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. Key mous that is verified by the password requires the separate implementation of a password (which may be smaller than a key) in a way that is both private and integrity. These are designed to withstand man-in-the-middle and other active attacks on the password and established keys. For example, DH-EKE, SPEKE and SRP are Diffie-Hellman password authentication variants. A widespread mechanism for repelling these attacks is the use of digitally signed keys, which must be secured for integrity: if Bob`s key is signed by a trusted third party guarantor of his identity, Alice can have great confidence that a signed key she receives is not an attempt to intercept Eve. If Alice and Bob have an infrastructure with public keys, they can digitally sign a Diffie Hellman key or exchange a Diffie Hellman public key. These signed keys, sometimes signed by a certification body, are one of the primary mechanisms used for secure web data traffic (including DEE, SSL or Transport Layer Security protocols). Other specific examples are: MQV, YAK and the ISAKMP component of the IPsec protocol suite for securing internet protocol communications.
However, these systems require care to support consistency between identity information and public keys by certification bodies in order to function properly. Many key exchange systems have a part that generates the key and simply sends that key to the other party — the other party has no influence on the key. The use of a key MEMORANDUM of understanding avoids some of the major distribution problems associated with these systems. In cryptography, a key memorandum of understanding is a protocol in which two or more parties can agree on a key so that both influence the outcome.