Network Working Group M. Jethanandani
Internet-Draft Cisco Systems
Intended status: Standards Track A. Mishra
Expires: June 8, 2016 Ciena Corporation
A. Saxena
Citrix
M. Bhatia
Ionos Networks
December 6, 2015
Optimizing BFD Authentication
draft-ietf-bfd-optimizing-authentication-00
Abstract
This document describes an optimization to BFD Authentication as
described in Section 6.7 of BFD [RFC5880].
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 8, 2016.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Authentication Mode . . . . . . . . . . . . . . . . . . . . . 3
3. NULL Auth TLV . . . . . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Authenticating every BFD [RFC5880] packet with a Simple Password, or
with a MD5 Message-Digest Algorithm [RFC1321] , or Secure Hash
Algorithm (SHA-1) algorithms is computationally intensive process,
making it difficult if not impossible to authenticate every packet -
particularly at faster rates. Also, the recent escalating series of
attacks on MD5 and SHA-1 [SHA-1-attack1] [SHA-1-attack2] raise
concerns about their remaining useful lifetime as outlined in Updated
Security Considerations for the MD5 Message-Digest and the HMAC-MD5
Algorithm [RFC6151] and Security Considerations for the SHA-0 and
SHA-1 Message-Digest Algorithm [RFC6194]. If replaced by stronger
algorithms, the computational overhead, will make the task of
authenticating every packet even more difficult to achieve.
This document proposes that only BFD frames that signal a state
change in BFD be authenticated. Rest of the frames can be
transmitted and received without authentication enabled. Most frames
that are transmitted and received have no state change associated
with them. Limiting authentication to frames that affect a BFD
session state allows more sessions to be supported for
authentication. Moreover, most BFD frames that signal a state change
are generally transmitted at a slower interval of 1s leaving enough
time to compute the hash.
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Section 2 talks about the changes to authentication mode as described
in BFD [RFC5880].
2. Authentication Mode
The cryptographic authentication mechanisms specified in BFD
[RFC5880] describes enabling and disabling of authentication as a one
time operation. As a security precaution, it mentions that
authentication state be allowed to change at most once. Once
enabled, every packet must have Authentication Bit set and the
associated Authentication TLV appended. In addition, it states that
an implementation SHOULD NOT allow the authentication state to be
changed based on the receipt of a BFD Control packet.
This document proposes that the authentication mode be modified to be
enabled on demand. Instead of authenticating every packet, BFD peers
decide which frames need to be authenticated, and authenticate only
those frames. For example, the two ends can decide that BFD frames
that indicate a state change should be authenticated and enable
authentication on those frames only. If the two ends have not
previously negotiated which frames they will transmit or receive with
authentication enabled, then the BFD session will fail to come up,
because at least one end will expect every frame to be authenticated.
The state changes for which authentication is being suggested
include:
Poll Sequence
Demand Mode
BFD packet with the Diag flag set
Authenticated frames already carry the sequence number. The rest of
the frames MUST contain the TLV specified in Section 3. This enables
a monotonically increasing sequence number to be carried in each
frame, and prevents man-in-the-middle from capturing and replaying
the same frame again.
3. NULL Auth TLV
This section describes a new Authentication TLV as:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Type | TLV Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender timestamp |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
NULL Auth TLV
where:
TLV Type: The TLV Type. This field MUST be set to <IANA assigned>.
TLV Length: The length of the NULL Auth TLV, in bytes i.e. 8 bytes
Sequence Number: is a monotonically increasing number while the
session state is UP. Once the session goes down the Sequence number
SHOULD be set to 0.
Sender timestamp: is not used by authentication, and is documented to
be compatible with BFD Stability [I-D.ashesh-bfd-stability]. It
should be set to 0, and should be ignored by the receiver.
4. IANA Considerations
IANA is requested to assign a new Auth Type for the NULL Auth TLV.
Note to RFC Editor: this section may be removed on publication as an
RFC.
5. Security Considerations
The approach described in this document enhances the ability to
authentication a BFD session by taking away the onerous requirement
that every frame be authenticated. By authenticating frames that
affect the state of the session, the security of the BFD session is
maintained. As such this document does not change the security
considerations for BFD.
