Crittografi

Crittografi, or cryptography in English, is the practice and science of securing information by transforming plaintext into ciphertext and back again. The goal is to ensure confidentiality, integrity, authenticity, and non-repudiation of communications and data. Crittografi relies on mathematical algorithms, protocol design, and key management to protect information from unauthorized access and tampering. It encompasses both the theory of secure communication and the practical engineering of secure systems.

Early examples include classical ciphers such as substitution (Caesar) and transposition. With the advent of mechanical and electrical devices, more systematic methods emerged. The modern era began in the 1970s with public-key cryptography, enabling secure key exchange without shared secrets (Diffie-Hellman) and practical public-key encryption (RSA). Since then, symmetric algorithms (AES), public-key systems (RSA, ECC), cryptographic hashes, and digital signatures have become standard building blocks.

Symmetric cryptography uses the same key to encrypt and decrypt; asymmetric cryptography uses a public key for encryption and a private key for decryption, enabling digital signatures and key exchange. Hash functions provide fixed-length digests and collision resistance. Protocols like TLS/SSL and PGP/SMIME rely on these primitives to secure communications. The field also includes cryptanalysis, security proofs, and post-quantum cryptography research to withstand quantum attacks.

Crittografi underpins secure online banking, messaging, software updates, and data protection regulations, as well as newer areas such as blockchain and privacy-preserving technologies.