Symmetric Key Cryptography: The notion of a symmetric key cryptography, Data Encryption Standard (DES), Double DES, Triple DES and cryptanalysis. Advanced Encryption Standard (AES). Public Key Cryptosystems: Fundamentals of Public-key Cryptography, RSA public key cryptosystem, ElGamal public key cryptosystem and Elliptic Curve Cryptosystems. Integer Factorization Problem: Trial division, Pollard’s rho factoring algorithm, Pollard’s p-1 factoring algorithm, Elliptic Curve Factoring, Random Square Factoring methods, Quadratic sieve Factoring, Number Field Sieve Factoring. Digital Signatures: RSA based signature scheme, ElGamal based signature scheme, Schnorr signature scheme, Digital Signature Algorithm (DSA). Key Distribution and Key Agreement Protocols: Key Pre-distribution, Diffie-Hellman key Exchange. Authentication: simple authentication protocol and possible attacks, Strong password protocols, Key Distribution Centers based authentication protocols.