This site from BarcodesInc gives a helpful overview of what Cryptography is and supplies a number of links to other sites dealing with various issues in cryptography, such as Public Key encryption, Applied Cryptography...

Many common questions about cryptography are answered in this May 2000 handbook by RSA Security, Inc. The contents include a basic introduction to cryptography, tools, applications, problems, cryptoanalysis, techniques,...

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...