]. From then on, the in Section 2 of [I-D.ietf-core-oscore-groupcomm]. From then on, the
joining node can exchange group messages secured with OSCORE as joining node can exchange group messages secured with Group OSCORE as
described in [I-D.ietf-core-oscore-groupcomm]. described in [I-D.ietf-core-oscore-groupcomm].
If the application requires backward security, the Group Manager If the application requires backward security, the Group Manager MUST
SHALL generate updated security parameters and group keying material,
and provide it to all the current group members (see Section 7).
When the OSCORE Security Context expires, as specified by the 'exp'
parameter of the Join Response, the node considers it invalid and to
be renewed. Then, the node retrieves updated security parameters and
keying material, by exchanging with the Group Manager a shortened
Join Request sent to the same Join Resource with the 'type' parameter
set to 3 ("update key") and a shortened Join Response message,
according to the approach defined in Section 6 of
[I-D.ietf-ace-key-groupcomm]. Finally, the node uses the updated
security parameters and keying material to set up the new OSCORE
Security Context as described in Section 2 of
[I-D.ietf-core-oscore-groupcomm].
Furthermore, as discussed in Section 2.2 of
[I-D.ietf-core-oscore-groupcomm], the node may at some point
experience a wrap-around of its own Sender Sequence Number in the
group. When this happens, the node MUST send to the Group Manager a
shortened Join Request message to the same Join Resource, with the
'type' parameter set to 4 ("new"). Upon receiving this request
message, the Group Manager either rekeys the whole OSCORE group as
discussed in Section 7, or generates a new Sender ID for that node
and replies with a shortened Join Response message where:
o Only the parameters 'type', 'kty', 'key', 'profile' and 'exp' are
present.
o The 'clientId' parameter of the 'key' parameter specifies the new
Sender ID of the node.
5. Leaving of a Group Member
A node may be removed from the OSCORE group, due to expired or
revoked authorization, or after its own request to the Group Manager.
If the application requires forward security, the Group Manager SHALL
generate updated security parameters and group keying material, and generate updated security parameters and group keying material, and
provide it to the remaining group members (see Section 7). The provide it to all the current group members (see Section 13).
leaving node must not be able to acquire the new security parameters
and group keying material distributed after its leaving.
Same considerations in Section 5 of [I-D.ietf-ace-key-groupcomm]
apply here as well, considering the Group Manager acting as KDC. In
particular, a node requests to leave the OSCORE group as described in
Section 5.2 of [I-D.ietf-ace-key-groupcomm], i.e. by sending to the
Group Manager a request to the same Join Resource with the 'type'
parameter set to 2 ("leave").
6. Public Keys of Joining Nodes 5. Public Keys of Joining Nodes
Source authentication of OSCORE messages exchanged within the group Source authentication of OSCORE messages exchanged within the group
is ensured by means of digital counter signatures (see Sections 2 and is ensured by means of digital counter signatures (see Sections 2 and
3 of [I-D.ietf-core-oscore-groupcomm]). Therefore, group members 3 of [I-D.ietf-core-oscore-groupcomm]). Therefore, group members
must be able to retrieve each other's public key from a trusted key must be able to retrieve each other's public key from a trusted key
repository, in order to verify source authenticity of incoming group repository, in order to verify source authenticity of incoming group
messages. messages.
As also discussed in [I-D.ietf-core-oscore-groupcomm], the Group As also discussed in [I-D.ietf-core-oscore-groupcomm], the Group
Manager acts as trusted repository of the public keys of the group Manager acts as trusted repository of the public keys of the group
skipping to change at page 18, line 40 skipping to change at page 17, line 48
o The joining node is going to join the group exclusively as o The joining node is going to join the group exclusively as
monitor. That is, it is not going to send messages to the group, monitor. That is, it is not going to send messages to the group,
and hence to produce signatures with its own private key. In this and hence to produce signatures with its own private key. In this
case, the joining node is not required to provide its own public case, the joining node is not required to provide its own public
key to the Group Manager, which thus does not have to perform any key to the Group Manager, which thus does not have to perform any
check related to the public key encoding, or to a countersignature check related to the public key encoding, or to a countersignature
algorithm and possible associated parameters for that joining algorithm and possible associated parameters for that joining
node. node.
o The Group Manager already acquired the public key of the joining o The Group Manager already acquired the public key of the joining
node during a past join process. In this case, the joining node node during a past joining process. In this case, the joining
MAY not provide again its own public key to the Group Manager, in node MAY choose not to provide again its own public key to the
order to limit the size of the Join Request. The joining node Group Manager, in order to limit the size of the Joining Request.
MUST provide its own public key again if it has provided the Group The joining node MUST provide its own public key again if it has
Manager with multiple public keys during past join processes, provided the Group Manager with multiple public keys during past
intended for different OSCORE groups. If the joining node joining processes, intended for different OSCORE groups. If the
provides its own public key, the Group Manager performs joining node provides its own public key, the Group Manager
consistency checks as in Section 4.3 and, in case of success, performs consistency checks as per Section 4.3 and, in case of
considers it as the public key associated to the joining node in success, considers it as the public key associated to the joining
the OSCORE group. node in the OSCORE group.
o The joining node and the Group Manager use an asymmetric proof-of- o The joining node and the Group Manager use an asymmetric proof-of-
possession key to establish a secure communication channel. Then, possession key to establish a secure communication channel. Then,
two cases can occur. two cases can occur.
1. The proof-of-possession key is consistent with the encoding as 1. The proof-of-possession key is compatible with the encoding as
well as with the counter signature algorithm and possible well as with the counter signature algorithm and possible
associated parameters used in the OSCORE group. Then, the associated parameters used in the OSCORE group. Then, the
Group Manager considers the proof-of-possession key as the Group Manager considers the proof-of-possession key as the
public key associated to the joining node in the OSCORE group. public key associated to the joining node in the OSCORE group.
