The Centre for Applied Cryptographic Research at the University of Waterloo, Ontario, Canada and publishers of the Handbook of Applied Cryptography, CRC Press, have recently granted free online access to all chapters of the handbook (.pdf). Written by Alfred J. Menezes, Paul C. van Oorschot, and Scott A. Vanstone, this outstanding resource begins with an overview of cryptography before launching into detailed discussions of the mathematical background to cryptography, number-theoretic reference problems, various types of ciphers, and much more. The handbook includes a bibliography, references, and an index.