How is PGP 6i compatible with other PGP versions?
PGP 6i can read and understand messages, keys and signatures created with PGP 2.0 and later. (Note, however, that the keys cannot be larger than 4096 bits. No official PGP version uses larger keys, though.) PGP 6i can generate messages, keys and signatures that can be read and understood by PGP 2.6.x and later, as long as you only use RSA keys. PGP 6i also supports DSS/Diffie-Hellman keys, but messages encrypted using this new key type cannot be read by versions prior to 5.0. Note, however, that PGP 6i messages cannot be understood by PGP 2.3a or earlier versions, regardless of which key type you are using.
