Digital Equipment Corporation

Hewlett-Packard Development Company, L.p.

Compaq Information Technologies Group, L.p.

Clifford Earl Kahn

Andrew Halstead Mason

Mary Ellen Zurko

Morrie Gasser

Judith Shelhorse Hall

Steven B Lipner

Paul Douglas Sawyer

Thomas Andrew Casey, Jr

Leslie Richard Kendall

Paul Ashley Karger

Paul T Robinson

John C Wray

Wei-Ming Hu

Anthony L Priborsky

Timothy E Leonard

A method for executing trusted commands, in which a trusted command is first received from a user at a user terminal and parsed by untrusted code; then passed to a trusted computing base for execution. The trusted computing base displays some indication of what is to be done back to the user for confirmation. Confirmation of the commands prevents unauthorized modification of the commands and increases system confidence. A randomly (or pseudo-randomly) generated process identifier is employed to verify the existence of a trusted path.

Verification of trusted-path commands

Processing trusted commands in trusted and untrusted environments

A method for executing trusted commands, in which a trusted command is first received from a user at a user terminal and parsed by untrusted code; then passed to a trusted computing base for execution. The trusted computing base displays to the user for confirmation indication of what is to be done. Confirmation of the commands prevents unauthorized modification of the commands and increases system confidence. A randomly (or pseudo-randomly) generated process identifier is employed to verify the existence of a trusted path.

Method for executing trusted-path commands

A browser for efficiently browsing large directory trees is presented. The browser uses authentication links as the structure through which the browser navigates. By adhering to the rules for a valid authentication chain, the browser increases efficiency by storing the results of preliminary steps to browsing.

System for selectively browsing a large, distributed directory tree

A digital computer system includes at least one process, an input/output subsystem, and an input/output interface. The process which input/output requests and receives input/output responses. The input/output system perform input/output operations and generates completion notifications in response thereto. The input/output interface generates input/output responses for the process in the order in which the process issued the input/output requests, to reduce the possibility of the process obtaining information from the order in which the input/output system processed input/output requests.

System and method for reducing storage channels in disk systems

A digital computer system for processing at least one process, said process generating operational requests for enabling selected operations. The computer system comprises a timer portion for generating two series of unpredictable timing indications. An operational processor portion is responsive to the timing indications from said timer and the operational requests for initiating operations enabled by the operational requests in response to one of the series of timing indications. The operational processor communicates with the processes regarding operations enabled with respective operational requests in response to the second series of timing indications. Since the timings of the operations by the operational processor are distinct from the timings of the communications between the operational processor and the process, the process is unable to determine timing information from the operations performed by the operational processor in response to the operational requests, thereby ensuring that the process will be unable to use the timings of the operations by the operational processor to determine timing intervals. In another aspect, the digital computer system includes a system timing generator for generating a system timing value that provides timing information. The system timing generator updates the system timing value at unpredictable intervals, but so that the system timing value provides timing information that is accurate as of the time of update. When the process requests the system timing value, the system timing generator supplies only a selected high-order portion of the system timing value, also ensuring that the process only has imprecise timing information. Since the process has access to only an imprecise system timing value, and since it is unable to use external operations, by the operational processor, for timing information, the bandwidth of any convert timing channels is reduced accordingly.

System and method for reducing timing channels in digital data

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Framingham, MA, United States of America

Clifford Earl Kahn