GNUnet is a peer-to-peer framework with focus on providing security. All peer-to-peer messages in the network are confidential and authenticated. The framework provides a transport abstraction layer and can currently encapsulate the network traffic in UDP, TCP, HTTP, HTTPS, or direct 802.11 (WLAN). GNUnet supports accounting to provide contributing nodes with better service. The services built on top of the framework include anonymous file sharing and a virtual network providing IPv4-IPv6 transition via protocol translation over the P2P network.
MatrixSSL is an embedded SSL and TLS implementation designed for small footprint devices and applications requiring low overhead per connection. The library is less than 50Kb on disk with cipher suites. It includes client and server support through TLS 1.2, mutual authentication, session resumption, and implementations of RSA, ECC, AES, 3DES, ARC4, SHA2, SHA1, and MD5. The source is well documented and contains portability layers for additional operating systems, cipher suites, and cryptography providers.
RFC 2015 defines a proposed Internet standard for sending PGP-encrypted email. This PGP/MIME has been incorporated into several MUAs such as Mutt and (with the AEGYPTEN project) KMail. However, a lot of email clients still don't support it. pgp-mime-handler can decrypt/verify such messages via a pipe, so it can be used as an email filter in many programs or scripts.
CAKE (Key Addressed Crypto Encapsulation) is a bunch of Python and C++ for implementing the CAKE protocol. The CAKE protocol is a protocol in which all messages have source and destination addresses that are public keys. This is in the same way that IP packets have a source and destination address that is an IP address.
Better ASN is a Java ASN.1 API that focuses on speed and efficiency rather than extended functionality. This strategy prescribes one-pass decoding and near 100% encoding efficiency for typical ASN.1 usage patterns. Although BASN was developed for use by a Certificate Authority, the release comes packaged with an ASN.1 to Java compiler, which can be used to generate Java implementations of ASN.1 structures. This allows the API to be used for any Java application that may require ASN.1 decoding/manipulation/encoding.
GPGlist is a Perl script to implement gpg encrypted alias lists in a mail server such as Sendmail or Postfix. It uses one XML config file to store information about lists. It backs up messages if an error occours, and sends out error messages to the sender of the mail. You can decide whether or not a list only accepts encrypted messages.