1. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Security PART VII

2. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Security Topics

3. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Chapters Chapter 29 Cryptography Chapter 30 Message Authentication, User Authentication, and Key Management Chapter 31 Security Protocols in The Internet

4. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Chapter 29 Cryptography

5. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 29.1 Introduction IntroductiontoCryptography

6. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.1 Cryptography components

7. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.2 Encryption and decryption

8. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 In cryptography, the encryption/decryption algorithms are public; the keys are secret. Note:

9. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 29.2 Symmetric-Key Cryptography Traditional Cipher Block Cipher Operation Modes

10. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.3 Symmetric-key cryptography

11. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 In symmetric-key cryptography, the same key is used by the sender (for encryption) and the receiver (for decryption). The key is shared. Note:

12. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 In symmetric-key cryptography, the same key is used in both directions. Note:

13. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Symmetric-key cryptography is often used for long messages. Note:

14. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.4 Caesar cipher

15. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.5 Example of monoalphabetic substitution

16. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 In monoalphabetic substitution, the relationship between a character in the plaintext to the character in the ciphertext is always one-to-one. Note:

17. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.6 Vigenere cipher

18. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 In polyalphabetic substitution, the relationship between a character in the plaintext and a character in the ciphertext is one-to-many. Note:

19. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.7 Transpositional cipher

20. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.8 Block cipher

21. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.9 P-box

22. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.10 S-box

23. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.11 Product block

24. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.12 DES

25. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.13 General scheme of DES

26. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.14 Iteration block

27. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.15 Triple DES

28. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 The DES cipher uses the same concept as the Caesar cipher, but the encryption/decryption algorithm is much more complex due to the sixteen 48-bit keys derived from a 56-bit key. Note:

29. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.16 ECB mode

30. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.17 CBC mode

31. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.18 CFM

32. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.19 CSM

33. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 29.3 Public-Key Cryptography RSA Choosing Public and Private Keys

34. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.20 Public-key cryptography

35. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Public-key algorithms are more efficient for short messages. Note:

36. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 29.21 RSA