6. References
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6.1. Normative References
[FIPS-180-2]
National Institute of Standards and Technology, FIPS PUB
180-2, "The Keyed-Hash Message Authentication Code
(HMAC)", August 2002.
[FIPS-198]
National Institute of Standards and Technology, FIPS PUB
198, "The Keyed-Hash Message Authentication Code (HMAC)",
March 2002.
[I-D.ashesh-bfd-stability]
Mishra, A., Jethanandani, M., Saxena, A., Networks, J.,
Chen, M., and P. Fan, "BFD Stability", draft-ashesh-bfd-
stability-03 (work in progress), June 2015.
[I-D.ietf-bfd-generic-crypto-auth]
Bhatia, M., Manral, V., Zhang, D., and M. Jethanandani,
"BFD Generic Cryptographic Authentication", draft-ietf-
bfd-generic-crypto-auth-06 (work in progress), April 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6039] Manral, V., Bhatia, M., Jaeggli, J., and R. White, "Issues
with Existing Cryptographic Protection Methods for Routing
Protocols", RFC 6039, DOI 10.17487/RFC6039, October 2010,
<http://www.rfc-editor.org/info/rfc6039>.
[RFC6151] Turner, S. and L. Chen, "Updated Security Considerations
for the MD5 Message-Digest and the HMAC-MD5 Algorithms",
RFC 6151, DOI 10.17487/RFC6151, March 2011,
<http://www.rfc-editor.org/info/rfc6151>.
[RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security
Considerations for the SHA-0 and SHA-1 Message-Digest
Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011,
<http://www.rfc-editor.org/info/rfc6194>.
6.2. Informative References
[Dobb96a] Dobbertin, H., "Cryptanalysis of MD5 Compress", May 1996.
[Dobb96b] Dobbertin, H., "The Status of MD5 After a Recent Attack",
CryptoBytes", 1996.
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[I-D.ietf-karp-design-guide]
Lebovitz, G. and M. Bhatia, "Keying and Authentication for
Routing Protocols (KARP) Design Guidelines", draft-ietf-
karp-design-guide-10 (work in progress), December 2011.
[MD5-attack]
Wang, X., Feng, D., Lai, X., and H. Yu, "Collisions for
Hash Functions MD4, MD5, HAVAL-128 and RIPEMD", August
2004.
[NIST-HMAC-SHA]
National Institute of Standards and Technology, Available
online at http://csrc.nist.gov/groups/ST/hash/policy.html,
"NIST's Policy on Hash Functions", 2006.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
DOI 10.17487/RFC1321, April 1992,
<http://www.rfc-editor.org/info/rfc1321>.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997,
<http://www.rfc-editor.org/info/rfc2104>.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005,
<http://www.rfc-editor.org/info/rfc4086>.
[RFC4822] Atkinson, R. and M. Fanto, "RIPv2 Cryptographic
Authentication", RFC 4822, DOI 10.17487/RFC4822, February
2007, <http://www.rfc-editor.org/info/rfc4822>.
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic
Authentication", RFC 5310, DOI 10.17487/RFC5310, February
2009, <http://www.rfc-editor.org/info/rfc5310>.
[RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M.,
Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic
Authentication", RFC 5709, DOI 10.17487/RFC5709, October
2009, <http://www.rfc-editor.org/info/rfc5709>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<http://www.rfc-editor.org/info/rfc5880>.
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[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<http://www.rfc-editor.org/info/rfc6234>.
[SHA-1-attack1]
Wang, X., Yin, Y., and H. Yu, "Finding Collisions in the
Full SHA-1", 2005.
[SHA-1-attack2]
Wang, X., Yao, A., and F. Yao, "New Collision Search for
SHA-1", 2005.
Authors' Addresses
Mahesh Jethanandani
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
USA
Phone: +1 (408) 526-8763
Email: mjethanandani@gmail.com
Ashesh Mishra
Ciena Corporation
3939 North 1st Street
San Jose, CA 95134
USA
Phone: +1 (408) 904-2114
Email: mishra.ashesh@gmail.com
Ankur Saxena
Citrix
4988 Great America Pkwy
Santa Clara, CA 95054
USA
Email: ankurpsaxena@gmail.com
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Manav Bhatia
Ionos Networks
Bangalore
India
Email: manav@ionosnetworks.com
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