EP3437246A1 - Verfahren zum erzeugen eines kryptographischen schlüssels, vorrichtung und elektrisches system - Google Patents
Verfahren zum erzeugen eines kryptographischen schlüssels, vorrichtung und elektrisches systemInfo
- Publication number
- EP3437246A1 EP3437246A1 EP17702345.4A EP17702345A EP3437246A1 EP 3437246 A1 EP3437246 A1 EP 3437246A1 EP 17702345 A EP17702345 A EP 17702345A EP 3437246 A1 EP3437246 A1 EP 3437246A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- electrical component
- sections
- cryptographic key
- types
- measurement data
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
- H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
- H04L9/0861—Generation of secret information including derivation or calculation of cryptographic keys or passwords
- H04L9/0866—Generation of secret information including derivation or calculation of cryptographic keys or passwords involving user or device identifiers, e.g. serial number, physical or biometrical information, DNA, hand-signature or measurable physical characteristics
Definitions
- the present invention relates to a method for generating a cryptographic key, a corresponding device and an electrical system
- DE 199 63 329 A1 shows, for example, a system in which sensors have cryptographic keystores to secure communication with a central controller.
- the present invention discloses a method having the features of claim 1, a device having the features of claim 12, and an electrical system having the features of claim 13.
- a method for generating a cryptographic key from in each case one measured value to a number, that is to say one or more, of types of measurement data of an electrical component, e.g. of a MEMS system comprising the steps of: determining the global distributions for each of the types of measurement data to the electrical device, e.g. by measurements over a representative section over the entirety of the corresponding electrical components, calculating sections of the global distributions in such a way that the occurrence probabilities for measured values in the individual sections are constant, ie at one
- the measured value with the same probability in all sections may lie, and generating the cryptographic key based on the measurements of the electrical component and the corresponding portions of a respective measured value.
- An apparatus for generating a cryptographic key from in each case a measured value to a number of types of measurement data of an electrical component with a data acquisition interface, which is designed to detect the measured values, and a computing device, which is designed to carry out a method according to the invention.
- An electrical system with a control device which is a first
- the method provides that for each feature, e.g. the frequency of a mode of a MEMS system, the global distribution is determined and divided into sections with equal occurrence probabilities. Each section is then assigned a unique identifier. The number of generated bits per feature thus depends on the number of sections. In order to create a specific binary key, all features are then determined and the respective identifier is used in accordance with the section in the global distribution in which the measured value of the respective feature is located.
- Section width is of particular importance. If the sections are chosen too narrow, there will be a large number of bit flips. That is, the measurement of a feature at different times or under different environmental conditions provides different bit combinations. If the section width is set too large, the safe distinction within a feature becomes more difficult as the number of sections decreases. In addition, this shortens the generated key length.
- Critical to the security of cryptographic keys in cryptographic procedures is the key length along with the entropy within the key. In a sense, entropy is a measure of the randomness of the appearance of signs or character combinations within the key. The entropy is maximal if the probability for the occurrence of all characters or character combinations is the same. Otherwise, the can be
- Compress keys which reduces the effective key length and thus the security of the key. If the sections in the global distribution are all the same size, this is exactly the case. Since the features are usually normally distributed, a constant width of the sections means that different identifiers have different ones
- the global distribution is divided into sections with identical probability of occurrence. So everyone has
- Cryptographic keys have the same probability of occurrence and the generated cryptographic keys have maximum entropy. As a result, the length of the generated cryptographic keys actually corresponds to their security.
- the types of measurement data of the electrical component may include sizes of the electrical component which have a predetermined stability, ie maximum deviation, in the component over the operating temperature range and the service life. This allows a secure reconstruction of the key among various
- the types of measurement data may at least comprise an electrical component embodied as a MEMS system:
- Capacitance values of the electrodes of the MEMS system are Capacitance values of the electrodes of the MEMS system.
- a local standard deviation that is to say the standard deviation of individual electrical components. Since the individual types of measurements in the device are stable over the operating temperature range and lifetime, so does the local standard deviation.
- Standard deviation is to be determined separately for each feature and depends on e.g. Signal-to-noise ratio, temperature influence, etc. It may be based on a few patterns, e.g. 1 - 100 can be determined. This local
- Standard deviation thus characterizes the scattering of a single electrical component and can therefore be used to define the width of the section.
- a width for each of the two portions directly to the right and left of the center of the respective global distribution may be determined as the local standard deviation multiplied by an optimization factor, wherein the optimization factor is between one and ten, and
- This value can e.g. be determined experimentally.
- the optimization factor ensures that the sections are chosen wide enough so that when measuring at one of the
- Bit Error Rate that is the number of bit-flips per generated key in relation to its total length, is minimal.
- the bit error rate is dependent on the average probability of the flipping of a bit as well as the total length of the generated key.
- Optimization factor causes a lower probability for bit flips with a shorter key length and vice versa.
- the widths for the other portions of the global distribution may be chosen such that the measured values are the "
- Occurrence probabilities in the sections are approximately identical to the occurrence probabilities in the two sections directly to the right and left of the mean and the middle point, respectively.
