4 ms·
Framing it as a mere anti-spam weakness rather than anti-phishing is kinda disingenuous.
by reinhardt 14y ago
Framing it as a mere anti-spam weakness rather than anti-phishing is kinda disingenuous.
- tptacek 14y agoHere I'm just going to refer you to "Three Myths About DKIM", linked from the front page of the DKIM site: http://jl.ly/Email/threemyths.html http://jl.ly/Email/threemyths.html
- Evbn 14y agoNone of those myths talk about spoofing the sender domain. DKIM doesn't validate the From line. But where is the weakness in trusting that someone with Google's private key approved the entire content of a message that is signed with Google's key, and so, my trust in Google should extend to the content of that email?
- tptacek 14y agoI already provided one specific example upthread: most domains people care about host applications with bugs that allow attackers to generate arbitrary mail from those domains. This is, please note, a very different problem than "being able to generate arbitrary mail under a specific signature". It is considerably easier to forge mail from BANKOFAMERICA.COM than it is to forge mail under the S/MIME signature of a specific Bank of America employee. Domains simply are not a meaningful security boundary. At no point in the life of the commercial Internet have they ever been. Yes, there are security mechanisms on the Internet that are simultaneously (a) important and (b) misguided enough to ignore this fact. Fortunately, the most important of them are in practice difficult to reliably and scalably exploit. This whole story is a tempest in a teacup. As Matthew Green said on Twitter: a 512 bit DKIM key says more about how little Google cares about DKIM than it does about any laxity on Google's part. Google is not lax about security. Since this thread is also dead, we'll have to wait until someone else tries to get to the top of the front page with a DKIM story to continue arguing about DKIM.