Patent ID: 6487661
Filing Date: 2002-11-26
Classification: G06F,H04L

Abstract:
A method of authenticating a pair of correspondents A, B in a public key data communication system to permit exchange of information therebetween over a communication channel, each of said correspondents having a respective private key a, b and a public key pA, pB derived from a generator &agr; and respective ones of said private keys a, b, said method including the steps of:i) a first of said correspondents A selecting a first random integer x and exponentiating a first function f(&agr;) including said generator to a power g(x) to provide a first exponentiated function f(&agr;)g(x); ii) said first correspondent A forwarding to a second correspondent B a message including said first exponentiated function f(&agr;)g(x); iii) said correspondent B selecting a second random integer y and exponentiating a second function fâ€²(&agr;) including said generator to a power g(y) to provide a second exponentiated function fâ€²(&agr;)g(y); iv) said second correspondent B constructing a session key K from information made public by said first correspondent A including said public key pA, and information that is private to said second correspondent B, said session key K also being constructible by said first correspondent A from information made public by said second correspondent B including said public key pB, and information that is private to said first correspondent A; v) said second correspondent B generating a value h of a function F[&pgr;, K] where F[&pgr;, K] denotes a cryptographic function F applied conjointly to &pgr; and K to bind the values of &pgr; to K and where &pgr; is obtained from said information made public by said second correspondent B to permit construction of said session key K; vi) said second of said correspondents B forwarding a message to said first correspondent A including said second exponentiated function fâ€²(&agr;)g(y) and said value h of said cryptographic function F[&pgr;, K]; vii) said first correspondent receiving said message and computing a session key Kâ€² from said information made public by said second correspondent B and private to said first correspondent A; viii) said first correspondent A computing a value hâ€² by application of a cryptographic function F to &pgr; and Kâ€²; and ix) comparing said values obtained from said application of said cryptographic functions F to confirm their correspondence.