Abstract: A decryption scheme is provided for encrypted configuration bitstreams in a programmable logic device. One embodiment includes circuitry for altering a decryption key for a plurality of encrypted bitstream portions, thereby providing a high level of security of the circuit layout embodied in the bitstream.
Abstract: A method of decrypting data comprising encrypting bit-wise data, using a first plural bit mask, modulating the data into symbol format, and transmitting the symbol format data to a receiving apparatus, in a receiving apparatus, rotating a current received symbol sample by an amount equal to one of (i) its difference in phase from an immediately preceding received symbol sample toward the phase of the immediately preceding received symbol sample phase, and (ii) by an amount equal to estimated carrier phase towards zero phase, generating a second bit mask subset derived from values of the first bit mask, comprising plural bits for each symbol, reflecting the rotated symbol by a phase defined by the plural bits to form a symbol which is devoid of encryption, and providing the symbol devoid of encryption to a soft-decision decoder.
Abstract: The present invention provides a cryptosystem for encrypting an original image or voice file by using a camouflaging image or voice file. Each of the original and camouflaging files comprises a plurality of basic units arranged according to a predetermined sequence. The cryptosystem comprises a memory for storing the original and camouflaging files and programs, a processor for executing the programs stored in the memory, and an encrypting program stored in the memory for encrypting the original file by using the camouflaging file.