It appears that Murray S. Kucherawy <[email protected]> said: >(a) Inertia will mean "l=" is generated and/or accepted for a long time to >come no matter what we say or do; and
Yup. >(b) Even if (a) weren't true, "l=" then becomes an unrecognized tag at >verifiers, which will mean those signatures break and we have an >interoperability problem (though likely a tolerable one). It Depends(TM). I see some mail with l=1 which means that the signature won't verify if you ignore the l=. But I also see a fair amount from what appear to be Ironport appliances with the l= covering the entire body. If you ignore the l= you still hash the entire body, so the signature should be OK, right? >SHOULD be signed, and I think Content-Type was one of them; RFC 6376 >removed the explicit list in favor of more abstract guidance that should >lead anyone toward the same original list at least. So even that aspect of >this attack was anticipated. More than anticipated, explicitly described on page 41: If the "l=" signature tag is in use (see Section 3.5), the Content- Type field is also a candidate for being included as it could be replaced in a way that causes completely different content to be rendered to the receiving user. Rather than revising 6376 I was thinking about an AS or BCP that tells you how to make strong signatures. Nothing exotic, use reasonbly strong keys and sign all the headers that make sense to sign. R's, John _______________________________________________ Ietf-dkim mailing list -- [email protected] To unsubscribe send an email to [email protected]
