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US Patent 4525599 - Software protection methods and apparatus
US Patent Issued on June 25, 1985
Estimated Patent Expiration Date:
June 25, 2002Estimated 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.
Estimated Patent Expiration Date:
June 25, 2002Estimated 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.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
| 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 FirmUS Patent References3996449, Operating system authenticatorIssued on: 12/07/1976 Inventor: Attanasio , et al.4120030, Computer software security system Issued on: 10/10/1978 Inventor: Johnstone4168396, Microprocessor for executing enciphered programs Issued on: 09/18/1979 Inventor: Best4183085, Protection of data processing system against unauthorized programs Issued on: 01/08/1980 Inventor: Roberts , et al.4246638, Method and apparatus for controlling usage of a programmable computing machine Issued on: 01/20/1981 Inventor: Thomas4278837, Crypto microprocessor for executing enciphered programs Issued on: 07/14/1981 Inventor: Best4306289, Digital computer having code conversion apparatus for an encrypted program Issued on: 12/15/1981 Inventor: Lumley4319079, Crypto microprocessor using block cipher Issued on: 03/09/1982 Inventor: Best4446519Method and apparatus for providing security for computer software Issued on: 05/01/1984 Inventor: Thomas International ClassesG06F 12/14 (20060101)G06F 21/00 (20060101) G06F 1/00 (20060101) |
