TCP/IP Protocol Suite 1 Chapter 28 Upon completion you will be able to: Security Differentiate...

TCP/IP Protocol Suite 1

Chapter 28Chapter 28

Upon completion you will be able to:

SecuritySecurity

• Differentiate between two categories of cryptography schemes • Understand four aspects of security• Know how and where IPSec, TLS, and PGP provide security•Firewall

Objectives


28.1 CRYPTOGRAPHY

The word cryptography in Greek means “secret writing.” The term today The word cryptography in Greek means “secret writing.” The term today refers to the science and art of transforming messages to make them refers to the science and art of transforming messages to make them secure and immune to attacks.secure and immune to attacks.

The topics discussed in this section include:The topics discussed in this section include:

Symmetric-Key Cryptography Symmetric-Key Cryptography Asymmetric-Key Cryptography Asymmetric-Key Cryptography Comparison Comparison


Figure 28.1 Cryptography components


In cryptography, the encryption/decryption algorithms are

public; the keys are secret.

Note:Note:


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

Note:Note:


Figure 28.2 Symmetric-key cryptography


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

Note:Note:


Figure 28.3 Caesar cipher


Figure 28.4 Transpositional cipher


Figure 28.5 Data Encryption Standard (DES)


Figure 28.6 Iteration block


Figure 28.7 Triple DES


The DES cipher uses the same concept as the Caesar cipher, but the

encryption/ decryption algorithm is much more complex.

Note:Note:


Figure 28.8 Public-key cryptography


Figure 28.9 RSA


Symmetric-key cryptography is often used for long messages.

Note:Note:


Asymmetric-key algorithms are more efficient for short messages.

Note:Note:


28.6 SECURITY IN THE INTERNET

IP Level Security: IPSec IP Level Security: IPSec Transport Layer Security Transport Layer Security Application Layer Security: PGP Application Layer Security: PGP


Figure 28.27 Transport mode


Figure 28.28 Tunnel mode


Figure 28.29 Authentication Header (AH)


The AH protocol provides message authentication and integrity,

but not privacy.

Note:Note:


Figure 28.30 Encapsulating Security Payload (ESP)


ESP provides message authentication, integrity, and privacy.

Note:Note:


Figure 28.31 Position of TLS


Figure 28.35 PGP at the sender site


Figure 28.36 PGP at the receiver site


28.7 FIREWALLS

A firewall is a device (usually a router or a computer) installed between A firewall is a device (usually a router or a computer) installed between the internal network of an organization and the rest of the Internet. It is the internal network of an organization and the rest of the Internet. It is designed to forward some packets and filter (not forward) others.designed to forward some packets and filter (not forward) others.

The topics discussed in this section include:The topics discussed in this section include:

Packet-Filter Firewall Packet-Filter Firewall Proxy Firewall Proxy Firewall


Figure 28.37 Firewall


Figure 28.38 Packet-filter firewall


A packet-filter firewall filters at the network or transport layer.

Note:Note:


Figure 28.39 Proxy firewall


A proxy firewall filters at the application layer.

Note:Note:

TCP/IP Protocol Suite 1 Chapter 28 Upon completion you will be able to: Security Differentiate...

Documents

Transcript of TCP/IP Protocol Suite 1 Chapter 28 Upon completion you will be able to: Security Differentiate...