Abstract: A wireless location system for tracking and locating a wireless tag in a structure having defined areas that provides for differentiation between the defined areas has at least one ultrasonic transmitter positioned in each of the defined areas for transmitting an ultrasonic signal having area identification and/or transmitter ID information. A plurality of wireless tags are provided wherein each wireless tag transmits a last area identifying and/or transmitter ID information received and accepted by the wireless tag in a tag message. A plurality of location receivers is installed in the structure for receiving the tag message and for reporting the received message from the tag along with optional measured parameters to a common server. The common server determines the location of each wireless tags in the structure using the defined area or transmitter ID as reported by each wireless tag.

Abstract: A method and apparatus for repeated communication sessions between a sender (e.g., RFID tag) and a receiver (RFID reader) that employs a proactive information security scheme is based on the assumption that the information exchanged during at least one of every n successive communication sessions is not exposed to an adversary. The sender and the receiver maintain a vector of n entries that is repeatedly refreshed by pairwise XORING entries, with a new vector of n entries that is randomly chosen by the sender and sent to the receiver as a part of each communication session. Also, a computational secure scheme based on the information secure scheme is employed to ensure that even in the case that the adversary listens to all the information exchanges, the communication between the sender and the receiver is secure. In particular, the scheme can be used in the domain of remote controls (e.g., for cars).

Abstract: A wireless location system has at least one wireless tag to be located by the wireless location system, wherein the at least one wireless tag transmits two wireless signals having a known time relationship and having different bandwidths. A plurality of receivers is provided wherein a first receiver receives and processes a first of the two wireless signals and estimates a time to arrive (TOA) of the first wireless signal, and a second receiver receives and processes a second of the two wireless signals and estimates a TOA of the second wireless signal at the second transceiver. The plurality of receivers is time synchronized based on a common timing signal. A location server is coupled to each of the plurality of receivers. The location server receives the TOA of the first wireless signal from the first receiver and the TOA of the second wireless signal from the second receiver.

Abstract: A method for designing a high performance, small antenna that is matched to a required output impedance, does not require filtering, is simple and inexpensive to manufacture, and is easily integrable with an RF power amplifier- with minimum cost, minimum external components and minimum energy losses. The method includes finding a singular point (102) in the impedance vs. antenna geometrical dimension/wavelength ratio graph, the singular point (102) exhibiting a high very high positive reactance, setting the antenna geometry to match this point, and canceling the very high positive reactance (high inductance) resulting from this match by adding to the antenna a very small capacitance, preferably provided by at least one gap capacitor (202) The antenna is preferably a loop antenna (200), and both the antenna and the gap capacitor (202) (204) are preferably implemented by printing methods on printed circuit board or ceramic substrates. The antenna (200) may also be implemented in non-differential designs.

Abstract: A method for designing a high performance, small antenna that is matched to a required output impedance, does not require filtering, is simple and inexpensive to manufacture, and is easily integrable with an RF power amplifier- with minimum cost, minimum external components and minimum energy losses. The method includes finding a singular point (102) in the impedance vs. antenna geometrical dimension/wavelength ratio graph, the singular point (102) exhibiting a high very high positive reactance, setting the antenna geometry to match this point, and canceling the very high positive reactance (high inductance) resulting from this match by adding to the antenna a very small capacitance, preferably provided by at least one gap capacitor (202) The antenna is preferably a loop antenna (200), and both the antenna and the gap capacitor (202) (204) are preferably implemented by printing methods on printed circuit board or ceramic substrates. The antenna (200) may also be implemented in non-differential designs.

Abstract: A method and apparatus for factoring large numbers which utilizes an optoelectronic device that has a wafer at one end that contains a plurality of LEDs. Each LED is associated with at least one period pj and at least one delay dj. A clock drives the plurality of LEDs responsive to clock cycles to flash for one clock cycle at times described by the processing pj•r+dl for r≧0. The light intensity flashed by the LEDs is controlled by a filter to be proportional to log2 (pj), and a photodetector positioned at the other end of the cylinder collects the light flashed by the LEDs.

Abstract: A method and apparatus for protecting smart cards against simple and differential power attacks when they are inserted into card readers controlled by other entities. The technique is particularly useful in financial applications such as ATM cards, credit cards, and electronic wallets, in which cards have to be inserted into card readers which may be specifically manufactured or modified to perform undetectable measurements of the power supplied to the card during its normal operation. The basic technique is to use two capacitors embedded in the smart card in such a way that at any given time one of them is charged by the external power supply and the other one is discharged by powering the smart card chip. The roles of the two capacitors alternate rapidly, and the power supply is detached from the smart card chip in the sense that external power measurements do not reveal information about its internal operations.

Abstract: A well-known technique to discourage piracy of digital objects is to fingerprint the version each customer receives. The invention provides a novel way of fingerprinting the decryption functions given by broadcasters to their customers (usually in the form of smart cards). The main difficulty is to ensure that all the algorithms provided by the broadcaster implement the same decryption function, and yet to make it computationally difficult for a pirate who obtains a large number of such implementations to find even one fundamentally different implementation which is not traceable to a particular customer.

