PGP

"Pretty Good Privacy"

PGP is a public key encryption program originally written by Phil Zimmermann in 1991. It was distributed as shareware for MS-DOS and other platforms via the BBS/FTP scene. In 1995, the source code was published in book form. [1] At that time the software was surrounded by a host of legal issues, but it became the main basis for the OpenPGP standard (RFC 2440, RFC 3156). The current owner of the PGP trademark is PGP Corporation.

PGP does not necessarily refer to one specific piece of software, but rather to a security architecture that one adopts. The text files bundled with the old shareware version talked about things like wiping files, avoiding electromagnetic spying, and using a good passphrase. The software offered by PGP corporation includes an encrypted filesystem for Windows as well as e-mail-client plugins and a keyring-management tool.

Linux Alternatives

First of all, the PGP command-line tools are sold for Linux, although at a price higher than what a casual home user might be used to (US$612.00 for a 2-CPU send-only license, for example). The command-line tools are also sold for Solaris, AIX, Win2k server, etc.

However, there are several elements of Linux that together provide what PGP claims to provide. For signing and encrypting arbitrary files, and for console-based key management, we have GNU Privacy Guard. Several GUI key-manager interfaces have been written, including Kgpg. Some e-mail clients feature GPG integration; the list of such clients is too long to include here.

To maintain an encrypted disk partition under Linux, use the cryptoloop kernel module; see the HOWTO for details. PGP 9 also claims to include IM encryption; there are several plugins for GAIM that provide different kinds of encryption.

References

[1] Schneier, Bruce. Applied Cryptography, 2nd ed. Wiley: 1996. pp. 584-587; see also the book's references.

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