Page ii For quite a long time, computer security was a rather narrow field of study that was populated mainly by theoretical computer scientists, electrical engineers, and applied mathematicians With the proliferation of open systems in general, and the Internet and the World Wide Web (WWW) in particular, this situation has changed fundamentally Today, computer and network practitioners are equally interested in computer security, since they require technologies and solutions that can be used to secure applications related to electronic commerce (e-commerce) Against this background, the field of computer security has become very broad and includes many topics of interest The aim of this series is to publish state-of-the-art, high-standard technical books on topics related to computer security Further information about the series can be found on the WWW by following the URL: http://www.ifi.unizh.ch/~oppliger/serieseditor.html Also, if you would like to contribute to the series and write a book about a topic related to computer security, feel free to contact either the Commissioning Editor/Acquisitions Editor or the Series Editor at Artech House Recent Titles in the Artech House Computer Security Series Rolf Oppliger, Series Editor Information Hiding Techniques for Steganography and Digital Watermarking, Stefan Katzenbeisser and Fabien A P Petitcolas, Security Technologies for the World Wide Web, Rolf Oppliger Page iii Information Hiding Techniques for Steganography and Digital Watermarking Stefan Katzenbeisser Fabien A P Petitcolas editors Page iv Library of Congress Cataloging-in-Publication Data Information hiding techniques for steganography and digital watermarking / Stefan Katzenbeisser, Fabien A.P Petitcolas, editors p cm — (Artech House computing library) Includes bibliographical references and index ISBN 1-58053-035-4 (alk paper) Computer security Data protection Watermarks I Katzenbeisser, Stefan II Petitcolas, Fabien A.P QA76.9.A25 I54144 2000 99-052317 005.8—dc21 CIP British Library Cataloguing in Publication Data Information hiding techniques for steganography and digital watermarking — (Artech House computing library) Cryptography Data encryption (Computer science) Copyright I Katzenbeisser, Stefan II Petitcolas, Fabien A.P 005.8'2 ISBN 1-58053-035-4 Cover design by Igor Valdman © 2000 ARTECH HOUSE, INC 685 Canton Street Norwood, MA 02062 All rights reserved Printed and bound in the United States of America No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized Artech House cannot attest to the accuracy of this information Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark International Standard Book Number: 1-58053-035-4 Library of Congress Catalog Card Number: 99-052317 10 Page v CONTENTS Foreword Preface Introduction to Information Hiding xv xvii 1.1 Main Subdisciplines of Information Hiding 1.2 A Brief History of Information Hiding 1.2.1 Technical Steganography 1.2.2 Linguistic Steganography 1.2.3 Copyright Enforcement 1.2.4 Wisdom from Cryptography 1.3 Some Applications of Information Hiding References 11 I Secret Writing and Steganography 15 Principles of Steganography 17 2.1 Frameworks for Secret Communication 18 2.1.1 Pure Steganography 20 2.1.2 Secret Key Steganography 22 2.1.3 Public Key Steganography 23 2.2 Security of Steganography Systems 25 2.2.1 Perfect Security 26 2.2.2 Detecting Secret Messages 27 2.3 Information Hiding in Noisy Data 28 2.4 Adaptive Versus Nonadaptive Algorithms 30 Page vi 2.4.1 Laplace Filtering 30 2.4.2 Using Cover-Models 30 2.5 Active and Malicious Attackers 31 2.5.1 Active Attackers: Robust Steganography 32 2.5.2 Supraliminal Channels 33 2.5.3 Malicious Attackers: Secure Steganography 35 2.6 Information Hiding in Written Text 36 2.7 Examples of Invisible Communication 37 2.7.1 Subliminal Channels in Digital Signature Schemes 37 2.7.2 Covert Channels in Operating Systems 38 2.7.3 Video Communication Systems 38 2.7.4 Data Hiding in Executable Files 39 2.8 Conclusion 39 References 40 A Survey of Steganographic Techniques 43 3.1 Preliminary Definitions 44 3.2 Substitution Systems and Bitplane Tools 45 