questions about A2ID localpart encryption
I have some questions about the encrypted local part of an A2ID, because I'm missing the big picture. Say user A is the owner of the A2ID IDa
and wants to communicate with user B who owns the A2ID IDb
. User A is the sender and user B is the receiver and user A is in the posession of the public key of user B. For which scenario do we want to support encryption?
- User A wants to encrypt the local-part of the receivers address
IDb
with the public key of B so that only B can make sense of the local-part? - User A want to encrypt its own local-part (the senders address
IDa
) using the public key of B. - User A wants to encrypt both it's own and the remote local-part using the public key of B. So the local-part of
IDa
andIDb
both get encrypted using the public key of B - None of this all
Then second, if I understand correctly which public key is used is attached to the A2ID in the form of the hash of the public key. So in case of the above example, the hash of the public key of B would be part of the sigflags field of IDb
. And because the length of a portable local-part is limited only the first N bits of this hash are actually included, enough to give B an idea of which of its keys is used.