Pretty Good Privacy

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Pretty Good Privacy

(tool, cryptography)
(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.


Justice Dept. announcement.

["Protect Your Privacy: A Guide for PGP Users", William Stallings, Prentice-Hall, ISBN 0-13-185596-4].
This article is provided by FOLDOC - Free Online Dictionary of Computing (


(1) See Personal Genome Project.

(2) (Pretty Good Privacy) A data encryption program from PGP Corporation, Palo Alto, CA ( Published as freeware in 1991 and widely used around the world for encrypting email messages and securing files, PGP is available for commercial use and as freeware for personal use. Freeware versions are also available from PGP also supports digital signatures and PKI.

The Public Key Sends the Secret Key
For email, PGP sends the key and encrypted message at the same time. It encrypts the key using a public key algorithm such as RSA and encrypts the message using a secret key algorithm such as IDEA (the original), CAST5, Triple DES and AES. On the receiving side, the public key method decrypts the secret key first, which it uses to decrypt the message.

To Network Associates and Back
PGP was developed by Phil Zimmermann (, founder of Pretty Good Privacy, Inc., San Mateo, CA, and recipient of numerous awards for his pioneering work in cryptography. In 1997, Network Associates acquired his company, and the IETF formed the OpenPGP working group to support an open PGP standard. In 2002, the PGP assets of Network Associates were acquired by the newly formed PGP Corporation, and Zimmermann became a consultant to the company. See cryptography, digital signature and web of trust.
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References in periodicals archive ?
The most common security protocols used in eCommerce secure framework are Pretty Good Privacy (PGP), Secure Socket Layer (SSL) and Secure Electronic Transaction (SET).
(44) Encryption programs such as Pretty Good Privacy allow users to protect the privacy of their personal information by ensuring that only authorized users can access the information; in other words, users protect their private information by securing it.
The holiday parc at Domaine de Kerlann has more than 750 pitches, but clever landscaping and planting, incorporating native pines and hydrangeas, ensure pretty good privacy. It offers a broad range of family activities, including swimming pools, tennis, table tennis, mini-golf, basketball and kids' quad bikes.
For some time now the standard has been Pretty Good Privacy, now called PGP Desktop (
One effective and well-known tool is PGP, which stands for "Pretty Good Privacy." There are also operating system-based encryption tools, such as Windows EFS, "Encrypted File System." As a rule, the more encryption services used, the tighter the security.
Norris, for example, says his firm uses an MS Windows encryption file system combined with PGP (or "pretty good privacy," a computer program that provides cryptographic privacy and authentication) to secure files that are being transmitted.
Existing industry standard technologies such as secure file transfer protocol (FTP), pretty good privacy (PGP) encryption and secure sockets layer (SSL) transmission can ensure that any customer-sensitive data in transmission have a high degree of protection.
Other encryption algorithms have been in use for years and include Secure Sockets Layer (SSL) for Internet transactions, Pretty Good Privacy (PGP), and Secure Hypertext Transfer Protocol (S-HTTP).
Businesses should encrypt all traffic travelling over the WLAN by using application encryption such as Pretty Good Privacy, Secure Shell or Secure Sockets Layer.
By inventing and distributing Pretty Good Privacy, a free, easy, and damn-nigh uncrackable e-mail encryption program, he gave dissidents everywhere the ability to communicate without fear--all while challenging his own government's attempt to control that ability.
Another approach is the Pretty Good Privacy (PGP) system (PGP, 2002) in which a "Web of Trust" is built up from an established list of known and trusted identity/key bindings.
PGP, for Pretty Good Privacy, is a public key cryptography method generally used in email.