Digital computer having code conversion apparatus for an encrypted program
Patent 4306289 Issued on December 15, 1981. Estimated Expiration Date: 
February 4, 2000. 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.
February 4, 2000. 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 References 3846763 3889242 Microprogram data processing technique and apparatus Microcomputer with code conversion Computer software security system Microprocessor for executing enciphered programs Patent #: 4168396 InventorAssigneeApplicationNo. 06/118003 filed on 02/04/1980US Classes:713/190Computer instruction/address encryptionExaminersPrimary: Zache, Raulfe B.Attorney, Agent or FirmInternational ClassesG06F 21/00 (20060101)G06F 1/00 (20060101) AbstractThe architecture of a conventional digital computer, for example, a microprocessor, is modified by interposing a multiplexer (31), a logic array (32) and a demultiplexer (33) between the instruction register (17) and instruction decoder (18). The logic array "scrambles" the bits in each instruction code; however, if the program to be run is priorly encrypted with this "scrambling" in mind, it will run normally. On the other hand, if the encrypted program is copied, the copied program will not run on an unmodified computer. | |
