Abstract: A method and system for authenticating and enabling activation of a configuration used for controlling a product, where the configuration is implemented as safety critical logic functions in programmable logic blocks of a Field Programmable Gate Array, FPGA, having a volatile configuration-memory. The configuration is loaded into the volatile configuration-memory of the FPGA via an external interface input of the FPGA. The content of the configuration-memory of the FPGA is read via an interface of the FPGA. This is done immediately after completed loading of the configuration into the memory of the FPGA. A Cyclic Redundancy Check, CRC, checksum of the read content of the configuration-memory is computed in an CRC checksum generator, and a resulting generated CRC checksum value is compared with an externally stored valid CRC checksum value of the expected FPGA configuration.