Steganography and Cryptography are in fact complementary techniques. No matter how strong algorithm, if an encrypted message is discovered, it will be subject to cryptanalysis. Likewise, no matter how well concealed a message is, it is always possible that it will be discovered. By combining Steganography with Cryptography we can conceal the existence of an encrypted message. In doing this, we make it far less likely that an encrypted message will be found. Also, if a message concealed through Steganography is discovered, the discoverer is still faced with the formidable task of deciphering it.
Sunday, March 15, 2009
Cryptography vs. Steganography
Introduction to Steganography
Another historical exampls of Steganography are the use of invisible inks. A common experiment conducted by young kids everywhere is to use a toothpick dipped in vinegar to write a message on a piece of paper. Once the vinegar dries, the presence of the message is not obvious to a casual inspector (aside from the smell). Upon slight heating of the paper, a chemical reaction occurs which darkens the vinegar and makes the message readable. Other, less smelly, invisible inks have been used throughout history similarly even up until World War II.
A more recently developed Steganography technique was invented by the Germans in World War II, the use of microdots. Microdots were very small photographs, the size of a printed period, which contain very clear text when magnified. These microdots contained important information about German war plans and were placed in completely unrelated letters as periods.
Although Steganography is related to Cryptography, the two are fundamentally different.