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Re: Binary packet protocol rethink (was: Re: ChaCha20-Poly1305 for SSH)

Damien Miller <djm@mindrot.org> Sun, 29 November 2015 11:49 UTC

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Date: Sun, 29 Nov 2015 22:48:48 +1100
From: Damien Miller <djm@mindrot.org>
To: Simon Tatham <anakin@pobox.com>
cc: Niels Möller <nisse@lysator.liu.se>, Simon Josefsson <simon@josefsson.org>, ietf-ssh@netbsd.org
Subject: Re: Binary packet protocol rethink (was: Re: ChaCha20-Poly1305 for SSH)
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While we're dropping wishlist items for SSH v.3, here's one of mine:

Key exchange negotiates an AEAD rather than a cipher and a MAC
separately, and does so from a greatly trimmed set of options. E.g.
AES-GCM, chacha20+poly1305 and an AES-CTR+HMAC mode.

IMO the AEAD primitive is the right metaphor for the security properties
of the SSH transport protocol. Removing the large cartesian product of
ciphers x MACs will make testing faster and binaries smaller too.

-d

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