Dear Scott, Signatures normally offer options not easily supported by DKIM. One being use of a binary keys, rather than base64. Indeed shorter keys were a mistake. What other mistakes should be corrected? I can name a few.
Regards, Douglas Otis On 5/11/15 10:06 AM, Scott Kitterman wrote: > RFC 6376 (which I think is the latest) includes: > >> 3.3.3. Key Sizes >> >> Selecting appropriate key sizes is a trade-off between cost, >> performance, and risk. Since short RSA keys more easily succumb to >> off-line attacks, Signers MUST use RSA keys of at least 1024 bits for >> long-lived keys. Verifiers MUST be able to validate signatures with >> keys ranging from 512 bits to 2048 bits, and they MAY be able to >> validate signatures with larger keys. Verifier policies may use the >> length of the signing key as one metric for determining whether a >> signature is acceptable. > Since receivers have no good way of knowing what keys are long-lived, there's > no way on the receiver side to reliably determine if a key shorter than 1024 > bits is being appropriately used or not. I think it's time to kill keys > shorter than 1024 bits dead. It's not like the risks associated with them > are > new [1]. > > I propose a short draft that updates 6376 to say MUST use at least 1024 bits > and setting that as the minimum size verifiers must be able to validate. I'm > volunteering to write it if people agree it's appropriate. > > Scott K > > > [1] http://www.wired.com/2012/10/dkim-vulnerability-widespread/ > _______________________________________________ > NOTE WELL: This list operates according to > http://mipassoc.org/dkim/ietf-list-rules.html _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
