PKIF: The PKI Framework

"PKIF is a full-featured, standards compliant PKI enablement library. Its goal is to make it easy for your applications to take advantage of your PKI. PKIF runs on Windows and UNIX systems and is written in C++ with bindings for C# (and COM/.Net) and java. PKIF can validate certificates, create and verify signatures, encrypt and decrypt data, and much more." read more...

Website: http://pkif.sourceforge.net/index.html

Crypto++ Library

Crypto++ Library is a free C++ class library of cryptographic schemes. This library supports following algorithms: Panama, Salsa20, Sosemanuk,ES (Rijndael), RC6, MARS, Twofish, Serpent, CAST-256, IDEA, Triple-DES (DES-EDE2 and DES-EDE3), Camellia, RC5, Blowfish, TEA, XTEA, Skipjack, SHACAL-2, VMAC, HMAC, CBC-MAC, DMAC, Two-Track-MAC, SHA-1, SHA-2 (SHA-224, SHA-256, SHA-384, and SHA-512), Tiger, WHIRLPOOL, RIPEMD-128, RIPEMD-256, RIPEMD-160, RIPEMD-320, RSA, DSA, ElGamal, Nyberg-Rueppel (NR), Rabin, Rabin-Williams (RW), LUC, LUCELG, DLIES (variants of DHAES), ESIGN, Diffie-Hellman (DH), Unified Diffie-Hellman (DH2), Menezes-Qu-Vanstone (MQV), LUCDIF, XTR-DH, ECDSA, ECNR, ECIES, ECDH, ECMQV.

Website: http://www.cryptopp.com

OpenSSL: The Open Source toolkit for SSL/TLS

" The OpenSSL Project is a collaborative effort to develop a robust, commercial grade, full featured, and Open Source toolkit implementing the Secure Sockets Layer (SSL) and Transport Layer Security (TLSv1) protocols as well as a full-strength general purpose cryptography library. The project is managed by a worldwide community of volunteers that use the Internet to communicate, plan, and develop the OpenSSL toolkit and its related documentation. " read more...

Website: http://www.openssl.org