Shared secret arrangements and optical data transfer

• US 8,879,735 B2
• Filed: 01/18/2013
• Issued: 11/04/2014
• Est. Priority Date: 01/20/2012
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Lord, John Douglas
• Primary Examiner(s): Chao, Michael
• Assistant Examiner(s): Gao, Shu Chun
• Application Number:
  US13/745,270
• Publication Number:
  US 20130195273A1
• Time in Patent Office: 655 Days
• Field of Search: 380/270
• US Class Current: 380/270
• CPC Class Codes: H04B 10/1141 One-way transmission
• CPC Class Codes: H04B 10/116 Visible light communication
• CPC Class Codes: H04K 1/00 Secret communication
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/18 using different networks or channels, e.g. using out of band channels cryptographic mechanisms or cryptographic arrangements for key distribution involving distinctive intermediate devices or communication paths H04L9/0827; cryptographic mechanisms or cryptographic arrangements for authentication using a plurality of channels H04L9/3215
• CPC Class Codes: H04W 12/069 using certificates or pre-shared keys

Abstract

Digital data is optically broadcast through an environment by controllably switching the brightness or chrominance of LED solid state lamps, or of other illumination sources (e.g., television screens and backlit computer displays). This optical data channel is useful to convey cryptographic key data by which devices within the environment can authenticate themselves to a secure network. In some embodiments, the optical modulation is sensed by the camera of a smartphone. The row data output by the smartphone'"'"'s camera sensor is processed to extract the modulated data signal. In some monochrome embodiments, data communication speeds far in excess of the camera'"'"'s frame rate (e.g., 30/second), or even the camera'"'"'s row rate (e.g., 14,400/second) are achieved. Still greater rates can be achieved by conveying different data in different chrominance channels. A great number of other features and arrangements are also detailed.

Claims

1. A method employing a smartphone camera pointed at a subject, the camera comprising a grid-like array of plural photosensors on a substrate, with a lens that projects light from the subject onto said array of photosensors, the method comprising:

setting a focus of the smartphone camera so the subject is unfocused;

processing data captured by the camera to derive a cryptographic key; and

engaging in a secure wireless transaction with a remote device, through use of said derived cryptographic key.

2. The method of claim 1 in which said setting comprises setting a focus control signal to a default value that has no relationship to a distance between the camera and the subject.

3. The method of claim 1 in which said setting comprises setting a focus control signal to a value that results in a maximum blurriness of the subject as imaged by the camera.

4. A smartphone comprising a camera, a processor and a memory, the camera comprising a grid-like array of plural photosensors on a substrate, together with a lens that projects light from a subject onto said array of photosensors, the memory containing software instructions operable to cause the smartphone to perform acts including:

setting a focus of the smartphone camera so said subject is unfocused;

processing data captured by the camera to derive a cryptographic key; and

engaging in a secure wireless transaction with a remote device, through use of said derived cryptographic key.

5. The smartphone of claim 4 in which said setting comprises setting a focus control signal to a default value that has no relationship to a distance between the camera and the subject.

6. The smartphone of claim 4 in which said setting comprises setting a focus control signal to a value that results in a maximum blurriness of the subject as imaged by the camera.

7. A non-transitory computer readable medium containing software instructions for configuring a smartphone that is equipped with a camera, including a grid-like array of plural photosensors on a substrate, together with a lens that projects light from a subject onto said array of photosensors, to perform acts including:

setting a focus of the smartphone camera so the subject is unfocused;

processing data captured by the camera to derive a cryptographic key; and

engaging in a secure wireless transaction with a remote device, through use of said derived cryptographic key.

8. The computer readable medium of claim 7 in which said setting comprises setting a focus control signal to a default value that has no relationship to a distance between the camera and the subject.

9. The computer readable medium of claim 7 in which said setting comprises setting a focus control signal to a value that results in a maximum blurriness of the subject as imaged by the camera.