If the joining node is aware that the proof-of-possession key If the joining node is aware that the proof-of-possession key
is also valid for the OSCORE group, it MAY not provide it is also valid for the OSCORE group, it MAY not provide it
again as its own public key to the Group Manager. The joining again as its own public key to the Group Manager. The joining
node MUST provide its own public key again if it has provided node MUST provide its own public key again if it has provided
the Group Manager with multiple public keys during past join the Group Manager with multiple public keys during past
processes, intended for different OSCORE groups. If the joining processes, intended for different OSCORE groups. If
joining node provides its own public key in the 'client_cred' the joining node provides its own public key in the
parameter of the Join Request (see Section 4.2), the Group 'client_cred' parameter of the Joining Request (see
Manager performs consistency checks as in Section 4.3 and, in Section 4.2), the Group Manager performs consistency checks as
case of success, considers it as the public key associated to per Section 4.3 and, in case of success, considers it as the
the joining node in the OSCORE group. public key associated to the joining node in the OSCORE group.
2. The proof-of-possession key is not consistent with the 2. The proof-of-possession key is not compatible with the
encoding or with the counter signature algorithm and possible encoding or with the counter signature algorithm and possible
associated parameters used in the OSCORE group. In this case, associated parameters used in the OSCORE group. In this case,
the joining node MUST provide a different consistent public the joining node MUST provide a different compatible public
key to the Group Manager in the 'client_cred' parameter of the key to the Group Manager in the 'client_cred' parameter of the
Join Request (see Section 4.2). Then, the Group Manager Joining Request (see Section 4.2). Then, the Group Manager
performs consistency checks on this latest provided public key performs consistency checks on this latest provided public key
as in Section 4.3 and, in case of success, considers it as the as per Section 4.3 and, in case of success, considers it as
public key associated to the joining node in the OSCORE group. the public key associated to the joining node in the OSCORE
group.
o The joining node and the Group Manager use a symmetric proof-of- o The joining node and the Group Manager use a symmetric proof-of-
possession key to establish a secure communication channel. In possession key to establish a secure communication channel. In
this case, upon performing a join process with that Group Manager this case, upon performing a joining process with that Group
for the first time, the joining node specifies its own public key Manager for the first time, the joining node specifies its own
in the 'client_cred' parameter of the Join Request targeting the public key in the 'client_cred' parameter of the Joining Request
join endpoint (see Section 4.2). targeting the group-membership endpoint (see Section 4.2).
Furthermore, as described in Section 4.2, the joining node may have 6. Retrieval of Updated Keying Material
explicitly requested the Group Manager to retrieve the public keys of
the current group members, i.e. by including the 'get_pub_keys'
parameter in the Join Request. In this case, the Group Manager
includes also such public keys in the 'pub_keys' parameter of the
Join Response (see Section 4.3).
Later on as a group member, the node may need to retrieve the public At some point, a group member considers the OSCORE Security Context
keys of other group members. The node can do that by exchanging with invalid and to be renewed. This happens, for instance, after a
the Group Manager a shortened Join Request sent to the same Join number of unsuccessful security processing of incoming messages from
Resource with the 'type' parameter set to 5 ("pub keys") and a other group members, or when the Security Context expires as
shortened Join Response, according to the approach defined in specified by the 'exp' parameter of the Joining Response.
Section 7 of [I-D.ietf-ace-key-groupcomm].
7. Group Rekeying Process When this happens, the group member retrieves updated security
parameters and group keying material, by sending a Key Distribution
Request message to the Group Manager, as per Section 4.3 of
[I-D.ietf-ace-key-groupcomm]. In particular, it sends a CoAP GET
request to the endpoint /group-oscore/NAME at the Group Manager,
where NAME is the name of the OSCORE group. The Key Distribution
Request is formatted as defined in Section 4.1.2.2 of
[I-D.ietf-ace-key-groupcomm].
The Group Manager processes the Key Distribution Request according to
Section 4.1.2.2 of [I-D.ietf-ace-key-groupcomm]. The Key
Distribution Response is formatted as defined in Section 4.1.2.2 of
[I-D.ietf-ace-key-groupcomm].
Upon receiving the Key Distribution Response, the group member
retrieves the updated security parameters and group keying material,
and use them to set up the new OSCORE Security Context as described
in Section 2 of [I-D.ietf-core-oscore-groupcomm].
7. Retrieval of New Keying Material
As discussed in Section 2.2 of [I-D.ietf-core-oscore-groupcomm], a
group member may at some point experience a wrap-around of its own
Sender Sequence Number in the group.
When this happens, the group member MUST send a Key Renewal Request
message to the Group Manager, as per Section 4.4 of
[I-D.ietf-ace-key-groupcomm]. In particular, it sends a CoAP GET
request to the endpoint /group-oscore/NAME/node at the Group Manager,
where NAME is the name of the OSCORE group.
Upon receiving the Key Renewal Request, the Group Manager processes
it as defined in Section 4.1.6.2 of [I-D.ietf-ace-key-groupcomm], and
performs one of the following actions.
1. The Group Manager replies to the group member with a 4.06 (Not
Acceptable) error response, and rekeys the whole OSCORE group as
discussed in Section 13.
2. The Group Manager generates a new Sender ID for that group member
and replies with a Key Renewal Response, formatted as defined in
Section 4.1.6.2 of [I-D.ietf-ace-key-groupcomm]. In particular,
the CBOR Map in the response payload includes a single parameter
'clientId' defined in Section 15.5 of this document, specifying
the new Sender ID of the group member encoded as a CBOR byte
string.
8. Retrieval of Public Keys of Group Members
A group member may need to retrieve the public keys of other group
members. To this end, the group member sends a Public Key Request
message to the Group Manager, as per Section 4.5 of
[I-D.ietf-ace-key-groupcomm]. In particular, it sends the request to
the endpoint /group-oscore/NAME/pub-key at the Group Manager, where
NAME is the name of the OSCORE group.
