Krüptograafias

Krüptograafias is the Estonian term for cryptography, the study and practice of securing information and communications in the presence of adversaries. It combines mathematics, computer science, and information theory to transform plaintext into forms that only authorized parties can read and to verify the origin and integrity of data.

Core concepts include encryption, decryption, and keys. Encryption uses an algorithm and a key to convert plaintext into ciphertext; decryption uses a key to recover the original message. Cryptographic systems are designed with properties such as confidentiality, integrity, authenticity, and non-repudiation.

Two broad families of encryption are symmetric (the same key for encryption and decryption) and asymmetric or public-key cryptography (paired keys: a public key for encryption and a private key for decryption). Public-key cryptography enables digital signatures and secure key exchange without a shared secret.

Common primitives include encryption schemes (AES, ChaCha20-Poly1305), public-key algorithms (RSA, Elliptic Curve Cryptography), hash functions (SHA-256), and digital signatures (RSA, ECDSA). Message authentication codes and zero-knowledge proofs are other important tools.

Cryptography underpins secure communication protocols, digital certificates, e-commerce, and data protection standards. It evolves with advances in computing power and new threats; post-quantum cryptography studies algorithms believed to withstand quantum attacks. Standardization efforts, such as NIST guidelines, help ensure interoperability and security across systems.