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Table Of Contents

ABSTRACT............................................................................................................................4

List of Figures......................................................................................................................... 6

List of Tables.......................................................................................................................... 6

1. Introduction.........................................................................................................................7

2. SIGABA Machine...............................................................................................................8

2.1 Rotors............................................................................................................................ 8

2.2 Encryption................................................................................................................... 10

2.3 Decryption...................................................................................................................13

2.4 Physical Security & Operation Guidelines................................................................. 14

2.5 Theoretical Keyspace.................................................................................................. 15

2.6 Practical Keyspace...................................................................................................... 16

3. Attacks On SIGABA.........................................................................................................18

3.1 Previous Work.............................................................................................................18

3.2 SIGABA Attack.......................................................................................................... 18

3.3 Phase 1........................................................................................................................ 19

3.4 Phase 2........................................................................................................................ 23

4. Attack Refinements...........................................................................................................24

5. Attack Comparisons..........................................................................................................30

6. Simulator...........................................................................................................................32

7. Conclusion........................................................................................................................ 33

 8. References........................................................................................................................34

Appendix A: Rotor Permutations..........................................................................................35

Appendix B: Simulator Commands...................................................................................... 36

Appendix C: Glossary...........................................................................................................37

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