- the entire global distribution is covered with sections.
- Sections falls.
- the key can be determined based on the individual sections, or the respective bit sequence assigned to them, of all types of measurement data into which the respective measured value falls.
- error correction methods may be applied to the individual measured values and / or the generated cryptographic key.
- error correction techniques By using error correction techniques, readings that were outside their usual range during a measurement can be detected and corrected. However, the number of available bits for the cryptographic key is correspondingly reduced. For example, as
- the cryptographic key may be generated external to it, and the
- a controller can record the communication with the respective electrical component without the key having to be known beforehand.
- Fig. 2 is a block diagram of an embodiment of a device according to the invention.
- FIG. 3 is a block diagram of an embodiment of an electrical system according to the invention.
- FIG. 4 shows a diagram of an embodiment of a global distribution according to the invention.
- FIG. 1 shows a Georgianagramm of an embodiment of a method according to the invention for generating a cryptographic
- the cryptographic key 7, 18-20 is thereby determined based on a respective measured value 4, 5, 15-17 for a number of types of measurement data of an electrical component 3, 12-14.
- the types of measured values thereby identify different physical quantities which can be detected or measured on or in the electrical component 3, 12-14.
- the electrical component 3, 12-14 may be e.g. to trade a MEMS system.
- the types of measurement data may e.g. Frequencies of the fundamental modes of the MEMS system, frequencies of the parasitic modes of the MEMS system, capacitance values of the electrodes of the MEMS system, and / or quadrature movements of the MEMS system be. It is understood that this listing is merely exemplary and not exhaustive.
- the global distribution may e.g. by measurements for each of the types of measurement data at a plurality of
- Devices e.g. 100-1000 or more.
- step S2 sections 32-39 are now calculated in step S2 such that the occurrence probabilities for measured values 4, 5, 15-17 of the respective type of measurement date in the individual sections 32-39 are global, that is to say over the entirety of the electrical components 3, 12 - 14, considered constant.
- the cryptographic key 7, 18 - 20 is based on the measured values 4, 5, 15 - 17 of the electrical component 3, 12 - 14, ie
- a local standard deviation can be determined for one type of electrical components 3, 12-14 or for a single component in each case.
- the local standard deviation indicates the spread or standard deviation of a measured value 4, 5, 15 - 17, which is repeatedly measured on a single electrical component 3, 12 - 14.
- a width for the two sections 32, 33 directly to the right and left of the center of the respective global distribution 30 can be determined. For example, this width may be multiplied by the local standard deviation multiplied by a
- the optimization factor can be used for this purpose e.g. be determined experimentally, and be designed such that measurements of a type of measurement data with a predetermined probability, e.g. of more than 99% or 99.9% or 99.99% repeatedly in the same section.
- a predetermined probability e.g. of more than 99% or 99.9% or 99.99% repeatedly in the same section.
- an optimization factor of 5 was determined for MEMS sensors. This offers a sufficiently large number of sections, ie different bit sequences for the cryptographic key 7, 18 - 20, and a sufficiently high one
- the widths for the further sections 34-39 can be determined. These are determined in such a way that for measured values 4, 5, 15-17 the
- Occurrence probabilities in sections 34-39 are approximately identical to the occurrence probabilities in the two sections 32, 33 directly to the right and left of the center.
- each of the sections 32-39 can be assigned a unique value 40-47, ie a bit sequence. If a measured value 4, 5, 15 - 17 is now recorded for the electrical component 3, 12 - 14 for each of the types of measured data, this can also be the case
- Measured value 4 5, 15 - 17 corresponding bit sequence can be determined.
- the cryptographic key 7, 18-20 can be determined.
- the unique values 40-47 may be individual Measured values 4, 5, 15 - 17 are strung together or combined with each other in a predetermined sequence.
- the global distribution 30 is subdivided into sections 32-39 having an identical probability of occurrence (see FIG. 4).
- all bits or bit combinations in the generated cryptographic keys 7, 18-20 have the same occurrence probability and the generated ones
- Cryptographic keys 7, 18 - 20 have maximum entropy. As a result, the length of the generated cryptographic keys 7, 18-20 actually corresponds to their security.
- the method of the invention may e.g. be carried out in the manufacture of an electrical component 3, 12 - 14 and the
- corresponding cryptographic keys 7, 18 - 20 in the respective electrical component 3, 12 - 14 are stored.
- a system which knows the identifiers or unique values 40 - 47 and the corresponding types of measurement data can then carry out the same procedure and reconstruct the respective cryptographic key 7, 18 - 20.
- the cryptographic key 7, 18 - 20 can be stored in its production during the production of the electrical component 3, 12 - 14 in a component database or the like.
- the cryptographic key 7, 18-20 can be loaded as needed and used for communication.
- FIG. 2 shows a block diagram of an embodiment of a device 1 according to the invention, which has a data acquisition interface 2.
- the data acquisition interface 2 is used to acquire measured values 4, 5 from the electrical component 3. Two measured values 4, 5 are shown in FIG. 2, with more (indicated by three dots) or fewer measured values being possible. Each of the measured values 4, 5 corresponds to a type of measured data.
