Discrete Mathematics with Applications – Third Edition

Author: Susanna Epps

Publisher: Thompson Publishing

ISBN 0-534-35945-0

This book contains all you would need to know to understand the mathematics of cryptology. Predicate and propositional calculus, theorems of prime numbers, computational complexity, set theory, trees, and even a section on cryptography are presented in this text.

Applied Cryptography

Author: Bruce Schneier

Publisher: Wiley and Sons

ISBN 0-471-11709-9

This book is a digest of all things cryptographic: Algorithms, protocols, definitions, techniques, etc. This is the bible for cryptography.

Computer Security

Author: Matt Bishop

Publisher: Wiley and Sons

ISBN 0-471-11709-9

This book is a sort of a "pure cryptography in action" text. Very good later chapters on the math and theory of some of the more popular cryptographic protocols