MAGNETIC TUNNEL JUNCTION BASED RANDOM NUMBER GENERATOR

• US 20140108478A1
• Filed: 10/15/2012
• Published: 04/17/2014
• Est. Priority Date: 10/15/2012
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lee, Kangho, Kim, Taehyun, Zhu, Xiaochun, Jacobson, David M., Madala, Raghu Sagar, Wu, Wenqing, Kim, Jung Pill, Kang, Seung H.
• Application Number:
  US13/651,954
• Publication Number:
  US 20140108478A1
• Time in Patent Office: Days
• US Class Current: 708/250
• CPC Class Codes: G06F 7/588 Random number generators, i.e. based on natural stochastic processes

Abstract

A random number generator system that utilizes a magnetic tunnel junction (MTJ) that is controlled by an STT-MTJ entropy controller that determines whether to proceed with generating random numbers or not by monitoring the health of the MTJ-based random number generator is illustrated. If the health of the random number generation is above a threshold, the STT-MTJ entropy controller shuts down the MTJ-based random number generator and sends a message to a requesting chipset that a secure key generation is not possible. If the health of the random number generation is below a threshold, the entropy controller allows the MTJ-based random number generator to generate random numbers based on a specified algorithm, the output of which is post processed and used by a cryptographic-quality deterministic random bit generator to generate a security key for a requesting chipset.

Claims

1. A method for generating a random number using MTJ devices comprising:

generating raw random number data from an MTJ element;

monitoring a switching probability of the MTJ element to ensure that the raw random number data is random; and

post processing the raw random number data to generate the random number, if the monitoring indicates the raw random number data is random.

2. The method of claim 1, wherein the switching probability of the MTJ element is less than 0.5.

3. The method of claim 1, wherein monitoring the MTJ element is performed by an STT-MTJ entropy controller configured to manipulate random number generation operations based on specific generation algorithms used by the MTJ element.

4. The method of claim 1, wherein the monitoring of the MTJ element is dependent on an algorithm used by the MTJ element to generate the raw random number data.

5. The method of claim 1, further comprising:

receiving a request for a security key; and

generating the security key based on the random number data.

6. The method of claim 1, wherein the monitoring further comprises:

checking an output of the MTJ element to determine if the output is biased above a threshold limit; and

if the bias is not above the threshold limit, generating a second set of raw random number data from the MTJ element, to be used as the raw random number data for the post processing.

7. The method of claim 6, wherein generating a second set of raw random number data further comprises:

resetting the MTJ element to a preset state;

applying a biasing voltage that is near a write threshold to the MTJ element; and

reading a value of the MTJ element.

8. The method of claim 7, further comprising:

wherein reading a value of the MTJ element, includes reading the MTJ element and detecting if a preset state has changed to an opposite state; and

resetting the MTJ element to the preset state, if the opposite state is detected.

9. The method of claim 7, wherein the preset state is one of either a parallel state or an anti-parallel state.

10. The method of claim 7, wherein the preset state is an anti-parallel state, and wherein the biasing voltage is an anti-parallel write threshold and further comprising:

applying a second biasing voltage that is near a parallel write threshold to the MTJ element; and

reading the value of the MTJ element.

11. The method of claim 10, comprising:

repeating the step of applying a biasing voltage that is near an anti-parallel write threshold to the MTJ element; and

reading the value of the MTJ element.

12. The method of claim 10, comprising:

if a value read represents the anti-parallel state, applying a biasing voltage near an anti-parallel write threshold to each MTJ in the MTJ element; and

if the value read represents the parallel state, applying the biasing voltage near a parallel write threshold to each MTJ in the MTJ element.

13. A system for generating random numbers using MTJ devices comprising:

an MTJ-based random number generator to generate raw random number data;

an STT-MTJ entropy controller to monitor an MTJ element to ensure that the raw random number data is random; and

an entropy distillation unit to process the raw random number data, wherein the entropy distillation unit processes the raw random number data if the STT-MTJ entropy controller indicates that the raw random number data is random.

14. The system of claim 13 further comprising:

a cryptographic-quality deterministic random bit generator to generate a security key based on the raw random number data and in response to a security key request from a chip.

15. The system of claim 13, wherein the STT-MTJ entropy controller is configured to control the MTJ-based random number generator based on specific algorithms run by the raw random number generator to generate raw data.

16. The system of claim 15, wherein the algorithms used by the MTJ-based random number generator are configured to output biased random numbers.

17. The system of claim 15, wherein the STT-MTJ entropy controller is further configured to detect a biasness level of the biased output random numbers in conjunction with the specific algorithms used to generate the raw data.

18. The system of claim 17, wherein the biasness level is detected within a set threshold limit set by the STT-MTJ entropy controller.

19. The system of claim 18, wherein the STT-MTJ entropy controller is configured to check the biased output random numbers of the MTJ element to determine if the MTJ element output is biased beyond the set threshold limit, wherein if the MTJ element output bias is not above the set threshold limit, the STT-MTJ entropy controller allows for continued random number generation.

20. The system of claim 19, wherein if the MTJ element output bias is above the set threshold limit, the STT-MTJ entropy controller will stop random number generation operations.

21. The system of claim 20, wherein when MTJ element output bias is above the set threshold limit, the STT-MTJ entropy controller detects an external attack and produces an error message to be sent back to a random number key requestor.