If the Public Key Request uses the method POST, the Public Key
Request is formatted as defined in Section 4.1.3.1 of
[I-D.ietf-ace-key-groupcomm]. In particular, each element of the
'get_pub_keys' parameter is a CBOR byte string, which encodes the
Sender ID of the group member for which the associated public key is
requested.
Upon receiving the Public Key Request, the Group Manager processes it
as per Section 4.1.3.1 or 4.1.3.2 of [I-D.ietf-ace-key-groupcomm],
depending on the request method being POST or GET, respectively. If
the Public Key Request uses the method POST, the Group Manager
silently ignores identifiers included in the 'get_pub_keys' parameter
of the request that are not associated to any current group member.
The success Public Key Response is formatted as defined in
Section 4.1.3.1 of [I-D.ietf-ace-key-groupcomm].
9. Retrieval of Group Policies
A group member may request the current policies used in the OSCORE
group. To this end, the group member sends a Policies Request, as
per Section 4.6 of [I-D.ietf-ace-key-groupcomm]. In particular, it
sends a CoAP GET request to the endpoint /group-oscore/NAME/policies
at the Group Manager, where NAME is the name of the OSCORE group.
Upon receiving the Policies Request, the Group Manager processes it
as per Section 4.1.4.1 of [I-D.ietf-ace-key-groupcomm]. The success
Policies Response is formatted as defined in Section 4.1.4.1 of
[I-D.ietf-ace-key-groupcomm].
10. Retrieval of Keying Material Version
A group member may request the current version of the keying material
used in the OSCORE group. To this end, the group member sends a
Version Request, as per Section 4.7 of [I-D.ietf-ace-key-groupcomm].
In particular, it sends a CoAP GET request to the endpoint /group-
oscore/NAME/ctx-num at the Group Manager, where NAME is the name of
the OSCORE group.
Upon receiving the Version Request, the Group Manager processes it as
per Section 4.1.5.1 of [I-D.ietf-ace-key-groupcomm]. The success
Version Response is formatted as defined in Section 4.1.5.1 of
[I-D.ietf-ace-key-groupcomm].
11. Request to Leave the Group
A group member may request to leave the OSCORE group. To this end,
the group member sends a Group Leaving Request, as per Section 4.8 of
[I-D.ietf-ace-key-groupcomm]. In particular, it sends a CoAP POST
request to the endpoint /group-oscore/NAME/node at the Group Manager,
where NAME is the name of the OSCORE group to leave.
The Leaving Request is formatted as defined in Section 4.1.6.1 of
[I-D.ietf-ace-key-groupcomm], and MUST have an empty CBOR Map as
payload.
Upon receiving the Leaving Request, the Group Manager processes it as
per Section 4.1.6.1 of [I-D.ietf-ace-key-groupcomm].
12. Removal of a Group Member
Other than after a spontaneous request to the Group Manager as
described in Section 11, a node may be forcibly removed from the
OSCORE group, e.g. due to expired or revoked authorization.
In either case, if the leaving node is not configured exclusively as
monitor, the Group Manager performs the following actions.
o The Group Manager frees the OSCORE Sender ID value of the leaving
node, which becomes available for possible upcoming joining nodes.
o The Group Manager cancels the association between, on one hand,
the public key of the leaving node and, on the other hand, the
Group Identifier (Gid) associated to the OSCORE group together
with the freed OSCORE Sender ID value. The Group Manager deletes
the public key of the leaving node, if that public key has no
remaining association with any pair (Group ID, Sender ID).
If the application requires forward security, the Group Manager MUST
generate updated security parameters and group keying material, and
provide it to the remaining group members (see Section 13). As a
consequence, the leaving node is not able to acquire the new security
parameters and group keying material distributed after its leaving.
Same considerations in Section 5 of [I-D.ietf-ace-key-groupcomm]
apply here as well, considering the Group Manager acting as KDC.
13. Group Rekeying Process
In order to rekey the OSCORE group, the Group Manager distributes a In order to rekey the OSCORE group, the Group Manager distributes a
new Group ID of the group and a new OSCORE Master Secret for that new Group ID of the group and a new OSCORE Master Secret for that
group. When doing so, the Group Manager MAY take a best effort to group. When doing so, the Group Manager MUST increment the version
number of the group keying material. Also, the Group Manager MUST
preserve the same unchanged Sender IDs for all group members. This preserve the same unchanged Sender IDs for all group members. This
avoids affecting the retrieval of public keys from the Group Manager avoids affecting the retrieval of public keys from the Group Manager
as well as the verification of message countersignatures. as well as the verification of message countersignatures.
The Group Manager MUST support at least the following group rekeying The Group Manager MUST support at least the following group rekeying
scheme. Future application profiles may define alternative message scheme. Future application profiles may define alternative message
formats and distribution schemes. formats and distribution schemes.
The Group Manager uses the same format of the Join Response message The Group Manager uses the same format of the Joining Response
in Section 4.3. In particular: message in Section 4.3. In particular:
o Only the parameters 'type', 'kty', 'key', 'profile' and 'exp' are o Only the parameters 'kty', 'key', 'num', 'profile' and 'exp' are
present. present.
o The 'ms' parameter of the 'key' parameter specifies the new OSCORE o The 'ms' parameter of the 'key' parameter specifies the new OSCORE
Master Secret value. Master Secret value.
o The 'contextId' parameter of the 'key' parameter specifies the new o The 'contextId' parameter of the 'key' parameter specifies the new
Group ID. Group ID.
The Group Manager separately sends a group rekeying message to each The Group Manager separately sends a group rekeying message to each
group member to be rekeyed. Each rekeying message MUST be secured group member to be rekeyed. Each rekeying message MUST be secured
with the pairwise secure communication channel between the Group with the pairwise secure communication channel between the Group
Manager and the group member used during the join process. Manager and the group member used during the joining process.
