Introduction to Cryptography with Java Applets covers the mathematical basis of cryptography and cryptanalysis, like linear diophantine equations, linear congruences, systems of linear congruences, quadratic congruences, and exponential congruences. The chapters present theorems and proofs, and many mathematical examples. Cryptography with Java Applets also covers programming ciphers and cryptanalytic attacks on ciphers. In addition many other types of cryptographic applications, like digest functions, shadows, database encryption, message signing, establishing keys, large integer arithmetic, pseudo-random bit generation, and authentication are included. The author has developed various Java crypto classes to perform these functions, and many programming exercises are assigned to the reader. The reader should be someone with a basic working knowledge of Java, but knowledge of number theory or cryptography is not necessary.