GNU Privacy Guard

An encryption tool that encrypts emails, digitally signs them, and also encrypts documents.

GPG was an implementation of the Pretty Good Privacy (PGP) protocol. However, PGP is now owned by some random company that will go unnamed. They both follow the OpenPGP standard (RFC 4880)4880) for data encryption/decryption. GPG supports RSA, DSA, 3DES, IDEA, MD5, SHA, and more. However, GPG uses AES by default.

PGP supports either RSA or Diffie-Hellman for asymmetric encryption and IDEA for symmetric encryption.