Re: [Cfrg] Deoxys-II for AEAD

Thomas Peyrin <> Fri, 22 November 2019 09:00 UTC

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From: Thomas Peyrin <>
Date: Fri, 22 Nov 2019 17:00:31 +0800
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To: Vasily <>
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Subject: Re: [Cfrg] Deoxys-II for AEAD
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Hi Vasily,

actually, note that unlike mentioned in your slides, Deoxys-II is
inverse free. Looking at your comparison table, it seems then that
Deoxys-II is the best candidate.

I believe we should not compare nonce-misuse resistant schemes (for
which you need to make two passes on the message if you want to reach
MRAE security notion) and nonce-respecting schemes. They have quite
different goals.

Actually, if going for nonce-respecting design, note that Deoxys-I was
part of our CAESAR submission and is a nonce-respecting mode. It is
fully online, twice faster than Deoxys-II (it is actually faster than
GCM according to Supercop benchmarks), and provides full n-bit
security (unlike GCM). Only one call to the internal primitive per
message block is needed for Deoxys-I (from what I can see, you need 2
calls and some multiplications per message block in MGM mode ?).



Le ven. 22 nov. 2019 à 14:19, Vasily
<> a écrit :
> Hi all!
> Please consider this comparison of Deoxys-II and the MGM AEAD mode, discussed at the IETF 105 CFRG:
>, see slides 11 and 14.
> MGM does not have a nonce-misuse resistant mode - but because of that the message can be processed online before waiting for the whole message and, moreover, it allows precomputations.
> Also MGM allows crypto agility, since it is a general AEAD-mode that can be used with any block cipher, not limited to less studied (and not standardized) tweakable block ciphers, unlike Deoxys-II.
> Cheers,
> Vasily, TC 26
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