The GNU Privacy Assistant is a graphical frontend to GnuPG and may be used to manage the keys and encrypt/decrypt/sign/check files. It is much like Seahorse.
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.