minssl is in the process of approval by the French government, and has not yet been released. This documentation might be incomplete.
minssl is a set of tools used to establish a secure communication channel between two processes; its functionality is comparable to stunnel's. minssl has been designed to be as simple, fast and small as possible, without jeopardizing security. It should be small enough to fit in embedded devices.
minssl is not SSL-compliant: it does not use the SSL or TLS protocol. If you want an SSL-compliant tool with a nice interface, check out the excellent ucspi-ssl. Note that SSL-compliant tools are considerably bigger, probably slower, and that bugs are occasionally found in the OpenSSL library.
All these commands exit 111 if they encounter a temporary error, and 100 if they encounter a permanent error - such as a misuse.