BDC5eChapter18 - Chapter 18: Network Security Business Data...

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Chapter 18: Network Security Business Data Communications, 5e
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Business Data Communications, 5e 2 Types of Security Information Security Computer Security Network Security
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Business Data Communications, 5e 3 Security Requirements Confidentiality Integrity Availability Authenticity
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Business Data Communications, 5e 4 Security Threats Passive attacks Release of message contents Traffic analysis Difficult to detect because there is no data alteration Emphasis on prevention through encryption Active attacks Masquerae Replay Modification of messages Denial of Service
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Business Data Communications, 5e 5 Symmetric Encryption The only form of encryption prior to late 1970s Five components to the algorithm Plaintext The original message or data Encryption algorithm Secret key Ciphertext Decryption algorithm Two requirements Strong encryption algorithm Secure exchange of keys
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Business Data Communications, 5e 6 Conventional Encryption Operation
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Business Data Communications, 5e 7 Symmetric Encryption Attacks Cryptanalysis Exploits the algorithm to attempt to deduce a specific plaintext or key being used If successful, future and past messages encrypted with that key are compromised Brute Force Try every possible key on a piece of ciphertext until an intelligible translation into plaintext is obtained On average, half of all possible keys must be tried to achieve success
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Business Data Communications, 5e 8 Data Encryption Standard (DES) Dominant encryption algorithm after release in 1977 56-bit key made it too easy to crack by 1998 Life of DES extended by use of triple DES (3DES Repeats basic DES algorithm three times, using either two or three unique keys Key size of 112 or 168 bits Drawbacks: Algorithm is sluggish in software, 64-bit block size is inefficient
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Business Data Communications, 5e 9 Advanced Encryption Standard
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Business Data Communications, 5e 10 Location of Encryption Devices Link encryption Each vulnerable communications link is equipped on both ends with an encryption device. All traffic over all communications links is secured. Vulnerable at each switch End-to-end encryption Encryption process carried out at two end systems Encrypted data transmitted unaltered across network; destination shares key with source to decrypt data Packet headers cannot be secured
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Business Data Communications, 5e 11 Symmetric Encryption Key Distribution Both parties must have the secret key Key is changed frequently Requires either manual delivery of keys, or a third-party encrypted channel Most effective method is a Key Distribution Center (e.g. Kerberos)
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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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BDC5eChapter18 - Chapter 18: Network Security Business Data...

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