Utilizes two keys, one for encryption, one for decryption. Introduced in 1976 by Whitfield Diffie and Martin Hellman of Stanford University. Many systems can encrypt and one system can decrypt or vice versa. Private key is never transmitted or revealed to anyone. Can provide digital signatures that cannot be repudiated.
Systems are slower than symmetric systems.
System may be vulnerable to impersonation. A successful attack on a certification authority will allow an adversary to impersonate whomever he or she chooses by using a public-key certificate from the compromised authority to bind a key of the adversary's choice to the name of another user.