Re: [websec] HSTS: max-age=0 interacting with includeSubdomains

=JeffH <Jeff.Hodges@KingsMountain.com> Tue, 21 August 2012 18:53 UTC

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Date: Tue, 21 Aug 2012 11:53:13 -0700
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Cc: IETF WebSec WG <websec@ietf.org>
Subject: Re: [websec] HSTS: max-age=0 interacting with includeSubdomains
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Tobias wrote:
 >
 > Would agree with Adam.

agreed -- what Adam relates is how the spec and the implementations have worked 
for ages.


 > And for Brian, I think there is actually one more use case that you
 > haven't considered:
 > Look at it in reverse order:
 > 1. We visit https://sub.example.com and receive HSTS with max-age=1234567890
 > 2. We visit https://example.com and receive HSTS with max-age=0 ;
 > includeSubdomains
 >
 > as far as I remember that would actually clear HSTS for sub.example.com?

No, it would not do so.  As Adam said, the user agent maintains a list of 
distinct host names which have issued the HSTS Policy (aka STS header field).

The above scenario would result in no entry for example.com, and an entry for 
sub.example.com

=JeffH