REALLY TECHNICALLY SAVVY CRIMINALS will try to hide evidence on their computers. There are any number of techniques one can use to either hide or protect information so that, even if the computer is seized and searched, investigators are less likely to find the evidence. This chapter introduces the two ways of masking information: steganography and cryptography. These techniques predate modern computers. In fact, they are so old that they can trace their origins to ancient Greece. Steganography comes from the Greek steganos, meaning covered or protected. Cryptography comes from the Greek kryptos, meaning to hide (although encrypted information is clearly scrambled, and not hidden, per se).