An SRAM-based programmable logic device having decompression and decryption circuits between its EPROM nonvolatile programming data storage and its SRAM programming registers is secured against copying of the programming data because a would-be copyist would need to know the compression and encryption used. In a system and method for programming the device, a user station preferably contains a plurality of possible encryptions and a plurality of possible compression schemes. An encryption and compression scheme are selected, preferably at random, by the user or by the programming software in the user station. Data indicating which encryption and compression scheme were chosen are included in the programming data to allow decompression and decryption.