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Re: [Cfrg] Salsa20 stream cipher in TLS

Simon Josefsson <simon@josefsson.org> Mon, 18 March 2013 21:47 UTC

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From: Simon Josefsson <simon@josefsson.org>
To: "David McGrew (mcgrew)" <mcgrew@cisco.com>
References: <87ehfc784a.fsf@latte.josefsson.org> <747787E65E3FBD4E93F0EB2F14DB556B183EB9C5@xmb-rcd-x04.cisco.com>
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Date: Mon, 18 Mar 2013 22:47:39 +0100
In-Reply-To: <747787E65E3FBD4E93F0EB2F14DB556B183EB9C5@xmb-rcd-x04.cisco.com> (David McGrew's message of "Mon, 18 Mar 2013 21:11:57 +0000")
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Cc: "cfrg@irtf.org" <cfrg@irtf.org>, "joachim@secworks.se" <joachim@secworks.se>, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [Cfrg] Salsa20 stream cipher in TLS
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"David McGrew (mcgrew)" <mcgrew@cisco.com> writes:

> I'm not sure what you mean about the lack of a MAC field.  It would not be
> hard to define an AEAD algorithm based on Salsa20; I would be surprised if
> there is not a submission to CAESAR using that cipher.  And using the AEAD
> in TLSv1.2 is straightforward.   (Is the issue a desire to use Salsa20 in
> older versions?)

Yes.  If it is not possible to implement Salsa20 as a
GenericStreamCipher we'll reconsider.  Right now to me it seems Salsa20
is more similar to RC4 than to AES-GCM or other AEAD ciphers and there
is no advantage in specifying it as a GenericAEADCipher while the
advantage for GenericStreamCipher is potential compatibility with older
TLS versions.

/Simon

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