Pretty Good Privacy (PGP)

Computer Systems Lab Documentation : Frequently Asked Questions : Pretty Good Privacy (PGP)

1.7.1 What is PGP?

PGP is a program to securely encrypt email and data using public-key cryptography. With public-key cryptography, there is no need for a secure channel with which to exchange keys. In fact, your public key is supposed to be as widely distributed as possible. This way, you can communicate securely with people you've never met. PGP is robust and fast, with sophisticated key management, digital signatures, and data compression

Words of Warning

We strongly encourage you to read the PGP Documentation, and to understand the risks involved, before using PGP to protect sensitive data.


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1.7.2 What versions of PGP are installed?

PGP comes in two basic versions:

PGP 2.6.2:
The last release of the 'classic' PGP. GP 2.6.2 was released free for non-commercial use by MIT, in cooperation with Phil Zimmerman, the author of PGP. PGP 2.6.x was ported to a very long list of computer systems. An "International" version (available outside the US) of PGP 2.6.3 is called 2.6.3i.
PGP 5.x:
The current PGP series. It is a product of Network Associates, who bought PGP, Inc (Phil Zimmerman's company). The major changes are different encryption schemes (among other reasons, to avoid patent and copyright issues), and better user interfaces. PGP 5.x is available for Windows, Macs, and some flavors of Unix. MIT is distributing PGP 5.0 for Windows and Macs (but not for Unix) free for non-commercial use. PGP5.0i is the current default version of PGP on Unix systems.
In addition, the source code to PGP 5.0 was legally exported from the US in the form of printed books, and scanned by a group of volunteers, to be the basis for the "international" version of pgp, PGP 5.0i (US export regulations governing cryptogrpahy have made dealing with PGP and related programs very difficult. See the comp.security.pgp FAQ for more information).


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1.7.3 Where is PGP installed?

On UNIX systems:

PGP is installed in two flavors on Unix. For more information on the differences, see What versions of PGP are installed? .

  • PGP 5.0i (compiled with the rsaref cryptographic library) is installed in /s/pgp50i and /s/std. PGP 5.0 uses different programs for different function, instead of in one pgp program. pgpe, pgpk, pgps, and pgpv are in /s/pgp50i/bin, /s/pgp/bin, and /s/std/bin. PGP 5.0i is the currently supported default version of PGP.
  • PGP 2.6.3 is installed in /s/pgp-262 as /s/pgp-262/bin/pgp.

On Windows NT systems:

PGP 5.0 for Windows NT will be installed in the near future.


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1.7.4 How can I integrate PGP with my mail program?

There are various packages to use PGP with many mail programs. We will be installing more of them in the future (if you have a specific request, please send electronic mail to lab@cs.wisc.edu with as much information about the package as possible).

On UNIX systems:

Pine
The default .pinerc file has support for PGP 5 in a commented-out section. To enable PGP support in pine, uncomment the following lines from the default .pinerc file.
#display-filters=_BEGINNING("-----BEGIN PGP")_ /s/std/bin/pgpv -f
#sending-filters=/s/std/bin/pgpe -fas -r _RECIPIENTS_,
#        /s/std/bin/pgps -fat
Emacs Rmail, Emacs mh-e
Mailcrypt is a package for using PGP with the emacs editor. Consult the Mailcrypt Manual for instructions on how to configure emacs to use mailcrypt with with MH-E, VM, Rmail and Gnus.

To use mailcrypt with PGP 5.0, add this to your .emacs file:
(mc-setversion "5.0")

To use with PGP 2.6.2, add this instead:
(mc-setversion "2.6")

On Windows NT systems:

In the near future, we will support the use of PGP 5.0 with Eudora.


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1.7.5 Where can I get someone's PGP Public Key?

If you can, try to get someone's public key directly from them and verify that it is from them. If not, try the PGP Public Key Server.


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1.7.6 Where can I get more information on PGP?


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