CONTENTS
Page
ACKNOWLEDGEMENT iii
ABSTRACT iv
LIST OF TABLES ix
LIST OF FIGURES x
CHAPTER
I INTRODUCTION 1
1.1 Motivation 3
1.2 Problem Statement 3
1.3 Objectives of the Thesis 4
1.4 Scope of the Thesis 5
1.5 The Organization of the Thesis 5
II BACKGROUND 6
2.1 Mathematical Background 7
2.2 Basic Cryptography 14
2.2.1 Symmetric or Secret Key Cryptography 15
2.2.2 Asymmetric or Public Key Cryptography 16
2.3 Data Encryption Standard (DES) 16
2.4 Advanced Encryption Standard (AES) 22
2.5 Cryptanalysis 31
III LITERATURE REVIEW 34
3.1 DES with Multiple Keys 34
3.2 Taros Block Cipher 37
3.3 Big Encryption System (BES) 39
3.4 Big BES and CES 40
3.5 Observations on the Structure of the AES 40
vii
CONTENTS (CONT.)
Page
IV PROPOSED WORK 42
4.1 Design of the Data Structure 42
4.2 Number of Rounds Used 43
4.3 Key Expansion Process 44
4.4 Encryption Process 45
4.4.1 Forward Substitute Bytes Transformation 46
4.4.2 Forward Shift Rows Transformation 46
4.4.3 Forward Mix Columns Transformation 47
4.4.4 Forward Add Round Keys Transformation 49
4.5 Decryption Process 49
4.5.1 Inverse Substitute Bytes Transformation 50
4.5.2 Inverse Shift Rows Transformation 50
4.5.3 Inverse Mix Columns Transformation 51
4.5.4 Inverse Add Round Keys Transformation 53
4.6 Comparison of Data Structure and Operations 53
V IMPLEMENTATION AND EXPERIMENTAL RESULTS 55
5.1 Implementation of the 512-bit AES 55
5.2 Implementation of the Cube AES 55
5.3 Software and Hardware for the Implementation 55
5.4 Time Function 56
5.5 Mode of Operations 57
5.6 Experiments 58
5.6.1 Validity Test 58
5.6.2 Performance Test 59
5.6.3 Diffusion Test 60
5.7 Experimental Results 62
5.7.1 Validity Test 62
5.7.2 Performance Test 62
5.7.3 Diffusion Test 62
viii
CONTENTS (CONT.)
Page
VI DISCUSSIONS AND CONCLUSION 64
6.1 Summary of Our Contribution 64
6.1.1 The Effect of Data Structure 64
6.1.2 Expansion of Data and Key 64
6.1.3 Encryption Operation 65
6.1.4 Performance Measurement 65
6.1.5 Degree of Diffusion 66
6.2 Problems and Difficulties 66
6.2.1 Diffusion Measurement 66
6.2.2 Brute Force Attack 67
6.3 Suggestions for Future Work 67
6.3.1 Diagonal Operation 67
6.3.2 Other Geometric Structure 67
REFERENCES 68
BIOGRAPHY 71