Creating/inspecting key pair, encrypting/decrypting and sign/verify using OpenSSL

OpenSSL is a commercial-grade utility toolkit for Transport Layer Security (TLS) and Secure Sockets Layer (SSL) protocols. It’s also a general-purpose cryptography library. OpenSSL is licensed under an Apache-style license, which means that you’re free to get it and use it for commercial and non-commercial purposes (subject to some simple license conditions).