DH with shared secret

[Anton Stiglic]

----- Original Message ----- 
From: "Jack Lloyd" <lloyd at randombit.net>
To: <cryptography at metzdowd.com>
Sent: Friday, October 03, 2003 5:13 AM
Subject: DH with shared secret


> This was just something that popped into my head a while back, and I was
> wondering if this works like I think it does. And who came up with it
> before me, because it's was too obvious. It's just that I've never heard
of
> something alone these lines before.
>
> Basically, you share some secret with someone else (call it S).  Then you
> do a standard issue DH exchange, but instead of the shared key being
> g^(xy), it's g^(xyS)

Not exactly the same thing, but you get the same properties:  SKEME.
See section 3.3.2, Pre-shared key and PFS, of
SKEME:  A Versatile Secure Key Exchange Mechanism for internet,
Hugo Krawczyk.
http://citeseer.nj.nec.com/krawczyk96skeme.html


--Anton

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