Re: [Cfrg] draft-irtf-cfrg-eddsa -- one final proposal for domain separation (context labels) for ed25519

Martin Thomson <martin.thomson@gmail.com> Wed, 11 May 2016 00:47 UTC

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Date: Wed, 11 May 2016 10:47:30 +1000
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From: Martin Thomson <martin.thomson@gmail.com>
To: Watson Ladd <watsonbladd@gmail.com>
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Cc: Simon Josefsson <simon@josefsson.org>, "cfrg@ietf.org" <cfrg@ietf.org>, draft-irtf-cfrg-eddsa.all@ietf.org
Subject: Re: [Cfrg] draft-irtf-cfrg-eddsa -- one final proposal for domain separation (context labels) for ed25519
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On 11 May 2016 at 01:42, Watson Ladd <watsonbladd@gmail.com> wrote:
> TLS 1.3 cannot rely on the
> context mechanism of Ed25519ctx because it must work with RSA
> signatures as well.


That's not strictly true.  It can use contexts opportunistically: if
present, use it, otherwise use this alternative, crappier arrangement
for the signature input.