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Re: [TLS] Obscure ciphers in TLS 1.3

"Scott Fluhrer (sfluhrer)" <sfluhrer@cisco.com> Thu, 24 September 2015 03:00 UTC

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From: "Scott Fluhrer (sfluhrer)" <sfluhrer@cisco.com>
To: Dave Garrett <davemgarrett@gmail.com>, "tls@ietf.org" <tls@ietf.org>
Thread-Topic: [TLS] Obscure ciphers in TLS 1.3
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Date: Thu, 24 Sep 2015 03:00:28 +0000
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Subject: Re: [TLS] Obscure ciphers in TLS 1.3
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> -----Original Message-----
> From: TLS [mailto:tls-bounces@ietf.org] On Behalf Of Dave Garrett
> Sent: Wednesday, September 23, 2015 6:41 PM
> To: tls@ietf.org
> Subject: [TLS] Obscure ciphers in TLS 1.3
> 
> https://tlswg.github.io/tls13-spec/#cipher-suites
> https://www.iana.org/assignments/tls-parameters/tls-
> parameters.xhtml#tls-parameters-4
> 
> When I updated the lists in the TLS 1.3 draft, I just put everything in that is
> currently in the registry and usable. I'd like to now start a discussion on what
> should be allowed. Specifically, I have questions about ARIA and Camellia, as
> well as 8-bit authentication tag variants of AES-CCM or anything else.
> 
> How relevant is this ARIA attack?
> https://eprint.iacr.org/2010/168

That's not relevant to the use of ARIA -- against 256 bit ARIA, it breaks 8 of 16 rounds; against 192 bit ARIA, it breaks 7 of 14 rounds.  That gives us a factor-of-2 safety margin for both key sizes, which is rather a lot.

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