Digital Equipment Corporation

Wei-Ming Hu

Andrew Halstead Mason

Paul Ashley Karger

Clifford Earl Kahn

Paul T Robinson

John C Wray

A method and corresponding apparatus for authenticating a client for a server when the client and server have different security mechanisms. An intermediary system known as an authentication gateway provides for authentication of the client using the client security mechanism, and impersonation of the client in a call to a server that the client wishes to access. The client logs in to the authentication gateway and provides a user name and password. Then the authentication gateway obtains and saves security credentials for the client, returning an access key to the client. When the client wishes to call the server, the client calls the authentication gateway acting as a proxy server, and passes the access key, which is then used to retrieve the security credentials and to impersonate the client in a call to the server. Any output arguments resulting from the call to the server are returned to the client through the authentication gateway.

Method and apparatus for authenticating a client to a server in computer

A method for scheduling processes for execution in a computer system organizes the processes into run queues in accordance with the respective secrecy classes of the processes. A CPU time slot is assigned to each run queue. If all processes in a run queue give up the CPU before the expiration of the run queue's assigned time slot, the leftover time is given to a run queue whose secrecy class dominates that of the previous run queue. Covert-channel countermeasures are not taken in between two run queues if the secrecy class of the second run queue dominates the secrecy class of the first run queue.

Lattice scheduler method for reducing the impact of covert-channel

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.

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Arlington, MA, United States of America

Wei-Ming Hu