US 8,151,118 B2Granted

Master-slave security devices

AssigneeMicrosoft Corporation

InventorsDavid James Foster, Shon Schmidt, David Jaroslav Sebesta, Curt Andrew Steeb, William J. Westerinen, Zhangwei Xu, Todd L. Carpenter

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Abstract

A computer or other electronic device requiring physical integrity of its components, for example, a pay-per-use computer may use a master security device in communication with a plurality of slave security devices, known as security beans. Each security bean may be given a cryptographic key or keys for use in authenticating communication with the master security device. Each security bean may be coupled to an associated component and may have the ability to disable that associated component. In one embodiment, security bean has an analog switch that may be configured to block or attenuate a critical signal used by the associated component. The security bean may start up in the disable mode and respond to a verified signal from the master security device to enable its corresponding component.

Claims15

Dependent claims

A device for use in enforcing security in a system the device comprising:

a timeout timer configured to be reset in response to receipt of a signal from a master device that is separate from the device;
a processor, that at least in part, determines when an event has occurred, the event comprising an expiration of time at the timeout timer that occurs unless the device receives the signal from the master device that causes the timeout timer to reset;
a cryptographic function coupled to the processor for authenticating communications with the master device;
a switch coupled to the processor and responsive to a signal from the processor related to the event that blocks a “power OK” signal external to a corollary device, wherein blocking the “power OK” signal prevents the corollary device from beginning its power up sequence, and wherein the corollary device is coupled to and physically separate from the device;
and
a port coupled to the processor for communication with the master device, wherein the port is coupled to a communication channel dedicated to communication between the master device and one or more other devices, each of the other devices being substantially identical to the device and including a respective switch configured to block a “power OK” signal to a different, respective corollary device that is coupled to and physically separate from the other device.

3 more elements

A method of binding components in a system, the method comprising:

disposing a plurality of slave devices in the system, each slave device being coupled to and physically separate from a respective component of the system and including a respective switch capable of rendering inoperable the respective component of the system;
disposing a master device in the system wherein the master device sends a request message to each of the plurality of slave devices over a bus dedicated solely to communication between the master device and each of the plurality of slave devices;
determining a total of acknowledge messages received from the slave devices that are responsive to the request message;
sending a disable signal from the master device to each of the plurality of slave devices over the bus when the total of acknowledge messages responsive to the request message fails to meet a threshold level for acknowledgement messages;
and
at each of the plurality of slave devices, using the respective switch to impair operation of the respective component coupled to the slave device in response to receipt of the disable signal, the respective switch preventing the respective component from beginning its power up sequence by blocking a “power OK” signal.

3 more elements

A system for securing an electronic device having a plurality of components, the system comprising:

at least three slave devices operable to disable one or more respective components, the slave devices comprising:
a first slave device operable to interrupt a power OK signal to a processor of the electronic device, wherein the power OK signal comprises a digital signal to the processor that indicates the processor should remain non-operational until the signal is active;
a second slave device operable to interrupt communications between a keyboard and an I/O interface module of the electronic device;
and
a third slave device operable to connect a load to a system bus that alters transmission characteristics of the system bus to render the system bus inoperable;
and
a security master in communication with each of the first, second, and third slave devices, wherein each of the one or more slave devices disables its respective components when communication between the security master and the slave devices fails to reach a predetermined threshold, wherein the predetermined threshold is indicative of successful communication two from the security master to less than all of the slave devices such that the slave devices do not disable their respective components when communication between the security master and the slave devices is at or exceeds the predetermined threshold.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/668,446Filed 29 Jan 2007
Published: US 2008/0183305 A131 Jul 2008
Granted: 3 Apr 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

G06F 21/85
Protecting input, output or interconnection devices: interconnection devices, e.g. bus-connected or in-line devices
G06F 21/72
To assure secure computing or processing of information: in cryptographic circuits
G06F
Computing and data processing

Family

US 2008/0183305 A1Pre-grant publication · published 31 Jul 2008
US 8,151,118 B2This patent

From the US filing history. Foreign family members aren’t listed.

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