Re: [TLS] How ALPN makes the http2-tls-relaxed option less secure, compared to NPN (was Re: ALPN concerns)

Eric Rescorla <ekr@rtfm.com> Tue, 10 December 2013 01:21 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Tue, 10 Dec 2013 09:20:56 +0800
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To: Martin Thomson <martin.thomson@gmail.com>
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Cc: "<tls@ietf.org>" <tls@ietf.org>, Peter Gutmann <p.gutmann@auckland.ac.nz>
Subject: Re: [TLS] How ALPN makes the http2-tls-relaxed option less secure, compared to NPN (was Re: ALPN concerns)
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On Tue, Dec 10, 2013 at 1:16 AM, Martin Thomson
<martin.thomson@gmail.com> wrote:
> On 9 December 2013 05:56, Brian Smith <brian@briansmith.org> wrote:
>> Please see http://tools.ietf.org/html/draft-nottingham-http2-encryption-01#section-2.1
>> (read the whole document, but section 2.1 is especially interesting).
>> That document defines a mechanism wherein, through protocol
>> negotiation, a web browser and server can agree on a "relaxed" form of
>> TLS for HTTP where the client does not authenticate the server's
>> certificate. The goal is to enable a form of opportunistic encryption
>> to HTTP.
>
> My feedback to Mark on this point was that this negotiation was
> completely unnecessary.
>
> A server already has a way to signal that it doesn't care about
> certain security properties of a resource.  It does that by omitting
> the 's' in the resource URL.
>
> A client is then left to decide whether it cares about those
> properties.  What requirements are then placed on the subsequent
> interactions are up to the client.

Exactly so. I don't see an reason why one would wish to advertise this.

-Ekr