SECURITY ISSUES AND PRINCIPLES

STEGANOGRAPHY [n. stə nóggrəfi]
Steganography (literally meaning covered writing) dates back to ancient Greece, where common practices consisted of etching messages in wooden tablets and covering them with wax, and tattooing a shaved messenger's head, letting his hair grow back, and then shaving it again when he arrived at his contact point. Steganography comes from the Greek steganos, or "covered," and graphie, or "writing". Synonymous to abstraction, the art and science of hiding information by embedding messages within other, seemingly harmless messages. Steganography takes cryptography a step farther by hiding an encrypted message so that no one suspects it exists. Ideally, anyone scanning your data will fail to know it contains encrypted data by replacing bits of useless or unused data in regular computer files (such as graphics, sound, text, HTML, or even floppy disks ) with bits of different, invisible information. This hidden information can be plain text, cipher text, or even images. Steganography sometimes is used when encryption is not permitted or, more commonly, is used to supplement encryption. An encrypted file may still hide information using steganography, so even if the encrypted file is deciphered, the hidden message is not seen. In modern digital steganography, data is first encrypted by the usual means and then inserted, using a special algorithm, into redundant (that is, provided but unneeded) data that is part of a particular file format such as a JPEG image. Think of all the bits that represent the same color pixels repeated in a row. By applying the encrypted data to this redundant data in some random or nonconspicuous way, the result will be data that appears to have the "noise" patterns of regular, nonencrypted data. A trademark or other identifying symbol hidden in software code is sometimes known as a