Lecture # 6 - Intro to Cryptography and Classical Cryptography.pdf

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Lecture # 2: Introduction to Cryptographyand Classical CryptographyProf. Dr. Sufian HameedDepartment of Computer ScienceFAST-NUCESCS-446: Information Systems SecurityFAST-NUCES
CryptographyFAST-NUCES
ExamplesFAST-NUCES
CryptosystemFAST-NUCES
Attacks against CryptosystemsFAST-NUCES1.) Cipher text-only:Attacker possesses a string y of the ciphertext2.) Known plaintext:Attacker possesses a string x of the plaintextand the corresponding cipher text y. The problem now is to findout the key which produces y from x3.) Chosen plaintext:Attacker has access to the encryptionmachinery. Hence he can chose a plaintext string x and constructthe corresponding cipher text string y.4.) Chosen cipher text:Attacker has access to the decryptionmachinery. Hence, he can chose a cipher text string y andconstruct the corresponding plaintext string x.
Security of KeysFAST-NUCES
Kerckhoffs PrincipleFAST-NUCES
Cryptography is everywhereSecure communication:web traffic:HTTPSwireless traffic:802.11i WPA2(and WEP),GSM,BluetoothEncrypting files on disk:EFS (Encrypting File System)

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Term
Fall
Professor
NoProfessor
Tags
Cryptography, web traffic

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