This approach requires group members to act (also) as servers, in This approach requires group members to act (also) as servers, in
order to correctly handle unsolicited group rekeying messages from order to correctly handle unsolicited group rekeying messages from
the Group Manager. In particular, if a group member and the Group the Group Manager. In particular, if a group member and the Group
Manager use OSCORE [I-D.ietf-core-object-security] to secure their Manager use OSCORE [RFC8613] to secure their pairwise communications,
pairwise communications, the group member MUST create a Replay Window the group member MUST create a Replay Window in its own Recipient
in its own Recipient Context upon establishing the OSCORE Security Context upon establishing the OSCORE Security Context with the Group
Context with the Group Manager, e.g. by means of the OSCORE profile Manager, e.g. by means of the OSCORE profile of ACE
of ACE [I-D.ietf-ace-oscore-profile]. [I-D.ietf-ace-oscore-profile].
Group members and the Group Manager SHOULD additionally support Group members and the Group Manager SHOULD additionally support
alternative rekeying approaches that do not require group members to alternative rekeying approaches that do not require group members to
act (also) as servers. A number of such approaches are defined in act (also) as servers. A number of such approaches are defined in
Section 6 of [I-D.ietf-ace-key-groupcomm], and are based on the Section 4 of [I-D.ietf-ace-key-groupcomm]. In particular, a group
following rationale: member may subscribe for updates to the group-membership resource of
the group, at the endpoint /group-oscore/NAME of the Group Manager,
o A group member queries the Group Manager for updated group keying where NAME is the name of the OSCORE group. This can rely on CoAP
material, by sending a dedicated request to the same Join Resource Observe [RFC7641] or on a full-fledged Pub-Sub model
targeted when joining the group. Like for the case discussed in [I-D.ietf-core-coap-pubsub] with the Group Manager acting as Broker.
Section 4.3 where the OSCORE Security Context expires, the group
member exchanges with the Group Manager a shortened Join Request
sent to the same Join Resource with the 'type' parameter set to 3
("update key") and a shortened Join Response message, according to
the approach defined in Section 6 of [I-D.ietf-ace-key-groupcomm].
o A group member subscribes for updates to the join resource and its
associated group keying material on the Group Manager. This can
rely on CoAP Observe [RFC7641] or on a full-fledged Pub-Sub model
[I-D.ietf-core-coap-pubsub] with the Group Manager acting as
Broker.
Either case, the Group Manager provides the (updated) group keying
material as specified above in this section.
8. Security Considerations 14. Security Considerations
The method described in this document leverages the following The method described in this document leverages the following
management aspects related to OSCORE groups and discussed in the management aspects related to OSCORE groups and discussed in the
sections of [I-D.ietf-core-oscore-groupcomm] referred below. sections of [I-D.ietf-core-oscore-groupcomm] referred below.
o Management of group keying material (see Section 2.1 of o Management of group keying material (see Section 2.1 of
[I-D.ietf-core-oscore-groupcomm]). The Group Manager is [I-D.ietf-core-oscore-groupcomm]). The Group Manager is
responsible for the renewal and re-distribution of the keying responsible for the renewal and re-distribution of the keying
material in the groups of its competence (rekeying). According to material in the groups of its competence (rekeying). According to
the specific application requirements, this can include rekeying the specific application requirements, this can include rekeying
the group upon changes in its membership. In particular, renewing the group upon changes in its membership. In particular, renewing
the keying material is required upon a new node's joining or a the group keying material is required upon a new node's joining or
current node's leaving, in case backward security and forward a current node's leaving, in case backward security and forward
security have to be preserved, respectively. security have to be preserved, respectively.
o Provisioning and retrieval of public keys (see Section 2 of o Provisioning and retrieval of public keys (see Section 2 of
[I-D.ietf-core-oscore-groupcomm]). The Group Manager acts as key [I-D.ietf-core-oscore-groupcomm]). The Group Manager acts as key
repository of public keys of group members, and provides them upon repository of public keys of group members, and provides them upon
request. request.
o Synchronization of sequence numbers (see Section 5 of o Synchronization of sequence numbers (see Section 5 of
[I-D.ietf-core-oscore-groupcomm]). This concerns how a responder [I-D.ietf-core-oscore-groupcomm]). This concerns how a responder
node that has just joined an OSCORE group can synchronize with the node that has just joined an OSCORE group can synchronize with the
sequence number of requesters in the same group. sequence number of requesters in the same group.
Before sending the Join Response, the Group Manager MUST verify that Before sending the Joining Response, the Group Manager MUST verify
the joining node actually owns the associated private key. To this that the joining node actually owns the associated private key. To
end, the Group Manager can rely on the proof-of-possession challenge- this end, the Group Manager can rely on the proof-of-possession
response defined in Section 4. Alternatively, the joining node can challenge-response defined in Section 4. Alternatively, the joining
use its own public key as asymmetric proof-of-possession key to node can use its own public key as asymmetric proof-of-possession key
establish a secure channel with the Group Manager, e.g. as in to establish a secure channel with the Group Manager, e.g. as in
Section 3.2 of [I-D.ietf-ace-dtls-authorize]. However, this requires Section 3.2 of [I-D.ietf-ace-dtls-authorize]. However, this requires
such proof-of-possession key to be consistent with the encoding as such proof-of-possession key to be compatible with the encoding as
well as with the countersignature algorithm and possible associated well as with the countersignature algorithm and possible associated
parameters used in the OSCORE group. parameters used in the OSCORE group.
