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

Barry Leiba <> Tue, 29 November 2011 03:39 UTC

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From: Barry Leiba <>
To: oauth WG <>
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Subject: Re: [OAUTH-WG] TLS version requirements in OAuth 2.0 base
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> The OAuth base doc refers in two places to TLS versions (with the same
> text in both places:
> 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

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

Servers MAY also implement additional transport-layer
mechanisms that meet their security requirements.

Comments on this version?