Subject: Comment re 2-key and 3-key 3DES in PK-INIT

From: "Linn, John" <[email-masked]>
Date: Mon, 26 Jul 1999 14:26:02 -0400

Responding to the draft minutes, Sasha Medvinsky sent me the following
comment re use of 2-key vs. 3-key 3DES in pk-init.  I'm forwarding to the
list with his permission.

--jl

On my comment about the use of 2-key 3-DES: I was echoing its definition in
the CMS standard, on which PKINIT is based.  CMS (section 12.4.1) defines a
single 3-DES OID and says that it is the same for both 2-key and 3-key
3-DES.  An exact quote from CMS is: "When the length of the
content-encryption key to be wrapped is a 2-key Triple-DES key, a third key
with the same value as the first key is created." 

In the case that Diffie-Hellman-derived secret is used by PKINIT to directly
encrypt part of the Kerberos AS Reply, the above approach doesn't apply
because the encryption key in that case is not explicitly included in the
message.  For that case, if we wanted to use 2-key 3-DES, we would need to
define new Kerberos etypes, and it would not conflict with CMS.

==========================================================================
This message was posted through the Stanford campus mailing list
server.  If you wish to unsubscribe from this mailing list, send the
message body of "unsubscribe ietf-cat-wg" to [email-masked]