1. A method of operating a computer to provide access to a stored secret, the stored secret being stored on a non-transitory computer-readable medium, the method comprising: as part of an initialization process, (1) calculating and storing a signature of a trusted library file containing a trusted function usable to generate stable system values (SSVs) of the computer, and (2) calculating and storing a first value based on an initial set of SSVs generated by the trusted function, the first value to be used by an access control function to enable the access to the stored secret; and as part of a use process, (1) calculating a signature of a loaded library file containing an untrusted function used to generate a current set of SSVs, (2) comparing the respective signatures of the trusted library file and the loaded library file to generate a comparison result signal, and (3) only when the comparison result signal indicates a successful comparison, permitting an access-granting output of the access control function to enable the access to the stored secret.