Cryptology

Cryptology is the study of secure communication in the presence of adversaries. It comprises cryptography, the design of secure algorithms and protocols, and cryptanalysis, the study of breaking them. Together, it seeks to achieve confidentiality, integrity, authenticity, and non-repudiation of information and communications.

Its roots lie in ancient cryptography, such as substitution ciphers, and later frequency analysis. The modern discipline emerged with mathematical formalism in the 20th century and the invention of public-key cryptography in the 1970s, which enabled secure key exchange over insecure channels.

Subfields include symmetric-key cryptography, which uses shared secret keys; asymmetric-key cryptography, which uses public and private keys; cryptographic protocols such as key exchange, digital signatures, and authentication; cryptanalytic methods, including brute-force, mathematical attacks, and side-channel analysis; and cryptographic engineering, standards, post-quantum cryptography, and related areas that address implementation and security guarantees.

Common algorithms and constructs include AES for symmetric encryption; RSA and elliptic-curve cryptography for public-key encryption; hash functions such as SHA-256; digital signatures; and protocols like TLS. These tools enable secure messaging, data protection, and trusted online commerce.

Today, cryptology underpins much of digital security and privacy. Ongoing research addresses quantum threats, advances in zero-knowledge proofs and secure multiparty computation, and the development of standards and secure implementations.