Clarification on encryption

[Cantor, Scott]

Brent,

I think the reference to the EncryptionParameters class in
SecurityParametersContext was to the wrong class (per my check-in, please
double check). Assuming that's the case, seems like we should rename
support.EncryptionParameters to avoid confusion.

And is the intent that I manufacture the "lower level"
EncryptionParameters and KeyEncryptionParameters objects from the higher
level one(s)?

Related to this for multicast, I think we have to consider that case as
causing Encryption to be a bit different in how we go about resolving
algorithms. To make that work, I really need a candidate list of
algorithms to use for each relying party that I can intersect. Unless we
want to try and make the parameter resolver deal with all of the relying
parties at once. Either way is very ugly.

My preference I guess was to hang a new EncryptionContext off of each
RelyingPartyContext, and push the complexity around multicast into an
encrypting Action that would figure out what all to do.

If we want to make that part of the resolver, then EncryptionParameters
itself needs to understand multicast.

-- Scott