Introduction A Brief History of Cryptography and Data Security Cryptography and Data Security in the Modern World Existing Texts Book Organization Symmetric-Key Cryptography Cryptosystem Overview The Modulo Operator Greatest Common Divisor The Ring ZmHomework ProblemsSymmetric-Key Cryptography: Substitution Ciphers Basic Cryptanalysis Shift Ciphers Affine Ciphers Homework ProblemsSymmetric-Key Cryptography: Stream Ciphers Random Numbers The One-Time Pad Key Stream GeneratorsReal-World ApplicationsHomework ProblemsSymmetric-Key Cryptography: Block Ciphers The Data Encryption StandardThe Advanced Encryption StandardPublic-Key Cryptography Issues with Symmetric-Key Cryptosystems Public-Key Cryptosystem Overview One-Way Functions The Euclidean AlgorithmThe Extended Euclidean Algorithm Euler's Phi FunctionEuler's Theorem Fermat's Little Theorem Homework ProblemsPublic-Key Cryptography: RSACryptosystem Efficient ImplementationAttacks Homework ProblemsPublic-Key Cryptography: Discrete Logarithms Cyclic Groups The Discrete Logarithm Problem Diffie-Hellman Key Agreement Protocol Efficient Implementation ElGamal Encryption AttacksHomework ProblemsPublic-Key Cryptography: Elliptic Curves Cryptosystem Diffie-Hellman Key Agreement Protocol Efficient Implementation Menezes-Vanstone Encryption Attacks Homework ProblemsCryptographic Components Digital SignaturesHash FunctionsMessage Authentication CodesCryptographic Protocols Security Services Key EstablishmentApplicationsHomework ProblemsReferencesIndex