A large number of cryptographic authentication schemes and protocols have been designed to provide authenticated key agreements to prevent man-in-the-middle and related attacks. These methods link the generally mathematically agreed key to other agreed data, such as: key exchange algorithm, often called key exchange protocol, is any method in cryptography, with which secret cryptographic keys are exchanged between two parties, usually through a public communication channel. The exponential key exchange itself does not indicate prior agreement or subsequent authentication between participants. It has therefore been described as an anonymous key memorandum of understanding. The first public public key memorandum of understanding  that meets the above criteria was the Diffie-Hellman key exchange, in which two parties jointly exposed a generator to random numbers, so that an earpiece cannot easily determine what the resulting value is used to create a common key. The original and still most famous protocol for the key agreement was proposed by Diffie and Hellman (see the key agreement Diffie Hellman) as well as their concept of cryptography with public keys. Basically, Alice and Bob users send key public values through an uncertain channel. Based on the knowledge of the corresponding private keys, they are able to correctly and safely calculate a common key value. An earpiece, however, is not capable of this key with only the knowledge of… To avoid the use of additional off-band authentication factors, Davies and Price proposed the use of Ron Rivest and Adi Shamir`s Interlock protocol, which has come under subsequent attack and refinement. If you have a way to ensure the integrity of a freed key via a public channel, you can exchange Diffie-Hellman keys to deduct a short-term released key and then authenticate that the keys match. One option is to use a key reading, as in PGPfone.
However, voice authentication assumes that it is not possible for a middle man to summon the voice of one participant in real time to another, which may be an undesirable hypothesis. These protocols can be designed to work even with a small public value, for example. B a password. Variations on this topic have been proposed for Bluetooth coupling protocols.