A node may have joined multiple OSCORE groups under different non- A node may have joined multiple OSCORE groups under different non-
synchronized Group Managers. Therefore, it can happen that those synchronized Group Managers. Therefore, it can happen that those
OSCORE groups have the same Group Identifier (Gid). It follows that, OSCORE groups have the same Group Identifier (Gid). It follows that,
upon receiving a Group OSCORE message addressed to one of those upon receiving a Group OSCORE message addressed to one of those
groups, the node would have multiple Security Contexts matching with groups, the node would have multiple Security Contexts matching with
the Gid in the incoming message. It is up to the application to the Gid in the incoming message. It is up to the application to
decide how to handle such collisions of Group Identifiers, e.g. by decide how to handle such collisions of Group Identifiers, e.g. by
trying to process the incoming message using one Security Context at trying to process the incoming message using one Security Context at
the time until the right one is found. the time until the right one is found.
Further security considerations are inherited from Further security considerations are inherited from
[I-D.ietf-ace-key-groupcomm], the ACE framework for Authentication [I-D.ietf-ace-key-groupcomm], the ACE framework for Authentication
and Authorization [I-D.ietf-ace-oauth-authz], and the specific and Authorization [I-D.ietf-ace-oauth-authz], and the specific
transport profile of ACE signalled by the AS, such as transport profile of ACE signalled by the AS, such as
[I-D.ietf-ace-dtls-authorize] and [I-D.ietf-ace-oscore-profile]. [I-D.ietf-ace-dtls-authorize] and [I-D.ietf-ace-oscore-profile].
9. IANA Considerations 15. IANA Considerations
Note to RFC Editor: Please replace all occurrences of "[[This Note to RFC Editor: Please replace all occurrences of "[[This
specification]]" with the RFC number of this specification and delete specification]]" with the RFC number of this specification and delete
this paragraph. this paragraph.
This document has the following actions for IANA. This document has the following actions for IANA.
9.1. ACE Groupcomm Key Registry 15.1. ACE Groupcomm Key Registry
IANA is asked to register the following entry in the "ACE Groupcomm IANA is asked to register the following entry in the "ACE Groupcomm
Key" Registry defined in Section 11.5 of Key" Registry defined in Section 8.3 of [I-D.ietf-ace-key-groupcomm].
[I-D.ietf-ace-key-groupcomm].
o Name: Group_OSCORE_Security_Context object o Name: Group_OSCORE_Security_Context object
o Key Type Value: TBD o Key Type Value: TBD
o Profile: "coap_group_oscore_app", defined in Section 9.3 of this o Profile: "coap_group_oscore_app", defined in Section 15.3 of this
specification. specification.
o Description: A Group_OSCORE_Security_Context object encoded as o Description: A Group_OSCORE_Security_Context object encoded as
described in Section 4.3 of this specification. described in Section 4.3 of this specification.
o Reference: [[This specification]] o Reference: [[This specification]]
9.2. OSCORE Security Context Parameters Registry 15.2. OSCORE Security Context Parameters Registry
IANA is asked to register the following entries in the "OSCORE IANA is asked to register the following entries in the "OSCORE
Security Context Parameters" Registry defined in Section 9.2 of Security Context Parameters" Registry defined in Section 9.2 of
[I-D.ietf-ace-oscore-profile]. [I-D.ietf-ace-oscore-profile].
o Name: cs_alg o Name: cs_alg
o CBOR Label: TBD o CBOR Label: TBD
o CBOR Type: tstr / int o CBOR Type: tstr / int
o Registry: COSE Algorithm Values (ECDSA, EdDSA) o Registry: COSE Algorithm Values (ECDSA, EdDSA)
o Description: OSCORE Counter Signature Algorithm Value o Description: OSCORE Counter Signature Algorithm Value
o Reference: [[This specification]] o Reference: [[This specification]]
skipping to change at page 24, line 4 skipping to change at page 25, line 44
o Description: OSCORE Counter Signature Key Additional Parameters o Description: OSCORE Counter Signature Key Additional Parameters
o Reference: [[This specification]] o Reference: [[This specification]]
o Name: cs_key_enc o Name: cs_key_enc
o CBOR Label: TBD o CBOR Label: TBD
o CBOR Type: integer o CBOR Type: integer
o Registry: ACE Public Key Encoding o Registry: ACE Public Key Encoding
o Description: Encoding of Public Keys to be used with the OSCORE o Description: Encoding of Public Keys to be used with the OSCORE
Counter Signature Algorithm Counter Signature Algorithm
o Reference: [[This specification]] o Reference: [[This specification]]
9.3. ACE Groupcomm Profile Registry 15.3. ACE Groupcomm Profile Registry
IANA is asked to register the following entry in the "ACE Groupcomm IANA is asked to register the following entry in the "ACE Groupcomm
Profile" Registry defined in Section 11.6 of Profile" Registry defined in Section 8.4 of
[I-D.ietf-ace-key-groupcomm]. [I-D.ietf-ace-key-groupcomm].
o Name: coap_group_oscore_app o Name: coap_group_oscore_app
o Description: Application profile to provision keying material for o Description: Application profile to provision keying material for
participating in group communication protected with Group OSCORE participating in group communication protected with Group OSCORE
as per [I-D.ietf-core-oscore-groupcomm]. as per [I-D.ietf-core-oscore-groupcomm].
o CBOR Value: TBD o CBOR Value: TBD
o Reference: [[This specification]] o Reference: [[This specification]]
9.4. Sequence Number Synchronization Method Registry 15.4. Sequence Number Synchronization Method Registry
IANA is asked to register the following entries in the "Sequence IANA is asked to register the following entries in the "Sequence
Number Synchronization Method" Registry defined in Section 11.8 of Number Synchronization Method" Registry defined in Section 8.6 of
[I-D.ietf-ace-key-groupcomm]. [I-D.ietf-ace-key-groupcomm].
o Name: Best effort o Name: Best effort
o Value: 1 o Value: 1
o Description: No action is taken. o Description: No action is taken.
o Reference: [I-D.ietf-core-oscore-groupcomm] (Appendix E.1). o Reference: [I-D.ietf-core-oscore-groupcomm] (Appendix E.1).
