Use-authorization device for security-related applications

• US 20070118755A1
• Filed: 12/06/2004
• Published: 05/24/2007
• Est. Priority Date: 12/15/2003
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Scholze, Steffen
• Granted Patent: US 7,551,056 B2
• Time in Patent Office: Days
• US Class Current: 713/182
• CPC Class Codes: H04L 2209/84 Vehicles
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/50 using hash chains, e.g. blockchains or hash trees

Abstract

This description is given of a use-authorization device for security-related applications, in particular access control to secure areas or securing vehicles with a user operated key unit for generating consecutive, alternating user code information which exhibits 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(_vi,const), which function values are used in inverse order to the sequence formation to create the consecutive user code information, and an application-sided 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 target authorization information saved in the application, as well as for generating use-release information depending on the result of the comparison, wherein the target authorization information has a function value v; which has been transferred from the user code information processed during the previous positive use-authorization operation. The special feature of the invention is that there is a certain number of levels G provided, with at least one support point and one intermediate value, 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) wherein there are G=L(N)/b levels, with N as the starting value, L(N) as the number of bits required for representing N in the dual system and b as the basis.

Claims

1. 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.

2. A device as claimed in claim 1, characterized in that there is a support point s(i) where i=(1, . . . , G) provided for each level.

3. A device as claimed in claim 2, characterized in that the values for the support points s(i) are determined from the equation

4. A device as claimed in claim 2, characterized in that no function values can be calculated for support points with a negative index.

5. A device as claimed in claim 2, characterized in that the parameter b is adapted for a specified number of support points in such a way that the function value calculations per use authorization are minimized.

6. A device as claimed in claim 2, characterized in that, starting from the current support point s(i), there should be a certain number of function values calculated in each level in descending order and saved as intermediate values.

7. A device as claimed in claim 2, characterized in that an intermediate value for the support point in a level should be reset successively in this level once this intermediate value, as a new support point, has been transferred to the next level down.

8. A device as claimed in claim 1, characterized in that the starting value is N=(2^b)^G.

9. A device as claimed in claim 1, characterized in that the starting value is Nε

{(2^b)<sup>G−

1</sup>, . . . , (2^b)^G−

1}.

10. A device as claimed in claim 1, characterized in that there were several buffers provided for saving intermediate values which are calculated from the function values.

11. A device as claimed in claim 10, characterized in that the buffers are FIFO memories.