Subject: regarding rekey when compression is on

From: jimmy <[email-masked]>
Date: Fri, 19 Jan 2007 11:57:42 +0530

Hi,

In SSH2 during re-keying with compression on, how is the exchange hash 
calculated? The rfc (4253) mentions in section 8 that I_C and I_S as the 
*payload* of the SSH_MSG_KEXINIT.

Now, is this the compressed or the uncompressed contents of those messages?

I understand from section 6 (binary packet protocol) that payload refers 
to the compressed contents. But i can also see that openssh uses the 
uncompressed contents.

Can someone clarify?

Thanks,
jimmy

---

From: der Mouse <[email-masked]>
Date: Fri, 19 Jan 2007 04:01:06 -0500 (EST)

> The rfc (4253) mentions in section 8 that I_C and I_S as the

> Now, is this the compressed or the uncompressed contents of those

I'd say uncompressed, simply because it makes more sense to me. :)
I agree this point is underspecified; I wish we'd noticed it before the
drafts were turned into RFCs....

I note that section 8 also says

                    I_C is C's SSH_MSG_KEXINIT message and I_S is S's
   SSH_MSG_KEXINIT message that have been exchanged before this part
   begins.

To me, the "message" is the uncompressed version, though I can
certainly see it as a defensible stance that it is the compressed, or
even compressed and encrypted, version.

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