Apparatus and Method for Generating Random Numbers

• US 20090013019A1
• Filed: 02/19/2007
• Published: 01/08/2009
• Est. Priority Date: 02/22/2006
• Status: Active Grant

• Current Assignee: Qubitekk Inc.
• Original Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Inventors: Gorman, Philip Michael, Tapster, Paul Richard
• Granted Patent: US 8,768,992 B2
• 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

Random number generation apparatus (2) is described that comprises a threshold detector (4) and an electrical noise generator (6). The electrical noise generator (6) has at least two channels (8a-8d) and each channel is arranged to generate an electrical noise signal. The threshold detector (4), which may comprise a digital input-output (DIO) card, is arranged to periodically compare this electrical noise signal with a threshold and to provide a binary data output that indicates whether the threshold has been exceeded. Each channel of the electrical noise generator comprises at least two amplifiers (10a-10c) electrically connected in series that preferably provide a gain of 50,000 or more. Use of the random number generation apparatus (2) for quantum cryptography applications is also described.

Claims

1. Random number generation apparatus comprising a threshold detector and an electrical noise generator having at least two channels, each channel of the electrical noise generator being arranged to generate an electrical noise signal, wherein the threshold detector is arranged to periodically compare the electrical noise signal generated by each channel with a threshold and provide a binary data output indicative of whether said threshold has been exceeded, characterised in that each channel of the electrical noise generator comprises at least two amplifiers electrically connected in series.

2. An apparatus according to claim 1 wherein each channel of the electrical noise generator comprises feedback reduction means to minimise feedback through the series of at least two amplifiers.

3. An apparatus according to claim 1 wherein the at least two amplifiers of each channel of the electrical noise generator are arranged to provide an overall gain in the range of 50,000 to 150,000.

5. An apparatus according to claim 1 wherein each of the at least two amplifiers of each channel have a bandwidth within the range of 10 MHz to 100 MHz.

7. An apparatus according to claim 1 wherein each channel comprises three amplifiers connected in series.

8. An apparatus according to claim 1 wherein each channel comprises an equalisation filter.

10. An apparatus according to claim 1 wherein each channel comprises at least one bias control means, the at least one bias control means being connected to the input of one of said at least two amplifiers and arranged so as to provide control over the DC voltage level of the electrical noise signal output by the channel.

11. An apparatus according to claim 10 and further comprising a drift compensation controller for adjusting the at least one bias control means of each channel so as to maintain the bias of the binary data output of the threshold detector to within a predetermined range.

13. An apparatus according to claim 1 wherein each channel comprises a load resistor, the load resistor being connected to the input of the first amplifier of the series of at least two amplifiers.

15. An apparatus according to claim 1 wherein the threshold detector produces a separate binary data output stream for each electrical noise signal.

16. An apparatus according to claim 15 in which the threshold detector comprises a digital input/output (DIO) card having a plurality of inputs, wherein the electrical noise signal generated by each channel of the electrical noise generator is provided to a separate input of the DIO card.

17. An apparatus according to claim 1 wherein each electrical noise signal is sampled by the threshold detector at a rate within the range of 5 MHz to 15 MHz.

19. An apparatus according to claim 1 and further comprising a data processing module, the data processing module being configured to receive binary data output by the threshold detector and to perform a processing step on the received binary data to generate a processed binary data output having improved randomness characteristics, wherein said processing step comprises at least one exclusive OR (XOR) operation.

20. An apparatus according to claim 19 in which the data processing module is arranged to perform an XOR operation on pairs of binary data bits, wherein the data bits of each pair are derived by the threshold detector from the electrical noise signal of the same channel.

24. An apparatus according to claim 19 wherein the data processing module comprises at least one input data buffer for every channel of the electrical noise generator, each input data buffer being arranged to receive the binary data output generated by the threshold detector from the electrical noise signal of the respective channel of the electrical noise generator.

25. An apparatus according to claim 24 in which each input data buffer is divided into at least first and second segments, each segment being fully loaded, in turn, with binary data bits, wherein said at least one XOR operation is performed on pairs of binary data bits, each pair of binary data bits comprising a data bit from the first segment and data bit from the second segment.

26. An apparatus according to claim 25 wherein each input data buffer comprises at least first, second, third and fourth segments, wherein said at least one XOR operation is performed on data contained in the first and second segments whilst the third and fourth segments are being loaded with binary data.

4. (canceled)

6. (canceled)

9. (canceled)

12. (canceled)

14. (canceled)

18. (canceled)

21-23. -23. (canceled)

27-32. -32. (canceled)

33. Random number generation apparatus comprising threshold detection means and an electrical noise generator having at least one channel, wherein said at least one channel of the electrical noise generator is arranged to generate an electrical noise signal and the threshold detection means is arranged to periodically compare the electrical noise signal generated by said at least one channel with a threshold and provide a binary output indicative of whether said threshold has been exceeded, characterised in that said at least one channel of the electrical noise generator comprises amplifying means that provide a gain of at least 50,000 and in that said threshold detection means comprises a digital input/output (DIO) card.

34. (canceled)

35. A method of random number generation comprising the steps of;

(i) taking an electrical noise generator having at least two channels, (ii) periodically comparing the electrical noise signal generated by each channel of the electrical noise generator with a threshold and providing a binary data output indicative of whether said threshold has been exceeded, characterised by the step of (i) taking an electrical noise generator having at least two channels comprising the step of taking an electrical noise generator in which each channel comprises at least two amplifiers electrically connected in series.

36. (canceled)