Sensing Data From Physical Objects

• US 20080112596A1
• Filed: 04/24/2007
• Published: 05/15/2008
• Est. Priority Date: 01/23/2006
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B., Rodriguez, Tony F., Bradley, Brett A.
• Granted Patent: US 8,224,018 B2
• Time in Patent Office: Days
• US Class Current: 382/115
• CPC Class Codes: G06Q 20/347 Passive cards
• CPC Class Codes: G06Q 20/388 using mutual authentication without cards, e.g. challenge-response
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 2201/0062 Embedding of the watermark in text images, e.g. watermarking text documents using letter skew, letter distance or row distance
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: G06V 10/60 relating to illumination properties, e.g. using a reflectance or lighting model
• CPC Class Codes: G06V 20/80 Recognising image objects characterised by unique random patterns
• CPC Class Codes: G06V 30/413 Classification of content, e.g. text, photographs or tables
• CPC Class Codes: G07D 7/12 Visible light, infrared or ultraviolet radiation
• CPC Class Codes: G07D 7/2033 Matching unique patterns, i.e. patterns that are unique to each individual paper
• CPC Class Codes: G07F 7/08 by coded identity card or credit card or other personal identification means without personal verification means G07F7/02
• CPC Class Codes: G07F 7/0813 Specific details related to card security
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: G07F 7/1016 Devices or methods for securing the PIN and other transaction-data, e.g. by encryption arrangements for secret communication, see H04L9/00
• CPC Class Codes: G07F 7/125 Offline card verification
• CPC Class Codes: H04L 2209/608 Watermarking
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 9/3278 using physically unclonable functions [PUF]

Abstract

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. A variety of other features are also detailed.

Claims

1. A method comprising the acts:

sending challenge data from a first device to a second device;

at the second device, obtaining response data by reference to said challenge data and a physical object, wherein said obtaining includes illuminating the physical object with non-coherent illumination, capturing reflected non-coherent illumination from the illuminated object with a 2D photosensor to produce image data, and processing said image data; and

at the first device, checking said response data against expected data.

2. The method of claim 1 in which said capturing comprises capturing with a 2D optical sensor in a portable phone.

3. The method of claim 1 that includes maintaining a list of used challenge data, and checking candidate challenge data against said list.

4. The method of claim 1 in which said obtaining includes processing the image data in accordance with the challenge data to yield the response data.

5. The method of claim 1 in which the physical medium is a planar card.

6. A method comprising the acts:

sending challenge data from a first device to a second device;

at the second device, obtaining response data by reference to said challenge data and a physical object, said obtaining including capturing image data from the illuminated object with a 2D photosensor; and

at the first device, checking said response data against expected data;

wherein the method further includes determining the relative orientation between said object and said 2D photosensor by reference to said captured image data.

7. The method of claim 6 in which said determining includes decoding a steganographically encoded signal from said captured image data.

8. The method of claim 6 in which said capturing comprises capturing with a 2D optical sensor in a portable phone.

9. A method comprising:

capturing image data from an object using a 2D sensor;

estimating a relative position between said object and said sensor;

by reference to data previously acquired and stored in a data structure, obtaining a set of data that should correspond to image data captured from said object from said relative position; and

checking said captured image data and said obtained set of data for correlation.

10. A method comprising:

capturing plural views of a reference object, each from a different perspective;

storing data corresponding to the foregoing;

subsequently capturing plural views from a second object, each from a different perspective;

identifying a subset of the stored data corresponding to the perspectives from which views of the second object were subsequently captured; and

by reference to said subset, and said subsequently-captured views, determining whether the second object is the reference object.

11. The method of claim 10 that includes:

determining a first directional albedo function by reference to the subsequently captured views from the second object;

determining a second albedo function by reference to the identified subset of stored data; and

performing a correlation operation between said first and second albedo functions.

12. The method of claim 11 that includes:

determining a third albedo function by reference to a complete set of said stored data;

comparing said second and third albedo functions to determine elements thereof that diverge by more than a threshold.

13. The method of claim 12 that includes disregarding said determined elements when performing a correlation between the first and second albedo functions.

14. The method of claim 11 that includes:

determining a third albedo function by reference to a complete set of said stored data;

comparing said second and third albedo functions to determine elements thereof that match within a threshold.

15. The method of claim 14 that includes disregarding said determined elements when performing a correlation between the first and second albedo functions.