Cryptology and Cryptology. Classical ciphers; Security and Cryptanalysis. Monoalphabetical ciphers; Polyalphabetic ciphers. Absolute security; One-Time Pad; Computational security of encryption systems; Entropy and cryptographic security; Physical language redundancy; Randomness and Pseudorandomness. Modern Symmetric Cryptosystems: DES algorithm; Triple-DES, Simplified DES. Cipher modes: ECB, CBC, OFB, CFB, CT. Integrity and Message Authentication: Cryptographic Hash functions; Message Authentication Codes. Public Key Cryptography. Public Encryption Algorithms: RSA encryption, Rabin encryption. Deterninistic and Probabilistic encryption; Elgamal cryptosystem; Goldwasser-Micali cryptosystem. Digital Signature Algorithms: RSA signature; ElGamal signature; Digital Signature standard. Public Key infrastructures: Digital certificates; Trust models; PGP model.