Subject: Knowledge management
Course: Cryptology
ECTS credits: 5
Language: Croatian
Duration: 1 semester
Status: elective
Method of teaching: 1 lecture hour and 1 hour of seminar
Prerequisite: Data Protection
Assessment: written and oral exam

Course description:
Introduction. Basic cryptology terms. Brief history of cryptographic systems. System of codes and ciphers.
Traditional encryption. Substitutional crypto-systems, enciphering and deciphering. Transpositional crypto-systems, complete and incomplete squares, enciphering and deciphering. Complex (combined) cipher. Polyalphabetic crypto-systems, Vigenre tableaus cipher. Polygram ciphers, Playfair’s bigram cipher.
Crypto-analysis. Breaking substitutional, transpositional and polyalphabetic ciphers: prediction methods, frequency analysis and brute force attack. Exploiting the weaknesses of crypto-systems. Evaluation of attack efficiency.
Application of cryptology in information science. Binary crypto-systems, linear shift enciphering. Disguising data during saving, transmitting, processing and communication to prevent unauthorized access and modification. File protection. Finding errors and detecting misuse.
Contemporary approach to enciphering. Re-using the key. Complex and repeated transformations. Adequate security. Acquiring knowledge on actual computer enciphering products. Data Encryption Standard. Secret and public crypto-algorithms. Public key crypto-systems. Irreversible functions: prime factorization, moduli and residue sets. Digital signature as means for ensuring message source and content authenticity. PGP (Pretty Good Privacy) - program for enciphering and authentication of e-mail messages transmitted through Internet.

Course objective:
Present traditional methods of data encryption and decryption as well as basic cryptanalytic approaches and authentication of messages.

Quality check and success of the course: Quality check and success of the course will be done by combining internal and external evaluation. Internal evaluation will be done by teachers and students using survey method at the end of semester. The external evaluation will be done by colleagues attending the course, by monitoring and assessment of the course.

Reading list:
1. Beckett, Brian: Introduction to Cryptology, Blackwell Scientific Publication, Oxford, 1988.
2. Salomaa, Arto: Public-Key Cryptography, Springer-Verlag, Berlin, 1990.

Additional reading list:
1. Schneier, Bruce: E-mail Security: How to Keep Your Electronic Messages Private, John Wiley & Sons, New York, 1995.