BDC4e Chapter 20 - Chapter 20 Network Security Business...

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Chapter 20: Network Security Business Data Communications, 4e
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Business Data Communications, 4e 2 Security Threats Passive attacks Eavesdropping on, or monitoring, transmissions Electronic mail, file transfers, and client/server exchanges are examples of transmissions that can be monitored Active attacks Modification of transmitted data Attempts to gain unauthorized access to computer systems
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Business Data Communications, 4e 3 Encryption Methods The essential technology underlying virtually all automated network and computer security applications is cryptography Two fundamental approaches are in use: conventional encryption, also known as symmetric encryption public-key encryption, also known as asymmetric encryption
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Business Data Communications, 4e 4 Conventional Encryption The only form of encryption prior to late 1970s Five components to the algorithm Plaintext: The original message or data Encryption algorithm: Performs various substitutions and transformations on the plaintext. Secret key: Input to the encryption algorithm. Substitutions and transformations performed depend on this key Ciphertext: Scrambled message produced as output. depends on the plaintext and the secret key Decryption algorithm: Encryption algorithm run in reverse. Uses ciphertext and the secret key to produce the original plaintext.
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Business Data Communications, 4e 5 Conventional Encryption Operation
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Business Data Communications, 4e 6 Conventional Encryption Requirements A strong encryption algorithm Methods of Attack Cryptanalysis Brute force
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7 Data Encryption Standard (DES) Adopted in 1977, reaffirmed for 5 years in 1994, by NBS/NIST Plaintext is 64 bits (or blocks of 64 bits), key is 56 bits Plaintext goes through 16 iterations, each producing an intermediate value that is used in the next iteration. DES is now too easy to crack to be a useful
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This note was uploaded on 04/27/2010 for the course BAMU BSC taught by Professor Kmm during the Spring '10 term at University of New York in Prague.

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BDC4e Chapter 20 - Chapter 20 Network Security Business...

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