Quantum cryptography with multi-party randomness

• US 7,697,693 B1
• Filed: 03/09/2004
• Issued: 04/13/2010
• Est. Priority Date: 03/09/2004
• Status: Expired due to Fees

• Current Assignee: Raytheon BBN Technlogies Corp. (Rtx Corporation)
• Original Assignee: BBN Technologies (Rtx Corporation)
• Inventors: Elliott, Brig Barnum
• Primary Examiner(s): Orgad, Edan
• Assistant Examiner(s): Wang, Harris C
• Application Number:
  US10/795,313
• Time in Patent Office: 2,226 Days
• Field of Search: 380/278
• US Class Current: 380/278
• CPC Class Codes: H04B 10/70 Photonic quantum communication
• CPC Class Codes: H04L 9/0852 Quantum cryptography transmission systems employing electromagnetic waves other than radio waves, e.g. light, infrared H04B10/00; wavelength-division multiplex systems H04J14/02; WDM arrangements H04J14/03
• CPC Class Codes: H04L 9/0869 involving random numbers or seeds

Abstract

A method and system for performing a quantum key distribution process in a quantum cryptographic system (200, 400) is provided. A first endpoint (405a) contributes a first set of random values to a quantum key distribution process. A second endpoint (405b) contributes a second set of random values to the quantum key distribution process. The first and the second endpoints (405a, 405b) derive a key based on at least some of the first set of random values and at least some of the second set of random values. In some implementations, the first endpoint (405a) may send each of the first set of random values using a basis (act 702, act 902) and the second endpoint (405b) may send an indication of received pulses and a basis for each of the received pulses (act 704, act 904).

Claims

1. A method for performing quantum key distribution in a quantum cryptographic system, the method comprising:

contributing a first set of random values, from a first endpoint, to a quantum key distribution process;

contributing a second set of random values, from a second endpoint, to the quantum key distribution process, where the second contributing act comprises;

sending, from the second endpoint to the first endpoint, a plurality of random bits,

using, by the first endpoint, the plurality of random bits as a seed for a pseudo-random number generator, and

expanding, by the pseudo-random number generator, the seed to a series of pseudo-random values; and

deriving, at the first and the second endpoints, a key based on at least some of the first set of random values and one of at least some of the second set of random values or at least some of the pseudo-random values.

2. The method of claim 1, where:

the second contributing act is performed during a sifting process.

3. The method of claim 1, where:

the second contributing act is performed during an error detection and correction process.

4. The method of claim 1, where:

the first contributing act comprises;

sending each one of the first set of random values using a randomly generated basis.

5. The method of claim 4, where the basis includes a type of polarization.

6. The method of claim 4, where the basis includes a phase modulation.

7. The method of claim 4, where:

the second contributing act comprises;

sending an indication of received pulses and a basis for each of the received pulses.

8. The method of claim 7, where the deriving comprises:

sending, from the first endpoint, an indication of the pulses upon which the first and the second endpoints agree, and

using ones of the second set of random values, provided by the second endpoint, to perform an operation with ones of the first set of random values corresponding to the pulses upon which the first and the second endpoints, the key being based on a result of the operation.

9. The method of claim 7, where the second contributing act further comprises:

sending the second set of random values with the indication of received pulses, each one of the second set of random values corresponding to a different one of the received pulses.

10. The method of claim 7, where the second contributing act further comprises:

sending the second set of random variables in response to receiving, from the first endpoint, an indication of the pulses upon which the first and the second endpoints agree, each one of the second set of random variables corresponding to a different one of the pulses upon which the first and the second endpoints agree.

11. The method of claim 1, where the quantum cryptographic system is a one-way type quantum system.

12. The method of claim 1, where the quantum cryptographic system is a plug and play type quantum system.

13. The method of claim 1, where the quantum cryptographic system is based on entanglement.

14. The method of claim 1, where:

the first endpoint performs the quantum key distribution process via a freespace optical link.

15. The method of claim 1, where:

the first endpoint performs the quantum key distribution process via a link including fiber.

16. The method of claim 1, where the deriving comprises:

performing an exclusive-or operation on at least some of the first random values and at least some of the second random values, the key being based on a result of the exclusive- or operation.

17. The method of claim 1, where the second contributing act comprises:

sending the second set of random values unencrypted to the first endpoint.

