Phil Zimmermann - PGP

PGP

In 1991, he wrote the popular Pretty Good Privacy (PGP) program, and made it available (together with its source code) through public FTP for download, the first widely available program implementing public-key cryptography. Shortly thereafter, it became available overseas via the Internet, though Zimmermann has said he had no part in its distribution outside the US.

The very first version of PGP included an encryption algorithm, BassOmatic, developed by Zimmermann himself.