|Cover of Hidden in Plain Sight (2015)|
In Zerubavel's insightful and wide-ranging book, among the subjects introduced is a current encryption technique known as steganography. Now practiced in its digital form, the term was originated in 1499 (so says Wikipedia) by Johannes Trithemius in Steganographia, "a treatise on cryptography and steganography, disguised as a book on magic." We ourselves first learned about it in 2006 at an international conference at the University of Northern Iowa on Camouflage: Art, Science and Popular Culture, at which digital media scholar Eugene Wallingford (UNI Computer Science Professor) offered a wonderful overview of current uses of digital steganography.
Here is an excerpt from Zerubavel's text about steganography (pp. 35-36)—
There is a particular form of background-matching camouflage known as steganography, in which actual "signals" are purposely designed to be mistaken for mere "noise" and thereby effectively ignored. One can thus send a covert message in such a way that no one apart from oneself and one's intended audience (who are in fact usually alerted to expect it) even suspects its existence. Whereas in cryptography only the content of the hidden is concealed, in steganography, its very existence is concealed as well.