Security, security policy, security enforcement functions, security mechanisms, criteria for system security assessment. Mathematical foudations of cryptology. Substitution and transposition ciphers. Secret key encryption, AES data encryption standard, public key encryption, RSA system. Cryptographic keys and their management. Digital signatures, basic cryptographic protocols and their building blocks. Special algorithms for protocols, identification schemes. Security of data in computer networks. Internet and security, privacy protection. E-commerce security, application of cryptography in electronic publishing, legislative and ethical protection of data.