skipping to change at page 25, line 4 skipping to change at page 26, line 46
o Value: 2 o Value: 2
o Description: The first received request sets the baseline o Description: The first received request sets the baseline
reference point, and is discarded with no delivery to the reference point, and is discarded with no delivery to the
application. application.
o Reference: [I-D.ietf-core-oscore-groupcomm] (Appendix E.2). o Reference: [I-D.ietf-core-oscore-groupcomm] (Appendix E.2).
o Name: Echo challenge-response o Name: Echo challenge-response
o Value: 3 o Value: 3
o Description: Challenge response using the Echo Option for CoAP o Description: Challenge response using the Echo Option for CoAP
from [I-D.ietf-core-echo-request-tag]. from [I-D.ietf-core-echo-request-tag].
o Reference: [I-D.ietf-core-oscore-groupcomm] (Appendix E.3). o Reference: [I-D.ietf-core-oscore-groupcomm] (Appendix E.3).
9.5. ACE Public Key Encoding Registry 15.5. ACE Groupcomm Parameters Registry
This specification registers the value defined in Figure 2 in the IANA is asked to register the following entry in the "ACE Groupcomm
"ACE Public Key Encoding" IANA Registry. Parameters" Registry defined in Section 8.2 of
[I-D.ietf-ace-key-groupcomm].
10. References o Name: clientId
10.1. Normative References o CBOR Key: TBD
o CBOR Type: Byte string
o Reference: [[This document]] (Section 7).
16. References
16.1. Normative References
[I-D.ietf-ace-cwt-proof-of-possession]
Jones, M., Seitz, L., Selander, G., Erdtman, S., and H.
Tschofenig, "Proof-of-Possession Key Semantics for CBOR
Web Tokens (CWTs)", draft-ietf-ace-cwt-proof-of-
possession-11 (work in progress), October 2019.
[I-D.ietf-ace-key-groupcomm] [I-D.ietf-ace-key-groupcomm]
Palombini, F. and M. Tiloca, "Key Provisioning for Group Palombini, F. and M. Tiloca, "Key Provisioning for Group
Communication using ACE", draft-ietf-ace-key-groupcomm-02 Communication using ACE", draft-ietf-ace-key-groupcomm-03
(work in progress), July 2019. (work in progress), November 2019.
[I-D.ietf-ace-oauth-authz] [I-D.ietf-ace-oauth-authz]
Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
H. Tschofenig, "Authentication and Authorization for H. Tschofenig, "Authentication and Authorization for
Constrained Environments (ACE) using the OAuth 2.0 Constrained Environments (ACE) using the OAuth 2.0
Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-24 Framework (ACE-OAuth)", draft-ietf-ace-oauth-authz-25
(work in progress), March 2019. (work in progress), October 2019.
[I-D.ietf-ace-oscore-profile] [I-D.ietf-ace-oscore-profile]
Palombini, F., Seitz, L., Selander, G., and M. Gunnarsson, Palombini, F., Seitz, L., Selander, G., and M. Gunnarsson,
"OSCORE profile of the Authentication and Authorization "OSCORE profile of the Authentication and Authorization
for Constrained Environments Framework", draft-ietf-ace- for Constrained Environments Framework", draft-ietf-ace-
oscore-profile-07 (work in progress), February 2019. oscore-profile-08 (work in progress), July 2019.
[I-D.ietf-core-object-security]
Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
"Object Security for Constrained RESTful Environments
(OSCORE)", draft-ietf-core-object-security-16 (work in
progress), March 2019.
[I-D.ietf-core-oscore-groupcomm] [I-D.ietf-core-oscore-groupcomm]
Tiloca, M., Selander, G., Palombini, F., and J. Park, Tiloca, M., Selander, G., Palombini, F., and J. Park,
"Group OSCORE - Secure Group Communication for CoAP", "Group OSCORE - Secure Group Communication for CoAP",
draft-ietf-core-oscore-groupcomm-05 (work in progress), draft-ietf-core-oscore-groupcomm-05 (work in progress),
July 2019. 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>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252, Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014, DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/info/rfc7252>. <https://www.rfc-editor.org/info/rfc7252>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017, RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>. <https://www.rfc-editor.org/info/rfc8152>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
10.2. Informative References [RFC8613] Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
"Object Security for Constrained RESTful Environments
(OSCORE)", RFC 8613, DOI 10.17487/RFC8613, July 2019,
<https://www.rfc-editor.org/info/rfc8613>.
16.2. Informative References
[I-D.dijk-core-groupcomm-bis] [I-D.dijk-core-groupcomm-bis]
Dijk, E., Wang, C., and M. Tiloca, "Group Communication Dijk, E., Wang, C., and M. Tiloca, "Group Communication
for the Constrained Application Protocol (CoAP)", draft- for the Constrained Application Protocol (CoAP)", draft-
dijk-core-groupcomm-bis-00 (work in progress), March 2019. dijk-core-groupcomm-bis-01 (work in progress), July 2019.
[I-D.ietf-ace-dtls-authorize] [I-D.ietf-ace-dtls-authorize]
Gerdes, S., Bergmann, O., Bormann, C., Selander, G., and Gerdes, S., Bergmann, O., Bormann, C., Selander, G., and
L. Seitz, "Datagram Transport Layer Security (DTLS) L. Seitz, "Datagram Transport Layer Security (DTLS)
Profile for Authentication and Authorization for Profile for Authentication and Authorization for
Constrained Environments (ACE)", draft-ietf-ace-dtls- Constrained Environments (ACE)", draft-ietf-ace-dtls-
authorize-08 (work in progress), April 2019. authorize-08 (work in progress), April 2019.
[I-D.ietf-core-coap-pubsub] [I-D.ietf-core-coap-pubsub]
Koster, M., Keranen, A., and J. Jimenez, "Publish- Koster, M., Keranen, A., and J. Jimenez, "Publish-
Subscribe Broker for the Constrained Application Protocol Subscribe Broker for the Constrained Application Protocol
(CoAP)", draft-ietf-core-coap-pubsub-08 (work in (CoAP)", draft-ietf-core-coap-pubsub-09 (work in
progress), March 2019. progress), September 2019.
