TABLE OF CONTENTS ACKNOWLEDGEMENTS i TABLE OF CONTENTS iii LIST OF FIGURES .v LIST OF TABLES vi ABSTRACT . vii Chapter 1 INTRODUCTION .1 1.1 Rise of computer crime .1 1.2 Information security .2 1.3 Motivation .3 1.4 Secret sharing 4 1.5 Thesis outline 7 Chapter 2 RELATED WORKS .8 2.1 Shamir’s secret-sharing scheme .8 2.2 Voting strategy 11 2.3 Wang et al.’s (2, n) ProbVSS scheme for binary images .12 2.4 Gradual search algorithm for one single bitmap BTC 15 Chapter 3 PROPOSED SCHEMES .20 3.1 (2, n) Prob VSS for grayscale image 20 3.1.1 Share construction phase .21 3.1.2 Revealing phase .25 3.2 (2, n) Prob VSS for color image .33 3.2.1 Share construction phase .34 iv 3.2.2 Revealing phase .38 Chapter 4 EXPERIMENTAL RESULTS 43 4.1 (2, n) Prob VSS for grayscale image 44 4.2 (2, n) Prob VSS for color image .49 Chapter 5 SUMMARY AND CONCLUSIONS .55 APPENDICES .56 REFERENCES 57