Re: [OAUTH-WG] TLS version requirements in OAuth 2.0 base

Peter Saint-Andre <stpeter@stpeter.im> Thu, 01 December 2011 20:59 UTC

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Date: Thu, 01 Dec 2011 13:59:14 -0700
From: Peter Saint-Andre <stpeter@stpeter.im>
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Cc: Barry Leiba <barryleiba@computer.org>, oauth WG <oauth@ietf.org>
Subject: Re: [OAUTH-WG] TLS version requirements in OAuth 2.0 base
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On 12/1/11 1:57 PM, Stephen Farrell wrote:
> 
> 
> On 12/01/2011 08:10 PM, Peter Saint-Andre wrote:
>> On 12/1/11 1:09 PM, Rob Richards wrote:
>>> On 11/28/11 10:39 PM, Barry Leiba wrote:
>>>>> The OAuth base doc refers in two places to TLS versions (with the same
>>>>> text in both places:
>>>>>
>>>>> OLD
>>>>> The authorization server MUST support TLS 1.0 ([RFC2246]), SHOULD
>>>>> support TLS 1.2 ([RFC5246]) and its future replacements, and MAY
>>>>> support additional transport-layer mechanisms meeting its security
>>>>> requirements.
>>>>>
>>>>> In both the shepherd review and the AD review, this was called into
>>>>> question:
>>>>> 1. MUST for an old version and SHOULD for the current version seems
>>>>> wrong.
>>>>> 2. Having specific versions required locks us into those versions (for
>>>>> example, all implementations will have to support TLS 1.0, even long
>>>>> after it becomes obsolete, unless we rev the spec.
>>>> The comments I've gotten on this show a clear consensus against the
>>>> change I suggest, and against any attempt to require a version of TLS
>>>> other than 1.0.  I still, though, am concerned that locking this spec
>>>> into TLS 1.0 is limiting.  So let me propose an alternative wording,
>>>> which again tries to make the version(s) non-normative, while making
>>>> it clear which version(s) need to be implemented to get
>>>> interoperability:
>>>>
>>>> NEW
>>>> --------------------------------------------
>>>> The authorization server MUST implement TLS.  Which version(s)
>>>> ought to be implemented will vary over time, and depend on
>>>> the widespread deployment and known security vulnerabilities at
>>>> the time of implementation.  At the time of this writing, TLS version
>>>> 1.2 [RFC5246] is the most recent version, but has very limited
>>>> actual deployment, and might not be readily available in
>>>> implementation toolkits.  TLS version 1.0 [RFC2246] is the
>>>> most widely deployed version, and will give the broadest
>>>> interoperability.
>>>>
>>>> Servers MAY also implement additional transport-layer
>>>> mechanisms that meet their security requirements.
>>>> --------------------------------------------
>>>>
>>>> Comments on this version?
>>>>
>>>> Barry
>>>>
>>>
>>> Text is neutral enough for me as it's not mandating anything that isn't
>>> readily available. Only comment is whether or not there is a need to
>>> even talk about the specific versions or if just the following is
>>> enough:
>>>
>>> The authorization server MUST implement TLS. Which version(s) ought to
>>> be implemented will vary over time, and depend on the widespread
>>> deployment and known security vulnerabilities at the time of
>>> implementation.
>>>
>>> Servers MAY also implement additional transport-layer mechanisms that
>>> meet their security requirements.
>>
>> That seems fine to me.
> 
> FWIW, I think I'd prefer Barry's as Rob's would be more likely
> to generate discusses and we do know that there are some security
> advantages to TLS 1.2 vs. 1.0. (BTW, has anyone considered how
> or if the BEAST attack might affect oauth? Be good to know if
> someone's done that analysis.)
> 
> However, as AD, I could live with either, since lots of other
> specs just say TLS. (But you need to point to the latest RFC as
> normative or that will I bet generate discusses.)

Agreed.

Peter

-- 
Peter Saint-Andre
https://stpeter.im/