I agree that OpenSSL is likely the most robust library out there, and if you're talking about provisioning your web server / doing some https from a high-level

I agree that OpenSSL is likely the most robust library out there, and if you're talking about provisioning your web server / doing some https from a high-level language then it's definitely the sane choice. (fwiw, I had some work looking at a BouncyCastle TLS server and...eek) The one counter-example is the embedded space, particularly where code addition/modification for hardware integration is required. Here OpenSSL's footprint and APIs are a tad unwieldy compared to some alternatives. Basically I just wanted to give mbedTLS a shout-out as, IMO, the clear winner in that particular space.