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Re: [TLS] Working Group Last Call for draft-ietf-tls-downgrade-scsv-00

Bodo Moeller <bmoeller@acm.org> Thu, 16 October 2014 14:08 UTC

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From: Bodo Moeller <bmoeller@acm.org>
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Subject: Re: [TLS] Working Group Last Call for draft-ietf-tls-downgrade-scsv-00
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Salz, Rich <rsalz@akamai.com>:


> > Should it retry without the SCSV?  I guess you mean "no way!", but this
> is
> > only implicit.
>


> I disagree with Bodo.  It's a user-agent issue. A browser might pop up a
> warning about the loss of privacy features and ask if it should proceed.


Good point. So there is indeed a potential scenario in which retrying
without the SCSV could be acceptable.

A "MUST NOT" for *automatic* such retries might be right, but then Rich's
example already shows that we'd probably be over-regulating by going into
such details. The current "SHOULD NOT" is quite clear -- implementors
*could* still get this wrong, but would adding a "MUST NOT" for retries of
retries really make any difference?

(We'd end up with a more complexly written spec, which is not desirable
without good justification.)

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