System for preventing software piracy employing multi- encrypted keys and single decryption circuit modules

Abstract From the Canadian patent

A system (FIG. 1) which enables a protected program (e.g. prog. A, prog. B. ...) to run only a selected plurality of computers (e.g. computer 10) including a respective unique key Ki for each computer of the plurality, the key being triple encrypted (14a) in the form EFKEFKKi. A respective module (16) is coupled (via 17) to each computer (10) of the plurality. A checker program (15) in each computer responds to a request (from station 11) to use the protected program by performing a single decryption procedure E?? on the triple encrypted key (step 22 of FIG. 2) and sends the result (step 23) to the module (16) as a message. The module (16) performs a single decryption procedure E?? on the …