Physical unclonable functions having magnetic and non-magnetic particles
View Patent ↗A physical unclonable function (PUF) having magnetic and non-magnetic particles is disclosed. Measuring both magnetic field and image view makes the PUF difficult to counterfeit. PUF may be incorporated into a user-replaceable supply item for an imaging device. A PUF reader may be incorporated into an imaging device to read the PUF. Other systems are disclosed.
1. A system comprising:
a non-opaque substrate having a region having a volume of 100 cubic millimeters;
a plurality of magnetic particles dispersed in the region each having a diameter greater than 25 microns; and
a plurality of non-magnetic particles dispersed in the region each having a diameter greater than 100 microns,
wherein the magnetic particles have an average diameter of between 50 and 500 microns inclusive and the non-magnetic particles have an average diameter of between 200 and 2000 microns inclusive.
2. The system of claim 1 , wherein the magnetic particles are flakes each having an average thickness that is less than their diameter.
3. The system of claim 1 , wherein the non-magnetic particles are flakes each having an average thickness that is less than their diameter.
4. The system of claim 1 , wherein the average diameter of the non-magnetic particles is at least twice as large as the average diameter of the magnetic particles.
5. The system of claim 1 , wherein the non-magnetic particles are reflective.
6. The system of claim 1 , wherein the magnetic particles contain neodymium and iron and boron.
7. The system of claim 1 , wherein the magnetic particles contain samarium and cobalt.
8. The system of claim 1 , wherein the substrate is configured to rotate about an axis.
9. The system of claim 1 , wherein the substrate is a gear.
10. The system of claim 1 , further comprising a body and a non-volatile memory, the substrate and the non-volatile memory are mounted to the body, the non-volatile memory contains field data corresponding to a magnetic field generated by the magnetic particles and image data corresponding to a view of the magnetic particles and the non-magnetic particles.
11. A system comprising:
a non-opaque substrate;
a plurality of magnetic particles dispersed in the substrate; and
a plurality of non-magnetic particles dispersed in the substrate containing metal,
wherein the magnetic particles have an average diameter of between 50 and 500 microns inclusive and the non-magnetic particles have an average diameter of between 200 and 2000 microns inclusive.
12. The system of claim 11 , wherein the magnetic particles are flakes each having an average thickness that is less than their diameter.
13. The system of claim 11 , wherein the non-magnetic particles are flakes each having an average thickness that is less than their diameter.
14. The system of claim 11 , wherein the average diameter of the non-magnetic particles is at least twice as large as the average diameter of the magnetic particles.
15. The system of claim 11 , wherein the magnetic particles contain neodymium and iron and boron.
16. The system of claim 11 , wherein the magnetic particles contain samarium and cobalt.
17. The system of claim 11 , wherein the substrate is configured to rotate about an axis.
18. The system of claim 11 , wherein the substrate is a gear.
19. The system of claim 11 , further comprising a body and a non-volatile memory, the substrate and the non-volatile memory are mounted to the body, the non-volatile memory contains field data corresponding to a magnetic field generated by the magnetic particles and image data corresponding to a view of the magnetic particles and the non-magnetic particles.
20. A system comprising:
a non-opaque substrate;
a plurality of magnetic particles dispersed in the substrate; and
a plurality of non-magnetic particles dispersed in the substrate,
wherein the ratio of the number of non-magnetic particles to the number of magnetic particles is between 1/10 and 2/1 inclusive as measured in a region of the substrate having a volume of 100 cubic millimeters.
21. The system of claim 20 , wherein the magnetic particles in the region are flakes having an average thickness that is less than an average diameter of the flakes.
22. The system of claim 20 , wherein the magnetic particles in the region have an average diameter of between 50 and 500 microns inclusive.
23. The system of claim 20 , wherein the non-magnetic particles in the region have an average diameter of between 200 and 2000 microns inclusive.
24. The system of claim 20 , wherein the magnetic particles in the region have a first average diameter, the non-magnetic particles in the region have a second average diameter, and the second average diameter is at least twice as large as the first average diameter.
25. The system of claim 20 , wherein the non-magnetic particles are reflective.
26. The system of claim 20 , wherein the magnetic particles contain neodymium and iron and boron.
27. The system of claim 20 , wherein the magnetic particles contain samarium and cobalt.
28. The system of claim 20 , wherein the substrate is configured to rotate about an axis.
29. The system of claim 20 , wherein the substrate is a gear.
30. The system of claim 20 , further comprising a body and a non-volatile memory, the substrate and the non-volatile memory are mounted to the body, the non-volatile memory contains field data corresponding to the magnetic field generated by the magnetic particles and image data corresponding to a view of the magnetic particles and the non-magnetic particles.
31. A system comprising:
a non-opaque substrate;
a plurality of magnetic particles dispersed in the substrate having a first volume; and
a plurality of non-magnetic particles dispersed in the substrate having a second volume,
wherein, within a region of the substrate having a volume of 100 cubic millimeters, the first volume is between 0.0005% and 20% of the volume of the region and the second volume is between 0.003% and 33% of the volume of the region.
32. The system of claim 31 , wherein the magnetic particles in the region are flakes having an average thickness that is less than an average diameter of the flakes.
33. The system of claim 31 , wherein the magnetic particles in the region have an average diameter of between 50 and 500 microns inclusive.
34. The system of claim 31 , wherein the non-magnetic particles in the region have an average diameter of between 200 and 2000 microns inclusive.
35. The system of claim 31 , wherein the magnetic particles in the region have a first average diameter, the non-magnetic particles in the region have a second average diameter, and the second average diameter is at least twice as large as the first average diameter.
36. The system of claim 31 , wherein the non-magnetic particles are reflective.
37. The system of claim 31 , wherein the magnetic particles contain neodymium and iron and boron.
38. The system of claim 31 , wherein the magnetic particles contain samarium and cobalt.
39. The system of claim 31 , wherein the substrate is configured to rotate about an axis.
40. The system of claim 31 , wherein the substrate is a gear.
41. The system of claim 31 , further comprising a body and a non-volatile memory, the substrate and the non-volatile memory are mounted to the body, the non-volatile memory contains field data corresponding to the magnetic field generated by the magnetic particles and image data corresponding to a view of the magnetic particles and the non-magnetic particles.