2. SYMMETRIC CRYPTOSYSTEMS Symmetric Cryptosystems 6/05/2014 | pag. 2

3. Block Ciphers Symmetric Cryptosystems 6/05/2014 | pag. 3

4. Block Ciphers: Modes of Use Cryptography 6/05/2014 | pag. 4 ECB: Electronic Codebook CBC: Cipherblock Chaining CFB: Cipher Feedback OFB: Output Feedback

5. Block Ciphers: Classical examples Symmetric Cryptosystems 6/05/2014 | pag. 5 Affine Cipher Affine Linear and Linear Cipher Vigenère Hill We first need some linear algebra!

6. Intermezzo: Greatest Common Divisor Symmetric Cryptosystems 6/05/2014 | pag. 6

7. Intermezzo: Greatest Common Divisor Symmetric Cryptosystems 6/05/2014 | pag. 7

8. Intermezzo: Greatest Common Divisor Symmetric Cryptosystems 6/05/2014 | pag. 8

9. Intermezzo: Greatest Common Divisor Symmetric Cryptosystems 6/05/2014 | pag. 9

10. Intermezzo: Greatest Common Divisor Cryptography 6/05/2014 | pag. 10

11. Intermezzo: Euclidean Algorithm Cryptography 6/05/2014 | pag. 11

12. Intermezzo: Euclidean Algorithm Cryptography 6/05/2014 | pag. 12

13. Intermezzo: Euclidean Algorithm Cryptography 6/05/2014 | pag. 13

14. Intermezzo: Extended Euclidean Algorithm Cryptography 6/05/2014 | pag. 14

15. Intermezzo: Extended Euclidean Algorithm Cryptography 6/05/2014 | pag. 15

16. Intermezzo: Extended Euclidean Algorithm Cryptography 6/05/2014 | pag. 16

17. Intermezzo: Invertible Elements in a Residue Class Ring Cryptography 6/05/2014 | pag. 17

18. Intermezzo: Invertible Elements in a Residue Class Ring Cryptography 6/05/2014 | pag. 18

19. Affine Cipher Symmetric Cryptosystems 6/05/2014 | pag. 19

20. Example: Affine Cipher Symmetric Cryptosystems 6/05/2014 | pag. 20

21. Example: Cryptanalysis of the Affine Cipher Symmetric Cryptosystems 6/05/2014 | pag. 21

22. Example: Cryptanalysis of the Affine Cipher Symmetric Cryptosystems 6/05/2014 | pag. 22

23. Intermezzo: Matrices over Rings Cryptography 6/05/2014 | pag. 23

24. Intermezzo: Invertible Matrices Cryptography 6/05/2014 | pag. 24

25. Intermezzo: Invertible Matrices Cryptography 6/05/2014 | pag. 25

26. Intermezzo: Invertible Matrices Cryptography 6/05/2014 | pag. 26

27. Intermezzo: Invertible Matrices Cryptography 6/05/2014 | pag. 27

28. Intermezzo: Affine Linear Functions Cryptography 6/05/2014 | pag. 28

29. Intermezzo: Affine Linear Functions Cryptography 6/05/2014 | pag. 29

30. Affine Linear Cipher Cryptography 6/05/2014 | pag. 30

31. Affine Linear Cipher Cryptography 6/05/2014 | pag. 31