Security

1. PART VII Security

2. Security Topics

3. Chapters Chapter 29 Cryptography Chapter 30 Message Authentication, User Authentication, and Key Management Chapter 31 Security Protocols in The Internet

4. Chapter 29 Cryptography

5. 29.1 Introduction Introduction to Cryptography

6. Figure 29.1Cryptography components

7. Figure 29.2Encryption and decryption

8. Note: In cryptography, the encryption/decryption algorithms are public; the keys are secret.

9. 29.2 Symmetric-Key Cryptography Traditional Cipher Block Cipher Operation Modes

10. Figure 29.3Symmetric-key cryptography

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

12. Note: In symmetric-key cryptography, the same key is used in both directions.

13. Note: Symmetric-key cryptography is often used for long messages.

14. Figure 29.4Caesar cipher

15. Figure 29.5Example of monoalphabetic substitution

16. Note: In monoalphabetic substitution, the relationship between a character in the plaintext to the character in the ciphertext is always one-to-one.

17. Figure 29.6Vigenere cipher

18. Note: In polyalphabetic substitution, the relationship between a character in the plaintext and a character in the ciphertext is one-to-many.

19. Figure 29.7Transpositional cipher

20. Figure 29.8Block cipher

21. Figure 29.9P-box

22. Figure 29.10S-box

23. Figure 29.11Product block

24. Figure 29.12DES

25. Figure 29.13General scheme of DES

26. Figure 29.14Iteration block

27. Figure 29.15Triple DES

28. 29.3 Public-Key Cryptography RSA Choosing Public and Private Keys

29. Figure 29.20Public-key cryptography

30. Note: Public-key algorithms are more efficient for short messages.

31. Figure 29.21RSA