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Re: IPSEC Minutes - IETF28
Ward:
RECAP
In the IEEE 802.10 draft key management standard, key establishement goes
through two phases. First, a key is generated. We support many techniques,
including Diffie-Hellman, Needham-Schroder, and selecting keys from a manually
distributed cache. Second, attributes are negotiated. These attributes
determine how the key will be used; they include the algorithm and the security
protocol that will be used. The attribute negotiation exchange are encrypted
under the key that was generated to ensure that both parties have the same key.
When they do have the same key, authentication is achieved.
DIFFIE-HELLMAN
Diffie-Hellman is a four step process. I our protocol, these four steps would
be followed by two attribute negotiation steps.
Step 1) A to B: aX mod p
Step 2) B to A: aY mod p
Step 3) A to B: ENCRYPT {SIGN {aXY mod p, certificate of A}}
Step 4) B to A: ENCRYPT {SIGN {aXY mod p, certificate of B}}
Diffie-Hellman can be shortened to three key generation steps (again followed
by two attribute negotiation steps).
Step 1) A to B: aX mod p
Step 2) B to A: aY mod p, ENCRYPT {SIGN {aXY mod p}, certificate of B}
Step 3) A to B: ENCRYPT {SIGN {aXY mod p, certificate of A}}
PROPOSAL BEING INVESTIGATED
We really want to get the process down to two steps (again followed by two
attribute negotiation steps). Clearly, this the certificates are not kept
confidential in this approach. The question being researched is wheteher or
not some other weakness is introduced.
Step 1) A to B: aX mod p, SIGN {aX mod p}, certificate of A
Step 2) B to A: aY mod p, SIGN {aY mod p}, certificate of B
--Russ
References: