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Computing (FOLDOC) dictionary
Pretty Good Privacy
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tool, cryptography (PGP) A high security RSA public-keyencryption application for MS-DOS, Unix, VAX/VMS, and
other computers. It was written by Philip R. Zimmermann
pkz@acm.org 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-keyencryption 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-keycryptography.
PGP encrypts data using the International Data EncryptionAlgorithm 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.