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Re: [TLS] inappropriate_fallback

Benjamin Kaduk <bkaduk@akamai.com> Wed, 08 August 2018 13:21 UTC

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Date: Wed, 08 Aug 2018 08:21:51 -0500
From: Benjamin Kaduk <bkaduk@akamai.com>
To: Matt Caswell <matt@openssl.org>
Cc: "tls@ietf.org" <tls@ietf.org>
Message-ID: <20180808132151.GQ28516@akamai.com>
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Subject: Re: [TLS] inappropriate_fallback
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On Wed, Aug 08, 2018 at 02:05:00PM +0100, Matt Caswell wrote:
> Draft 28 defines the inappropriate_fallback alert as follows:
> 
> inappropriate_fallback  Sent by a server in response to an invalid
>       connection retry attempt from a client
> 
> With the introduction of the downgrade protection sentinels it now seems
> that an inappropriate fallback could also be detected by the client.
> Should this wording be changed?

Well, *fallback* specifically is inherently client-driven; the things the
client could detect would be more of an incorrectly negotiated version
(presumably due to an active attack).

-Ben

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