KARP KMP: Simplified Peer Authentication
draft-chunduri-karp-kmp-router-fingerprints-00
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Uma Chunduri
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Albert Tian
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2012-07-30
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Working Group U. Chunduri
Internet-Draft A. Tian
Intended status: Informational Ericsson Inc.
Expires: January 31, 2013 July 30, 2012
KARP KMP: Simplified Peer Authentication
draft-chunduri-karp-kmp-router-fingerprints-00
Abstract
This document describes the usage of Router Fingerprint
Authentication (RFA) with public keys. This can be used as a peer
authentication method with KARP Key Management Protocol (KMP). KARP
KMP automates key negotiation for securing TCP-based pairwise Routing
Protocols (RPs) like BGP, LDP. The advantage of RFA is, neither it
requires out-of-band, mutually agreeable symmetric keys nor a full
PKI based system (trust anchor or CA certificates) for mutual
authentication of the peers with KARP KMP deployments. Usage of
Router Fingerprints give a significant operational improvement from
symmetric key based systems and yet provide a secure authentication
technique.
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
working documents as Internet-Drafts. The list of current Internet-
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 January 31, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 4
1.2. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Router Fingerprint . . . . . . . . . . . . . . . . . . . . . . 4
3. Usage of Router Fingerprints with KARP KMP . . . . . . . . . . 5
4. Impact on the PAD . . . . . . . . . . . . . . . . . . . . . . . 5
5. Publishing Router Fingerprints . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
A Key Management Protocol (KMP) framework for TCP-based pair wise
routing protocols (BGP [RFC4271], PCEP [RFC5440], MSDP [RFC3618] and
LDP [RFC5036]) is detailed in
[chunduri-karp-using-ikev2-with-tcp-ao]. Usage of IKEv2[RFC5996] as
the KMP is also described in the same document. This draft explores
a simple and secure authentication method, which can be used for KARP
KMP deployments.
Currently operators don't often change the manual keys deployed for
protecting the Routing Protocol (RP) messages because of various
reasons as noted in Section 2.3 of KARP threat document [I-D.ietf-
karp-threats-reqs]. One of the KARP WG goals is to define mechanisms
to support key changes for all RPs which use either Manual Key
Management (MKM) or KMP with out much operational overhead.
Apart from Peer's identity verification, authentication and parameter
negotiation, deployment of KMP can be more useful, when it comes to
rekey the keys used by RPs. Rekeying can be achieved with out the
operator's intervention and as per the provisioned rekey policy.
But, the usage of IKEv2 KMP opens up numerous possibilities for peer
authentication. Various peer authentication mechanisms with the
advantages/drawbacks of each mechanisms are described in the Appendix
of the [chunduri-karp-using-ikev2-with-tcp-ao] document.
If symmetric pre-shared keys are used by IKEv2 KMP to authenticate
the peer before generating the shared key(s), apart from the other
issues with symmetric keys, the problem still remain the same when it
comes to changing these keys.
To reduce the operational costs for changing the keys at peering
points with 100s of peers, this document describes the use of one of
the available IKEv2 KMP peer authentication methods with raw or x.509
encoded public keys (to be called as Router Fingerprints in the rest
of the document). Router Fingerprint Authentication (RFA) mechanism
in conjunction with KARP KMP require neither out-of-band symmetric
keys nor a fully functional PKI based system with trust anchor
certificates as explained further in Section 2.
Section 2 describes the Router Fingerprints in the context of various
KMPs and specifically for IKEv2 KMP. Generation and usage of the
Router Fingerprints is described in Section 3 and Section 5 describes
an error free method for publishing the Router Fingerprints.
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1.1. 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].
1.2. Acronyms
EE - End Entity
KMP - Key Management Protocol (auto key management)
MKM - Manual Key management Protocols
PAD - Peer Authorization Database
RFA - Router Fingerprint Authentication
RP - Routing Protocol
2. Router Fingerprint
Router Fingerprint is a sequence of bytes used to authenticate the
public key before using the same to authenticate the peer in the
context of KMP.
Various forms of the fingerprint mechanism based on the public keys
are already in use as defined in [RFC4252] and [RFC4253].
Fingerprints are also used primarily for root key authentication in
x.509 based PKI [RFC5280]. This documents only highlights the usage
of raw public key based authentication mechanism already defined in
[RFC5996] for KARP deployments.
To generate a fingerprint:
1. A router need to generate an asymmetric Private/Public key pair.
Asymmetric crypto algorithms based on RSA [RFC3447] or for
shorter and still secure keys Elliptic Curve Cryptography (ECC)
[RFC4492] can be used for generating the Private/Public key pair.
2. Once the Asymmetric key pair is generated, if needed, the public
key can be in the form of raw public key as specified in
[RFC5996] or can be encoded with any additional data (specific to
the router) and can be in the form of more easily administrable
X.509 PKI Certificate profile [RFC5280].
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3. The result should be hashed with a cryptographic hash function,
preferably SHA-256 or hash functions with similar strength (see
more discussion on choosing preferred hash function in
Section 7).
The fingerprint generated is not a secret and can be distributed
publicly. This is further discussed in Section 5.
3. Usage of Router Fingerprints with KARP KMP
To use Router Fingerprints authentication with KARP KMP, a Private/
Public key-pair MUST be generated by the router as specified in
Section 2. Base IKEv2 [RFC5996] standard supports only raw RSA based
public keys. The type of the public keys and encoding has to be more
generic to deploy this peer authentication method.
