The openssl package contains c_rehash, openssl, libcrypto and libssl. No description is available for c_rehash. The openssl program is a command line tool for using the various cryptography functions of OpenSSL's crypto library from the shell. It can be used for various functions which are documented in man 1 openssl. The OpenSSL crypto library implements a wide range of cryptographic algorithms used in various Internet standards. The services provided by this library are used by the OpenSSL implementations of SSL, TLS and S/MIME, and they have also been used to implement SSH, OpenPGP, and other cryptographic standards. The OpenSSL ssl library implements the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols. It provides a rich API, documentation on which can be found by running man 3 ssl.