Free C++ library for cryptography: includes ciphers, message authentication codes, one-way hash functions, public-key cryptosystems, and key agreement schemes.

A collaborative effort to develop a robust, commercial-grade, full-featured, and Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library.

A powerful security toolkit which allows even inexperienced crypto programmers to easily add encryption and authentication services to their software.

Includes code for IDEA, Blowfish, SHA-1, MD5, RC16 (RC4 extension), an initial implementation of DES and a few related toys.

A free, public domain implementation of RSA Data Security's BSAFE API, using the SSLeay crypto library.

CTClib (PGP-interoperable ANSI C encryption software library) and CTCjava (Java crypto components and application).

Library of cryptographic primitives in ANSI C, including block ciphers and hash functions, together with generic modes of operation. Also includes simple key management system, multiprecision arithmetic, and public key algorithms.

Supports the following algorithms; BLOWFISH, TWOFISH, DES, TripleDES, 3-WAY, SAFER-sk64, SAFER-sk128, SAFER+, LOKI97, GOST, RC2, RC6, MARS, IDEA, RIJNDAEL-128 (AES), RIJNDAEL-192, RIJNDAEL-256, SERPENT, CAST-128, CAST-256, ARCFOUR and WAKE. ANSI C.

Mozilla's NSS, is a set of libraries designed to support cross-platform development of security-enabled server applications.

Gives your applications access to multi-precision integer math routines with just a function call. Full source code available. For VB, C++, or embedded systems.