With current specification [RFC5996] when sender needs to get the
certificate of the receiver, Certificate Request payload (CERTREQ as
specified in [RFC5996]) is sent with cert encoding set to "Raw RSA
Key" and Certification Authority field is empty. The receiver of
this CERTREQ payload, uses PKCS #1 encoding for the generated RSA
Public Key and sends the same in CERT payload as Certificate Data
with Certificate Encoding set to "Raw RSA Key" as described in
Section 3.6 of IKEv2 [RFC5996]. Once the public key of the sender is
received, the verification MUST be done with the already published/
stored fingerprints of the sender.
As noted above the current IKEv2[RFC5996] specification only supports
raw RSA public keys. [I-D.kivinen-ipsecme-oob-pubkey] enhances
support for other types of public keys and also defines new encoding
format to carry the public key fingerprint in the CERT payload. For
RPs to use Router Fingerprint Authentication in the context of IKEv2
MUST follow the encoding format as specified in [I-D.kivinen-ipsecme-
oob-pubkey].
4. Impact on the PAD
The Peer Authorization Database (PAD) and the role it plays in peer
authentication is defined in section 4.4.3 of [RFC4301]. One of the
functions of the PAD is to provide the authentication data for each
peer. [RFC4301] supports X.509 certificate or pre-shared secret
authentication data types. So, it is necessary to encode the raw
public keys as X.509 certificates before sending the same in CERT
payload. Though the public key received is in the form of x.509
certificate, for RFA, the PAD entry need not contain a trust anchor
via which the end entity (EE) certificate or the public key for the
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peer must be verifiable. The PAD entry MUST rather contain the
published finger print of the peer.
5. Publishing Router Fingerprints
The router fingerprint generated is not a secret and can be exchanged
out-of-band through Service Level Agreements (SLAs) at the RP peering
points or can be distributed publicly. A KARP KMP deployment using
router fingerprints need to resort to out-of-band public key
validation procedure to verify authenticity of the keys being used.
The router fingerprints should be part of the KMP Peer Authorization
Database (PAD) to validate the public key received in the KMP
messages. For conveying router fingerprints data bytes in a clear
unambiguous way PGP (Pretty Good Privacy) wordlists can be used.
6. IANA Considerations
This document defines no new namespaces.
7. Security Considerations
If collision attacks are perceived as a threat, the hash function to
generate the fingerprints SHOULD also possess the property of
collision-resistance. To mitigate preimage attacks, the
cryptographic hash function used for a fingerprint SHOULD possess the
property of second preimage resistance.
If generated fingerprints are truncated to make those short, the
truncated fingerprints MUST be long enough to preserve the relevant
properties of the hash function against brute-force search attacks.
Considering the above facts, it's recommended to use SHA-256 or
similar hash functions with good security properties to generate the
fingerprints.
8. Acknowledgements
The authors would like to thank Jari Arkko for initial and valuable
discussions on operationally simplified authentication mechanisms in
general and RFA mechanism as described in this document in
particular. Thanks to Tero Kivinen for extended discussion on
applicability and usage of authentication method described for KARP
KMP. Thanks to Joel Halpern for supporting this work and providing
continuous feedback.
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9. References
9.1. Normative References
[I-D.chunduri-karp-using-ikev2-with-tcp-ao]
Chunduri, U., Tian, A., and J. Touch, "Using IKEv2 with
TCP-AO", draft-chunduri-karp-using-ikev2-with-tcp-ao-01
(work in progress), March 2012.
[I-D.kivinen-ipsecme-oob-pubkey]
Kivinen, T., Wouters, P., and H. Tschofenig, "More Raw
Public Keys for IKEv2",
draft-kivinen-ipsecme-oob-pubkey-00 (work in progress),
March 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
"Internet Key Exchange Protocol Version 2 (IKEv2)",
RFC 5996, September 2010.
9.2. Informative References
[I-D.ietf-karp-threats-reqs]
Lebovitz, G. and M. Bhatia, "Keying and Authentication for
Routing Protocols (KARP) Overview, Threats, and
Requirements", draft-ietf-karp-threats-reqs-05 (work in
progress), May 2012.
[RFC3447] Jonsson, J. and B. Kaliski, "Public-Key Cryptography
Standards (PKCS) #1: RSA Cryptography Specifications
Version 2.1", RFC 3447, February 2003.
[RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery
Protocol (MSDP)", RFC 3618, October 2003.
[RFC4107] Bellovin, S. and R. Housley, "Guidelines for Cryptographic
Key Management", BCP 107, RFC 4107, June 2005.
[RFC4252] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH)
Authentication Protocol", RFC 4252, January 2006.
[RFC4253] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH)
Transport Layer Protocol", RFC 4253, January 2006.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
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[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC4492] Blake-Wilson, S., Bolyard, N., Gupta, V., Hawk, C., and B.
Moeller, "Elliptic Curve Cryptography (ECC) Cipher Suites
for Transport Layer Security (TLS)", RFC 4492, May 2006.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element
(PCE) Communication Protocol (PCEP)", RFC 5440,
March 2009.
[RFC6518] Lebovitz, G. and M. Bhatia, "Keying and Authentication for
Routing Protocols (KARP) Design Guidelines", RFC 6518,
February 2012.
Authors' Addresses
Uma Chunduri
Ericsson Inc.
300 Holger Way
San Jose, California 95134
USA
Phone: +1 (408) 750-5678
Email: uma.chunduri@ericsson.com
Albert Tian
Ericsson Inc.
300 Holger Way
San Jose, California 95134
USA
Phone: +1 (408) 750-5210
Email: albert.tian@ericsson.com
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