This library must be built with dub.
Books and other resources
It's a very good idea if you have some knowledge of cryptography before trying to use the library. This is an area where it is very easy to make mistakes, and where things are often subtle and/or counterintuitive. Obviously the library tries to provide things at a high level precisely to minimize the number of ways things can go wrong, but naive use will almost certainly not result in a secure system.
Especially recommended are:
by Niels Ferguson, Bruce Schneier, and Tadayoshi Kohno
Security Engineering -- A Guide to Building Dependable Distributed Systems
by Ross Anderson
Handbook of Applied Cryptography available online
by Alfred J. Menezes, Paul C. Van Oorschot, and Scott A. Vanstone
If you're doing something non-trivial or unique, you might want to at the very least ask for review/input on a mailing list such as the metzdowd or randombit crypto lists. And (if possible) pay a professional cryptographer or security company to review your design and code.