Subject: RE: Deriving a symmetric key from the DH key

From: "Paul Leach" <[email-masked]>
Date: Tue, 19 Oct 2004 14:16:07 -0700

-----Original Message-----
From: Sam Hartman [mailto:[email-masked]] 
Sent: Tuesday, October 19, 2004 12:49 PM
To: Paul Leach
Cc: Liqiang(Larry) Zhu; [email-masked]; [email-masked]
Subject: Re: Deriving a symmetric key from the DH key

pkinit implementation will have to know what unkeyed checksums they
support.
This is not ideal.
[pjl] If H is defined as get_mic with a constant key, how does PKINIT
know for which cipher suites the output has no extra structure? 

    Paul> 2. I thought that putting in seq numbers etc in
    Paul> the get_mic output for replay detect etc was both common and
    Paul> a good way to do so -- what replaces that.

As Larry said, not provided by kcrypto. 
[pjl] I don't understand this answer. It observes that cipher suites may
use the flexibility provided by the definition of get_mic to embed
structure for other purposes (which may not be provided by kcrypto, but
are provided by the package). If this is common, then any cipher_suite
that uses it can't be used with PKINIT.

---

From: Sam Hartman <[email-masked]>
Date: Tue, 19 Oct 2004 17:26:49 -0400

Well, h is actually a particular checksum type--the same type as used
in pkauthenticator.  So the implementation needs to know whether that
h has structure.