Source : Free On-Line Dictionary of Computing

Pretty Good Privacy
     
         (PGP) A high security {RSA} {public-key
        encryption} application for {MS-DOS}, {Unix}, {VAX/VMS}, and
        other computers.  It was written by {Philip R. Zimmermann}
         of Phil's Pretty Good(tm) Software and later
        augmented by a cast of thousands, especially including Hal
        Finney, Branko Lankester, and Peter Gutmann.
     
        PGP was distributed as "{guerrilla freeware}".  The authors
        don't mind if it is distributed widely, just don't ask Philip
        Zimmermann to send you a copy.  PGP uses a {public-key
        encryption} {algorithm} claimed by US patent #4,405,829.  The
        exclusive rights to this patent are held by a California
        company called {Public Key Partners}, and you may be
        infringing this patent if you use PGP in the USA.  This is
        explained in the PGP User's Guide, Volume II.
     
        PGP allows people to exchange files or messages with {privacy}
        and {authentication}.  Privacy and authentication are provided
        without managing the keys associated with conventional
        cryptographic software.  No secure channels are needed to
        exchange keys between users, which makes PGP much easier to
        use.  This is because PGP is based on {public-key
        cryptography}.
     
        PGP encrypts data using the {International Data Encryption
        Algorithm} with a random {session key}, and uses the {RSA}
        algorithm to encrypt the session key.
     
        In December 1994 Philip Zimmermann faced prosecution for
        "exporting" PGP out of the United States but in January 1996
        the US Goverment dropped the case.  A US law prohibits the
        export of {encryption} software out of the country.
        Zimmermann did not do this, but the US government hoped to
        establish the proposition that posting an encryption program
        on a {BBS} or on the {Internet} constitutes exporting it - in
        effect, stretching export control into domestic censorship.
        If the government had won it would have had a chilling effect
        on the free flow of information on the global network, as well
        as on everyone's privacy from government snooping.
     
        {FAQ (ftp://ftp.netcom.com/pub/mp/mpj/getpgp.asc)}.  {UK FTP
        (ftp://src.doc.ic.ac.uk/packages/pgp/)}.  {USA FTP
        (http://web.mit.edu/network/pgp-form.html)}.
        {(http://www.pegasus.esprit.ec.org/people/arne/pgp.html)}.
     
        {Justice Dept. announcement
        (http://www.eff.org/pub/Alerts/usatty_pgp_011196.announce)}.
     
        ["Protect Your Privacy: A Guide for PGP Users", William
        Stallings, Prentice-Hall, ISBN 0-13-185596-4].
     
        (1996-04-07)