Fundamentals of CryptographyMövzu planı

This topic covers the fundamental concepts of cryptography, its objectives, and its role in ensuring information security. Fundamental concepts such as plaintext, ciphertext, encryption, decryption, cryptographic keys, and cryptosystems are introduced. The historical development of cryptography and the main characteristics of classical encryption methods are examined. Classical ciphers based on substitution and transposition principles, their operating mechanisms, application characteristics, and major security limitations are studied. The construction and application of classical ciphers, as well as basic cryptanalysis methods, are also examined within seminar sessions.

This topic covers the concept of cryptanalysis, its objectives, and its role in evaluating the security of cryptographic systems. The main approaches to cryptanalysis, attack models, and principles for analyzing encrypted data are examined. The structural characteristics of substitution ciphers and analytical methods based on letter frequency, symbol distribution, and statistical properties of language are explained. Frequency analysis and the principles of analyzing simple substitution ciphers and recovering the original plaintext are also studied.

This topic covers the fundamental operating principles, structure, and application characteristics of stream ciphers. The encryption of plaintext as sequences of individual bits or symbols, the generation of a keystream, and its use in the encryption process are examined. The characteristics of synchronous and self-synchronizing stream ciphers and the differences between them are explained. The generation of pseudorandom sequences, key requirements for secure keystream generation, and security risks associated with keystream reuse are studied. The main application areas, advantages, limitations, and comparative characteristics of stream ciphers and block ciphers are also examined.

This topic covers the structure, fundamental operating principles, and historical significance of DES, a symmetric block cipher. The block and key sizes of DES, as well as its Feistel network-based structure, are examined. The role of the initial and final permutations, round-key generation, expansion, S-box substitutions, and permutation operations in the encryption process is explained. The decryption process, major security characteristics, vulnerabilities arising from its key size, and the reasons for its limited use in modern cryptographic systems are also examined.

This topic covers the structure, fundamental operating principles, and role of AES in modern cryptographic systems. The block and key sizes of AES, including the AES-128, AES-192, and AES-256 variants, as well as the structure of its encryption rounds, are examined. The role of the SubBytes, ShiftRows, MixColumns, and AddRoundKey transformations in the encryption process, as well as the principles of round-key generation, are explained. The AES decryption process, its main security characteristics, its comparative advantages over DES, and its major application areas in data protection are also studied.

This topic covers the various modes of operation of block ciphers and their fundamental application principles. The Electronic Codebook (ECB), Cipher Block Chaining (CBC), Cipher Feedback (CFB), Output Feedback (OFB), and Counter (CTR) modes are examined. The role of initialization vectors (IVs), nonces, and padding in the implementation of block ciphers is explained. Different modes of operation are compared in terms of security, parallel processing, error propagation, and performance. Security risks associated with improper mode selection and the reuse of IVs or nonces are also examined.

This topic covers the fundamental principles, structure, and role of public-key cryptography in information security. The concepts of public and private key pairs, key generation, and the use of keys for different purposes are examined. The principles of encryption and decryption, digital signatures, and key exchange in asymmetric cryptography are explained. The mathematical problems underlying the security of public-key cryptosystems and their comparative characteristics with symmetric cryptography are examined. The authentication of public keys, key management, and the major application areas of public-key cryptography in modern information and communication systems are also discussed.

This topic covers the mathematical foundations, structure, and operating principles of the RSA public-key cryptosystem. Prime numbers, modular arithmetic, and the role of Euler’s totient function in the construction of the RSA algorithm are examined. The main stages of public and private key-pair generation, encryption, and decryption are explained. The security of the RSA cryptosystem and its dependence on the difficulty of factoring large integers are examined. The applications of RSA in digital signatures and key protection, the importance of padding mechanisms in practical implementations, and the main security limitations of the algorithm are also discussed.

This topic covers the mathematical foundations, structure, and operating principles of public-key cryptosystems based on the discrete logarithm problem. Finite groups, modular exponentiation, and the role of the discrete logarithm problem in cryptographic security are examined. Major cryptographic approaches based on the discrete logarithm problem, key generation, key exchange, encryption, and digital signature principles are explained. The fundamental operating principles, application characteristics, and security requirements of Diffie–Hellman key exchange and the ElGamal cryptosystem are also examined.

This topic covers the fundamental principles, characteristics, and role of cryptographic hash functions in information security. The process of converting data of arbitrary length into a fixed-length hash value and the main security requirements of cryptographic hash functions are examined. Preimage resistance, second-preimage resistance, and collision resistance are explained. Major hash algorithms, including MD5, SHA-1, and the SHA-2 family, as well as their security characteristics and limitations, are examined. The applications of cryptographic hash functions in data integrity verification, password protection, digital signatures, and other cryptographic mechanisms are also discussed.

This topic covers the concept of digital signatures, their fundamental operating principles, and their role in information security. The role of digital signatures in ensuring data authenticity, integrity, and non-repudiation is examined. The processes of creating and verifying digital signatures based on cryptographic hash functions and public-key cryptography are explained. The operating principles and application characteristics of major digital signature schemes, including RSA, DSA, and ECDSA, are examined. The secure management of keys, the role of digital certificates, and the main security requirements of digital signature schemes are also discussed.

This topic covers the fundamental concepts, structure, and operating principles of cryptocurrency and blockchain technology. The structure of blocks, transaction formation, and the role of cryptographic hash functions and digital signatures in blockchain systems are examined. The fundamental principles of distributed ledgers, decentralization, and consensus mechanisms are explained. The use of public and private keys, cryptographic addresses, and digital wallets in cryptocurrency transactions is studied. The major application areas, security characteristics, advantages, and limitations of cryptocurrency and blockchain systems are also examined.

This topic covers the potential impact of quantum computing on modern cryptographic systems and the fundamental principles of post-quantum cryptography. The threats posed by the development of quantum computers to public-key cryptosystems based on RSA and the discrete logarithm problem are examined. The main characteristics of cryptographic approaches resistant to quantum attacks, including lattice-based, code-based, hash-based, and other post-quantum cryptographic methods, are explained. Post-quantum key encapsulation mechanisms and digital signature schemes, the transition from existing cryptographic systems to quantum-resistant solutions, and hybrid cryptographic approaches are also examined.