Resources

For people interested in reading further, there are several good books:

• Singh, Simon (2000). "The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography". ISBN 0-385-49532-3.
• Kahn, D (1973) "The CodeBreakers: The Comprehensive History of Secret Communication". Macmillan

For a look at more modern algorithms, try:

• Schneier, Bruce (1996). "Applied Cryptography", John Wiley & Sons
• Mao, Wenbo (2003). "Modern Cryptography: Theory and Practice", Prentice Hall.
• Menezes, A. van Oorschot, P. Vanstone, S. (1996) "Handbook of Applied Cryptography", Crc Press.
• Stinson, Douglas (2005). "Cryptography: Theory and Practice"

If you're looking for something online that you can access immediately, try:

• "Introduction to Modern Cryptography" subject at University of California, San Diego
• Simon Singh's website
• A Cryptographic Compendium
• Handbook of Applied Cryptography
• An overview of cryptography
• Cryptography FAQ
• Mathematics at MIT OpenCourseWare