Abstract: A user device is configured for communication with a distributed verification system over a network. The user device generates first and second keys from a master key for a password vault or other credential store, provides the first key to the distributed verification system, encrypts the credential store based at least in part on the second key, and provides the encrypted credential store to the distributed verification system. The credential store is encrypted utilizing the second key and information that is stored in a distributed manner over a plurality of servers of the distributed verification system. For example, encrypting the credential store illustratively comprises generating a ciphertext by encrypting the credential store utilizing the second key, obtaining a third key stored in the distributed manner over the servers, and encrypting the ciphertext utilizing the third key to generate the encrypted credential store that is provided to the distributed verification system.

Abstract: An improved technique for verifying a license of a software product includes performing license checks with a server and passing to the server, as part of the license checks, a drifting digital code. The drifting code forms a particular drift pattern, which the server detects over the course of multiple license checks. The drift pattern is typically unique, or relatively unique, to the machine on which the software product is run, and changes in a manner that is difficult for malicious users to replicate on other machines. If a second copy of the software is installed, e.g., if the software is pirated, the second copy will produce a drifting code that has its own drift pattern, which differs from that of the initial copy. The server detects the duplicate copy by observing a divergence in the codes it receives during license checks.

Abstract: Access control systems are provided that mediate access to derivatives of sensitive data. A method is provided for processing a data request from a client, the data request comprising a client identifier and an indication of the intended use of the data, by receiving the data request from the client; providing the client identifier and indicated use to an access manager, wherein the access manager assesses a risk of providing access to the data for the indicated use; if the access manager grants access for the indicated use, receiving one or more keys with corresponding computing restrictions from the access manager; computing a result; and providing the result to the client, wherein the provided result comprises the derivative of sensitive data. The access manager grants the access for the indicated use, for example, based on a risk score.

Abstract: A detection system includes a receiver configured to generate a receiver signal representative of detected electromagnetic energy, and an analog-to-digital converter (ADC) configured to generate a plurality of signal samples based on the receiver signal. The detection system also includes a detection module configured to identify a plurality of sample offsets for the signal samples, and execute a plurality of autocorrelation functions on the signal samples to provide an output of each of the autocorrelation functions, wherein each autocorrelation function is executed on at least a portion of the signal samples identified by a sample offset of the plurality of sample offsets. The detection module is also configured to compute a sum of the autocorrelation function outputs, normalize the sum of the autocorrelation function outputs, and determine whether a signal of interest is present within the electromagnetic energy based on the normalized sum.

Abstract: Embodiments of the invention provide systems and methods for systems and methods for adaptively canceling interfering signals generated by a transmission antenna. Under one aspect, a system includes: an auxiliary antenna co-located with the main antenna, the auxiliary antenna configured to transmit an auxiliary signal to the victim antenna; a sensing antenna located on a line-of-sight path between the transmission antenna and the victim antenna, the sensing antenna configured to receive a composite of the interference and the auxiliary signal, and to output a first signal based on the received composite; a controller comprising an input coupled to the sensing antenna and configured to receive the first signal, the controller being configured to adjust at least one of an amplitude, a phase, a polarization, and a frequency characteristic of the auxiliary signal based on the first signal so as to reduce the composite of the interference and the auxiliary signal received by the sensing antenna.

Abstract: Systems and methods for increasing communications bandwidth using non-orthogonal polarizations are provided herein. Under one aspect, a method of transmitting M independent signals, where M is at least 3, includes receiving the M signals from respective sources; at a transmitter polarization module, obtaining first and second linear combinations of the M signals; providing the first and second linear combinations to first and second input ports of a transmitter antenna; and transmitting with the transmitter antenna the first linear combination at a first polarization and the second linear combination at a second polarization orthogonal to the first polarization. The method may further include receiving at a receiver antenna the first linear combination at the first polarization, and the second linear combination at the second polarization; obtaining at receiver circuitry the M signals based on the received first and second linear combinations; and outputting the M signals on respective output ports.

Abstract: Systems and methods for increasing communications bandwidth using non-orthogonal polarizations are provided herein. Under one aspect, a method of transmitting M independent signals, where M is at least 3, includes receiving the M signals from respective sources; at a transmitter polarization module, obtaining first and second linear combinations of the M signals; providing the first and second linear combinations to first and second input ports of a transmitter antenna; and transmitting with the transmitter antenna the first linear combination at a first polarization and the second linear combination at a second polarization orthogonal to the first polarization. The method may further include receiving at a receiver antenna the first linear combination at the first polarization, and the second linear combination at the second polarization; obtaining at receiver circuitry the M signals based on the received first and second linear combinations; and outputting the M signals on respective output ports.

