Cryptage

Cryptage is the act of converting plaintext into ciphertext to hide its content, typically using an encryption algorithm and a cryptographic key. It is a central practice of information security, alongside authentication and data integrity.

The process relies on algorithms that transform input data; the key controls the specific transformation. Symmetric cryptography uses the same key for encryption and decryption, with examples such as AES and ChaCha20. Asymmetric cryptography uses a key pair (public and private) to enable secure key exchange and digital signatures.

Encryption protects data at rest and in transit. It underpins secure communications, privacy-preserving storage, and many modern protocols. Widely used algorithms include AES for bulk data, RSA and elliptic curve cryptography for key exchange and signatures, and TLS as a protocol that negotiates encryption for network connections.

Cryptage is distinct from encoding, which re-represents data without secrecy, and from hashing, a one-way function used for integrity checks. Proper cryptage also depends on key management, algorithm choice, and proper implementation to avoid vulnerabilities.

Legal and regulatory considerations include export controls, surveillance exemptions, and compliance regimes that mandate or restrict the use of encryption in different jurisdictions.