Object reuse protection with error correction
First Claim
1. A method for combined error detection/correction and object reuse protection in a computer, the method comprising the steps of:
- computing an original error detection/correction code associated with a data word;
applying a first forward bias to the original error detection/correction code to create a first forward-biased error detection/correction code when a first subject writes the data word into a memory location;
copying the first forward-biased error detection/correction code to a tag associated with the data word;
applying a first reverse-bias to the first forward-biased error detection/correction code when the memory location is read by the first subject;
permitting the first subject to read the data word with the first reverse-bias canceling the first forward-biased error detection/correction code;
applying a second reverse-bias to the first-biased error detection/correction code to create a still-biased error detection/correction code when a second subject attempts to access the data word; and
denying access to the data word if the still-biased error detection/correction code comprises an uncorrectable error.
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Accused Products
Abstract
A method and apparatus for providing error detection, correction and prevention of unauthorized access to data using memory tags. The method and apparatus includes computing an original error detection/correction code associated with a data word. The original error detection/correction code, using a CPU and a subject identification register, is copied to a tag associated with the data word when an original subject writes the data word into a memory. A single-error-correction/double-error detection (SEC/DED) device applies a first bias to the tag to create a first-biased error detection/correction code when the memory is assigned to a first subject. The SEC/DED device applies a second bias to create a twice-biased error detection/correction code when a second subject attempts to access the data word. Access to the data word is denied if the twice-biased error detection/correction code comprises an uncorrectable error.
40 Citations
16 Claims
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1. A method for combined error detection/correction and object reuse protection in a computer, the method comprising the steps of:
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computing an original error detection/correction code associated with a data word; applying a first forward bias to the original error detection/correction code to create a first forward-biased error detection/correction code when a first subject writes the data word into a memory location; copying the first forward-biased error detection/correction code to a tag associated with the data word; applying a first reverse-bias to the first forward-biased error detection/correction code when the memory location is read by the first subject; permitting the first subject to read the data word with the first reverse-bias canceling the first forward-biased error detection/correction code; applying a second reverse-bias to the first-biased error detection/correction code to create a still-biased error detection/correction code when a second subject attempts to access the data word; and denying access to the data word if the still-biased error detection/correction code comprises an uncorrectable error. - View Dependent Claims (2, 3, 4, 5, 6)
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7. In a computer, a device for providing combined error detection/correction and object reuse protection, the device comprising:
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a central processing unit (CPU); a memory means for storing a data word and a corresponding tag identifying a first process with a first identification (ID), the memory means coupled to the CPU; a subject ID register for storing a current process ID for a current process, the subject ID register coupled to the CPU and the memory means; and single-error-correction/double-error-detection (SEC/DED) means for determining errors in the data word, the SEC/DED means comprising; a SEC/DED generator for generating an error code pattern, the SEC/DED generator coupled to the CPU; and a bias adder for changing the error code pattern to a first forward-biased error code pattern based on the first ID when the data word is written into the memory, the bias adder coupled to the memory means, to the subject ID register, and to the SEC/DED generator. - View Dependent Claims (8, 9)
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10. A device for providing combined error detection/correction and object reuse protection, the device comprising:
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a central processing unit (CPU); a memory means for storing a data word and a corresponding tag identifying a first process with a first identification (ID), the memory means coupled to the CPU; a subject ID register for storing a current process ID for a current process, the subject ID register coupled to the CPU and the memory means; and single-error-correction/double-error-detection (SEC/DED) means for determining errors in the data word, the SEC/DED means comprising; a SEC/DED generator for generating an error code pattern, the SEC/DED generator coupled to the CPU; and a bias adder for changing the error code pattern to a first biased error code pattern based on the first ID when the data word is written into the memory, the bias adder coupled to the memory means, to the subject ID register, and to the SEC/DED generator. - View Dependent Claims (11, 12)
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13. A method for providing error detection/correction and prevention of unauthorized access to data using memory tags, the method comprising the steps of:
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computing an original error detection/correction code associated with a data word; applying a first bias to the original error detection/correction code to create a first-biased error detection/correction code when the memory is assigned to a first subject; copying the first-biased error detection/correction code to a tag associated with the fata word when the first subject writes the data word into a memory location; applying a second bias to the first-biased error detection/correction code to create a twice-biased error detection/correction code when a second subject attempts to access the data word; and denying access to the data word if the twice-biased error detection/correction code comprises an uncorrectable error. - View Dependent Claims (14, 15, 16)
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Specification