P: M301 or M303. The course covers encryption and decryption in secure codes. Topics include cryptosystems and their cryptanalysis, Data Encryption Standard, cryptanalysis, Euclidean algorithm, Chinese remainder theorem, RSA cryptosystem, primality testing, factoring algorithyms, EIGamal cryptosystem, discrete log problem, other public key cryptosystems, signature schemes, hash functions, key distribution and key agreement.