GB2447243A - Random number generation method - Google Patents

Random number generation method Download PDF

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Publication number
GB2447243A
GB2447243A GB0704196A GB0704196A GB2447243A GB 2447243 A GB2447243 A GB 2447243A GB 0704196 A GB0704196 A GB 0704196A GB 0704196 A GB0704196 A GB 0704196A GB 2447243 A GB2447243 A GB 2447243A
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United Kingdom
Prior art keywords
generate
digital
unpredictable
random number
value
Prior art date
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Withdrawn
Application number
GB0704196A
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GB0704196D0 (en
Inventor
Richard Hoptroff
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Individual
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Individual
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Publication date
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Priority to GB0704196A priority Critical patent/GB2447243A/en
Publication of GB0704196D0 publication Critical patent/GB0704196D0/en
Publication of GB2447243A publication Critical patent/GB2447243A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F7/00—Methods or arrangements for processing data by operating upon the order or content of the data handled
    • G06F7/58—Random or pseudo-random number generators
    • G06F7/588—Random number generators, i.e. based on natural stochastic processes

Abstract

The invention relates to a method of generating random numbers in digital electronic devices such as microcontrollers, such that two devices, when programmed and operated in the same manner, generate different random numbers. The method involves using a variable property of a component in a digital device to generate an unpredictable value for a random number seed. Internal clock inaccuracies of an oscillator, ADC conversion variations or digital logic trigger level variations can be used to generate an unpredictable value. The properties may vary as a result of manufacture, temperature or operating voltage.

Description

Random Number Generation Method This invention relates to a method of
generating random numbers in digital electronic devices such as microcontrollers, such that two devices, when programmed and operated in exactly the same manner, generate different random numbers.
Typically, random numbers are generated from a nonlinear mathematical sequence and a seed' value which is used to derive the next value in the sequence and the next seed'. The numbers are pseudo-random, since knowledge of the seed makes the sequence entirely predictable. Without knowledge of the seed, however, the numbers generated are effectively
unpredictable.
A limitation of seed-based random number generators is that the seed must be unique and unknown if the random numbers are to be unpredictable. At some point a seed has to be imparted to the device, and this point is a potential weakness, for example if the random number generator is intended for purposes of encryption of sensitive information.
Accordingly, the Invention is a method for deriving a random number seed within a digital electronic device such that the seed cannot be externally determined, and such that if two devices follow the same method, they will derive different seeds. The method is to rely on analogue components within the device having unpredictable and non-repeatable properties. These properties are measured in order to derive to generate a seed value.
Three embodiments are now detailed.
A. Using internal clock inaccuracies. Many microcontrollers contain internal clocks, such as watch-dog timers, based on resistor-capacitor switching networks. Their timing is subject to variations in manufacturing, temperature and operating voltages. The embodiment is to determine a time-related value with reference to the clock. This event may be an external event, such as state of an externally imparted signal, or an internal event such as another timer with an independent clock. The result of the timed event will vary from device to device, and may form the basis of a random number seed.
B. Using analog to digital conversion variationr. Many microcontrollers contain analog to digital converters. Their accuracy is such that the least significant bits are subject to fluctuation, even when the input pin is held as constant as possible, due to leakages from other signal lines, power rail fluctuations, etc. The embodiment is to capture the least significant bits, repeatedly if necessary, to form the basis of a random number seed.
C. Digital logic trigger level variations. Digital inputs are not designed to be operated at voltages intermediate to their intended logic levels, and their trigger thresholds are not predictable. For example, if an analogue input voltage slowly increases from logic 0 to logic 1, the exact moment that the digital electronics will switch from 0 to 1 is subject to variations in manufacturing, temperature and operating voltages. In this embodiment, the device is provided with an external analogue signal and resulting digital input value is recorded. This measurement will vary from device to device, and may form the basis of a random number seed.

Claims (5)

1. A method for generating values within digital electronic devices by taking measurements using an analog component therein, and such that variations in analog properties of said component render the generated value unpredictable, even if the method is known.
2. A method as claimed in claim 1 where the digital electronic device is a microcontroller.
3. A method as claimed 1 or 2 wherein the timing of an internal oscillator circuit is the analog property used to generate an unpredictable value.
4. A method as claimed in claim I or 2 wherein an analog-to-digital converter measures a voltage, and where such voltage is liable to slight fluctuation, in order to generate an unpredictable value.
5. A method as claimed in claim I or 2 wherein the state of a digital input is measured when stimulated with voltages intermediate to its normal logic voltage levels in order to generate an unpredictable value.
GB0704196A 2007-03-05 2007-03-05 Random number generation method Withdrawn GB2447243A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0704196A GB2447243A (en) 2007-03-05 2007-03-05 Random number generation method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0704196A GB2447243A (en) 2007-03-05 2007-03-05 Random number generation method

Publications (2)

Publication Number Publication Date
GB0704196D0 GB0704196D0 (en) 2007-04-11
GB2447243A true GB2447243A (en) 2008-09-10

Family

ID=37965917

Family Applications (1)

Application Number Title Priority Date Filing Date
GB0704196A Withdrawn GB2447243A (en) 2007-03-05 2007-03-05 Random number generation method

Country Status (1)

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GB (1) GB2447243A (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001092640A (en) * 1999-09-21 2001-04-06 Sony Corp Random number generating device
WO2001079989A1 (en) * 2000-04-18 2001-10-25 Advanced Micro Devices, Inc. Method and apparatus for generating random numbers
US20030219928A1 (en) * 2001-12-28 2003-11-27 Semiconductor Energy Laboratory Co., Ltd. Substrate identification circuit and semiconductor device
JP2005044090A (en) * 2003-07-28 2005-02-17 Renesas Technology Corp Random number generator
US20060020647A1 (en) * 2004-07-23 2006-01-26 Simon Harris S Method and apparatus for random-number generator

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001092640A (en) * 1999-09-21 2001-04-06 Sony Corp Random number generating device
WO2001079989A1 (en) * 2000-04-18 2001-10-25 Advanced Micro Devices, Inc. Method and apparatus for generating random numbers
US20030219928A1 (en) * 2001-12-28 2003-11-27 Semiconductor Energy Laboratory Co., Ltd. Substrate identification circuit and semiconductor device
JP2005044090A (en) * 2003-07-28 2005-02-17 Renesas Technology Corp Random number generator
US20060020647A1 (en) * 2004-07-23 2006-01-26 Simon Harris S Method and apparatus for random-number generator

Also Published As

Publication number Publication date
GB0704196D0 (en) 2007-04-11

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