Abstract: 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.

Abstract: A cross-domain call system for use in a digital data processing system includes a cross-domain call stack through which cross-domain transfer information is passed from a calling program in one domain for use in connection with a called program in another domain. When a calling program in one domain needs to call another, called, program in another domain, it pushes information on the cross-domain call stack, including a capability identifying data to be used by the called program and conditions a flag whose condition indicates whether the capability is to be erased on return. During the cross-domain call and return, the digital data processing system saves and clears selected registers when transferring control from the calling program to the called program, and restores the saved registers when transferring control from the called program to the calling program, the restored registers containing values to be used by the calling program after it has resumed control.

Abstract: Apparatus and methods, readily adapted to interface with a standard data transmission network having an unsecure transmission channel, e.g., "Ethernet," for the provision of secure transmission of data over the network channel in a manner which is essentially transparent to the standard network devices and users, thereof, are provided. Various encryption keys are generated and utilized within the system to disguise or encrypt information transferrred between network nodes. The encryption keys are made known only to those network devices which are permitted to handle information encrypted with the encryption keys.

Abstract: Apparatus and methods, readily adapted to interface with a standard data transmission network having an unsecure transmission channel, e.g., "Ethernet," for the provision of secure transmission of data over the network channel in a manner which is essentially transparent to the standard network devices and users thereof, are provided. Various encryption keys are generated and utilized within the system to disguise or encrypt information transferred between network nodes. The encryption keys are made known only to those network devices which are permitted to handle information encrypted with the encryption keys.

Abstract: A computer system including a processor and memory, the processor having a virtual mode of operation in which it uses a virtual machine monitor which allows it to service a plurality of users contemporaneously in a multiplexed manner, and a non-virtual, or real, mode of operation. The computer system has a set of at least three operation mode protection rings representing a hierarchy of access privilege levels in both the real and virtual modes, with the number of privilege levels in both the real and virtual modes being the same. The privilege levels govern the accessibility of memory locations to programs and the executability of certain privileged instructions, which cause control to be transferred to the virtual machine monitor when the processor is in a virtual mode.