Applied Cryptography

Short Description:
The course aims to provide students with a comprehensive understanding of both fundamental and modern cryptographic techniques, focusing on communication security and cryptanalysis methods. Students will learn the operational principles of encryption and digital signature algorithms, as well as the mathematical foundations underpinning them. Furthermore, the course explores modern applications of cryptography, such as public-key algorithms and Public Key Infrastructure (PKI) systems.

Objectives - Learning Outcomes:
Upon successful completion of the course, students will be able to:

• Encrypt and decrypt messages using substitution and transposition ciphers.
• Apply modern symmetric and asymmetric algorithms to ensure message confidentiality, integrity, and authenticity.
• Identify weaknesses in cryptographic algorithms and understand cryptanalysis techniques.
• Implement and evaluate algorithms such as DES and RSA, proposing appropriate modes of operation.
• Design and apply secure communication systems in unstable network environments using public-key cryptography.

Students will develop skills in the design, implementation, and analysis of cryptographic algorithms and digital signatures, gain a deep understanding of the security of cryptographic protocols and key management theory, and be able to develop practical encryption and pseudorandom generation applications. They will also learn to apply cryptographic techniques to real-world networks, emphasizing communication security, and recognize contemporary challenges in cybersecurity and cryptography.

Syllabus:
Introduction to Cryptology: Historical overview and fundamental concepts. Objectives of cryptography and its role in cybersecurity.

• Encryption System Principles: Analysis of fundamental principles, including symmetric and asymmetric encryption algorithms.
• Symmetric Encryption Algorithms: Study of well-known algorithms such as DES and AES, and their protocols.
• Asymmetric Encryption Algorithms: Examination of RSA, ElGamal, and related algorithms, including characteristics and advantages.
• Digital Signatures and Authentication Checks: Functionality, applications, and importance in information security.
• Secure Communication Protocols: Study of protocols such as SSL/TLS and their cryptographic foundations.
• Application-Level Encryption – Files and Networks: Data protection in computing systems through encryption mechanisms.
• Cryptanalysis Mechanisms: Presentation of attack types (e.g., brute-force, differential attacks) and security enhancement techniques.
• Public Key Infrastructures (PKI): Architecture, digital certificate management, and trust hierarchies.
• Key Management Systems: Security mechanisms for protecting and storing encryption keys.
• System Security and Cryptographic Protocols: Application of cryptographic protocols in high-security systems and infrastructures.
• Cryptography and Blockchain: Relationship between cryptography and blockchain technologies, and their contribution to digital currency security.
• Contemporary Issues in Cryptology: Review and synthesis of core concepts, with discussion and clarification of advanced topics.

Suggested Bibliography:

• Alexandris, N., Chryssikopoulos, V., & Patsakis, K. (2015). Introduction to Information Theory, Codes, and Cryptography. Varvarigou Publications. ISBN 9789607996398.
• Hoffstein, J., Pipher, J., & Silverman, J. (2021). Computational Cryptography. Fountas Publications. ISBN 9789603307952.
• Stallings, W. (2011). Cryptography and Network Security: Principles and Practice. Ion Publications. ISBN 9789604117307.
• Patsakis, K., & Fountas, E. (2016). Cryptography and Applications. Varvarigou Publications. ISBN 9789607996572.
• Gritzalis, S. (2010). Modern Cryptography. Papasotiriou Publications. ISBN 9789607182760.

Teaching Methods:
The course combines theoretical instruction with practical application to ensure a thorough understanding of cryptology and cryptography. Teaching includes lectures introducing key theoretical concepts and algorithms, laboratory exercises involving the implementation of symmetric and asymmetric algorithms, digital signatures, and secure communication protocols, as well as case studies analyzing real-world cryptographic applications and cybersecurity incidents. Students engage in assignments that reinforce comprehension through complex problem-solving and applied projects.

New Technologies:
Students use computational environments and cryptographic software tools (e.g., CrypTool, SEED Labs) to implement symmetric and asymmetric algorithms, generate digital signatures, and analyze secure communication protocols. The online course platform provides theoretical material, assignment submission tools, and simulation-based exercises to support the understanding of cryptanalysis and key management mechanisms.

Evaluation Methods:
Coursework (30%) – A practical assignment applying theoretical concepts and skills in cryptography. Final Written Examination (70%) – Tests comprehension of theoretical foundations, algorithms, protocols, and cryptographic applications. This assessment structure ensures a balanced evaluation of both theoretical understanding and practical competence.