Thanks Rob and Ryan for pointing that out. Will the web servers need to send down a group of cross certs and then let the client use the ones they need in order to chain up to a root in their local trust store since the web server might not know which roots it has?
From: Alex Gaynor [mailto:agay...@mozilla.com] Sent: Tuesday, May 16, 2017 10:31 AM To: Rob Stradling <rob.stradl...@comodo.com> Cc: Doug Beattie <doug.beat...@globalsign.com>; r...@sleevi.com; Peter Gutmann <pgut...@cs.auckland.ac.nz>; Gervase Markham <g...@mozilla.org>; Nick Lamb <tialara...@gmail.com>; MozPol <mozilla-dev-security-pol...@lists.mozilla.org>; Cory Benfield <c...@lukasa.co.uk> Subject: Re: [FORGED] Re: Configuring Graduated Trust for Non-Browser Consumption While the internet is moderately good at handling a single cross-sign (modulo the challenges we had with 1024-bit root deprecation due to a bug in OpenSSL's path building -- now fixed), as we extend the chains, it seems evident to me that server operators are unlikely to configure their servers to serve a chain which works on all clients -- the likely result is clients will need AIA chasing. Most (all?) non-browsers do not implement AIA chasing. This isn't an objection, just a flag and a potential action item on the "non-browser" side of this. Alex On Tue, May 16, 2017 at 10:27 AM, Rob Stradling <rob.stradl...@comodo.com<mailto:rob.stradl...@comodo.com>> wrote: On 16/05/17 14:45, Doug Beattie via dev-security-policy wrote: Ryan, If you look at the wide range of user agents accessing google.com<http://google.com> today you'd see many legacy applications and older versions of browsers and custom browsers built from variants of the commercial browsers. By the time all/most users upgraded to new browsers, it would be time to change the roots out again and this will impact the ability for web site operators to enable TLS for all visitors. Before we can implement a short Root usage policy we'd need to convince all browsers to follow a process for rapid updates of root stores. Hi Doug. Imagine a root cert A, valid for a short duration; and a root cert B, valid for a long duration. Under Ryan's proposal, Mozilla would put A (but not B) in NSS, whereas other less agile root stores would contain B. A doesn't have to be in every root store, because B can cross-certify A. (Let's call the cross-certificate A'). A widely compatible cert chain would therefore look like this: B -> A' -> Intermediate -> Leaf If you're already cross-certifying from an older root C, then an even more widely compatible cert chain would look like this: C -> B' -> A' -> Intermediate -> Leaf -- Rob Stradling Senior Research & Development Scientist COMODO - Creating Trust Online _______________________________________________ dev-security-policy mailing list dev-security-policy@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-security-policy
