Event Name Seminar by Prof. K. Gopalan on Information Hiding in Audio and Image Signals for Watermarking, Steganography and Covert Communication Applications
Start Date 10th Feb 2009 10:00am
End Date
Duration N/A

Title: Information Hiding in Audio and Image Signals for Watermarking, Steganography and Covert Communication Applications


K. Gopalan
Department of Electrical and Computer Engineering
Purdue University Calumet
Hammond, IN 46323, U.S.A.

Time and Date: 10:00 am, 10 Feb 2009

Place: Brown Theatre, EEE, University of Melbourne


Steganography, or information hiding in a medium, is concerned with embedding information in an audio, image, or video file in an imperceptible manner. Human auditory and visual imperfections, which lead to psychoacoustic masking effects in hearing and vision, are exploited for modifying a host, or cover, audio or image in accordance with a given piece of covert information. Since the modification is carried out in the masked regions of perceptibility, the information-embedded medium, or the ‘stego’ signal, appears to be the same as the original host signal. While encryption of a media signal (an audio or image) alters the signal to conceal its contents so that it becomes unintelligible, embedding uses the media signal as a carrier for hiding covert information without altering the perceptual quality of the carrier. Hence, the success of embedding information in a media signal depends, among others, on the detectability of any difference between the original host signal and the embedded, stego signal. Recovery of embedded information without requiring the original host media signal – oblivious recovery – and robustness of the hidden information under adverse conditions during transmission are also essential in many applications of steganography. Additionally, the hidden information must withstand intentional or unintentional attacks, in attempts to illegally access the information, on the innocuously appearing stego audio or image.

Applications of general steganographic techniques abound in modern Internet based communication and file sharing. Watermarking of an audio signal, for instance, is used to determine the legal use of a music or image file that carries a hidden logo or other information without causing any perceptible change in quality. Embedding biometric data such as a person’s fingerprint features in his/her picture identification card for use in access-controlled areas such as military installations can thwart illegal entry. By concealing the existence of hidden information, the technique can be applied for covert communication using unclassified channels without undue demand for bandwidth.

The presentation will provide an overview of steganography based on the psychoacoustic masking effect of the human auditory system. It will focus on the masking-based audio embedding techniques with examples using spectral and cepstral domain modifications. New patented techniques using insertion of inaudible tones at selected frequencies in the masked regions of audio frames will be discussed. The talk will continue with a discussion on extending the tone insertion techniques for image embedding and the resulting high payload. Preliminary results and examples of image steganography will conclude the presentation.

Brief Bio:

K. ‘Gopal’ Gopalan received his Bachelor’s degree in Electrical Engineering from P.S.G.College of Technology (University of Madras), Coimbatore, India, Master’s degree in Electrical Engineering from the Indian Institute of Technology, Kanpur (IITK), India, and Ph.D. degree in Engineering from the University of Akron, Akron, OH. From 1974 to 1979, he was employed as a research engineer at IITK developing research instrumentation systems. After obtaining his Ph.D. degree in 1983, he taught at Lafayette College, Easton, PA as an Assistant Professor of
Electrical Engineering. Since 1985, he has been with the Department of Electrical and Computer Engineering at Purdue University Calumet, Hammond, IN, currently holding the position of Professor and Coordinator of the Computer Engineering program. From 1987 to 1995 he conducted research in the areas of signal and image processing for nondestructive evaluation of advanced materials at Argonne National Laboratory, Argonne, IL, first as a summer faculty research participant and later as a consultant. In addition, he has been a summer faculty research
associate at Wright-Patterson Air Force Base, OH, and the Air Force Research Laboratory (AFRL), Rome, NY. His research in speech analysis, speaker recognition, audio steganography and keyword recognition has been funded by AFRL. He has received two U.S. patents and has one U.S. patent pending, all on audio steganography.
Gopalan is a Senior Member of the IEEE and is the author of two textbooks, Introduction to Digital Microelectronic Circuits (Irwin/McGraw-Hill, 1996), and Introduction to Signal and System Analysis (Cengage, 2009).

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