GnuPG is theÂ GNU project’s complete and free implementation of the OpenPGP standard as defined byÂ RFC4880 . GnuPG allows to encrypt and sign your data and communication, features a versatile key management system as well as access modules for all kinds of public key directories. GnuPG, also known asÂ GPG, is a command line tool with features for easy integration with other applications. A wealth ofÂ frontend applications andÂ libraries are available. Version 2 of GnuPG also provides support for S/MIME.
GnuPG isÂ Free Software (meaning that it respects your freedom). It can be freely used, modified and distributed under the terms of theGNU General Public License .
GnuPG comes in two flavours:Â 1.4.11 is the well known and portable standalone version, whereasÂ 2.0.16 is the enhanced and somewhat harder to build version.
Some of its features include:
* Full OpenPGP implementation
* Full replacement of PGP
* Easy implementation of new algorithms using extension modules
* Does not use any patented algorithms
* Can be used as a filterÂ program
* Better functionality than PGP and some security enhancements over PGP 2
* Decrypts and verifies PGP 5, 6 and 7 messages
* Supports ElGamal, DSA, RSA, AES, 3DES, Blowfish, Twofish, CAST5, MD5, SHA-1, RIPE-MD-160 and TIGER
* Integrated support for HKP keyservers