There are a large number of steganographic methods that most of us are familiar with (especially if you watch a lot of spy movies!), ranging from invisible ink and microdots to secreting a hidden message in the second letter of each word of a large body of text and spread spectrum radio communication. In this article, I will discuss what steganography is, what purposes it serves, and will provide an example using available software. Whereas the goal of cryptography is to make data unreadable by a third party, the goal of steganography is to hide the data from a third party. Steganography is the science of hiding information. Encrypted data sticks out like a sore thumb. Besides being nonsensical to a casual reader, the other indication that this is encrypted is that the characters comprising the message appear more-or-less at random and do not adhere to the relative frequency counts that one would expect in a non-encrypted message.

The message above is a sentence in English that is encrypted using Pretty Good Privacy (PGP), probably the most commonly used e-mail encryption software today. HdlLQRPQdrmnWskKznOSarxq4GjpRTQo4hpCRJJ5aU7tZO9HPTZXFG6iRIT0wa47ĪR5nvkEKoIAjW5HaDKiJriuWLdtN4OXecWvxFsjR32ebz76U8aLpAK87GZEyTzBxĭV+lH0hwyT/y1cZQ/E5USePP4oKWF4uqquPee1OPeFMBo4CvuGyhZXD/18Ft/53Y MJJuQ53Ob9ThaFH8YcE/VqUFdw+bQtrAJ6NpjIxi/x0FfOInhC/bBw7pDLXBFNaX

GLYcPrcn4s3EriUgv元OzPR4P1chNu6sa3ZJkTBbriDoA3VpnqG3hxqfNyOlqAka YBS+dzFDw5desMFSo7JkecAS4NB9jAu9K+f7PTAsesCBNETDd49BTOFFTWWavAfE ULLem2/fQHZhGcQvkqZVqXx8SmNw5gzuvwjV1WHj9muDGBY0MkjiZIRI7azWnoU9ģKCnmpR60VO4rDRAS5uGl9fioSvze+q8XqxubaNsgdKkoD+tB/4u4c4tznLfw1L2 Z/9Ak4/OLnLiJRk05/2UNE5Z0a+3lcvITMmfGajvRhkXqocavPOKiin3hv7+Vx88 ZBIEFtjyqCd96qF38sp9IQiJIKlNaZfx2GLRWikPZwchUXxB+AA5+lqsG/ELBvRaĬ9XefaYpbbAZ6z6LkOQ+eE0XASe7aEEPfdxvZZT37dVyiyxuBBRYNLN8Bphdr2zv QANQR1DBwU4D/TlT68XXuiUQCADfj2o4b4aFYBcWumA7hR1Wvz9rbv2BR6WbEUsy Consider the following text file what else is it likely to be if not encrypted? If a nefarious government or Internet service provider (ISP) is looking for encrypted messages, they can easily find them. But cryptography does not always provide safe communication.Ĭonsider an environment where the very use of encrypted messages causes suspicion. Ĭryptography the science of writing in secret codes addresses all of the elements necessary for secure communication over an insecure channel, namely privacy, confidentiality, key exchange, authentication, and non-repudiation.

An edited version of this paper with the title 'Hiding Data in Data' originally appeared in the April 2002 issue of Windows &.

Steganography uses