Abstract: Systems and methods for increasing communication throughput by superimposing multiple signal components in the same bandwidth are disclosed. Cochannel interference is reduced by using signal separation algorithms. The signal separation algorithms may use both a priori information about the superimposed signals and measured channel parameters. In addition, error correction encoding and interleaving may be used to reduce signal power and obviate the need for ideal signal separation.

Abstract: Systems and methods for increasing communications bandwidth using non-orthogonal polarizations are provided herein. Under one aspect, a method of transmitting M independent signals, where M is at least 3, includes receiving the M signals from respective sources; at a transmitter polarization module, obtaining first and second linear combinations of the M signals; providing the first and second linear combinations to first and second input ports of a transmitter antenna; and transmitting with the transmitter antenna the first linear combination at a first polarization and the second linear combination at a second polarization orthogonal to the first polarization. The method may further include receiving at a receiver antenna the first linear combination at the first polarization, and the second linear combination at the second polarization; obtaining at receiver circuitry the M signals based on the received first and second linear combinations; and outputting the M signals on respective output ports.

Abstract: Systems and methods for increasing communication throughput by superimposing multiple signal components in the same bandwidth are disclosed. Cochannel interference is reduced by using signal separation algorithms. The signal separation algorithms may use both a priori information about the superimposed signals and measured channel parameters. In addition, error correction encoding and interleaving may be used to reduce signal power and obviate the need for ideal signal separation.

Abstract: Embodiments of the invention provide systems and methods for systems and methods for adaptively canceling interfering signals generated by a transmission antenna. Under one aspect, a system includes: an auxiliary antenna co-located with the main antenna, the auxiliary antenna configured to transmit an auxiliary signal to the victim antenna; a sensing antenna located on a line-of-sight path between the transmission antenna and the victim antenna, the sensing antenna configured to receive a composite of the interference and the auxiliary signal, and to output a first signal based on the received composite; a controller comprising an input coupled to the sensing antenna and configured to receive the first signal, the controller being configured to adjust at least one of an amplitude, a phase, a polarization, and a frequency characteristic of the auxiliary signal based on the first signal so as to reduce the composite of the interference and the auxiliary signal received by the sensing antenna.

Abstract: A method for acquiring Global Positioning System (GPS) code includes describing GPS code as a Low Density Parity Check (LDPC) code, and decoding the LDPC code to achieve acquisition by directly solving for the correct code phase.

Abstract: An apparatus includes antenna elements configured to receive a signal including pseudo-random code, and electronics configured to use the pseudo-random code to determine time delays of signals incident upon the antenna elements and to compensate the signals to coherently combine the antenna elements.

Abstract: An apparatus includes antenna elements configured to receive a signal including pseudo-random code, and electronics configured to use the pseudo-random code to determine time delays of signals incident upon the antenna elements and to compensate the signals to coherently combine the antenna elements.

Abstract: A method for acquiring Global Positioning System (GPS) code includes describing GPS code as a Low Density Parity Check (LDPC) code, and decoding the LDPC code to achieve acquisition by directly solving for the correct code phase.

Abstract: A convolutional despreading method takes advantage of the algebraic structure of the spreading code and applies convolutional type decoding to received signal chip symbols to rapidly estimate code phase, preferably used for rapid acquisition of direct sequence spread spectrum signals. Modeled reduced-state structures having branchword transitions are used to reduce metric computations. The reduced state structures and algebraic structures provide additive constraints for modifying convolutional sequential metric searching for improved speed of code phase determination. The convolution despreading method preferably uses a modified convolutional sequential search algorithm, such as, a modified Fano Tree convolutional sequential search, or, a modified Viterbi trellis convolutional sequential search. The method can also directly determine a modulated data stream, when present, to provide demodulated data without necessarily performing conventional cross correlation despreading.

Abstract: An adaptive transmitting antenna includes an array of antenna elements having respective weighing coefficients to respectively transmit components of a transmit signal which reduces locally reflective multipath signals received by the transmitting antenna to sample respective reflective components which are summed and cross correlated to a time delayed transmit signal to produce a correlated output indicative of the reflective signal strength. The correlated output is minimized by adjusting the weighing coefficients so that the transmit signal has reduced multipath distortions. The adaptive technique is well suited for mobile telephone transmitters moving about objects tending to reflect and distort transmitted signals.

Abstract: An adaptive receiving antenna reduces interference arriving in the main beam of the antenna by redirecting the antenna beam away from the interference source. The receiving antenna projects the main beam to receive desired source signals from a source direction and may receive interfering signals from the interfering source. The antenna system measures the strength of the source signal and interference signal for controlling the direction of the main beam to marginally decrease the received desired source signal while substantially decreasing the received interfering signal to increase the desired source signal to interfering signal ratio so that the desired source signal can be received in the presence of interference.