Re: Help with DH key exchange on SSHv2.0

[Markus Friedl <markus%openbsd.org@localhost>]

On Tue, Jul 02, 2002 at 10:36:15AM +0100, Manik Surtani wrote:
> Hey all.
> 
> Apologies if this is the wrong place to post this question.
> 
> I'm developing an open source Java SSH (v2) client API, and need a bit 
> of help.
> 
> 1) After receiving the KEXDH_RESPONSE packet, reading SSH Transport 
> Layer Protocol (March 2002), Section 5.2, Output from Key Exchange:  do 
> I assume that, in HASH (K || H || "A" || session_id), H is a mpint?  The 
> spec states that K is a mpint but doesnt specify for H.

check draft-ietf-secsh-transport-XX, and search for
   The hash H is computed as the HASH hash of the concatenation of the
   following: ...

H is a hash, it's the raw output of sha1, in the 
"diffie-hellman-group1-sha1" key exchange.

> 2) Also, how do I communicate my public key to the server?  From the 
> spec, I gather that the next packet to send is a SSH_MSG_NEWKEYS with no 
> data following ... am I wrong?

check draft-ietf-secsh-transport-XX, and search for

   First, the client sends the following:

     byte      SSH_MSG_KEXDH_INIT
     mpint     e

-m