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Computer Security (CS4800)
Survey Prepared by Dr. Lamiaa Elshenawy
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Survey Book (CRYPTOGRAPHY AND NETWORK SECURITY PRINCIPLES AND PRACTICE, 5th edition, William Stallings) Computer security concepts OSI security architecture 1- Security Attacks 2- Security Services 3- Security Mechanisms Access Control Classical Encryption Techniques
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Computer security concepts
Confidentiality Data ----Privacy Integrity Data----System Availability Authenticity Accountability - CIA triad
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OSI security architecture
Security Attack Security Mechanism Security Service
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Security Attack Security Attack Passive attacks Active attacks
- not detect - easy prevent - detect - not prevent 1- Release of message contents 2- traffic analysis 1- masquerade 2- Replay 3- modification of message 4- denial of service
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Security Services Security Services Authentication Access control
Data confidentiality Data Integrity Nonrepudiation Availability
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Authentication Exchange
Security Mechanism Security mechanism Encipherment Digital signature Access control Data Integrity Authentication Exchange Traffic padding Routing Control Notarization
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Symmetric Cipher Model
Plaintext input 1- encryption algorithm 2- secret key Encryption Cipher text output Cipher text input 1- Decryption algorithm 2- secret key Decryption Plaintext output
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Symmetric Cipher Model
1- Cryptography (enciphering) - Cryptology 2- Cryptanalysis (deciphering) - Cryptanalyst
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Symmetric Cipher Techniques
- Substitution techniques Caesar Cipher Monoalphabetic Ciphers Playfair Cipher Hill Cipher Polyalphabetic Ciphers (Vigenère cipher –Vernam cipher) One-Time Pad - Transposition techniques Rail fence
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Symmetric Cipher Techniques
- Rotor machines - Steganography Character marking Invisible ink Pin puncture Type writer correction ribbon
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