This book provides a good introduction to the classical elementary number theory and the modern algorithmic number theory, and their applications in computing and information technology, including computer systems design, cryptography and network security. In this 2nd edition proofs of many theorems have been provided, further additions and corrections were made.

Foreword by Martin E. Hellman.- Preface to the Second Edition.- Preface to the First Edition.- 1. Elementary Number Theory.- 2. Computational/Algorithmic Number Theory.- 3. Applied Number Theory.- Bibliography.- Index.