Re: [TLS] An SCSV to stop TLS fallback.

Manuel Pégourié-Gonnard <mpg@elzevir.fr> Wed, 04 December 2013 19:12 UTC

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To: Wan-Teh Chang <wtc@google.com>, Bodo Moeller <bmoeller@acm.org>
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Subject: Re: [TLS] An SCSV to stop TLS fallback.
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Hi,

On 04/12/2013 19:59, Wan-Teh Chang wrote:
> I don't fully agree with this rationale. The work to implement TLS
> version negotiation correctly should be similar to the work to add
> support for TLS_FALLBACK_SCSV. Why don't we require that servers that
> support TLS_FALLBACK_SCSV must also do version negotiation correctly?

Unless I'm mistaken, the problem TLS_FALLBACK_SCSV tries to adress is not
servers that don't implement version negotiation correctly, but MITM actively
doing a downgrade attack (and faulty middleboxes, which have the same effect).

Manuel.