RE: [TLS] TLS 1.2 hash agility

Russ Housley <housley@vigilsec.com> Thu, 27 September 2007 23:56 UTC

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Date: Thu, 27 Sep 2007 12:26:01 -0400
To: Pasi.Eronen@nokia.com
From: Russ Housley <housley@vigilsec.com>
Subject: RE: [TLS] TLS 1.2 hash agility
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For backward compatibility, wouldn't it be cleaner to add a new 
rsa_xxx type to indicate the different semantics.  The new type would 
not be supported by non-TLS v1.2 implementations, nut the handling of 
rsa_sign wouid be the same in all cases.

Russ


  At 05:41 AM 9/27/2007, Pasi.Eronen@nokia.com wrote:
>mike-list@pobox.com wrote:
>
> > The only thing I could come up with is that putting the list of
> > signature algorithms in the CertificateRequest is a change to the
> > format of that message, so it requires version-specific processing,
> > whereas if you use the server extension, the format of Certificate
> > Request is the same as previous TLS versions.
>
>CertificateRequest will require version-specific processing anyway,
>because its semantics will change. For example, in TLS 1.0/1.1
>ClientCertificateType "rsa_sign" meant a certificate containing
>an RSA key, and signed with RSA. In TLS 1.2, it will probably
>mean just a cert containing an RSA key; the signature algorithm
>part will be specified separately.
>
>(Another difference is that in TLS 1.0/1.1, clients that didn't
>have certificates often just ignored CertificateRequest;
>current draft of TLS 1.2 mandates sending an empty Certificate
>message instead.)
>
>Best regards,
>Pasi
>
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