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Re: [TLS] I-D Action:draft-ietf-tls-rfc4366-bis-09.txt

Juho Vähä-Herttua <juhovh@iki.fi> Tue, 15 June 2010 06:37 UTC

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From: Juho Vähä-Herttua <juhovh@iki.fi>
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Date: Tue, 15 Jun 2010 09:37:27 +0300
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To: Peter Gutmann <pgut001@cs.auckland.ac.nz>
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Subject: Re: [TLS] I-D Action:draft-ietf-tls-rfc4366-bis-09.txt
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On 15.6.2010, at 9.26, Peter Gutmann wrote:
> =?UTF-8?B?SnVobyBWw6Row6QtSGVydHR1YQ==?= <juhovh@iki.fi> writes:
>> One of the biggest bottlenecks in TLS decryption performance I can see, is
>> the stream and CBC block ciphers requiring decryption before the MAC
>> calculation can be initiated. Therefore, if the decryption and encryption
>> performance is really important, I'd rather concentrate on getting the AES-
>> GCM and AES-CCM ciphers into wider use in TLS.
> 
> Why not allow encrypt-then-MAC to be negotiated in an extension?  This is a
> really trivial change to existing code (arguably it could have been done for
> TLS 1.2, since that incompatibly changes lots of the other crypto as well),
> and means it'd follow encrypt-then-MAC best practice for security.

I think this sounds like a good idea. I always found it weird that TLS, since 1.1, mentions in its documentation that encrypt-then-authenticate is best practice, but we just happen to use authenticate-then-encrypt and there's nothing you can do about it.


Juho

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