OpenSSL is The Open Source toolkit for Secure Sockets Layer and Transport Layer Security.

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 v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library.

OpenSSL 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.

OpenSSL is based on the excellent SSLeay library developed by Eric A. Young and Tim J. Hudson. The OpenSSL toolkit is licensed under an Apache-style licence, which basically means that you are free to get and use it for commercial and non-commercial purposes subject to some simple license conditions.

Here are some key features of "OpenSSL":

· Creation of RSA, DH and DSA key parameters
· Creation of X.509 certificates, CSRs and CRLs
· Calculation of Message Digests
· Encryption and Decryption with Ciphers
· SSL/TLS Client and Server Tests
· Handling of S/MIME signed or encrypted mail