A crypto library aimed at auditability

I am not suggesting "inventing a new protocol so you can use NaCl". I'm suggesting that if you're in a position to be selecting openssl (or one of its large competitors) as a library of raw cryptographic functions, while implementing a custom protocol, file format or message format yourself, you may also want to give NaCl a look, for the same role.

If you just want a stock cryptographic tunnel to send some bytes over a socket without being overheard, of course there are well-debugged programs that talk to file descriptors, and there's little reason to even know what the internal crypto libraries are, much less how their APIs are organized.