A security program distributed by MIT that allows users to send information securely using two-key encryption.

GnuPG Mac OS X port the open source OpenPGP client.

A text-encryption program that can be used to send encrypted messages to recipients. This is considered a low security product.

A shareware utility provides drag and drop encryption/decryption of files and folders.

The maker of Tresor, a file and folder encryption tool for Mac. Offers a newsletter, downloadable demo, product registration, support, and bug reporting.