I'm making a C++ back end for an application that'll heavily rely on AES-256 and DH. Should I trust third party libraries, or spend (lots of) time to learn about cryptographic implementation and write my own? Is there any reliable authority that can audit the security of a library (like Crypto++ in this case)? I hope this question doesn't come off as opinion based, but it's quite hard to find reputable data on this. I have no idea where to even start.
TL;DR: What's worse: risking vulnerabilities in a third party library, or risking novice mistakes in a custom implementation?