Security: An Overview of GPG

In 1991 Philip Zimmerman released a program called Pretty Good Privacy or PGP. It used RSA to encrypt and decrypt messages and became quite famous. Mr. Zimmerman, in the mid 1990's lived through interesting times, courtesy of the U. S. Government. But despite publishing the source code for PGP and allowing free use, PGP was never an "open source" program by modern definitions. There were some variously open versions released by Mr. Zimmerman's commercial successors but the end result was that in 1999 the FSF released it's own completely free version of those programs, keeping a great deal of command compatibility as GPG, Gnu Privacy Guard. The uses of that program will be our concern for the rest of this article.