Web and XML Glossary

Diffie-Hellman key agreement describes a method whereby two parties, without any prior arrangements, can agree upon a secret key that is known only to them (and, in particular, is not known to an eavesdropper listening to the dialogue by which the parties agree on the key). This secret key can be used, for example, to encrypt further communications between the parties using Secret-Key Cryptography. The intended application of this standard is in Protocols for establishing secure connections. Details on the interpretation of the agreed-upon secret key are outside the scope of Diffie-Hellman key agreement, as are details on sources of the pseudo-random bits required by this method. The Diffie-Hellman key exchange is vulnerable to a middleperson attack. This vulnerability is due to the fact that Diffie-Hellman key exchange does not authenticate the participants.