: Problems testing modular arithmetic , number theory, and linear feedback shift registers (LFSRs).

This free online book includes full solutions to many problems (both odd and even) at the end of each chapter.

If you do not have the even manual, here is the framework to solve it yourself—and confirm you are correct.

If you are studying applied cryptography, chances are you have a copy of on your desk. It is widely considered the gold standard for bridging the gap between pure math and real-world implementation.