Public Key

1. A cryptographic key used with a public key cryptographic algorithm, uniquely associated with an entity, and which may be made public; it is used to verify a digital signature; this key is mathematically linked with a corresponding private key. (FIPS 196) (NISTIR) A cryptographic key that may be widely published and is used to enable the operation of an asymmetric cryptography scheme. This key is mathematically linked with a corresponding private key. Typically, a public key can be used to encrypt, but not decrypt, or to validate a signature, but not to sign. (CNSSI-4009) (NISTIR) In an asymmetric (public) cryptosystem, the public key is associated with a private key. The public key may be known by anyone and, depending on the algorithm, may be used, for example, to: 1) Verify a digital signature that is signed by the corresponding private key, 2) Encrypt keys that can be decrypted by the corresponding private key, or 3) Compute a shared secret during a key-agreement transaction. (SP 800-57 Part 1) (NISTIR) 2. A cryptographic key that may be widely published and is used to enable the operation of an asymmetric (public key) cryptographic algorithm. Extended Definition: The public part of an asymmetric key pair that is uniquely associated with an entity and that may be made public. Related Term(s): private key, asymmetric cryptography (Adapted from: CNSSI 4009, NIST SP 800-63 Rev 1, FIPS 201-2, FIPS 140-2, Federal Bridge Certificate Authority Certification Policy 2.25) (NICCS)