KEM
also: Key Encapsulation Mechanism
KEM (Key Encapsulation Mechanism) is a cryptographic algorithm that securely generates and encapsulates symmetric encryption keys for transmission to another party. It's a core component of public-key cryptography used in modern secure communication.
A Key Encapsulation Mechanism is a cryptographic primitive that combines a public-key algorithm with a symmetric key derivation process. The sender uses the recipient's public key to encapsulate (wrap) a randomly generated symmetric key, producing a ciphertext that only the recipient can decrypt using their private key.
KEMs are essential building blocks in hybrid encryption schemes, where asymmetric cryptography handles key exchange and symmetric cryptography handles the actual data encryption. For example, TLS 1.3 uses KEMs like ML-KEM (formerly Kyber) to establish shared secrets between client and server before encrypting the session data with AES.
Modern post-quantum cryptography standards, including those standardized by NIST, define KEMs as security-focused alternatives to traditional key exchange methods, offering resistance against attacks by future quantum computers.