Subject: [Isis-wg] Question for HMAC-MD5 authentication

From: May Lu <[email-masked]>
Date: Wed, 5 Jun 2002 15:11:10 -0500

In draft-ietf-isis-hmac-03.txt, the "Authentication Procedures" talked about
how to calculate the authentication value. I need to conform the HMAC-MD5
validation. Here is what I though (authentication validation part only):

When validate incoming LSP with HMAC-MD5 authentication TLV, the Checksum,
Remaining Lifetime fields and the 16 bytes Authentication Value field in the
authentication information tlv in the LSP are zeroed out first. The HMAC-MD5
algorithm takes a key and the modified LSP (length not modified) as input.
The 16 byte result of the HMAC-MD5 algorithm is then compared with the
original incoming authentication value. If all 16 bytes match, the
authentication passed.

Is this the right procedure?

Thanks for your help.
Xiaomei

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