On Mon, Jan 27, 2025 at 12:55 PM Michael Thomas <m...@mtcc.com> wrote:
> Sorry, no. From a security standpoint they are identical problems so if > you're making an argument against l= then you are also making an argument > against anything else that allows you to know how to reconstruct the original > signature. The receiver in both cases needs to consider the mutations and > whether they are acceptable and potentially consider it the light of who made > those mutations and their reputation. > > In fact, I would argue that a more complex mutation algebra would be even > more dangerous than the simple minded l= which just allows appending content. > For example, suppose it allowed in-body changes (eg, ostensibly for MIME > changes), evil.com could add a hyperlink to text in the body of the original > message: > > <a href=evil.com>Click here for free money!</a> > > which you can't do with l=. Something doesn't compute here. Back when the concern around the L tag hit the public consciousness in May 2024, I observed a fair amount of mail hitting my spamtrap network with the L tag set up in a way where I was able to grab messages and modify the body to change it to add "evil" links just fine, and then inject the message, receive it, and it passes DKIM. So either I don't understand, or you're wrong about that. L was implemented in a way that didn't "just allow appending content," it also effectively allows modifying content beyond byte X with no corresponding failure in the DKIM signature checks. In my opinion, Wei is correct here. Cheers, Al Iverson -- Al Iverson // 312-725-0130 // Chicago http://www.spamresource.com // Deliverability http://www.aliverson.com // All about me https://xnnd.com/calendar // Book my calendar _______________________________________________ Ietf-dkim mailing list -- ietf-dkim@ietf.org To unsubscribe send an email to ietf-dkim-le...@ietf.org
