Tptacek said it's a bad idea to read Applied Cryptography. "Take that book Applied Cryptography that's on your bookshelf and burn it. Do that as a commitment to really learning crypto. But absolutely don't read it. If you don't read it, you have nothing to unlearn, so you're much better off." Source: http://wiki.securityweekly.com/wiki/index.php/Episode292 time index 22:10, but the whole podcast is good.

Instead, he recommends Cryptography Engineering: http://www.amazon.com/Cryptography-Engineering-Principles-Pr...

Another way to get a primer on crypto is to do the Matasano crypto challenges: http://cryptopals.com/

The solutions aren't (yet?) published, but don't let that stop you. It will be fairly obvious when you've come up with a solution that solves the challenge. It's also an excellent way to get you really thinking about all of the problems with crypto. And it will hopefully scare you from ever implementing your own crypto scheme, which is always a good thing.

Make sure to do all the challenges though. They get exponentially more difficult, but the best ones are near the end.

I would highly recommend reading Cryptography Engineering [0] cover to cover. It's amazingly readable, covers the basics, the theory necessary to understand how things works and includes ample practical advice and observations on the industry.

The first thing I did after the Snowden leaks was read through the entire thing and after doing so I really wished I had done this years earlier. There's very few books that I think should be required reading across the board for software engineers, but this is one that I do think everyone writing code should read every page of.

[0] http://www.amazon.com/Cryptography-Engineering-Principles-Pr...

TLDR; Get "Cryptography Engineering"[0] instead.

0: http://www.amazon.com/Cryptography-Engineering-Principles-Pr...