Knowra Cryptography Cryptography Cryptography is the study and practice of techniques that protect information through mathematical transformations and protocols. It supports goals such as confidentiality, integrity, authentication, and non-repudiation.
Symmetric-key cryptography : Cryptography that uses the same secret key, or closely related keys, for encryption and decryption. It provides efficient encryption when communicating parties already share a secret.
Advanced Encryption Standard : A standardized block cipher that encrypts data with 128-bit blocks and 128-, 192-, or 256-bit keys. AES is a widely deployed example of symmetric encryption.
Caesar cipher : A substitution cipher that shifts each letter in the alphabet by a fixed number of positions. It exemplifies simple classical encryption based on a shared, easily discovered rule.
Transport Layer Security : A protocol that protects data exchanged between applications over a network using encryption and authentication. TLS secures web traffic by combining certificates, key exchange, and authenticated encryption.
Steganography : The practice of concealing the existence of a message within another medium or communication. Cryptography hides message meaning; steganography aims to hide that a message exists.
Public-key cryptography : Cryptography using mathematically related public and private keys for encryption, signatures, or key agreement. It enables secure communication and authentication without first sharing a secret key.
RSA : A public-key cryptosystem whose security is based on the difficulty of factoring large composite integers. RSA illustrates how computationally hard mathematical problems can underpin cryptography.
Al-Kindi : A ninth-century Arab polymath who described frequency analysis as a method for breaking substitution ciphers. His work helped establish systematic cryptanalysis as a mathematical discipline.
Public key infrastructure : A system of policies, certificates, and authorities for binding public keys to identities. It lets browsers and services assess which public keys belong to which organizations.
Quantum cryptography : Cryptographic methods that use quantum-mechanical effects, especially for key distribution. It uses physical measurement properties rather than only classical computational assumptions.
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