[I-D.ietf-core-echo-request-tag] [I-D.ietf-core-echo-request-tag]
Amsuess, C., Mattsson, J., and G. Selander, "CoAP: Echo, Amsuess, C., Mattsson, J., and G. Selander, "CoAP: Echo,
Request-Tag, and Token Processing", draft-ietf-core-echo- Request-Tag, and Token Processing", draft-ietf-core-echo-
request-tag-05 (work in progress), May 2019. request-tag-08 (work in progress), November 2019.
[I-D.tiloca-core-oscore-discovery] [I-D.tiloca-core-oscore-discovery]
Tiloca, M., Amsuess, C., and P. Stok, "Discovery of OSCORE Tiloca, M., Amsuess, C., and P. Stok, "Discovery of OSCORE
Groups with the CoRE Resource Directory", draft-tiloca- Groups with the CoRE Resource Directory", draft-tiloca-
core-oscore-discovery-02 (work in progress), March 2019. core-oscore-discovery-03 (work in progress), July 2019.
[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>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012, RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>. <https://www.rfc-editor.org/info/rfc6749>.
[RFC7390] Rahman, A., Ed. and E. Dijk, Ed., "Group Communication for [RFC7390] Rahman, A., Ed. and E. Dijk, Ed., "Group Communication for
skipping to change at page 27, line 29 skipping to change at page 29, line 39
Application Protocol (CoAP)", RFC 7641, Application Protocol (CoAP)", RFC 7641,
DOI 10.17487/RFC7641, September 2015, DOI 10.17487/RFC7641, September 2015,
<https://www.rfc-editor.org/info/rfc7641>. <https://www.rfc-editor.org/info/rfc7641>.
Appendix A. Profile Requirements Appendix A. Profile Requirements
This appendix lists the specifications on this application profile of This appendix lists the specifications on this application profile of
ACE, based on the requiremens defined in Appendix A of ACE, based on the requiremens defined in Appendix A of
[I-D.ietf-ace-key-groupcomm]. [I-D.ietf-ace-key-groupcomm].
o Communication protocol that the members of the group must use: o REQ1 - Specify the encoding and value of the identifier of group
CoAP, possibly over IP multicast. of 'scope': see Section 3.1.
o Security protocols that the group members must use to protect
their communication: Group OSCORE.
o Specify the encoding and value of the identifier of group and role o REQ2 - Specify the encoding and value of the identifier of roles
of 'scope': see Section 3.1. of 'scope': see Section 3.1.
o Profile identifier: coap_group_oscore_app o REQ3 (Optional) - Specify the acceptable values for 'sign_alg':
values from Tables 5 and 6 of [RFC8152].
o Acceptable values of 'kty': Group_OSCORE_Security_Context object o REQ4 (Optional) - Specify the acceptable values for
'sign_parameters': values from the "Counter Signature Parameters"
Registry (see Section 9.1 of [I-D.ietf-core-oscore-groupcomm]).
o Specify the format and content of 'group_policies' entries: three o REQ5 (Optional) - Specify the acceptable values for
values are defined and registered, as content of the entry 'sign_key_parameters': values from the "Counter Signature Key
"Sequence Number Synchronization Method" (see Section 9.4). Parameters" Registry (see Section 9.2 of
[I-D.ietf-core-oscore-groupcomm]).
o (Optional) specify the format and content of 'mgt_key_material': o REQ6 (Optional) - Specify the acceptable values for 'pub_key_enc':
no. 1 ("COSE_Key") from the 'Confirmation Key' column of the "CWT
Confirmation Method" Registry defined in
[I-D.ietf-ace-cwt-proof-of-possession]. Future specifications may
define additional values for this parameter.
o (Optional) specify the transport profile of ACE o REQ7 - Format of the 'key' value: see Section 4.3.
[I-D.ietf-ace-oauth-authz] to use between Client and Group
Manager: any transport profile of ACE that complies with the
requirements in Appendix C of [I-D.ietf-ace-oauth-authz].
o (Optional) specify the encoding of public keys, of 'client_cred', o REQ8 - Acceptable values of 'kty': Group_OSCORE_Security_Context
and of 'pub_keys' if COSE_Keys are not used: no. object (see Section 4.3).
o (Optional) specify the acceptable values for parameters related to o REQ9: Specify the format of the identifiers of group members: see
signature algorithm and signature keys: 'sign_alg' takes value Section 4.3 and Section 8.
from Tables 5 and 6 of [RFC8152]; 'sign_parameters' takes values
from the "Counter Signature Parameters" Registry (see Section 9.1
of [I-D.ietf-core-oscore-groupcomm]); 'sign_key_parameters' takes
values from the "Counter Signature Key Parameters" Registry (see
Section 9.2 of [I-D.ietf-core-oscore-groupcomm]); 'pub_key_enc'
takes value from Figure 2 in Section 4.1.
o (Optional) specify the negotiation of parameter values for o REQ10 (Optional) - Specify the format and content of
'group_policies' entries: three values are defined and registered,
as content of the entry "Sequence Number Synchronization Method"
(see Section 15.4).
o REQ11 - Communication protocol that the members of the group must
use: CoAP, possibly over IP multicast.
o REQ12 - Security protocols that the group members must use to
protect their communication: Group OSCORE.
o REQ13 - Profile identifier: coap_group_oscore_app
o REQ14 (Optional) - Specify the encoding of public keys, of
'client_cred', and of 'pub_keys' if COSE_Keys are not used: no.
o REQ15 - Specify policies at the KDC to handle member ids that are
not included in 'get_pub_keys': see Section 8.
o REQ16 - Specify the format and content of 'group_policies': see
Section 4.3.
