cryptography book or resource I am trying to write a multiple currency hd wallet.
I am using javascript libraries but I feel unsafe as I am new to most cryptography concepts and terms like elliptic curve, seeds, entropy etc.

I can not be a cryptography expert but I want to learn terms and concepts at least to know what it is doing when I am using third party libraries.

Can you recommend any books or online resources?
Mastering Bitcoin is an amazing book that'll definitely get you started. It's freely available online here: http://chimera.labs.oreilly.com/books/1234000001802/index.html