3.2.1 Least Significant Bit Substitution 45 3.2.2 Pseudorandom Permutations 47 3.2.3 Image Downgrading and Covert Channels 49 3.2.4 Cover-Regions and Parity Bits 50 3.2.5 Palette-Based Images 51 3.2.6 Quantization and Dithering 52 3.2.7 Information Hiding in Binary Images 53 3.2.8 Unused or Reserved Space in Computer Systems 55 3.3 Transform Domain Technique 56 3.3.1 Steganography in the DCT Domain 58 3.3.2 Hiding Information in Digital Sound: Phase Coding 61 3.3.3 Echo Hiding 62 3.3.4 Information Hiding and Data Compression 63 3.4 Spread Spectrum and Information Hiding 64 3.4.1 A Spread Spectrum Model 64 3.4.2 SSIS: A Case Study 66 3.5 Statistical Steganography 67 3.6 Distortion Techniques 69 3.6.1 Encoding Information in Formatted Text 69 3.6.2 Distortion of Digital Images 70 3.7 Cover Generation Techniques 3.7.1 Mimic Functions 71 71 Page vii 3.7.2 Automated Generation of English Texts 72 3.8 Conclusion 75 References 75 Steganalysis 79 4.1 Steganalysis Introduction and Terminology 79 4.2 Looking for Signatures: Detecting Hidden Information 82 4.2.1 Palette-Based Images 83 4.2.2 Image Distortion and Noise 84 4.3 Extracting Hidden Information 87 4.4 Disabling Hidden Information 88 4.5 Discussion and Conclusion 91 References 92 II Watermarking and Copyright Protection 95 Introduction to Watermarking Techniques 97 5.1 Introduction 97 5.2 History and Terminology 98 5.2.1 History 5.2.2 Watermarking Terminology 98 100 5.3 Basic Watermarking Principles 101 5.4 Watermarking Applications 103 5.4.1 Watermarking for Copyright Protection 104 5.4.2 Fingerprinting for Traitor Tracking 104 5.4.3 Watermarking for Copy Protection 104 5.4.4 Watermarking for Image Authentication 105 5.5 Requirements and Algorithmic Design Issues 105 5.5.1 Imperceptibility 106 5.5.2 Robustness 106 5.5.3 Watermark Recovery with or without the Original Data 107 5.5.4 Watermark Extraction or Verification of Presence for a Given Watermark 108 5 Watermark Security and Keys 108 5.5.6 Resolving Rightful Ownership 5.6 Evaluation and Benchmarking of Watermarking Systems 109 109 5.6.1 Performance Evaluation and Representation 109 5.6.2 Watermark Removal Software and Benchmarking 117 5.7 Future and Standardization 117 Page viii References A Survey of Current Watermarking Techniques 119 121 6.1 Introduction 121 6.2 The Choice of Host Locations in the Cover: Cryptographic and Psychovisual Aspects 123 6.2.1 The Patchwork Algorithm 123 6.2.2 Public Key Cryptography and Public Watermark Recovery 124 6.2.3 Predictive Coding for Psychovisual Watermark Management 125 6.3 The Choice of a Workspace 125 6.3.1 Discrete Fourier Transform 125 6.3.2 Discrete Cosine Transform 126 6.3.3 Mellin-Fourier Transform 127 6.3.4 Wavelet Domain 128 6.3.5 Split Image in Perceptual Bands 131 6.4 Formatting the Watermark Bits 132 6.4.1 Spread Spectrum 132 6.4.2 Low Frequency Watermark Design 135 6.4.3 Error-Correcting Codes 135 6.5 Merging the Watermark and the Cover 136 6.5.1 Phase Modulation 137 6.5.2 Amplitude Modulation 137 6.5.3 Merging that Preserves the Luminance Average 138 6.5.4 Merging Based on DCT Coefficient Quantization 139 6.5.5 Merging Based on Block Substitution in Fractal Coding 140 6.6 Optimization of the Watermark Receiver 142 6.6.1 Image Prefiltering 142 6.6.2 Phase-Correlation Maxima for Reorientation and Resizing 143 6.6.3 Adaptive Threshold Improving Decision Robustness 144 6.7 Extensions from Still Images to Video 144 6.7.1 Motion Vector Quantization 144 6.8 Concluding Remarks 145 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Oppliger, Series Editor Information Hiding Techniques for Steganography and Digital Watermarking, Stefan Katzenbeisser and Fabien A P Petitcolas, Security Technologies for the World Wide Web,... iii Information Hiding Techniques for Steganography and Digital Watermarking Stefan Katzenbeisser Fabien A P Petitcolas editors Page iv Library of Congress Cataloging-in-Publication Data Information. .. Page v CONTENTS Foreword Preface Introduction to Information Hiding xv xvii 1.1 Main Subdisciplines of Information Hiding 1.2 A Brief History of Information Hiding 1.2.1 Technical Steganography