Re: [TLS] early IANA code point assignment request for draft-ietf-tls-ecdhe-psk-aead

John Mattsson <> Sun, 09 October 2016 05:32 UTC

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From: John Mattsson <>
To: Martin Thomson <>, Nikos Mavrogiannopoulos <>
Thread-Topic: [TLS] early IANA code point assignment request for draft-ietf-tls-ecdhe-psk-aead
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Date: Sun, 9 Oct 2016 05:32:30 +0000
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Subject: Re: [TLS] early IANA code point assignment request for draft-ietf-tls-ecdhe-psk-aead
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Hi Martin,

AES_256_CCM_8 was not in the first versions of the draft but added later
after request from IoT people (probably afraid of quantum computers).

While I think it makes very much sense to have short tags in wireless
radio, I do not know how large need there is for AES-256 in IoT for
constrained devices, or how large the need would be to truncate the tag in
these cases.

My current understanding is that Grover’s algorithm may never be more
cost-effective than a cluster of classical computers, and that quantum
computers therefore likely do not affect the lifetime of AES-128.

I do not have any strong opinions regarding keeping AES_256_CCM_8 or not.
We should not give the impression that AES-256 is needed for practical
resistance to quantum computers anytime soon, it is however a requirement
for use by US government. Agree that AES_128_CCM_8 and AES_256_CCM seems
like the best choices in most cases.


On 12/08/16 08:29, "TLS on behalf of Martin Thomson" <
on behalf of> wrote:

>Looking at those emails, I am prompted to wonder if anyone can justify
>the existence of a ciphersuite with a double-sized key and half-sized
>authentication tag.  RFC 6655 doesn't really explain how that is a
>useful thing.
>On 10 August 2016 at 19:33, Nikos Mavrogiannopoulos <>
>> On Tue, 2016-08-09 at 14:45 -0400, Sean Turner wrote:
>>> All,
>>> We've received a request for early IANA assignments for the 6 cipher
>>> suites listed in
>>> e-psk-aead/.  Please respond before August 23rd if you have concerns
>>> about early code point assignment for these cipher suites.
>> I have previously raised an issue [0] on these ciphersuites. The same
>> requirement was noted also by Peter Dettman as something special in
>> [1]. However, there has been no reaction from the authors (now in CC).
>> regards,
>> Nikos
>> [0]. 
>> [1]. 
>> _______________________________________________
>> TLS mailing list
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