Patent ID: 6526509
Filing Date: 2003-02-25
Classification: G06F,H04L

Abstract:
A method for computer-aided interchange of cryptographic codes between a first computer unit and a second computer unit, comprising the steps of:forming a first value in the first computer unit from a first random number of a finite group using a generating element; transmitting a first message from the first computer unit to the second computer unit, the first message having at least said first value; forming a session code in the second computer unit using a first hash function, a first input variable of the first hash function having at least one first term which is formed by exponentiation of the first value with a secret network code; forming a response in the second computer unit by use of said session code; transmitting a second message from the second computer unit to the first computer unit, whereby the second message comprises at least the response, said response being transmitted serving for checking of the session code to be formed in the first computer unit and not for formation of the session code in the first computer unit; forming the session code in the first computer unit using the first hash function, a second input variable of the first hash function having at least one second term which is formed by exponentiation of a public network code using the first random number; checking the session code in the first computer unit on the basis of the response; forming a fourth input variable in the first computer unit using one of a second hash function or the first hash function, a third input variable for the first hash function or for the second hash function having at least the session code in order to form the fourth input variable; forming a signature term in the first computer unit from at least the fourth input variable using a first signature function; transmitting a third message from the first computer unit to the second computer unit, the third message having at least the signature term of the first computer unit; and verifying the signature term in the second computer unit.