Kriptograafiat

Kriptograafiat is the study and practice of protecting information by transforming it into formats that are unreadable without authorized access. It encompasses the design of algorithms, the construction of secure protocols, and the management of cryptographic keys, with aims including confidentiality, data integrity, authenticity, and non-repudiation.

Its historical roots lie in classical ciphers such as substitution and transposition, but modern cryptography emerged from mathematical advances in the 20th century. Information theory, introduced by Claude Shannon, formalized the limits of secure communication. In the 1970s, public-key cryptography revolutionized the field with algorithms like Diffie-Hellman for key exchange and RSA for encryption and digital signatures; later, elliptic-curve cryptography offered comparable security with shorter keys.

Two broad categories are symmetric-key cryptography, which uses the same secret key for encryption and decryption, and public-key (asymmetric) cryptography, which uses a key pair. Core concepts include cryptographic hash functions, digital signatures, random number generation, and secure key exchange. Cryptanalysis studies how to break schemes and improve designs, while formal security models provide proofs of security under specified assumptions.

Kriptograafiat underpins many technologies: secure web communication (TLS/HTTPS), digital payments, authentication systems, and blockchain-based protocols. It also covers secure protocols, provable-security constructions, and post-quantum cryptography, which seeks algorithms expected to resist quantum attacks. Standards and compliance activities are led by organizations such as NIST and ISO/IEC.

Challenges include ensuring practical security against implementation flaws and side-channel attacks, managing cryptographic keys at scale, and adapting to emerging threats such as quantum computers. Ongoing research aims to develop more efficient algorithms, stronger security proofs, and interoperable standards across industries.