Public-Key Encryption Scheme

A public-key, or asymmetric, encryption scheme uses a mathematically related key pair: a public key that anyone may use to encrypt a message, and a private key, known only to the recipient, needed to decrypt it. Security rests on a hard computational problem, such as integer factorization for RSA-family schemes or the discrete logarithm problem for ElGamal and elliptic-curve variants, that makes deriving the private key from the public key infeasible with current computing methods. Because asymmetric operations are comparatively slow, public-key schemes are commonly used to establish or wrap a symmetric session key rather than to encrypt bulk data directly.