Subject: RE: problem with message integrity of KDC-REP messages

From: "Medvinsky, Sasha (SD-EX)" <[email-masked]>
Date: Thu, 22 Feb 2001 18:29:58 -0500

Tom> I presume that they consider a denial of service involving modifiying
Tom> a KDC-REP to be more important than other sorts of denials of service
Tom> that may be easier to execute?

I verified today that yes - the overwhelming majority of the PacketCable
security
working group is concerned about this threat and would like it to be solved
in the IETF.

Tom> My current changes do not include modifying the KDC-REP, though they
Tom> could conceivably do so, since checksumming the padata would also be
Tom> useful for various purposes.
Tom> 
Tom> Basically, it would probably be best to create new types with new tag
Tom> numbers, and have some sort of "body" message that contains the
Tom> cleartext components of an existing KDC-REP and have a keyed checksum
Tom> be computed over the encoding of the.  The new KDC-REP2 message would
Tom> then contain the "body" message, the keyed checksum, and the encrypted
Tom> "EncPart".  This means that you don't have to modify the definition of
Tom> the "EncPart" and chew up more tag number space that way.

This seems like a good solution.  Also, I recall that the IETF WG
agreed to issue new tag numbers anyway for some messages that differ between
RFC 1510 and RFC1510bis?

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From: "Douglas E. Engert" <[email-masked]>
Date: Fri, 23 Feb 2001 09:24:08 -0600

> agreed to issue new tag numbers anyway for some messages that differ between

Yes, I believe we did. Tom was working on these. 

-- 

 Douglas E. Engert  <[email-masked]>
 Argonne National Laboratory
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