draft-ietf-bfd-secure-sequence-numbers-00.txt   draft-ietf-bfd-secure-sequence-numbers-01.txt 
Network Working Group M. Jethanandani Network Working Group M. Jethanandani
Internet-Draft S. Agarwal Internet-Draft S. Agarwal
Intended status: Standards Track Cisco Systems, Inc Intended status: Standards Track Cisco Systems, Inc
Expires: November 23, 2017 A. Mishra Expires: May 25, 2018 A. Mishra
O3b Networks O3b Networks
A. Saxena A. Saxena
Ciena Corporation Ciena Corporation
A. Dekok A. Dekok
Network RADIUS SARL Network RADIUS SARL
May 22, 2017 November 21, 2017
Secure BFD Sequence Numbers Secure BFD Sequence Numbers
draft-ietf-bfd-secure-sequence-numbers-00 draft-ietf-bfd-secure-sequence-numbers-01
Abstract Abstract
This document describes a security enhancements for the BFD packet's This document describes a security enhancements for the BFD packet's
sequence number. sequence number.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 23, 2017. This Internet-Draft will expire on May 25, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Theory of operations . . . . . . . . . . . . . . . . . . . . 2 2. Theory of operations . . . . . . . . . . . . . . . . . . . . 2
3. Impact of using a hash . . . . . . . . . . . . . . . . . . . 4 3. Impact of using a hash . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 4 7.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction 1. Introduction
BFD [RFC5880] section 6.7 describes the use of monotonically BFD [RFC5880] section 6.7 describes the use of monotonically
incrementing 32-bit sequence numbers for use in authentication of BFD incrementing 32-bit sequence numbers for use in authentication of BFD
packets. While this method protects against simple replay attacks, packets. While this method protects against simple replay attacks,
the monotonically incrementing sequence numbers are predictable and the monotonically incrementing sequence numbers are predictable and
vulnerable to more complex attack vectors. This document proposes vulnerable to more complex attack vectors. This document proposes
the use of non-monotonically-incrementing sequence numbers in BFD the use of non-monotonically-incrementing sequence numbers in BFD
skipping to change at page 3, line 29 skipping to change at page 3, line 29
Sender Receiver Sender Receiver
[O] [S] [A] ------------- [A] [S] [O] [O] [S] [A] ------------- [A] [S] [O]
In order to encode a sequence number, the sender would identify a In order to encode a sequence number, the sender would identify a
hash algorithm (symmetric) that would create a 32 bit hash. The hash algorithm (symmetric) that would create a 32 bit hash. The
hashing key is provisioned securely on the sender and receiver of the hashing key is provisioned securely on the sender and receiver of the
BFD session. The mechanism of provisioning such a key is outside the BFD session. The mechanism of provisioning such a key is outside the
scope of this draft. Instead of using the sequence number, the scope of this draft. Instead of using the sequence number, the
sender encodes the sequence number with the hashing key to produce a sender encodes the sequence number with the hashing key to produce a
hash. Upon receiving the BFD Control packet, the receiver decodes hash.
the hash with the provisioned hashing key by performing a reverse
hash. Note: The first sequence number can be obtained using the same Upon receiving the BFD Control packet, the receiver compares the
logic as the My Discriminator value. received sequence number against the expected sequence number. The
mechanism used for comparing is an implementation detail
(implementations may pre-calculate the expected hashed sequence
number, or decrypt the received sequence number before comparing
against expected value). To tolerate dropped frames, the receiver
MUST compare the received sequence number against the current
expected seuqence number (previous received sequence number + 1) and
N subsequent expected sequence numbers (where N is greater than or
equal to the detect multiplier). Note: The first sequence number can
be obtained using the same logic as the My Discriminator value.
k: hashing key k: hashing key
s: sequence number s: sequence number
O: original RFC 5880 packet with monotonically increasing sequence O: original RFC 5880 packet with monotonically increasing sequence
number number
R: remainder of packet R: remainder of packet
skipping to change at page 4, line 38 skipping to change at page 4, line 46
6. Acknowledgements 6. Acknowledgements
7. References 7. References
7.1. Normative References 7.1. Normative References
[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,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<http://www.rfc-editor.org/info/rfc5880>. <https://www.rfc-editor.org/info/rfc5880>.
7.2. Informative References 7.2. Informative References
[I-D.ietf-bfd-optimizing-authentication] [I-D.ietf-bfd-optimizing-authentication]
Jethanandani, M., Mishra, A., Saxena, A., and M. Bhatia, Jethanandani, M., Mishra, A., Saxena, A., and M. Bhatia,
"Optimizing BFD Authentication", draft-ietf-bfd- "Optimizing BFD Authentication", draft-ietf-bfd-
optimizing-authentication-02 (work in progress), January optimizing-authentication-03 (work in progress), June
2017. 2017.
Authors' Addresses Authors' Addresses
Mahesh Jethanandani Mahesh Jethanandani
Cisco Systems, Inc Cisco Systems, Inc
170 West Tasman Drive 170 West Tasman Drive
San Jose, CA 95070 San Jose, CA 95070
USA USA
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