Abstract:
The invention provides techniques for secure messages transmission using a public key system to exchange secret keys. A first entity creates public and private keys by generating a product n of two large, randomly chosen prime numbers, and then generating random matrices {A, C}, in the group GL(r,Zn) with a chosen matrix rank r such that AC is not equal to CA, and then generating a matrix B=CAC, and finding a matrix G that commutes with C. Matrices A, B, G and the integers n and r are then published as the public key and matrix C is then kept as the private key. A second entity then obtains the public key and calculates a secret matrix D that commutes with G, and further calculates the matrices K=DBD and E=DAD. The message to be sent is then encrypted using matrix K as the secret key and then sent to the first entity with matrix E. First entity then retrieves secret matrix K using K=CEC and then decrypts the received encrypted message using the retrieved secret matrix K.
Abstract:
A system and method for identifying whether sample values of pixel samples in a sample region have two or fewer different sample values represented, such as in graphics data representing text images. Identification is performed by hierarchically dividing the samples of the sample region into sample pairs and comparing the sample values of a first sample pair and a second sample pair to determine if two or fewer sample values are represented by the sample values of the first and second sample pairs. Where two or fewer levels are represented by the sample values of the samples, a tally value is generated and the first and second sample values are recorded. The recorded sample values are compared to the sample values of another sample pair to determine if two or fewer values are represented therein. If so, a new tally value is generated and the sample values are recorded. Comparing and recording continues until the remaining sample pairs of the sample region have been compared and a combined tally value indicative of whether two or fewer sample values are represented by the samples of the sample region is produced.
Abstract:
A FIR filter for programmable decimation by powers of two has an input coupled to receive an input signal and an output coupled to the input. The FIR filter uses context registers, where the number of contexts per context register is equal to the maximum desired decimation power m. An output context register coupled to provide the output simultaneously contains all of the decimation output results, the desired decimation result being selected as one of the output contexts. A cascade of timing circuits in response to an initial clock signal and an initial valid signal at one-half the frequency of the initial clock signal provide timing signals for storing the decimation results as separate contexts in each context register. At any time any desired decimation result is available for output.
Abstract:
A method for positioning cursors at a specific point on a displayed waveform uses a cursor to determine the maximum and minimum points on the waveform about a transition portion. For each position of the cursor between the maximum and minimum points an intersection between the cursor and the waveform is computed as a percentage of the difference between the maximum and minimum points. The cursor is then positioned at a point on the transition portion where the percentage is a desired value for the specific point.
Abstract:
A cursor interface for a waveform display provides for movement of a waveform relative to a first cursor. When the first cursor overlies a desired point on the waveform, the cursor is locked to the waveform by transforming the cursor coordinates from display coordinates to waveform coordinates. The waveform may then be moved together with the first cursor relative to a second cursor. When the second cursor overlies another desired point on the waveform, a measurement value is displayed indicating the difference in positions on the waveform of the cursors. The cursors may be centered independently, and when locked to the waveform the result is to correspondingly move the waveform.
Abstract:
A linearity corrector is provided that reduces distortion in a signal processing system, such as an ADC. The linearity corrector provides a first order signal path having distortion components connected to an adder, and a filter product circuit that is also connected to the adder. A method is provided for reducing distortion by calculating a filter product and adding the filter product to a first order signal having a relative delay such that the filter product reduces, or eliminates, the order of distortions corresponding to the order of the filter product.
Abstract:
A method and apparatus for operating a content addressable memory (CAM) and a ternary CAM (TCAM) are described including an encoding circuit for encoding an incoming CAM or TCAM word to produce an encoded CAM or TCAM word such that a one-bit mismatch between a comparand and the incoming CAM or TCAM word results in at least a M-bit mismatch between said encoded CAM or TCAM word and a similarly encoded comparand, a circuit for precharging a match line to a predetermined state before a comparison between the encoded CAM or TCAM word and said similarly encoded comparand and a memory storage location for storing the encoded CAM or TCAM word.
Abstract:
A resampling system and method for producing a resampled destination image from a source image by solving coefficients for a cubic polynomial transition model between first and second adjacent source pixels from the sample values of the first and second samples and approximations of the first and second sample gradients at the first and second samples, respectively. Approximations of the first and second color gradients are based on a multiple of first and second color slopes, such as twice the value of the color slope. The first color slope is calculated from the sample values of a previous pixel and the first sample and the second sample slope is calculated from the sample values of a subsequent sample and the second sample. The resulting gradient approximations and sample values are used in the cubic transition model to calculate an output sample value for rendering a resampled destination image.
Abstract:
A resampling circuit and method where input sample values for samples arranged along a row of a source image are received by a row resampling circuit. The row resampling circuit calculates row output values which are provided to a column resampling circuit that calculates output sample values therefrom. The column resampling circuit includes a shift register that receives the row output values and shifts the row output values through the shift register as the row output samples are calculated. The shift register has a plurality of evenly spaced sample output terminals from which the row output values are sampled by an interpolation circuit for calculation of the output sample values.
Abstract:
An improved FIR filter based upon squaring is used to self-determine a filter constant equal to the sum-of-squares of the filter coefficients. An input signal is forced to zero for T samples, where T is the number of accumulator cells in an accumulator stage, and at the end of such zero samples the output from the filter is latched as the filter constant for use in filtering the normal input signal. The FIR filter may also be placed in a co-processor mode, using a FIFO register between the input of the FIR filter and a processor bus. A CPU on the bus initiates the co-processor mode and loads data into the FIFO. When the FIFO has data the data is read out and input to the FIR filter. The output of the FIR filter is placed on the processor bus. To determine the values of the filter coefficients loaded in the FIR filter, the data loaded by the CPU is an impulse signal having T−1 zero samples before and after an impulse sample, the output for each sample representing one of the filter coefficients.