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Chapter 28 - Security. In this chapter, you will learn to: Differentiate between two categories of cryptography schemes; understand four aspects of security; understand the concept of digital signature; understand the role of key management in entity authentication; know how and where IPSec, TLS, and PPG provide security. | Chapter 28 Upon completion you will be able to: Security Differentiate between two categories of cryptography schemes Understand four aspects of security Understand the concept of digital signature Understand the role of key management in entity authentication Know how and where IPSec, TLS, and PPG provide security Objectives TCP/IP Protocol Suite 28.1 CRYPTOGRAPHY The word cryptography in Greek means “secret writing.” The term today refers to the science and art of transforming messages to make them secure and immune to attacks. The topics discussed in this section include: Symmetric-Key Cryptography Asymmetric-Key Cryptography Comparison TCP/IP Protocol Suite Figure 28.1 Cryptography components TCP/IP Protocol Suite In cryptography, the encryption/decryption algorithms are public; the keys are secret. Note: TCP/IP Protocol Suite In symmetric-key cryptography, the same key is used by the sender (for encryption) and the receiver (for decryption). The key is shared. . | Chapter 28 Upon completion you will be able to: Security Differentiate between two categories of cryptography schemes Understand four aspects of security Understand the concept of digital signature Understand the role of key management in entity authentication Know how and where IPSec, TLS, and PPG provide security Objectives TCP/IP Protocol Suite 28.1 CRYPTOGRAPHY The word cryptography in Greek means “secret writing.” The term today refers to the science and art of transforming messages to make them secure and immune to attacks. The topics discussed in this section include: Symmetric-Key Cryptography Asymmetric-Key Cryptography Comparison TCP/IP Protocol Suite Figure 28.1 Cryptography components TCP/IP Protocol Suite In cryptography, the encryption/decryption algorithms are public; the keys are secret. Note: TCP/IP Protocol Suite In symmetric-key cryptography, the same key is used by the sender (for encryption) and the receiver (for decryption). The key is shared. Note: TCP/IP Protocol Suite Figure 28.2 Symmetric-key cryptography TCP/IP Protocol Suite In symmetric-key cryptography, the same key is used in both directions. Note: TCP/IP Protocol Suite Figure 28.3 Caesar cipher TCP/IP Protocol Suite Figure 28.4 Transpositional cipher TCP/IP Protocol Suite Figure 28.5 DES TCP/IP Protocol Suite Figure 28.6 Iteration block TCP/IP Protocol Suite Figure 28.7 Triple DES TCP/IP Protocol Suite The DES cipher uses the same concept as the Caesar cipher, but the encryption/ decryption algorithm is much more complex. Note: TCP/IP Protocol Suite Figure 28.8 Public-key cryptography TCP/IP Protocol Suite Figure 28.9 RSA TCP/IP Protocol Suite Symmetric-key cryptography is often used for long messages. Note: TCP/IP Protocol Suite Asymmetric-key algorithms are more efficient for short messages. Note: TCP/IP Protocol Suite 28.2 PRIVACY Privacy means that the sender and the receiver expect confidentiality. The .
