Apparatus and method for generating random numbers

• US 8,768,992 B2
• Filed: 02/19/2007
• Issued: 07/01/2014
• Est. Priority Date: 02/22/2006
• Status: Active Grant

• Current Assignee: Qubitekk Inc.
• Original Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Inventors: Tapster, Paul Richard, Gorman, Philip Michael
• Primary Examiner(s): Bullock, Jr., Lewis A
• Assistant Examiner(s): Dang, Christine
• Application Number:
  US12/280,219
• Publication Number:
  US 20090013019A1
• Time in Patent Office: 2,689 Days
• Field of Search: None
• 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:

an electrical noise generator having at least two channels, each channel of the electrical noise generator being arranged to generate an electrical noise signal and each channel comprising at least two amplifiers electrically connected in series, wherein the two amplifiers of one of the at least two channels is separate from the two amplifiers of the other of the at least two channels,

a threshold detector, wherein the threshold detector is arranged to periodically compare the electrical noise signal generated by each channel with a predetermined threshold voltage to provide a binary data output stream, wherein the binary data output stream is indicative of whether said threshold has been exceeded for each channel,

a feedback reduction means in each channel of the electrical noise generator to minimize feedback through the series of the at least two amplifiers, and

a data processing module, the data processing module comprising at least one input data buffer for each channel of the electrical noise generator, and the at least one input data buffer is configured to receive binary data output stream from the threshold detector to perform a processing step on the received binary data output stream to generate a processed binary data output, wherein each input data buffer is divided into at least first and second segments, and each segment is fully loaded with binary data bits of the received binary data output stream, and wherein the processing step comprises performing at least one XOR operation on pairs of binary data bits, each pair of binary data bits comprising a data bit from the first segment and a data bit from the second segment.

2. 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.

3. 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.

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

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

6. 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 an 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.

7. An apparatus according to claim 6 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.

8. 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.

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

10. An apparatus according to claim 9 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.

11. 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.

12. An apparatus according to claim 1, in which the data bits of each pair are derived by the threshold detector from the electrical noise signal of the same channel.

13. An apparatus according to claim 1 wherein, each input data buffer is 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.

14. An apparatus according to claim 1 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.

15. Random number generation apparatus comprising:

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 each channel of the electrical noise generator comprises amplifying means wherein the amplifying means of one of the at least two channels is separate from the amplifying means of the other of the at least two channels and wherein each of the amplifying means providing a gain of at least 50,000;

threshold detector means wherein the threshold detector is arranged to periodically compare the electrical noise signal generated by each channel with a predetermined threshold voltage and provide a binary data output stream wherein the binary data output stream is indicative of whether said threshold has been exceeded for each channel, and wherein said threshold detection means comprise a digital input/output (DIO) card;

a feedback reduction means in each channel of the electrical noise generator to minimize feedback through the series of the at least two amplifiers; and

a data processing module, the data processing module comprising at least one input data buffer for each channel of the electrical noise generator, and the at least one input data buffer is configured to receive binary data output stream from the threshold detector to perform a processing step on the received binary data output stream to generate a processed binary data output, wherein each input data buffer is divided into at least first and second segments, and each segment is fully loaded with binary data bits of the received binary data output stream, and wherein the processing step comprises performing at least one XOR operation on pairs of binary data bits, each pair of binary data bits comprising a data bit from the first segment and a data bit from the second segment.

16. A method of random number generation:

using an apparatus including an electrical noise generator having at least two channels, each channel of the electrical noise generator being arranged to generate an electrical noise signal and each channel comprising at least two amplifiers electrically connected in series, wherein the two amplifiers of one of the at least two channels is separate from the two amplifiers of the other of the at least two channels;

a feedback reduction means in each channel of the electrical noise generator to minimize feedback through the series of the at least two amplifiers; and

a data processing module, the data processing module comprising at least one input data buffer for each channel of the electrical noise generator wherein the at least one input data buffer is configured to receive binary data output stream from the threshold detector;

the method comprising the steps of;

periodically comparing the electrical noise signal generated by each channel of the electrical noise generator with a predetermined threshold and providing a binary data output stream indicative of whether said threshold has been exceeded for each channel; and

processing the received binary data output stream to generate a processed binary data output, wherein each input data buffer is divided into at least first and second segments, and each segment is fully loaded with binary data bits of the received binary data output stream, and wherein the processing step comprises performing at least one XOR operation on pairs of binary data bits, each pair of binary data bits comprising a data bit from the first segment and a data bit from the second segment.