A version of this paper was presented at the fourth Conference Telecommunications in Modern Satellite and Cable Services, TELSKI'99, October 1999, Nis, Serbia.

In this paper we will present general principles of steganography, basic terminology, and an overview of applications and techniques. In particular we will consider data hiding within audio signals, basic requirements and the state of the art techniques. We will propose a novel technique, the short-term autocorrelation modulation, with several variations. The proposed method is characterized by perfect transparency, robustness, high bit rate, low processing load, and, particularly, high security.