Ah, I was looking at XKMS1, the SRV was added in XKMS2. So
what do you do with the selector? Use it as part of the name
of the SRV? Use it as it the KeyName in the request? Do you
send along the i= identity as a UseKeyWith Identifier? What
application name goes in UseKeyWith? In the query, should
you include a TimeInstant for the date of the message? What
response type should it ask for, RSAKeyValue or something else?
Like I said, XKMS appears to be a reasonable way to look up
keys, but its binding to DKIM is severely underspecified. I
hope we all agree that defining something in two minutes
without trying it out to see how it interoperates with real
XKMS servers isn't a very good way to design a protocol. So
we're not gonna do it right now.
Actually the logical thing to do would be to have the XKMS group look at
this.
As far as the protocol goes there are slots for stating (1) the protocol
to use (2) the address to use with the protocol.
The protocol slot is simply a URI that stands for the protocol (the URN
of the RFC is the default).
The address slot is simply the selector.