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Re: [Cfrg] AES-SIV versus AES-GCM for Encrypted Key Data

Paul Lambert <paul@marvell.com> Mon, 16 May 2016 21:20 UTC

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From: Paul Lambert <paul@marvell.com>
To: Russ Housley <housley@vigilsec.com>
Thread-Topic: [Cfrg] AES-SIV versus AES-GCM for Encrypted Key Data
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Date: Mon, 16 May 2016 21:20:51 +0000
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Subject: Re: [Cfrg] AES-SIV versus AES-GCM for Encrypted Key Data
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I would think that nonce/counter misuse protection would be an advantage for this type of application.

I do not see how.  There is a fresh key-encryption key for each wrap.  Where can the counter be reused.

Why would the NSA want to change an algorithm that apparently works (AES-SIV) with one that adds complexity in counter processing for this application?

AES-SIV (IMHO) has better properties for 'key wrapping' than AES-GCM.

While the key usage as currently specified in these draft specification might make a AES-GCM usable with careful utilization, it is a fragile construction that is not as readily extended because of the considerations of the counter usage.

Paul



Russ

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