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From: Andy Lutomirski <luto@amacapital.net>
Date: Mon, 30 Jan 2017 19:55:34 -0800
Message-ID: <CALCETrVssRGYCaUgPe382NOY6nuM4W_tiOK4OjQkpriPdbBGPw@mail.gmail.com>
To: Adam Langley <agl@imperialviolet.org>
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Archived-At: <https://mailarchive.ietf.org/arch/msg/cfrg/RsX_vq7kv81_LJsuW35x3vQDKqo>
Cc: "cfrg@irtf.org" <cfrg@irtf.org>
Subject: Re: [Cfrg] AES GCM SIV analysis
Precedence: list

On Fri, Jan 27, 2017 at 12:21 PM, Adam Langley <agl@imperialviolet.org> wrote:
> On Thu, Jan 26, 2017 at 6:26 PM, Dan Harkins <dharkins@lounge.org> wrote:
>>   But that is the definition used in the seminal work on the matter, [1].
>> If you want to have a different notion concerning a lesser restriction on
>> nonce reuse then you should use a different term.
>
> That paper formalises an advantage that an attacker might have over an
> ideal scheme. In the same way that block ciphers aren't ideal PRFs,
> nonce-misuse-resistant schemes aren't hitting that ideal either. RFC
> 5297 doesn't hit it, at minimum because it'll run out of counter-space
> after enough messages. AES-GCM-SIV isn't hitting it either.
>
> But that doesn't mean that they aren't practically useful.
>
> I'm not sure what an ideal NMR AEAD would look like, but it's probably
> quite different to both RFC 5297 and AES-GCM-SIV and probably looks
> like a wide-block construction. If someone can point at something they
> think does hit it, that would be interesting to me at least. (Although
> perhaps it's well trodden ground for those who are more familiar with
> the literature than I.)

AEZ looks promising to me:

http://web.cs.ucdavis.edu/~rogaway/aez/

--Andy