| (I) A modern branch of cryptography (popularly known as "public-
key cryptography") in which the algorithms employ a pair of keys
(a public key and a private key) and use a different component of
the pair for different steps of the algorithm. (See: key pair.)
(C) Asymmetric algorithms have key management advantages over
equivalently strong symmetric ones. First, one key of the pair
does not need to be known by anyone but its owner; so it can more
easily be kept secret. Second, although the other key of the pair
is shared by all entities that use the algorithm, that key does
not need to be kept secret from other, non-using entities; so the
key distribution part of key management can be done more easily.
(C) For encryption: In an asymmetric encryption algorithm (e.g.,
see: RSA), when Alice wants to ensure confidentiality for data she
sends to Bob, she encrypts the data with a public key provided by
Bob. Only Bob has the matching private key that is needed to
decrypt the data.
(C) For signature: In an asymmetric digital signature algorithm
(e.g., see: DSA), when Alice wants to ensure data integrity or
provide authentication for data she sends to Bob, she uses her
private key to sign the data (i.e., create a digital signature
based on the data). To verify the signature, Bob uses the matching
public key that Alice has provided.
(C) For key agreement: In an asymmetric key agreement algorithm
(e.g., see: Diffie-Hellman), Alice and Bob each send their own
public key to the other person. Then each uses their own private
key and the other's public key to compute the new key value.
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