Patent ID: 7327846
Filing Date: 2008-02-05
Classification: H04L

Abstract:
1. In a protocol for cryptographic communication via a communication channel “I” in which a sending cryptographic unit “S” transmits onto the communication channel I an encrypted cyphertext message “M” obtained by supplying both a plaintext message “P” and a cryptographic key “K” to a first cryptographic device, and in which a receiving cryptographic unit “R” receives the cyphertext message M from the communication channel I and by supplying the cyphertext message M together with the key K to a second cryptographic device decrypts the plaintext message P therefrom, a method by which the units S and R mutually establish a cryptographic key K by first exchanging messages before the sending unit S transmits the cyphertext message M comprising the steps of: a. the receiving unit R transmitting for storage in a publicly accessible repository a plurality of public quantities; b. the sending unit S: c. the receiving unit R, using at least one of the plurality of sender's quantities received from the sending unit S computing the key K.