22. An apparatus for generating a random number using MTJ devices comprising:

means for generating raw random number data from an MTJ element;

means for monitoring a switching probability of the MTJ element to ensure that the raw random number data is random; and

means for post processing the raw random number data to generate the random number, if the monitoring indicates the raw random number data is random.

23. The apparatus of claim 22, wherein the switching probability of the MTJ element is less than 0.5.

24. The apparatus of claim 22, wherein the means for monitoring the MTJ element is performed by an STT-MTJ entropy controller configured to manipulate random number generation operations based on specific generation algorithms used by the MTJ element.

25. The apparatus of claim 22, wherein the means for monitoring of the MTJ element are dependent on an algorithm used by the MTJ element to generate the raw random number data.

26. The apparatus of claim 22, further comprising:

means for receiving a request for a security key; and

means for generating the security key based on the random number data.

27. The apparatus of claim 22, wherein the means for monitoring further comprises:

means for checking an output of the MTJ element to determine if the output is biased above a threshold limit; and

if the bias is not above the threshold limit, means for generating a new set of raw random number data from the MTJ element, to be used as the raw random number data for the post processing.

28. The apparatus of claim 27, wherein generating a new set of raw random number data further comprises:

means for resetting the MTJ element to a preset state;

means for applying a biasing voltage that is near a write threshold to the MTJ element; and

means for reading a value of the MTJ element.

29. The apparatus of claim 28, further comprising:

wherein the means for reading a value of the MTJ element, includes means for reading the MTJ element and means for detecting if a preset state has changed to an opposite state; and

means for resetting the MTJ element to the preset state, if the opposite state is detected.

30. The apparatus of claim 28, wherein the preset state is one of either a parallel state or an anti-parallel state.

31. The apparatus of claim 28, wherein the preset state is an anti-parallel state, and wherein the means for biasing voltage is an anti-parallel write threshold and further comprising:

means for applying a second biasing voltage that is near a parallel write threshold to the MTJ element; and

means for reading the value of the MTJ element.

32. The apparatus of claim 31, comprising:

means for repeating the means for applying a biasing voltage that is near an anti-parallel write threshold to the MTJ element; and

means for reading the value of the MTJ element.

33. The apparatus of claim 31, comprising:

if a value read represents the anti-parallel state, means for applying a biasing voltage near an anti-parallel write threshold to each MTJ in the MTJ element; and

if the value read represents the parallel state, means for applying the biasing voltage near a parallel write threshold to each MTJ in the MTJ element.

34. A method for generating a random number using MTJ devices comprising:

step for generating raw random number data from an MTJ element;

step for monitoring a switching probability of the MTJ element to ensure that the raw random number data is random; and

step for post processing the raw random number data to generate the random number, if the monitoring indicates the raw random number data is random.

35. The method of claim 34, wherein the switching probability of the MTJ element is less than 0.5.

36. The method of claim 34, wherein the step for monitoring the MTJ element are performed by an STT-MTJ entropy controller configured to manipulate random number generation operations based on specific generation algorithms used by the MTJ element.

37. The method of claim 34, wherein the step for monitoring of the MTJ element are dependent on an algorithm used by the MTJ element to generate the raw random number data.

38. The method of claim 34, further comprising:

step for receiving a request for a security key; and

step for generating the security key based on the random number data.

39. The method of claim 34, wherein the step for monitoring further comprises:

step for checking an output of the MTJ element to determine if the output is biased above a threshold limit; and

if the bias is not above the threshold limit, step for generating a new set of raw random number data from the MTJ element, to be used as the raw random number data for the post processing.

40. The method of claim 39, wherein generating a new set of raw random number data further comprises:

step for resetting the MTJ element to a preset state;

step for applying a biasing voltage that is near a write threshold to the MTJ element; and

step for reading a value of the MTJ element.

41. The method of claim 40, further comprising:

wherein the step for reading a value of the MTJ element, includes step for reading the MTJ element and step for detecting if a preset state has changed to an opposite state; and

step for resetting the MTJ element to the preset state, if the opposite state is detected.

42. The method of claim 40, wherein the preset state is one of either a parallel state or an anti-parallel state.

43. The method of claim 40, wherein the preset state is an anti-parallel state, and wherein the step for biasing voltage is an anti-parallel write threshold and further comprising:

step for applying a second biasing voltage that is near a parallel write threshold to the MTJ element; and

step for reading the value of the MTJ element.

44. The method of claim 43, comprising:

repeating the step for applying a biasing voltage that is near an anti-parallel write threshold to the MTJ element; and

step for reading the value of the MTJ element.

45. The method of claim 43, comprising:

if a value read represents the anti-parallel state, step for applying a biasing voltage near an anti-parallel write threshold to each MTJ in the MTJ element; and

if the value read represents the parallel state, step for applying the biasing voltage near a parallel write threshold to each MTJ in the MTJ element.

46. A non-transitory computer-readable storage medium storing computer-executable instructions for generating a random number, wherein executing the computer-executable instructions on a processor causes the processor to:

generate a raw random number data from an MTJ element;

monitor a switching probability of the MTJ element to ensure that the raw random number data is random; and

post process the raw random number data to generate the random number, if the monitoring indicates the raw random number data is random.