[ietf-dkim] Re: 1368 straw-poll

[Mark Delany]

Dave Crocker wrote:

> The proposed mechanism incurs an additional lookup for every signed 
> message.

Whatever algorithm policy you embed in a separate SSP can just as easily 
be embedded in the Selector of the weakened key.

But maybe that just means I don't get any of the discussion about 
downgrade attacks or weakened keys needing a separate SSP. As others 
have said TTL is irrelevant because they are always going to be many 
orders of magnitude smaller than the response time of human 
administrators. Heck most administrators haven't even heard of DKIM yet 
alone the discovery of any algorithmic weakness.

I was under the impression that a separate SSP can only add value for 
domains *not* verified by the signature.


Mark.