Patent ID: 7551056

Claim:
A use-authorization device for security-related applications, in particular access control to secure areas or for securing vehicles, with a user-end key unit for generating consecutive, alternating user code information which has a sequence of consecutive function values v i+1 =F (v i ,const) for i=0, . . . , N through the repeated use of a one-way function F(v i ,const), which function values are used in inverse order to the sequence formation to create the consecutive user code information; and an application-end processing unit for determining actual authorization information which is dependent upon the user code information received from the key unit and for performing a use-authorization checking process by comparing this actual authorization information with the application-end desired authorization information, as well as for generating use-release information depending on the result of the comparison, wherein the desired authorization information has a function value v i which has been transferred from the user code information which had been processed during the previous positive use-authorization operation; characterized in that there is a certain number of levels G provided from which a certain number of iterative function value calculations can be performed in each level by means of the one-way function F(v i ,const), and there are G=┌L(N)/b┐ levels, wherein N is the starting value, L(N) is the number of bits required for representing N in the dual system and b is the basis.