Re: [TLS] Encrypt-then-MAC again (was Re: padding bug)

Watson Ladd <watsonbladd@gmail.com> Sat, 30 November 2013 18:02 UTC

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Date: Sat, 30 Nov 2013 10:02:36 -0800
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From: Watson Ladd <watsonbladd@gmail.com>
To: Alfredo Pironti <alfredo@pironti.eu>
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Subject: Re: [TLS] Encrypt-then-MAC again (was Re: padding bug)
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On Sat, Nov 30, 2013 at 9:58 AM, Alfredo Pironti <alfredo@pironti.eu> wrote:
> Hi Kenny,
>
>> But, at the risk of repeating myself, I very much prefer the simplicity
>> and robustness of an Encrypt-then-MAC construction.
>
> I agree with you. Indeed, Encrypt-then-MAC and (or within) AEAD are
> the only two cipher modes I'd like to see in TLS 1.3.
You do realize EtM is an AEAD if properly designed?
>
> In practice however, we witness the disastrous experience in widely
> deploying any change which is not a small patch to TLS1.0. So I'm
> afraid that to get something deployed in reasonable times we may have
> to get content with such a patch, like pad-MAC-Encrypt, that makes
> more robust (if not provably secure) what we already have.
How is pad-MAC-Encrypt less of a change then Encrypt then MAC?
We still can't kill RC4, which is a *configuration change*.
Patches aren't getting deployed even if painless, so arguing about the
ease of deployment is a red herring.
>
> Alfredo



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