Physical credentials and related methods
View Patent ↗Directional albedo of a particular article, such as an identity card, is measured and stored. When the article is later presented, it can be confirmed to be the same particular article by re-measuring the albedo function, and checking for correspondence against the earlier-stored data. The re-measuring can be performed through us of a handheld optical device, such as a camera-equipped cell phone. The albedo function can serve as random key data in a variety of cryptographic applications. The function can be changed during the life of the article through use of a variety of different card constructions (e.g., involving quantum dots, phase change materials, MEMS structures, etc.). A variety of other arrangements and features are also detailed.
1. An identity credential comprising a substrate conveying information related to an individual, and further comprising a phase-changing medium that serves to vary a credential-identifying directional albedo function.
2. The credential of claim 1 wherein said medium, in one state, is crystalline.
3. The credential of claim 1 wherein said medium comprises a chalcogenide glass.
4. The credential of claim 1 wherein said medium comprises silver-indium-antimony-tellurium.
5. The identity credential of claim 1 in which the substrate is printed with textual information related to the individual, so that the credential serves to identify said individual.
6. The identity credential of claim 1 in which the phase-changing medium is responsive to stimulus to change a directional attribute of the credential-identifying directional albedo function.
7. A system comprising the identity credential of claim 1 , in conjunction with an apparatus adapted to sense plural data relating to directional albedo wobble or azimuth angles from said credential and to make a decision based thereon.
8. An identity credential comprising a substrate conveying information related to an individual, and further comprising a microelectromechanical system structure adapted to reconfigure a credential-identifying directional albedo characteristic.
9. The identity credential of claim 8 , wherein said structure resides in a buried layer, rather than on an exterior thereof.
10. The identity credential of claim 9 , wherein the microelectromechanical system structure comprises an array of micromirrors resting on bases including heat-deformable material, wherein the micromirrors are steered through selective application of heat energy, rather than being electronically steered.
11. The identity credential of claim 8 in which the substrate is printed with textual information related to the individual, so that the credential serves to identify said individual.
12. The identity credential of claim 8 in which the microelectromechanical system structure is responsive to stimulus to change a directional attribute of the directional albedo function.
13. A method of authenticating a transaction conducted using a wireless telecommunications device, comprising sensing directional albedo data from a credential, and using said sensed directional albedo data in authenticating the transaction.
14. The method of claim 13 in which said authentication also makes use of data from a machine readable feature on the credential, other than directional albedo.
15. The method of claim 13 wherein the method includes a challenge-response procedure based, at least in part, on said sensed directional albedo data.