Editing Key-agreement protocol (section)

=== Other tricks ===
If one has an integrity-assured way to verify a shared key over a public channel, one may engage in a [[Diffie–Hellman key exchange]] to derive a short-term shared key, and then subsequently authenticate that the keys match. One way is to use a voice-authenticated read-out of the key, as in [[PGPfone]]. Voice authentication, however, presumes that it is infeasible for a man-in-the-middle to spoof one participant's voice to the other in real-time, which may be an undesirable assumption. Such protocols may be designed to work with even a small public value, such as a password. Variations on this theme have been proposed for [[Bluetooth]] pairing protocols.

In an attempt to avoid using any additional out-of-band authentication factors, Davies and Price proposed the use of the [[interlock protocol]] of [[Ron Rivest]] and [[Adi Shamir]], which has been subject to both attack and subsequent refinement.