摘要:
A trusted display device (1) for, upon being superimposed on an untrusted display (2), reconstructing a graphical message, said device comprising a display screen (1a) having a plurality of independently addressable pixels. A plurality of sensors (1c) are associated with at least a subset of the pixels of said display screen (1a) and arranged such that they, when the displays (1, 2) are superimposed, are able to detect optically encoded information presented by an underlying pixel of the untrusted display (2) and adapt the activation of its pixels based on said information sensed.
摘要:
A method of verifying the authenticity of an image (1) rendered on a display screen (10) involves using a graphical representation of an authentication code (2) associated with the image. The graphical representation of the authentication code is also rendered on the display screen, while optional guide marks (3) may also be displayed. Both the image (1) and the associated authentication code (2) are read using a scanner (20), preferably a handheld linear scanner. The scanner calculates an authentication code based upon the image and compares the calculated authentication code with the authentication code read from the display.
摘要:
A method of and a device (501) for reconstructing a graphical message (520) using visual cryptography. Cells (303, 304) in a first liquid crystal display (701) are activated if a bit in a message sequence represents ‘1’, and not activated if said bit represents ‘0’. Cells (303, 304) in a second liquid crystal display (511) are activated if a bit in a key sequence represents ‘0’, and not activated if said bit represents ‘1’. The first and second displays (701, 511) are then superimposed so as to visually reconstruct the graphical message (520). Preferably a portion of a polarization filter (305) in an area of the first liquid crystal display (701), and a corresponding portion of a polarization filter (302) in an area of the second liquid crystal display (511) have been omitted to allow superimposition of the first and second liquid crystal displays (701, 511) at said areas.
摘要:
An image decryption device (1) comprises a screen (10) on which a decrypted image may be visible. The decrypted image may the combination of two partial images, an encrypted image (A) displayed by a display device (2) and a key image or decrypting image (B) superimposed on the encrypted image by the decryption device. To properly align the encrypted image (A) and the key image (B), the decryption device is provided with sensors (11) capable of sensing the position of the decryption device relative to the display device. Corresponding alignment images (22) may be arranged around the screen (20 of the display device, or may be part of the encrypted image. Manual or automatic alignment may be provided.
摘要:
A method of encoding a graphical message (220, 221) based on a key sequence as an encoded sequence of information units. For each pixel of the message, said pixel having a normalized intensity I, a total rotation α which results in a liquid crystal display in a pixel with substantially the intensity I is determined. The key sequence contains arbitrary rotations. The difference between the total rotation a and a corresponding rotation in the key sequence is output as an element of the encoded sequence. A device (201) presents pixels with rotations indicated by the encoded sequence on a first display (701) and pixels with rotations indicated by the key sequence on a second display (211). Superimposing the two displays reveals the graphical message. The method can be repeated for red, green and blue intensities of color pixels, allowing colored graphical messages to be encoded and reconstructed.
摘要:
A method of and server (100) for enabling composition of a message at a remote terminal (101). The method comprises generating an image comprising a plurality of symbols representing input means, the symbols having an associated particular visual characteristic which is mutually different for at least two of the symbols, transmitting the image for display on the remote terminal (101), receiving a sequence of coordinates from the remote terminal (101), reconstructing the message as a sequence of input means represented by the symbols comprised in the image at the received coordinates, constructing an authentication code as a sequence of visual characteristics associated with the symbols comprised in the image at the received coordinates, and accepting the message as authentic if the authentication code matches a predetermined sequence of visual characteristics.
摘要:
A device (1) for decrypting encrypted images comprises an array of sensor elements (11) for sensing a first image, for example an encrypted image, and an array of display elements (12) for displaying a second image, for example a decrypted image. At least some display elements comprise integrated sensor elements, thus reducing the number of parts of the device. The integrated display/sensor elements (13) may be constituted by polymeric LED elements. The sensor function of the integrated elements may also be used for positioning the device relative to a terminal, and/or for checking a biometric feature of the user.
摘要:
A method of generating a common secret between a first party and a second party, preferably devices (101-105) in a home network (100) that operate in accordance with a Digital Rights Management (DRM) framework. The devices calculate the common secret by evaluating the product of two polynomials P(x, y) and Q(x, z) using parameters previously distributed by a Trusted Third Party (TTP) and parameters obtained from the other party. Preferably the parties subsequently verify that the other party has generated the same secret using a zero-knowledge protocol or a commitment-based protocol. The method is particularly suitable for very low power devices such as Chip-In-Disc type devices.
摘要:
An authentication system 600 includes optical authentication devices 620, 630, 640. Each optical authentication device includes an optical layer 622, 632, 642. The optical layer includes a representation of a first image visually encrypted under control of an encryption key. The encrypted first image uniquely identifies the respective authentication device. An inspection device 610 decrypts the optical layer of the optical authentication device under control of the encryption key and visualizes the first image to enable verification of the unique identification of the authentication device.
摘要:
The present invention relates to a method and a system of verifying the identity of an individual by employing biometric data associated with the individual while providing privacy of said biometric data. A basic idea of the present invention is to represent a biometric data set XFP with a feature vector. A number of sets XFP1, XFP2, . . . XFPm of biometric data and hence a corresponding number of feature vectors is derived, and quantized feature vectors X1, X2, . . . , Xm are created. Then, noise robustness of quantized feature components is tested. A set of reliable quantized feature components is formed, from which a subset of reliable quantized feature components is randomly selected. A first set W1 of helper data is created from the subset of selected reliable quantized components. The helper data W1 is subsequently used in a verification phase to verify the identity of the individual.