Public key distribution protocol Diffie-Hellman

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Public key distribution protocol Diffie-Hellman - cryptographic key exchange protocol proposed in 1976, based on asymmetric cryptoschemes. This protocol provides a shared secret, which becomes available to two or more parties for later use. The resulting shared secret (key) can be transmitted over insecure channels by listening.

Description of the protocol for the two parties

This protocol is very simple, in table 1 below its description.

There are two party protocol: A and B, and there is a trusted party. On the trusted side produced some data available to both parties.


The simple key exchange protocol Diffie-Hellman does not provide any of the major properties of the distribution protocols keys: no authentication, no confirmation key, no authentication of parties to the protocol. An active opponent can build attack on the protocol by switching in a channel (attack of the "Man in the middle"), as shown in table 2. In the end, he will be able to monitor all communication between the parties.

Table 2. Attack of the active opponent of the Protocol Diffie-Hellman.



  • Запечников С.В. Криптографические протоколы и их применение в финансовой и коммерческой деятельности. Учебное пособие для вузов. – М.: Горячая линия – Телеком, 2007. – 320 с.