18. A quantum cryptographic system comprising:

a first quantum key distribution endpoint; and

a second quantum key distribution endpoint, where the second quantum key distribution endpoint;

contributes a second set of random values to a quantum key distribution process, and

sends a plurality of random bits, including the second set of random values, to the first quantum key distribution endpoint,

where the first quantum key distribution endpoint;

contributes a first set of random values to the quantum key distribution process, and

uses the plurality of random bits as a seed for a pseudo-random number generator, such that the pseudo-random number generator expands the seed to a series of pseudo-random values, and

where the first and second key distribution endpoints;

communicate via a quantum channel therebetween, and

derive a key based on at least some of the first set of random values and one of at least some of the second set of random values or at least some of the pseudo-random values.

19. The quantum cryptographic system of claim 18, where:

the second quantum key distribution endpoint is configured to contribute the second set of random values during a sifting process.

20. The quantum cryptographic system of claim 18, where:

the second quantum key distribution endpoint is configured to contribute the second set of random values during an error detection and correction process.

21. The quantum cryptographic system of claim 18, where:

the at least some of the first set of random values are ones of the first set of random values that are correctly received and measured by the second quantum key distribution endpoint, and

each of the at least some of the second set of random values corresponds to a different one of the at least some of the first set of random values.

22. The quantum cryptographic system of claim 21, where:

the first and the second endpoints are further configured to derive the key based on a result of performing an exclusive-or operation on each one of the at least some of the second set of random values with corresponding ones of the at least some of the first set of random values.

23. The quantum cryptographic system of claim 18, where:

the first quantum key distribution endpoint is configured to;

send each one of the first set of random values using a basis, and

the second quantum key distribution endpoint is configured to;

receive at least a portion of the first set of random values and measure each one of the at least a portion of the first set of random values using a separately selected basis, and

send an indication for each of the at least a portion of the first set of random values and an indication of the separately selected basis for the each of the at least a portion of the first set of random values to the first quantum key distribution endpoint.

24. The quantum cryptographic system of claim 23, where:

each of the bases includes a type of polarization.

25. The quantum cryptographic system of claim 23, where:

each of the bases includes a phase modulation.

26. The quantum cryptographic system of claim 23, where:

each of the bases is randomly selected.

27. The quantum cryptographic system of claim 23, where:

the first quantum key distribution endpoint is further configured to;

send an indication of ones of the first set of random values, in which the first and the second quantum key distribution endpoints are in agreement on the basis, to the second quantum key distribution endpoint.

28. The quantum cryptographic system of claim 23, where:

when the second quantum key distribution endpoint sends the at least a portion of the first set of random values to the first quantum key distribution endpoint, the second quantum key distribution endpoint includes a second set of random values, each of the second set of random values corresponding to a different one of the at least a portion of the first set of random values.

29. The quantum cryptographic system of claim 27, where:

when the second quantum key distribution endpoint receives the indication of ones of the first set of random values, in which the first and the second quantum key distribution endpoints are in agreement on the basis, the second quantum key distribution endpoint is configured to send, to the first quantum key distribution endpoint, the second set of random values.

30. The quantum cryptographic system of claim 18, where:

the first and the second endpoints are further configured to derive the key based on a result of performing an exclusive-or operation on at least some of the second set of random values with corresponding ones of at least some of the first set of random values.

31. The quantum cryptographic system of claim 18, where:

the quantum cryptographic system is a one-way type quantum system.

32. The quantum cryptographic system of claim 18, where:

the quantum cryptographic system is a plug and play type quantum system.

33. The quantum cryptographic system of claim 18, where:

the quantum cryptographic system is based on entanglement.

34. The quantum cryptographic system of claim 18, where:

the second quantum key distribution endpoint is configured to send, unencrypted, the second set of random values to the first quantum key distribution endpoint.

35. A quantum key distribution endpoint comprising:

a bus;

a transceiver coupled to the bus;

a memory coupled to the bus; and

a processing unit coupled to the bus, wherein;

the memory includes a plurality of instructions for the processing unit, such that when the quantum key distribution endpoint is configured as a first quantum key distribution endpoint, the processing unit is configured to;

contribute a first set of random values to a quantum key distribution process with a second quantum key distribution endpoint,

receive a second set of random values from the second quantum key distribution endpoint,

receive a plurality of random bits, including the second set of random values, from the first quantum key distribution endpoint,

use the plurality of random bits as a seed for a pseudo-random number generator, such that the pseudo-random number generator is configured to expand the seed to a series of pseudo-random number values, and

derive a key based on at least some of the first set of random values and one of at least some of the second set of random values or at least some of the pseudo-random number values.

36. The quantum key distribution endpoint of claim 35, where:

when the quantum key distribution endpoint is a second quantum key distribution endpoint, the processing unit is further configured to;

contribute the second set of random values during a sifting process.

