Granted Patent B1

US 7,262,420 · App. 11/367,973 · Granted Aug 28, 2007

Abstract

Claims (34)

1. A secure tag validation method comprising:

exciting the secure tag;

accessing a time delay;

measuring a luminescence spectrum after elapse of the accessed time delay;

deriving a luminescence signature from the measured luminescence spectrum;

creating a control signature using the accessed time delay;

comparing the derived luminescence signature with the control signature;

ascertaining if the derived luminescence signature matches the control signature; and

validating the secure tag in the event of a match.

2. The method of claim 1 , wherein accessing a time delay further comprises generating a new time delay for each validation.

3. The method of claim 1 , wherein the time delay is constrained between a minimum value and a maximum value.

4. The method of claim 1 , wherein creating a control signature involves using the accessed time delay as an input to a function that operates on the accessed time delay to generate the control signature.

5. The method of claim 4 , wherein the function is a calculation.

6. The method of claim 4 , wherein the function models the luminescence from the secure tag over time, so that for any given time the function provides the luminescence intensity at each of multiple wavelengths.

7. The method of claim 4 , wherein the function models the luminescence signature of the secure tag over time.

8. The method of claim 1 , wherein ascertaining if the derived luminescence signature matches the control signature comprises ascertaining whether the derived luminescence signature differs from the control signature by less than a predetermined amount.

9. The method of claim 8 , wherein the derived luminescence signature has to match the control signature perfectly.

10. A reader for validating a secure tag, the reader comprising:

an optical source operable to illuminate the secure tag;

a processor coupled to the optical source and operable to activate and de-activate the optical source; and

a luminescence detector coupled to the processor and operable to measure a luminescence spectrum after a time delay has elapsed;

the processor being operable to create a control signature using the time delay and to validate the secure tag in the event that a predetermined acceptance criterion is met.

11. The reader of claim 10 , wherein the predetermined acceptance criterion comprises: a luminescence signature derived from the measured luminescence spectrum matching the control signature.

12. The reader of claim 10 , wherein the reader includes a network connection to receive an updated time delay.

13. The reader of claim 11 , wherein the reader includes a number generator operable to generate a random or pseudo-random number.

14. A secure tag validation method comprising:

exciting the secure tag;

generating a random or pseudo-random time delay;

measuring a luminescence spectrum after elapse of the random or pseudo-random time delay;

deriving a luminescence signature from the measured luminescence spectrum;

creating a control signature using the random or pseudo-random time delay;

comparing the derived luminescence signature with the control signature;

ascertaining if the derived luminescence signature matches the control signature; and

validating the secure tag in the event of a match.

Assignments (13)