Software protection methods and apparatus
June 25, 2002. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesOperating system authenticator Computer software security system Microprocessor for executing enciphered programs Protection of data processing system against unauthorized programs Method and apparatus for controlling usage of a programmable computing machine Crypto microprocessor for executing enciphered programs Digital computer having code conversion apparatus for an encrypted program Crypto microprocessor using block cipher Method and apparatus for providing security for computer software Patent #: 4446519 InventorsAssigneeApplicationNo. 06/380771 filed on 05/21/1982US Classes:713/190, Computer instruction/address encryption273/460, Electric705/51, Usage protection of distributed data files713/193By stored data protectionExaminersPrimary: Cangialosi, SalvatoreAttorney, Agent or FirmInternational ClassesG06F 12/14 (20060101)G06F 21/00 (20060101) G06F 1/00 (20060101) AbstractMethods and apparatus are disclosed for inhibiting the unauthorized copying of ROM-resident computer software or the like, for example, the audio-visual display of an electronic video game. A protection circuit including encryption/decryption means is coupled between the microprocessor and the ROM-memory and is operable in a first mode to properly encrypt/decrypt the program information according to a first algorithm and in a second mode to prevent proper encryption/decryption. The address-data buses are monitored by the protection circuit to detect an invalid program event, such as may occur when a microprocessor emulator is used to attempt an unauthorized copying or "dumping" of the program information. Upon detection of the invalid program event or "trap condition", the protection circuit switches to its second operating mode thereby to prevent copying of the decrypted program information.Other References
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