CRYPTOGRAPHY AND NETWORK SECURITY (CNS) Unit I to V Click Here Attacks on Computers and Computer Security SYLLABUS UNIT – I Security Concepts : Introduction, The need for security, Security approaches, Principles of security, Types of Security attacks, Security services, Security Mechanisms, A model for Network Security Cryptography Concepts and Techniques : Introduction, plain text and cipher text, substitution techniques, transposition techniques, encryption and decryption, symmetric and asymmetric key cryptography, steganography, key range and key size, possible types of attacks. UNIT – II Symmetric key Ciphers : Block Cipher principles, DES, AES, Blowfish, RC5, IDEA, Block cipher operation, Stream ciphers, RC4. Asymmetric key Ciphers : Principles of public key cryptosystems, RSA algorithm, Elgamal Cryptography, Diffie-Hellman Key Exchange, Knapsack Algorithm. UNIT – III Cryptographic Hash Functions : Message Authentication, Secure Hash Alg...