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 50K on disk with cipher suites. It includes SSL and TLS client and server support, session resumption, and implementations of RSA, AES, 3DES, ARC4, SHA1, and MD5. The source is well documented and contains portability layers for additional operating systems, cipher suites, and cryptography providers.
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.
GNU SASL is an implementation of the Simple Authentication and Security Layer framework and a few common SASL mechanisms. SASL is used by network servers such as IMAP and SMTP to request authentication from clients, and in clients to authenticate against servers. The library includes support for the SASL framework (with authentication functions and application data privacy and integrity functions) and at least partial support for the CRAM-MD5, EXTERNAL, GSSAPI, ANONYMOUS, PLAIN, SECURID, DIGEST-MD5, LOGIN, NTLM, and KERBEROS_V5 mechanisms.
PolarSSL is a light-weight cryptographic and SSL/TLS library written in C. PolarSSL makes it easy for developers to include cryptographic and SSL/TLS capabilities in their (embedded) applications with as little hassle as possible. Loose coupling of the components inside the library means that it is easy to separate the parts that are needed, without needing to include the total library. PolarSSL is written with embedded systems in mind and has been ported on a number of architectures, including ARM, PowerPC, MIPS, and Motorola 68000. The source is written to have very loose coupling, enabling easy integration of parts in other software projects. Very loosely coupled cryptographic algorithms for MD2, MD4, MD5, SHA1, SHA-256, SHA-512, AES, Camellia, DES, Triple DES, ARC3, and RSA are included.
The Shrew Soft VPN Client for Unix is a free IPsec Client for FreeBSD, NetBSD, and Linux based operating systems. It can be used to communicate with systems running ipsec-tools. The Unix client utilizes the IPsec kernel support included with the operating system, and comes with the complete Internet Key Exchange daemon and client front end application source code. A Windows version is also available.
Lite Security Module is a daemon to handle Secure Boxes (files containing cryptographic keys, X509 certificates and data objects), accessible through a PKCS#11 shared library, and supporting the development of non-certified (i.e. lite) software security modules (SSM) or hardware security modules (HSM).