Nicholas Hopper(Carnegie Mellon University):
Steganography: Undercover Cryptography
Steganography is typically described as the art of hiding secret
messages in "innocent-looking messages" in such a way that the hidden
messages cannot be detected. There is a substantial literature
describing protocols which heuristically satisfy this goal, and
attacks which detect or even recover the messages hidden by these
protocols. A likely reason for this phenomenon is the lack of a
rigorous definition of steganography, along the lines of the
definitions for secure encryption developed by Blum-Micali, Yao,
Micali-Goldwasser, and others in the 1980s.
In this talk I will present a formal definition of a stegosystem; give
strong definitions of steganographic security against passive and
active adversaries; and present constructions which provably satisfy
these definitions, under the assumption that pseudorandom function
families exist.