Functionality

PGP and GPG are used to encrypt and apply digital signatures to communications such as email. Their purpose is to make communications impossible for others to read unless they have the right decryption key. Both programs do this by using asymmetric, symmetric and public key pairs. If you’re sending an email, for example, you can generate a key and give it to someone else, allowing him to decrypt a message from you. By using this security, you prevent hackers and other unwanted parties from reading your communications, should they intercept them.

Development and Licensing

Phil Zimmermann wrote PGP under the GNU General Public License. At one time it could be freely used and modified. However, Zimmermann eventually converted PGP into paid-license software. Symantec purchased the rights to PGP in 2010. The company now manages the licensing of PGP as part of its Enterprise products division. The developers of GPG essentially recoded PGP, maintaining all its features, and released it again under the GNU General Public License, meaning that the code can be modified, used and freely distributed. GPG remains free, as of the date of publication.

Usage

PGP and GPG are both command-line programs. They are designed to be used from shell scripts and command prompts rather than via the graphical interfaces most computer users prefer. To make GPG and PGP easier for mainstream computer users to adopt, several graphical user interfaces have been developed by third parties for Linux, Windows and Mac OS X computers.

Additional Information

GPG and PGP are both OpenPGP and RFC4880-compliant. A message encrypted in a current version of GPG, for example, can be decrypted using a current version of PGP. This was not always the case. Previous versions of PGP used different algorithms that could not be read by GPG.

GPG has support for a broader variety of languages than PGP. Compatible languages include English, Spanish, French, German, Dutch, Danish, Portuguese, Polish, Italian, Russian, Japanese and Turkish.