Re: [TLS] Antw: Re: Suspicious behaviour of TLS server implementations

Peter Gutmann <pgut001@cs.auckland.ac.nz> Thu, 22 September 2016 05:00 UTC

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From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: Andreas Walz <andreas.walz@hs-offenburg.de>, "martin.thomson@gmail.com" <martin.thomson@gmail.com>
Thread-Topic: Antw: Re: [TLS] Suspicious behaviour of TLS server implementations
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Date: Thu, 22 Sep 2016 05:00:07 +0000
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Subject: Re: [TLS] Antw: Re: Suspicious behaviour of TLS server implementations
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Andreas Walz <andreas.walz@hs-offenburg.de>; writes:
>>>> Peter Gutmann <pgut001@cs.auckland.ac.nz>; 21.09.16 17.54 Uhr >>>
>> If you're writing a strict validating protocol parser than disconnecting in
>> this case is a valid response, but if it's software that will be used by
>> actual humans then failing a connect based on something like this makes no
>> sense.
>
>Wouldn't this argument apply to any "decode_error"?

Nope.  There's a big difference between "I can't continue" and "I can 
continue without any problems but don't want to".  The example I gave of
"Couldn't connect to Amazon because no suitable encryption was available"
would be the error message to display in the case of a decode error that
garbled the cipher suites, an "I can't continue" condition.  The current
thread starter was a case of "I can continue without any problems but don't
want to", which pretty much any user of the product will perceive as a buggy
product, meaning they'll drop it and switch to something that works.

Peter.