{{library}} From the [http://www.openssl.org/ OpenSSL site]: 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 provides libraries for [[C|C language]], and the [http://www.openssl.org/docs/apps/openssl.html openssl(1)] command for [[UNIX Shell|shell scripts]]. Several other languages provide access to OpenSSL. [[Ruby]] has 'openssl' in its standard library.

OpenSSL has two libraries:

• [http://www.openssl.org/docs/crypto/crypto.html crypto(3)] implements cryptographic algorithms, such as ciphers, message digests, and X.509 certificates. crypto(3) also exposes features, including [[arbitrary-precision integers (included)|arbitrary-precision integers]] called BIGNUMs, and a secure random number generator.
• [http://www.openssl.org/docs/ssl/ssl.html ssl(3)] implements SSL and TLS.

To link OpenSSL to a C program, a typical [[Unix]] command is

cc -o program program.c -lcrypto -lssl