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Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: Re: Working Group Last Call for draft-ietf-tls-downgrade-scsv-00)

Bodo Moeller <bmoeller@acm.org> Mon, 20 October 2014 23:48 UTC

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Date: Tue, 21 Oct 2014 01:48:19 +0200
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From: Bodo Moeller <bmoeller@acm.org>
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Archived-At: http://mailarchive.ietf.org/arch/msg/tls/pGDWRjHvvVeh6RezPXzaSU_Rg2I
Subject: Re: [TLS] The TLS_FALLBACK_SCSV time bomb (was: Re: Working Group Last Call for draft-ietf-tls-downgrade-scsv-00)
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Marsh Ray <maray@microsoft.com>:


> > You should be able to get away without the actual renegotiation_info
>
> > extension if you don't support renegotiation.
>


> The thing with the renegotiation attack is the client doesn’t know in
> advance that the server is renegotiating.
>
>
>
> If clients don’t send RI, the server can’t protect them from renegotiation
> attacks.
>

I know. What I meant is that expecting TLS_EMPTY_RENEGOTIATION_INFO_SCSV
would be sufficient if you don't do renegotiation. (The server still needs
to respond with an empty extension, but that's just a fixed string.)

Bodo

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