Side Channel Communications

• US 20130044798A1
• Filed: 12/22/2011
• Published: 02/21/2013
• Est. Priority Date: 08/18/2011
• Status: Abandoned Application

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Eguro, Kenneth, Forin, Alessandro, Bittner, Ray A. Jr., Sun, Ji
• Application Number:
  US13/334,054
• Publication Number:
  US 20130044798A1
• Time in Patent Office: Days
• US Class Current: 375/224
• CPC Class Codes: G06F 21/554 involving event detection and direct action
• CPC Class Codes: G06F 21/86 Secure or tamper-resistant housings
• CPC Class Codes: G06F 2221/2101 Auditing as a secondary aspect
• CPC Class Codes: H04L 63/1425 Traffic logging, e.g. anomaly detection

Abstract

A side channel communications system disclosed herein includes a receiver device with an internal circuitry where the operational speed of the internal circuitry changes in response to an external signal. When the receiver device receives an external signal, the operational speed of the internal circuitry changes. A detector detects the change in the operational speed of the internal circuitry to generate an output value, which is decoded to determine the information communicated by the external signal. In one implementation of the side channel communications system, the external transmitter communicates the external signal in the form of a temperature signal. Alternatively, the external transmitter communicates the external signal in the form of a change in the supply voltage.

Claims

1. A method comprising:

generating an external signal representing an external information to be conveyed to a receiver device, operational speed of internal circuitry of the receiver device being dependent upon the external signal;

receiving the external signal at the receiving device;

measuring a value of the operational speed of the internal circuitry; and

decoding the measured value of the operational speed to generate a value of the external information.

2. The method of claim 1 wherein the internal circuitry is a ring oscillator.

3. The method of claim 2 wherein measuring a value of the operational speed of the internal circuitry further comprises measuring an output frequency of the ring oscillator.

4. The method of claim 1 further comprising comparing the measured value of the operational speed with a stored value of the operational speed to generate a differential value of the operational speed.

5. A method comprising:

receiving an external signal at a receiving device, the external signal representing external information;

measuring a value of operational speed of internal circuitry of the receiving device, the operational speed of the internal circuitry being dependent upon an external signal received at the receiving device; and

decoding the measured value of the operational speed of the internal circuitry to generate a value of the external information.

6. The method of claim 5 wherein decoding the measured value of the operational speed further comprising comparing the measured value of the operational speed with a stored value of the operational speed.

7. The method of claim 5 wherein measuring a value of operational speed of an internal circuitry further comprising measuring an output frequency of a ring oscillator in the receive device.

8. The method of claim 7 further comprising comparing the output frequency of the ring oscillator with a threshold value of the ring oscillator output frequency.

9. The method of claim 5 wherein the external signal is a temperature signal.

10. The method of claim 5 wherein the external signal is a supply voltage signal.

11. The method of claim 5 wherein decoding the measured value of the operational speed further comprises:

generating a differential value of the output frequency of the internal circuitry based on the comparison of a measured value of the output frequency of the internal circuitry and a stored value of the output frequency of the internal circuitry; and

comparing the differential value of the output frequency of the internal circuitry with a number of look-up table values, each of the look-up table values corresponding to a value of the external information.

12. A device comprising:

circuitry configured to receive an external signal at a receiving device, the external signal representing external information;

a detector configured to measure a value of operational speed of internal circuitry of the receiving device, the operational speed of the internal circuitry being dependent upon an external signal received at the receiving device; and

a decoder coupled to the detector to receive the output value from the detector and configured to decode the measured value of the operational speed of the internal circuitry to generate a value of the external information.

13. The device of claim 12 wherein the circuitry is a temperature sensitive circuitry with the operational speed that changes based on a change in an operating temperature of the circuitry.

14. The device of claim 12 wherein the circuitry is a voltage level sensitive circuitry with the operational speed that changes based on a change in an operating voltage level of the circuitry.

15. The device of claim 12 wherein the detector is configured to generate an output value based on a value of the operational speed of the circuitry based on a propagation delay on the circuitry.

16. The device of claim 12 wherein the circuitry is a ring oscillator having an output frequency that is influenced by the signal from an external source.

17. The device of claim 16 wherein the ring oscillator is configured using look up tables (LUTs) of various configurable logic blocks (CLBs) on an integrated circuit.

18. The device of claim 12 wherein the decoder is further configured to generate the information value communicated by the signal from the external source by comparing the output value from the detector with a stored value of the operational speed of the circuitry.

19. The device of claim 18 further comprising:

generating a differential value of the operational speed of the circuitry based on the comparison of the output value from the detector and the stored value of the operational speed of the circuitry; and

comparing the differential value with a threshold value.

20. The device of claim 18 further comprising:

generating a differential value of the operational speed of the circuitry based on the comparison of the output value from the detector and the stored value of the operational speed of the circuitry; and

comparing the differential value with a number of look-up table values, each of the look-up table values corresponding to an information value communicated by the signal from the external source.