Re: [Cfrg] Adopting "AES-GCM-SIV: Nonce Misuse-Resistant Authenticated Encryption" as a CFRG document ---- Some clarifications

"Blumenthal, Uri - 0553 - MITLL" <uri@ll.mit.edu> Fri, 08 April 2016 13:49 UTC

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From: "Blumenthal, Uri - 0553 - MITLL" <uri@ll.mit.edu>
To: "cfrg@irtf.org" <cfrg@irtf.org>
Thread-Topic: [Cfrg] Adopting "AES-GCM-SIV: Nonce Misuse-Resistant Authenticated Encryption" as a CFRG document ---- Some clarifications
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Date: Fri, 08 Apr 2016 13:49:22 +0000
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Subject: Re: [Cfrg] Adopting "AES-GCM-SIV: Nonce Misuse-Resistant Authenticated Encryption" as a CFRG document ---- Some clarifications
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> OK, let me explain:
> . . . . . . 
> The "256-bit" case, is covered in my previous explanation, basically:
> 
> AES256 (NONCE[127:1] || 0) || AES256 (NONCE[127:1] || 1)  (using the 256-bit
> key, and producing 256 bits altogether).

Another way to explain it – you run AES256 as a PRF to generate 256
pseudo-random bits with it, and take those 256 bits as a record key for
AES256.

(Sounds solid to me.)