RE: Why only group1 diffie-hellman

["Murphy, Gearoid P" <gearoid.murphy@xxxxxx>]

Aris + Andreas

I would be interested in attempting this more as a technical exercise than anything else, if libssh can but the fruits of my labor to good use, then all the better. I would obviously defer to your collective expertise when it comes to the evaluation of the security of the submitted code.

Unless I am gravely mistaken, the difference between group1 and group14 Diffie-Hellman kex is parametric only, there is no algorithmic change required, but the reply of Aris suggests that this is not the case, can anyone comment?

Thanks
 - Gearoid
________________________________________
From: Andreas Schneider [asn@xxxxxxxxxxxxxx]
Sent: 08 July 2011 14:55
To: libssh@xxxxxxxxxx
Subject: Re: Why only group1 diffie-hellman

On Friday 08 July 2011 13:39:42 you wrote:
> Hi all

Hi Gearoid,

> Is there a particular design decision behind only only supporting  group1
> diffie-hellman key exchange?

I don't think so, but we should support it.

> I would be interested in attempting the implementation for group14
> diffie-hellman kex for integration into the libssh mainline

RFC 4253 states that it MUST be supported. We would appreciate a patch for it.
Recently Aris added support for ecdh-sha2-nistp256 kex in master. It shouldn't
be to hard to add diffie-hellman-group14-sha1 now.


        -- andreas

--
Andreas Schneider                   GPG-ID: F33E3FC6
www.cryptomilk.org                asn@xxxxxxxxxxxxxx