IS-IS WG IS-IS Cryptographic Authentication Requirements draft-bhatia-manral-crypto-req-isis-01 Manav Bhatia, Alcatel-Lucent Vishwas Manral, IPInfusion IETF 68, Prague

IS-IS – Current Authentication Schemes Clear Text and MD5 Recent Reports of attacks on collision resistance properties of MD5 and SHA-1 Cryptographic stronger algorithms have been suggested in the WG (HMAC-SHA-1, etc)

New Algorithms Keep Coming .. In Cryptography new algorithms surface continuously and existing ones are continuously attacked .. Thus the choice of mandatory-to-implement algorithms should be conservative to minimize the likelihood of IS-IS being compromised. Would not want to change the IS-IS spec each time a cryptographically stronger algorithm is suggested. Eg., DES in the older IPsec RFC was a MUST but now has become a SHOULD NOT. Same goes with MD5 in the IPsec space.

Interoperability Issues Need a standard that tells which algorithms to support and which not for minimum interoperability. With time the number of algorithms to support will increase and we need a minimum set of algorithms as well as their current state of support documented The document would specify the MUST/ MAY/ SHOULD/ SHOULD NOT for algorithms that are to be supported This would be a running document that can be changed as and when newer algorithms come and the older ones get deprecated For IPsec the algorithms supported in RFC2401 and the ones in RFC4305 have changed. In fact some MUST have become SHOULD NOT etc.

Additional RFC 2119 terms SHOULD+ Same as SHOULD. However, it is likely that an algorithm marked as SHOULD+ will be promoted at some future time to be a MUST. MUST- Same as MUST for now. However, its expected that at some point in future this algorithm will no longer be a MUST MAY+ - Same as MAY for now. However, its expected that this algorithm may get promoted at some future time to be a SHOULD.

Auth Scheme Selection when Security is required! Old Old New Req Doc Requirement Authentication Scheme ------ -------- ------------------ -------------------------------- MUST ISO 10589/ SHOULD NOT Clear Text Password (1) RFC 1195 MUST RFC 3567 MUST- HMAC-MD5 -- -- SHOULD+ Cryptographic Auth (2) Used mostly to avoid accidental introduction of router in a domain. Not useful if security is required Bhatia, M., Manral, V. and White, R. " IS-IS HMAC Cryptographic Authentication”, Work in Progress, draft-ietf-isis-hmac-sha-01.txt

Authentication Algo Selection Old Old New Req RFC Requirement Authentication Algorithm ------ -------- ------------------ -------------------------------- MUST 3567 MUST- HMAC-MD5 - - SHOULD+ HMAC-SHA-1 (1) - - MAY+ HMAC-SHA-256/ HMAC-SHA-384/ HMAC-SHA-512 (1) Bhatia, M., Manral, V. and White, R. " IS-IS HMAC Cryptographic Authentication”, Work in Progress

Feedback?