Re: [TLS] DISCUSS on Client Certificate URLs Section of 4366-bis

Joe Salowey <jsalowey@cisco.com> Mon, 30 August 2010 23:19 UTC

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Date: Mon, 30 Aug 2010 16:20:04 -0700
From: Joe Salowey <jsalowey@cisco.com>
To: tls@ietf.org
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Thread-Topic: [TLS] DISCUSS on Client Certificate URLs Section of 4366-bis
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Subject: Re: [TLS] DISCUSS on Client Certificate URLs Section of 4366-bis
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Any other feedback on the recommendations (especially comment 1)?

Thanks, 
Joe


On 8/17/10 10:41 AM, "Joseph Salowey   (jsalowey)" <jsalowey@cisco.com>
wrote:

> Alexey logged some DISCUSS comments on section 5 of
> draft-ietf-tls-rfc4366-bis-10 during IESG review.  Below are the
> comments and the proposed resolutions.  Please review and send comments
> to the list. 
> 
> Thanks,
> 
> Joe 
> 
> 1) Comment 1
> 
> "  The TLS server is not required to follow HTTP redirects when
>    retrieving the certificates or certificate chain.
> 
> This is not strong enough for interoperability. Either redirects MUST be
> followed, or they MUST NOT be followed. Alternatively there need to be
> some
> explanation of why SHOULD (or even MAY) is appropriate here.
> 
>    The URLs used in
>    this extension SHOULD therefore be chosen not to depend on such
>    redirects."
> 
> It seems that since we recommend not depending upon redirects so I
> propose:
> 
> "The TLS server MUST NOT follow HTTP redirects when retrieving the
> certificates or certificate chain. The URLs used in this extension MUST
> NOT be chosen to depend on such redirects."
> 
> If we want to leave the possibility for redirects then we need to text
> to describe when redirects are allowed.
> 
> 2) "If a server encounters an unreasonable delay in obtaining
> 
> This is not very specific. Can a minimal value be recommended here?
> 
>    certificates in a given CertificateURL, it SHOULD time out and signal
>    a certificate_unobtainable(111) error alert.
> 
> What are possible alternatives to the SHOULD?
> 
>    This alert MAY be fatal;
>    for example, if client authentication is required by the server for
>    the handshake to continue. "
> 
> I propose the following text to resolve this:
> 
> "If a server is unable to obtain certificates in a given CertificateURL,
> it MUST send a fatal unrecognized_name(112) alert if it requires the
> certificates to complete the handshake.  If the server does not require
> the certificates then the server continues the handshake.  The server
> MAY send a warning level alert in this case.  Clients receiving such an
> alert SHOULD log the alert and continue with the handshake if possible."
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