PGP/OpenPGP History

Phil Zimmermann in 1991 introduced the first version of PGP
-> Legal issue
-> Usable tools

PGP Inc in 1996 -> NAI
-> John Callas (and others) -> OpenPGP / RFC

GnuPG (Werner Koch) 
full OpenPGP implementation 
released under GNU GPL and part of the GNU project
backward compatibility with old proprietary PGP NAI