The Arcanum Editor is a small but powerful tool to encrypt and decrypt messages. The program also comes with it's own format CTXT. This format is based on XML and allows you to save texts with the Advanced Encryption Standard.
Open source project that offer summary and download services on this page is a project that carry out their development work on other open source development sites. Their work is linked to this page via a feature called OFI, and their work is not carried out here on OSDN site.