The Internet PEM (Privacy Enhanced Mail) standard uses the concept which Dean Tribble mentioned of multiple encryption (using each recipient's public key) of a single session key which encrypts the message. PGP's data structures do not currently provide for this but could be extended pretty easily to allow it. On the entropy measure - I thought entropy was how many bits of information you get per character. Encrypted binary text would be pretty close to 8 bits per character. The RFC1113 Ascii encoding used by PGP reduces this to 6 bits per character (e.g. a character set with 64 printable characters) neglecting line separators and message beginnings and endings. So there should be a little less than 6 bits per character for encrypted, Ascii-encoded messages. Hal 74076.1041@compuserve.com