Re: [Cfrg] [TLS] Additional Elliptic Curves (Curve25519 etc) for TLS ECDH key agreement

Jon Callas <jon@callas.org> Mon, 13 January 2014 08:17 UTC

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From: Jon Callas <jon@callas.org>
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Date: Mon, 13 Jan 2014 00:08:14 -0800
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Cc: "cfrg@irtf.org" <cfrg@irtf.org>, Jon Callas <jon@callas.org>
Subject: Re: [Cfrg] [TLS] Additional Elliptic Curves (Curve25519 etc) for TLS ECDH key agreement
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On Jan 12, 2014, at 5:08 PM, Peter Gutmann <pgut001@cs.auckland.ac.nz>; wrote:

> That assumes you need a single application of a hash function to do the job,
> which as several people have pointed out is going to bite you at some point
> when you run out of appropriately-sized hash functions.  Why not use HKDF, RFC
> 5869, which works with any hash function you like?

Or use a hash function that has variable output, like Skein or SHA-512/z or others.

	Jon


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