Abstract: Improved methods and apparatus are provided for protecting public key schemes based on modular exponentiation (including RSA and Diffie-Hellman) from indirect cryptanalytic techniques such as timing and fault attacks. Known methods for making the implementation of number-theoretic schemes resistant to such attacks typically double their running time, whereas the novel methods and apparatus described in this patent add only negligible overhead. This improvement is particularly significant in smart card and software-based implementations, in which the modular exponentiation operation is quite slow, and doubling its time may be an unacceptable solution.

Abstract: Memory efficient variants of public key encryption and identification schemes for smart card applications with severely limited RAM without using dedicated coprocessors. The variants replace the memory-intensive modular multiplication operation z=x*y (mod n) by a new randomized multiplication operation z'=x*y+r*n, where r is a randomly chosen integer in a suitable range 0,b!, and a double convolution process to compute z' is used. Method and apparatus are described.

Abstract: A method and device for protecting visual information against unauthorized access and modification using a printed cryptographic watermark includes printing a first array of shapes on a first sheet of material to be protected and printing a second array of shapes on a second sheet of material, which is transparent so as to form a developer for developing a watermark encoded in a combination of the first and second arrays of shapes. The watermark is encoded by preparing each array using black and white pixels. Each pixel, which may be a square, rectangle, circle, hexagon or other shape, is split into first and second collections of subpixels, the first collection of subpixels appearing in the first array of shapes and the second collection of subpixels appearing in the second array of shapes.

Abstract: A birational permutation is a function f which is a one-to-one and onto mapping over k-tuples of numbers, where both f and its inverse are low degree rational functions. This patent describes a novel digital signature scheme which is based on a new class of birational permutations which have small keys and require few arithmetic operations.

Abstract: A new type of digital signature scheme whose security is based on the difficulty of solving systems of k polynomial equations in m unknowns modulo a composite n is proposed. The scheme uses a simple technique (called sequential linearization) for embedding trapdoors into such systems of equations.

Abstract: A method of encrypting a video signal employing a pseudorandom Space Filling Curve having a highly irregular scanning pattern for scanning the pixel addresses of a video picture stored in a frame buffer. The method is used with a video scrambler/descrambler device and is characterized by a much higher cryptographic strength than existing techniques, which is not subject to simple correlation attacks by comparing and matching of line portions. In addition, the method features a reduction in the video signal bandwidth for typical pictures.

Abstract: A method and apparatus are disclosed and claimed which enable an entity to generate proofs of identity and signatures of messages that everyone can verify but no one can forge. Compared to other schemes of this type (such as the RSA), the Fiat-Shamir scheme is faster by one to two orders of magnitude. In the present invention disclosed and claimed in this patent application, two improved variants of the Fiat-Shamir scheme are described which are even faster. One variant uses small public values to optimize the vertification procedure, and the other variant uses particular secret values to optimize the generation procedure.

Abstract: A method and apparatus for identification of a prover to a verifier in which the prover demonstrates his knowledge of a secret permutation .pi. such that V.sub..pi. .epsilon. K(A) for publicly known A and V where all the arithmetic operations are carried out modulo p. The actual proof does not reveal any knowledge of .pi., and thus it cannot be misused by dishonest verifiers or eavesdroppers to later misrepresent themselves as the prover. The new scheme is much faster than the RSA and Fiat-Shamir identification schemes.

Abstract: A method of encrypting a video signal employing a pseudo-random Space Filling Curve having a highly irregular scanning pattern for scanning the pixel addresses of a video picture stored in a frame buffer. The method is used with a video scrambler/descrambler device and is characterized by a much higher cryptographic strength than existing techniques, which is not subject to simple correlation attacks by comparing and matching of line portions. In addition, the method features a reduction in the video signal bandwidth for typical pictures.

Abstract: A method and apparatus for simple identification and signature which enable any user to prove his identity and the authenticity of his messages to any other user. The method and apparatus are provably secure against any known or chosen message attack if factoring is difficult, and require only 1% to 4% of the number of modular multiplications previously required. The simplicity, security and speed of the method and apparatus derive from microprocessor-based devices which may be incorporated into smart cards, personal computers, passports, and remote control systems.

Abstract: Storage media such as digital optical disks, PROMS, and paper tape consist of a number of bit positions which initially contain a "zero" and which can later be irreversibly overwritten with a "one". An apparatus and method provide for rewriting in such "non-erasable memories" for expanding their capacity by allowing the non-erasable memory to be rewritten one or more time.

Abstract: A cryptographic communications system and method. The system includes a communications channel coupled to at least one terminal having an encoding device and to at least one terminal having a decoding device. A message-to-be-transferred is enciphered to ciphertext at the encoding terminal by first encoding the message as a number M in a predetermined set, and then raising that number to a first predetermined power (associated with the intended receiver) and finally computing the remainder, or residue, C, when the exponentiated number is divided by the product of two predetermined prime numbers (associated with the intended receiver). The residue C is the ciphertext.