I am writing Bitcoin-related software in C/C++ and I need to select a cryptography library that supports the usual stuff -- ECDSA, ECC math, SHA2, RIPEMD, PBKDF2, HMAC, and a secure RNG. Any suggestions?

I just assumed that I would be using OpenSSL, but I have discovered that with OpenSSL 3, all of the "low-level" functionality has been deprecated, and that is exactly what I was intending to use. Perhaps, I could the new "high-level" features, but I don't know how. Also, I can't find any examples of anyone using the new features anywhere, which s weird.

Perhaps sticking with a legacy version of OpenSSL is a good solution.

A friend suggested WolfSSL. It does what I need but it has some drawbacks -- it is a pain to integrate and 75% of the API is undocumented.

What are you using?