A method of authenticating a board, assembly or system including one or more devices associated therewith, each of the one or more devices being configured with: a scan or boundary scan component adapted to shift in and shift out test scans of the device, a unique code adapted to uniquely identify the device, an interrogation code component adapted to interact with interrogation information applied to the device, a hidden seed element which is of unique value per device of a given type wherein the hidden seed is inaccessible via test/scan procedures and initially known only to an IC fabricator that fabricated the device, and a signature encryption component that provides an output signature code that is unique to the device, for given interrogation information, the output signature code also being a function of the hidden seed and the interrogation information, the method comprising: prior to authentication, providing to a trusted authenticator the hidden seed, the unique code and an indication of a mounted position of each of the one or more devices; providing a unique interrogation information for each authentication; during each authentication, the trusted authenticator and the one or more devices each determining the output signature code based upon the hidden seed for each of the one or more devices and the unique interrogation information; during each authentication, using the scan or boundary scan component for each of the one or more devices to determine the unique code and the indication of a mounted position of the one or more devices, and providing the results from the scan or boundary scan component to the trusted authenticator; during each authentication, the trusted authenticator comparing the unique code and the indication of a mounted position provided prior to authentication with the unique code and the indication of a mounted position provided during each authentication; during each authentication, the trusted authenticator comparing the output signature code determined by the trusted authenticator with the output signature code determined by the one or more devices; and employing the comparisons made during each authentication to authenticate the board, assembly or system. a scan or boundary scan component adapted to shift in and shift out test scans of the device, a unique code adapted to uniquely identify the device, an interrogation code component adapted to interact with interrogation information applied to the device, a hidden seed element which is of unique value per device of a given type wherein the hidden seed is inaccessible via test/scan procedures and initially known only to an IC fabricator that fabricated the device, and a signature encryption component that provides an output signature code that is unique to the device, for given interrogation information, the output signature code also being a function of the hidden seed and the interrogation information, the method comprising: prior to authentication, providing to a trusted authenticator the hidden seed, the unique code and an indication of a mounted position of each of the one or more devices; prior to authentication, providing to a trusted authenticator the hidden seed, the unique code and an indication of a mounted position of each of the one or more devices; providing a unique interrogation information for each authentication; during each authentication, the trusted authenticator and the one or more devices each determining the output signature code based upon the hidden seed for each of the one or more devices and the unique interrogation information; during each authentication, using the scan or boundary scan component for each of the one or more devices to determine the unique code and the indication of a mounted position of the one or more devices, and providing the results from the scan or boundary scan component to the trusted authenticator; during each authentication, the trusted authenticator comparing the unique code and the indication of a mounted position provided prior to authentication with the unique code and the indication of a mounted position provided during each authentication; during each authentication, the trusted authenticator comparing the output signature code determined by the trusted authenticator with the output signature code determined by the one or more devices; and employing the comparisons made during each authentication to authenticate the board, assembly or system.