Chapter 8

# Chapter 8 - 1 Learning Objectives: Upon completion of this...

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Learning Objectives: Upon completion of this chapter you should be able to: •Define and identify the various types of firewalls. •Discuss the approaches to firewall implementation. •Discuss the approaches to dial-up access and protection. •Identify and describe the two categories of intrusion detection systems. •Discuss the two strategies behind intrusion detection systems. •Discuss the process of encryption and define key terms. •Identify and discuss common approaches to cryptography. •Compare and contrast symmetric and asymmetric encryption. •Discuss various approaches to biometric access control. 2
Cryptography And Encryption-Based Solutions Although not a specific application or security tool, encryption represents a sophisticated approach to security that is implemented in many security systems. In fact, many security-related tools use embedded encryption technologies to protect sensitive information handled by the application. Encryption is the process of converting an original message into a form that is unreadable by unauthorized individuals that is anyone without the tools to convert unreadable by unauthorized individuals, that is anyone without the tools to convert the encrypted message back to its original format. The science of encryption, known as cryptology encompasses cryptography, from the Greek words kryptos, meaning hidden, and graphein, meaning to write, and cryptanalysis, the process of obtaining the original message (or plaintext) from an encrypted message (or ciphertext), without the knowledge of the algorithms and keys used to perform the encryption. 3

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Encryption Definitions Algorithm: the mathematical formula used to convert an unencrypted message into an encrypted message. Cipher: the transformation of the individual components (characters, bytes or bits) of an unencrypted message into encrypted components. Ciphertext or cryptogram: the unintelligible encrypted or encoded message resulting from an encryption. Code: the transformation of the larger components (words or phrases) of an unencrypted message into encrypted components. Cryptosystem: the set of transformations necessary to convert an unencrypted message into an encrypted message. Decipher: to decrypt or convert ciphertext to plaintext. Encipher: to encrypt or convert plaintext to ciphertext. Key or cryptovariable: the information used in conjunction with the algorithm to create ciphertext from plaintext. Keyspace: the entire range of values that can possibly be used to construct an individual key. Link encryption: a series of encryptions and decryptions between a number of systems, whereby each node decrypts the message sent to it and then re-encrypts it using different keys and sends it to the next neighbor, until it reaches the final destination. Plaintext: the original unencrypted message that is encrypted and results from successful decryption.
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## This note was uploaded on 01/13/2012 for the course IS 3020 taught by Professor Staff during the Spring '08 term at Kennesaw.

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Chapter 8 - 1 Learning Objectives: Upon completion of this...

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