o REQ17 - Specify the format of newly-generated individual keying
material for group members, or of the information to derive it,
and corresponding CBOR label: see Section 7.
o REQ18 - Specify how the communication is secured between the
Client and KDC: by means of any transport profile of ACE
[I-D.ietf-ace-oauth-authz] between Client and Group Manager that
complies with the requirements in Appendix C of
[I-D.ietf-ace-oauth-authz].
o OPT1 (Optional) - Specify the encoding of public keys, of
'client_cred', and of 'pub_keys' if COSE_Keys are not used: no.
o OPT2 (Optional) - Specify the negotiation of parameter values for
signature algorithm and signature keys, if 'sign_info' and signature algorithm and signature keys, if 'sign_info' and
'pub_key_enc' are not used: pre-knowledge by using the approach 'pub_key_enc' are not used: possible early discovery by using the
based on the CoRE Resource Directory described in approach based on the CoRE Resource Directory described in
[I-D.tiloca-core-oscore-discovery]. [I-D.tiloca-core-oscore-discovery].
o OPT3 (Optional) - Specify the format and content of
'mgt_key_material': no.
o OPT4 (Optional) - Specify policies that instruct clients to retain
unsuccessfully decrypted messages and for how long, so that they
can be decrypted after getting updated keying material: no.
Appendix B. Document Updates Appendix B. Document Updates
RFC EDITOR: PLEASE REMOVE THIS SECTION. RFC EDITOR: PLEASE REMOVE THIS SECTION.
B.1. Version -01 to -02 B.1. Version -02 to -03
o New sections, aligned with the interface of ace-key-groupcomm .
o Exchange of information on the countersignature algorithm and
related parameters, during the Token POST (Section 4.1).
o Nonce 'rsnonce' from the Group Manager to the Client
(Section 4.1).
o Client PoP signature in the Key Distribution Request upon joining
(Section 4.2).
o Local actions on the Group Manager, upon a new node's joining
(Section 4.2).
o Local actions on the Group Manager, upon a node's leaving
(Section 12).
o IANA registration in ACE Groupcomm Parameters Registry.
o More fulfilled profile requirements (Appendix A).
B.2. Version -01 to -02
o Editorial fixes. o Editorial fixes.
o Changed: "listener" to "responder"; "pure listener" to "monitor". o Changed: "listener" to "responder"; "pure listener" to "monitor".
o Changed profile name to "coap_group_oscore_app", to reflect it is o Changed profile name to "coap_group_oscore_app", to reflect it is
an application profile. an application profile.
o Added the 'type' parameter for all requests to a Join Resource. o Added the 'type' parameter for all requests to a Join Resource.
skipping to change at page 29, line 17 skipping to change at page 32, line 43
o Extended security considerations: proof-of-possession of signature o Extended security considerations: proof-of-possession of signature
keys; collision of OSCORE Group Identifiers (Section 8). keys; collision of OSCORE Group Identifiers (Section 8).
o Registered three entries in the IANA Registry "Sequence Number o Registered three entries in the IANA Registry "Sequence Number
Synchronization Method Registry" (Section 9). Synchronization Method Registry" (Section 9).
o Registered one public key encoding in the "ACE Public Key o Registered one public key encoding in the "ACE Public Key
Encoding" IANA Registry (Section 9). Encoding" IANA Registry (Section 9).
B.2. Version -00 to -01 B.3. Version -00 to -01
o Changed name of 'req_aud' to 'audience' in the Authorization o Changed name of 'req_aud' to 'audience' in the Authorization
Request (Section 3.1). Request (Section 3.1).
o Added negotiation of countersignature algorithm/parameters between o Added negotiation of countersignature algorithm/parameters between
Client and Group Manager (Section 4). Client and Group Manager (Section 4).
o Updated format of the Key Distribution Response as a whole o Updated format of the Key Distribution Response as a whole
(Section 4.3). (Section 4.3).
o Added parameter 'cs_params' in the 'key' parameter of the Key o Added parameter 'cs_params' in the 'key' parameter of the Key
Distribution Response (Section 4.3). Distribution Response (Section 4.3).
o New IANA registrations in the "ACE Authorization Server Request o New IANA registrations in the "ACE Authorization Server Request
Creation Hints" Registry, "ACE Groupcomm Key" Registry, "OSCORE Creation Hints" Registry, "ACE Groupcomm Key" Registry, "OSCORE
Security Context Parameters" Registry and "ACE Groupcomm Profile" Security Context Parameters" Registry and "ACE Groupcomm Profile"
Registry (Section 9). Registry (Section 9).
Acknowledgments Acknowledgments
The authors sincerely thank Santiago Aragon, Stefan Beck, Martin The authors sincerely thank Santiago Aragon, Stefan Beck, Carsten
Gunnarsson, Rikard Hoeglund, Jim Schaad, Ludwig Seitz, Goeran Bormann, Martin Gunnarsson, Rikard Hoeglund, Daniel Migault, Jim
Selander and Peter van der Stok for their comments and feedback. Schaad, Ludwig Seitz, Goeran Selander and Peter van der Stok for
their comments and feedback.
The work on this document has been partly supported by VINNOVA and The work on this document has been partly supported by VINNOVA and
the Celtic-Next project CRITISEC; and by the EIT-Digital High Impact the Celtic-Next project CRITISEC; and by the EIT-Digital High Impact
Initiative ACTIVE. Initiative ACTIVE.
Authors' Addresses Authors' Addresses
Marco Tiloca Marco Tiloca
RISE AB RISE AB
Isafjordsgatan 22 Isafjordsgatan 22
Kista SE-164 29 Stockholm Kista SE-164 29 Stockholm
Sweden Sweden
Email: marco.tiloca@ri.se Email: marco.tiloca@ri.se
Jiye Park Jiye Park
Universitaet Duisburg-Essen Universitaet Duisburg-Essen
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