PEM, [...] reveals in the clear who signed the message, outside of the encrypted portion. Also [...] to be PEM compliant, you *must* always sign your messages.
Perhaps it's time we polished the edges, added a few of the features that are lacking, and wrote up up an RFC for the PGP message format. Some features I'd like to see in PGP are: The ability to send an encrypted message to multiple recipients without duplicating the entire message. The most logical way to do this would probably be to encrypt the random IDEA key once for each recipient. There needs to be a facility for having multiple signatures on a single document without making the signers sign each others signatures. Besides the obvious application of removing a signature from a document, this would also facilitate things like petitions where many people could asynchronously sign a single document, and latter assemble all the signatures together. It should be possible (though certainly not mandatory) to hide the recipient's identity entirely. The message format needs to allow for alternate forms of encryption (besides IDEA). Furthermore, the (shared key) algorithm used to encrypt a message should be hidden in the RSA encrypted part of the message along with the shared key. Ideally, a list of algorithms could be given which would allow the message to be optionally compressed before being encrypted, or encrypted two or more times with different algorithms. If I'm confused and the PGP message format already supports some of these features, please correct me. brad