The present disclosure relates to a device and method for processing masked binary data values, comprising extracting and inserting a first part of a first masked binary data value in a second masked binary data value, in which the first and second masked binary data values stay masked throughout all of the processing.

A secure digital communications method is provided in which a Certificate Authority generates an improved RSA key pair having a modulus, a public key exponent, a public key, and a private key. The public key exponent can contain descriptive attributes and a digital signature. The digital signature can be responsive to the descriptive attributes and the modulus. A secure session can be established between a first system and a second system, within a secure digital communication protocol. The second system can verify the digital signature to authenticate the public key.

The secret calculation system comprises three secret calculation apparatuses. An i.sup.th secret calculation apparatus (i=1, 2, 3) comprises a holder that holds (S[i], T[i]) and (S[i], T[i]) as distributed values of an n-bit number W and an n-bit W (n is any natural number), respectively; a first multiplicator that derives a logical conjunction of S[i] and S[i]; a second multiplicator that derives a logical conjunction of T[i] and T[i]; and a first subtractor that derives a difference between the logical conjunction derived by the first multiplicator and the logical conjunction derived by the second multiplicator.

Methods and decompression units for decompressing data from a compressed block of image data, the compressed block of image data representing a block of image data comprising a plurality of image element values, the image element values being divisible into at least a first value and a second value such that the block of image data comprises a two-dimensional block of first values. The method comprises: analysing a header of the compressed block of image data to identify (i) a location in a body of the compressed block of image data of a fixed-length parameter that corresponds to a first desired value in the two-dimensional block of first values, and (ii) common base information for the first desired value, the common base information being common to a first set of values comprising all of the two-dimensional block of first values or a portion of the two-dimensional block of first values that includes the first desired value; retrieving the fixed-length parameter that corresponds to the first desired value from the identified location in the body of the compressed block of image data; and generating the first desired value from the common base information and the fixed-length parameter.

A method and decompression unit for performing decompression to determine image element values from compressed data representing a block of image element values each comprising one or more data values relating to a respective one or more channels. An indication of an origin value for each of the channels is read from the compressed data. For each of the channels, an indication of a first number of bits for representing difference values between the data values and the origin value for the channel is read from the compressed data. For each of the one or more channels, a second number of bits is obtained, wherein representations of the difference values for each of the channels are included in the compressed data using the second number of bits for that channel. The obtained second numbers of bits for the respective channels are used to read the representations of the difference values for the image element values being decompressed from the compressed data. Based on the representations of the difference values read from the compressed data, for each of the channels and for each of the image element values being decompressed, a difference value is determined in accordance with the first number of bits for the channel. For each of the one or more channels, the data value relating to the channel for each of the image element values being decompressed is determined using: (i) the origin value for the channel, and (ii) the determined difference value for the channel for the image element value.

A method and compression unit for compressing a block of image data to satisfy a target level of compression, wherein the block of image data comprises a plurality of image element values, each image element value comprising one or more data values relating to a respective channel. For each of the channels: (i) an origin value for the channel for the block is determined, (ii) difference values are determined representing differences between the data values and the determined origin value for the channel for the block, and (iii) a first number of bits for losslessly representing a maximum difference value of the difference values for the channel for the block is determined. The determined first number of bits for each of the channels is used to determine a respective second number of bits for each of the channels, the second number of bits being determined such that representing each of the difference values for the channels with the respective second number of bits satisfies the target level of compression for compressing the block of image data. Compressed data is formed, having for each of the one or more channels an indication of the determined origin value for the channel, an indication of the determined first number of bits for the channel, and representations of the determined difference values for the channel, wherein each of the representations of the determined difference values for the channel uses the determined second number of bits for the channel, such that the target level of compression is satisfied.

Methods and compression units for compressing a block of image data, the block of image data comprising a plurality of image element values, the image element values being divisible into at least a first value and a second value such that the block of image data comprises a two-dimensional block of first values, the method comprising: compressing a first data set comprising all or a portion of the two-dimensional block of first values in accordance with a first fixed-length compression algorithm to generate a first compressed block by: identifying common base information for the first data set; and identifying a fixed-length parameter for each first value in the first data set, the fixed-length parameter being zero, one or more than one bits in length; and forming a compressed block for the block of image data based on the first compressed block.

A system performs logic simulation of a circuit design specified using a hardware description language such as Verilog. The system performs constraint solving based on an expression specified in the specification of the circuit design. The system identifies required bits for each variable in the expression. The number of required bits is less than the number of bits specified in the variable declaration. The system performs bit-level constraint solving by performing a bit operation on the set of required bits and a simplified processing of the remaining bits of the variable. Since the original circuit design is preserved with the original bit-widths for simulation, those required bits are used on the fly internally during constraint solving. Furthermore, dynamic bit reductions on arithmetic operations are performed on the fly. The system improves computational efficiency by restricting bit operations to fewer bits of variables and operators of the expression.

This disclosure relates to data encryption and decryption. In one aspect, a method includes receiving, by a second peer end computing device, first data from a first peer end computing device. The second end computing device generates a random term based on a result range pre-agreed upon with the first peer end computing device. The result range includes a minimum result value and a maximum result value. The random term is a product of a random number and an agreed upon constant. The agreed upon constant is greater than a difference between the maximum result value and the minimum result value. The second peer end computing device performs a homomorphic operation based on the first data, local private second data, and the random term to obtain an encryption result. The second peer end computing device returns the encryption result to the first peer end computing device.

A secure digital communications method is provided in which a Certificate Authority generates an improved RSA key pair having a modulus, a public key exponent, a public key, and a private key. The public key exponent can contain descriptive attributes and a digital signature. The digital signature can be responsive to the descriptive attributes and the modulus. A secure session can be established between a first system and a second system, within a secure digital communication protocol. The second system can verify the digital signature to authenticate the public key.