Well, the point is that in addition to removing the optionality, the added information must bind the RWC to the request. I actually like JC’s change as a good step in the right direction.
Writing generic descriptions of validation methods tends to allow more bad things than it helps. I’d rather see a description of enough of the ACME protocol to capture it’s necessary security features. If people want to add similar validation schemes in the future, they should be added as new methods after being adequately reviewed, instead of trying to anticipate all possible similar future methods in advance. -Tim From: Richard Barnes [mailto:[email protected]] Sent: Wednesday, May 04, 2016 10:18 AM To: J.C. Jones Cc: Tim Hollebeek; Ryan Sleevi; CABFPub Subject: Re: [cabfpub] Pre-Ballot 169: Revised Validation Requirements On Tue, May 3, 2016 at 8:06 PM, J.C. Jones <[email protected]<mailto:[email protected]>> wrote: Tim, Ryan: Your points are well-made. As it sounds like we'd prefer to err being more ACME-specific, I propose changing the definition of Required Website Content (RWC) to: Required Website Content: Either a Random Value or a Request Token, optionally concatenated with additional information +{to uniquely identify the Subscriber}+ as specified by the CA. I would think the change needed would be in the other direction -- rather than adding description, remove the optionality: "Required Website Content: A byte string specified by the CA containing either a Random Value or a Request Token, as well as some additional information" This should preclude concatenating a fixed prefix, or other such simple validation schemes. I've also made a one-word clarification to my change from yesterday, clarifying that the RWC can't be contained in its entirety anywhere in the whole request, not only the path. Both of these changes are reflected in the diff at GitHub [1]. 1) https://github.com/cabforum/documents/compare/Ballot-169...jcjones:Ballot-169?expand=1 Cheers, J.C. On Tue, May 3, 2016 at 4:21 PM, Tim Hollebeek <[email protected]<mailto:[email protected]>> wrote: Given the goal of this ballot is to remove "any other method", and we explicitly agreed at the start of this process to simply enumerate existing practice (unless egregiously wrong), I'm not going to hold things up over my concerns. I'd like to see any other method go away ASAP. That said, this language allows "Tim's Zero Fuss Certificate Authority", which uses Random Value + "ZFCA" as the challenge, and "Tim's Zero Fuss Web Server" which simply parrots back Request + "ZFCA" for all requests for any file under .well_known/pki-validation. I predict my product will be extremely popular, as issuance will always succeed without any configuration or manual steps. Once my web server achieves ubiquity, it will succeed even if you accidentally use the wrong domain name in your CSR! Basically, I don't see anywhere in the proposed text where there is a requirement that the validation method must include the essential security that account_key_thumbprint might provide. -Tim ________________________________ From: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> on behalf of Ryan Sleevi <[email protected]<mailto:[email protected]>> Sent: Tuesday, May 3, 2016 6:07:23 PM To: Richard Barnes Cc: CABFPub Subject: Re: [cabfpub] Pre-Ballot 169: Revised Validation Requirements On Tue, May 3, 2016 at 3:02 PM, Richard Barnes <[email protected]<mailto:[email protected]>> wrote: Hey Ryan, I'm confused about where you're going here. It seems like the property that we need to remedy the flaw that Peter exposed is that the server's response cannot be generated based on the request from the CA. It seems to me that the right response is just to make that requirement explicitly. As I think JC's text does, though perhaps it could be made clearer. Do you agree with that approach, and we're just arguing about wording? Or do you think the HTTP validation method needs to be even more prescriptive? Well, the wording is to make the HTTP validation method more prescriptive ;) To be clear: We're discussing wording. Tim proposed some more restrictive changes, and J.C. raised the concern that ACME relies on the lax language. The question is fundamentally trying to find out what options we have to tweak wording or implementation - to try to close the gap so that everyone is happy. ________________________________ This transmission may contain information that is privileged, confidential, and/or exempt from disclosure under applicable law. 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