37. The quantum key distribution endpoint of claim 35, where:

when the quantum key distribution endpoint is a second quantum key distribution endpoint, the processing unit is further configured to;

contribute the second set of random values during an error detection and correction process.

38. The quantum key distribution endpoint of claim 35, where:

the processing unit is further configured to;

use a basis when sending each of the first set of random values.

39. The quantum key distribution endpoint of claim 38, where:

the basis is a type of polarization, the polarization being one of diagonal and rectilinear.

40. The quantum key distribution endpoint of claim 38, where:

the basis includes a phase modulation.

41. The quantum key distribution endpoint of claim 38, where:

each one of the bases is randomly selected.

42. The quantum key distribution endpoint of claim 35, where:

when the quantum key distribution endpoint is a second quantum key distribution endpoint, the processing unit is further configured to;

send an indication of received ones of the first set of random values and a selected basis for each of the received ones of the first set of random values.

43. The quantum key distribution endpoint of claim 35, where:

when the quantum key distribution endpoint is a first quantum key distribution endpoint, the processing unit is further configured to;

receive an indication of received ones of the first set of random values and a basis from a second quantum key distribution endpoint, and

send an indication, to the second quantum key distribution endpoint, of which ones of the first set of random values the first and the second quantum key distribution endpoints agree.

44. The quantum key distribution endpoint of claim 35, where:

when the quantum key distribution endpoint is a second quantum key distribution endpoint, the processing unit is further configured to;

send, to a first quantum key distribution endpoint, an indication of received ones of the first set of random values and the second set of random values, each one of the second set of random values corresponds to a received one of the first set of random values.

45. The quantum key distribution endpoint of claim 35, where:

the processing unit is further configured to;

derive the key based on a result of performing an exclusive-or operation on the at least some of the first set of random variables and the at least some of the second set of random variables.

46. The quantum key distribution endpoint of claim 35, where:

when the quantum key distribution endpoint is a second quantum key distribution endpoint, the processing unit is further configured to;

send a plurality of random bits, including the second set of random values, to a first quantum key distribution endpoint.

47. The quantum key distribution endpoint of claim 35, where:

the processing unit is further configured to derive the key based on a result of performing an exclusive-or operation on at least some of the series of pseudo-random values with corresponding ones of the at least some of the first set of random values.

48. The quantum key distribution endpoint of claim 35, where:

the quantum key distribution endpoint is configured to operate in a one-way type quantum system.

49. The quantum key distribution endpoint of claim 35, where:

the quantum key distribution endpoint is configured to operate in a plug and play type quantum system.

50. The quantum key distribution endpoint of claim 35, where:

the quantum key distribution endpoint is configured to operate in system based on entanglement.

51. The quantum key distribution endpoint of claim 35, where when the quantum key distribution endpoint is a second quantum key distribution endpoint, the processing unit is further configured to:

send the second set of random values unencrypted to a first quantum key distribution endpoint.

52. A machine-readable medium having a plurality of instructions recorded therein, such that when the plurality of instructions are executed by a processor of a quantum key distribution endpoint, the processor is configured to:

contribute a first set of random values to a quantum key distribution process,

receive a second set of random values, for the quantum key distribution process, from a second endpoint,

receive a plurality of random bits, including the second set of random values, from the second endpoint,

use the plurality of random bits as a seed to a pseudo-random number generator,

expand, via the pseudo-random number generator, the seed to a series of pseudo-random values, and

derive a key based on at least some of the first set of random values and one of at least some of the second set of random values or at least some of the pseudo-random values.

53. The machine-readable medium of claim 52, where the processor is further configured to:

send each one of the first set of random values, to another quantum key distribution endpoint, using a basis.

54. The machine-readable medium of claim 53, where each of the bases includes a type of polarization.

55. The machine-readable medium of claim 53, where each of the bases is a phase modulation.

56. The machine-readable medium of claim 53, where each of the bases is randomly selected.

57. The machine-readable medium of claim 52, where processor is further configured to:

receive an indication of received ones of a plurality of pulses and a plurality of selected bases from the second endpoint, each one of the received ones of the pulses corresponding to one of at least some of the first set of random values, and

send an indication of the pulses upon which the quantum key distribution endpoint agrees with the second endpoint.

58. The machine-readable medium of claim 57, where:

the processor is further configured to;

receive at least some of the second set of random values with the indication of the received ones of the pulses and the plurality of selected bases from the second endpoint.

59. The machine-readable medium of claim 57, where:

the processor is further configured to;

receive at least some of the second set of random values from the second endpoint after sending the indication of the pulses upon which the quantum key distribution endpoint agrees with the second endpoint.

60. The machine-readable medium of claim 52, where:

the operation includes an exclusive-or operation.