Digital computer system for executing encrypted programs
July 11, 2006. 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 ReferencesMethod and apparatus for controlling usage of a programmable computing machine Crypto microprocessor for executing enciphered programs Simple and effective public-key cryptosystem Digital computer having code conversion apparatus for an encrypted program Cryptographic decoder for computer programs Software security method using partial fabrication of proprietary control word decoders and microinstruction memories Software protection methods and apparatus Split-cycle cache system with SCU controlled cache clearing during cache store access period Computer software protection system User authentication system employing encryption functions Patent #: 4590470 InventorAssigneeApplicationNo. 06/579089 filed on 02/10/1984US Classes:713/190Computer instruction/address encryptionExaminersPrimary: Buczinski, Stephen C.Assistant: Gregory, Bernarr E. Attorney, Agent or FirmInternational ClassesG06F 12/08 (20060101)G06F 21/00 (20060101) G06F 1/00 (20060101) AbstractA digital computer system adapted for executing a set of instructions including at least one encrypted instruction. The system includes a main memory for storing the instructions, a cache memory for storing selected instructions with a relatively fast access time, a selectively operable decryption system for decrypting selected encrypted instructions from the main memory, and a central processing unit. The system is adapted so that the program stored in the main memory may be executed by the central processing unit. To this end, the decrypted instructions are decrypted only during execution when those instructions are transferred from the main memory to the cache memory so that plaintext versions of those encrypted instructions exist only in the cache memory in response to requests by the central processing unit while executing the program.Other References
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