[dmarc-ietf] Other potential work items for the ARC spec
Allessandro Veseley had suggested (on the arc-discuss) list that the semantics and construction of the ARC sets could be defined in a generalized DKIM-like recipe. When I had discussed this with Dave Crocker, he pointed out that such an idea would align with the (never quite finalized) DOSETA ( https://datatracker.ietf.org/doc/draft-crocker-doseta-base/) idea and that having both ARC and DKIM as potential instantiations of the abstract concept could be enough to bring DOSETA to realization. --Kurt ___ dmarc mailing list dmarc@ietf.org https://www.ietf.org/mailman/listinfo/dmarc
Re: [dmarc-ietf] [arc-discuss] Proposal to adopt ARC documents into the WG (toward phase 2 milestone)
On Wed, May 11, 2016 at 7:19 PM, Roland Turner wrote: > > I'd suggest not. AS[1] permits a receiver (or other assessor) to determine > with some confidence that the putative signer made such an assertion about > the putative originator, it provides no information about the involvement > of the putative originator except to the extent that the assessor > additionally trusts the assertions of the putative signer. Decisions to > trust are necessarily outside the specification. This argument applies > equivalently to AS[0] independent origination scenarios and to AS[>0] > forwarding scenarios. > What would an i=0 ARC Set tell you that the i=1 set does not? As I understand it, an i=0 set would be the author asserting "I validated my own mail, and it was good." How would one consume such an assertion in a meaningful way? > > Yes, AS[1] testifies to the Authenticated-Results of receiving the >> message >> > from the originator. >> >> That only proves the first receiver was involved. A final receiver may >> trust >> its results or not. >> > > What is the first receiver reporting if not the authentication claims made > by the originator? > > > They could equally be reporting fraudulent claims in order to defeat email > security systems at (a) downstream receiver(s). > ...meaning nodes 0 (originator) and 1 are in collusion? Sure, that's possible, but how would requiring an i=0 thwart such an arrangement? -MSK ___ dmarc mailing list dmarc@ietf.org https://www.ietf.org/mailman/listinfo/dmarc
Re: [dmarc-ietf] Proposal to adopt ARC documents into the WG (toward phase 2 milestone)
On Wed 11/May/2016 22:35:29 +0200 Kurt Andersen (b) wrote: > On Wed, May 11, 2016 at 11:40 AM, Alessandro Vesely wrote: > >> If the body was altered the original DKIM-Signature is broken. If AS(0) is >> good --which is possible since it didn't sign the body-- and rfc5322.from >> matches the AS(0) signer, can we then bypass DMARC validation? To address >> Brandon's concern, high value targets should never produce an AS(0) in the >> first place. > > AS[0] will not be "good" in the way you propose because nearly all of the > transformations that will break DKIM will also break the AMS > (ARC-Message-Signature) and, per > https://tools.ietf.org/html/draft-andersen-arc-04#section-5.1.1.5 bullet 3, > AMS must pass for the overall ARC set to be considered valid. That requirement is not necessarily about AMS(0). It can be AMS(i), i > 0. (Indeed, the current spec contemplates i > 0 only.) > I'd like to respectfully suggest that "bypassing DMARC validation" is > pretty far out of scope for what we've intended with ARC. Yet, I share the feeling which originated this thread, namely that ARC can do more than validate email address portability (via forwarding) among a private group of huge mailbox providers. If a single solution can be used for both solving DMARC's indirect mail flows problem and participating in safe forwarding, that can make life easier for mail system maintainers. Ale ___ dmarc mailing list dmarc@ietf.org https://www.ietf.org/mailman/listinfo/dmarc
