Re: [websec] handling STS header field extendability

Yoav Nir <> Sat, 18 August 2012 06:21 UTC

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From: Yoav Nir <>
To: =JeffH <>
Date: Sat, 18 Aug 2012 09:21:34 +0300
Thread-Topic: [websec] handling STS header field extendability
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Subject: Re: [websec] handling STS header field extendability
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On Aug 18, 2012, at 1:55 AM, =JeffH wrote:

> Yoav Nir noted:
>> As a reminder, the proposed resolution is as follows:
>> * Do not establish a registry now
>>      Let the first new header field specification establish it
>> * A client that gets an unknown field ignores it
>>      This means no mandatory-to-understand extensions
> Thanks, Yoav.
> I'd also noted that we need to decide on a IANA policy to declare.

Do we need to do this?  Assuming the proposed resolution achieves consensus (and there have been no nays yet), we're not setting up a registry. I don't think we get to set a policy for a registry we're not setting up.

> My original message is here..
> ..and I suggested that, since HSTS is a security policy, I lean towards wanting 
> to have relatively rigorous review applied to any registry and its contents 
> created for HSTS directives and thus am thinking a policy of "IETF Review" is 
> what we ought to state (for "FOO" in the below excerpt from -12 at the end of 
> section 6.1)..
>    Additional directives extending the semantic functionality of the STS
>    header field can be defined in other specifications, with a registry
>    (having an IANA policy definition of FOO [RFC5226]) defined for them
>    at such time.
>    NOTE:  Such future directives will be ignored by UAs implementing
>           only this specification, as well as by generally non-
>           conforming UAs.  See Section 14.1 "Non-Conformant User Agent
>           Implications" for further discussion.

HSTS is a security policy. Suppose an extension requires that the certificate contain a logo. Is that security-relevant?  According to section 2 of RFC 5226, policies are made to avoid hoarding of resources (I don't think that's relevant here), and to make sure it makes sense. I think "expert review" would be OK, but I don't think we need to bother with deciding this now.