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Authentication and Certification of Image Transmission Disclosure Number: IPCOM000004831D
Original Publication Date: 2001-Jun-27
Included in the Prior Art Database: 2001-Jun-27
Document File: 7 page(s) / 134K

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Austin Harton: AUTHOR [+2]


Authentication and Certification of Image Transmission

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Authentication and Certification of Image Transmission


Austin Harton, Francisco Castro and Jacques Hara

The transmission of multimedia information from remote sources in digital communication networks is vulnerable to the illegal reception of private or confidential data. Consequently, there is great interest by those wishing to expand the range of multimedia services to provide the remote user with robust data security techniques. In the case of secure image transmission from remote sensors, protection is provided by encryption techniques that have large computational requirements and generally involve post-capture encoding of the image by an off-chip processor. Encoding is achieved either through value transformation, where the value of each pixel is changed using a transform of the image plane, or though position permutation, where the positions of individual pixels are rearranged or scrambled using a specified algorithm. Both of these techniques require the end user to have significant processing capabilities in addition to sufficient data storage.

We propose an alternative to current post-capture methods in which the encryption process is carried out at the image sensor in order to simplify hardware requirements and minimize cost. The technique proposed in this paper allows encryption to occur during image capture using the time integrating pixel sensor (TIPS) architecture. The TIPS image sensor maps light intensity to a digital value that represents the pixel integration time and stores this value in a register inside the pixel. This mapping technique allows for individual exposure control at each pixel resulting in the ability to capture large dynamic range images. By taking advantage of the bus architecture and the memory resident inside a TIPS pixel we can extend the capabilities of the sensor to encrypt the stored pixel data through a value transformation process, thus reducing or even eliminating the need for post-capture processing hardware and memory.

As shown in Figure 1, the TIPS architecture consists of two lookup tables (LUT)'s. One lookup table, LUT1, stores digital codes to be converted to analog voltages that will be used as the reference signal in the pixel comparator while the other lookup table, LUT2, stores the digital codes to be latched into the pixel register when the photogenerated voltage equals the reference signal and the comparator is triggered. Using this configuration, pixel encryption can easily be accomplished by loading LUT2 with an encoded sequence. While this can be viewed as a form of value transformation, it does not provide sufficient protection for image transmission because pixels exposed to the same light intensity are mapped to identical digital codes.

In order to achieve a robust encryption scheme we transform the value of the digital code stored in the pixel by operating upon it with an assigned digital value. This is acc...