1. Do you want the key selector because it hides the public key so
that people cannot factor the modulus?
Yes.
2. If yes, would simply using a digest of the public key suffice (as
Burt Kaliski of RSADSI proposes, see included message below)?
Yes.
3. Do you want the key selector because it wards off traffic analysis
so that the identities of the originators and recipients can be
concealed?
Qualified Yes. I recognize that using the key selector in this fashion
is necessary but not sufficient to thwart traffic analysis. Although
I believe it is pre-mature to make thwarting traffic analysis a goal,
I would rather not make it harder later.
4. If yes, should we formally propose this as a design goal for
MIME/PEM and spend the time necessary to address all the issues
implied by such a goal (versus adding this service later, etc.)?
No.
-Jeff