- the electrical component 3 can be a MEMS sensor or actuator 3 and the measured data can be the frequencies of the basic modes of the MEMS sensor or actuator 3, the frequencies of the parasitic modes of the MEMS sensor or actuator 3, capacitance values of the electrodes of the MEMS sensor or actor 3 and / or quadrature movements of the MEMS sensor or actuator 3 be.
- the data acquisition interface 2 can have corresponding measuring elements which are necessary for detecting measured values 4, 5 from the electrical component 3.
- the data acquisition interface 2 may be designed for communication with the electrical component 3, that is to say be a bus interface, for example.
- the electrical component 3 detects the measured values
- a computing device 6 which generates and outputs a cryptographic key 7 from the measured values 4, 5.
- the computing device 6 may e.g. an ASIC, a microcontroller, or any other suitable digital circuit.
- the measured values 4, 5 are processed in accordance with the method of FIG. 1 in order to generate the cryptographic key 7.
- a memory may be provided in which the computing means 6 stores, for each of the types of measurement data, the corresponding global distribution 30 or sections 32-39 and the corresponding identifiers 40-47 (see FIG. 4).
- the computing device 6 can thus identify a corresponding section 32-39 for each measured value 4, 5 and select the respective identifier 40-47 as part of the cryptographic key 7.
- the order in which the individual identifiers 40-47 can be combined to form the cryptographic key 7 can be determined in advance.
- FIG. 3 shows a block diagram of an electrical system designed as an automation network 10.
- the automation network 10 has a central control device 10 which evaluates individual sensors 12, 13 and actuates actuators 14.
- the sensors 12, 13 and actuators 14 are merely exemplary. Further electrical components are indicated by three points.
- the control device 10 has a first communication interface.
- the sensors 12, 13 and the actuator 14 each have a second communication interface _ ⁇
- Communication interface 22 - 23 which represent the opposite sides for the first communication interface 21.
- the communication interfaces 21, 22 - 23 are designed as bus interfaces of a fieldbus system, thus allowing digital data communication between the control device 10, the sensors 12, 13 and the actuator 14. To this data communication
- the device 9 is provided for this purpose, which device is coupled to the individual sensors 12, 13 and the actuator 14 in order to record these measured values 15-17. It is understood that the device 9 can receive any number of measured values of different types of measurement data from the sensors 12, 13 and the actuator 14 and the
- Measured values 15 - 17 are shown by way of example only.
- the device 9 has a computing device 26, which the
- Cryptographic keys 18-20 are determined according to the method of FIG. Furthermore, the computing device 26 may be designed in accordance with the computing device 6 of FIG. 2.
- the computing device 26 If the computing device 26 has determined the cryptographic keys 18-20, it transmits them to the control device 11, which uses the cryptographic keys 18-20 for communication with the sensors 12, 13 and the actuator 14.
- the cryptographic keys 18-20 may be e.g. in a volatile memory (not shown separately). They are thus generated again each time the control device 11 is started. Thus, it is possible to prevent the cryptographic keys 18-20, e.g. from a non-volatile memory of a stolen
- Control device 11 are read.
- the computing device 26 may also use the cryptographic keys 18-20 once, for example when the sensors 12, 13 and the actuator 14 are being put into operation.
- the cryptographic keys 18-20 can then be stored, for example, in a database and used to communicate with them.
- the transmission of the cryptographic keys 18 - 20 itself should not be in plain text. Rather, they are for protection Listening Precautions taken to transfer the cryptographic keys 18-20.
- an asymmetric encryption method can be used in which the cryptographic keys 18 - 20 the individual electrical
- an ASIC in the individual electrical components 12-14 have the functions for generating and using the cryptographic keys 18-20.
- the device 9 is also arranged in the control device 11 and at least partially as a component of e.g. a processor or operating program of the controller 11 may be formed.
- FIG. 4 shows a diagram of a global distribution 30 for illustrating the division of the global distribution 30 into different broad sections
- the global distribution 30 corresponds to a normal distribution whose maximum lies in the middle of the diagram. This normal distribution 30 may be e.g. over a large number, e.g. between 100 and 1000, to be determined by electrical components.
- the diagram also shows a local distribution 31 which is located in a section 33 of the global distribution 30.
- This local distribution 30 represents the dispersion between measured values of a single type of measurement data on repeated measurements on the same electrical component.
- the size ratio between the local distribution 31 and the section 33 is selected only schematically.
- the size or width of the sections 32 and 33 is calculated in one embodiment from the standard deviation of the local distribution 31. To do this, it is multiplied by an optimization factor, e.g. can be determined experimentally. For example, the optimization factor may be 5
- Standard deviation of local distribution 31 Given the global distribution is known, the probability of occurrence of a measured value in one of the sections 32, 33 can be determined. The further regions 34-39 are then determined to be the same, respectively
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- Engineering & Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Lock And Its Accessories (AREA)
- Storage Device Security (AREA)
- Testing Or Calibration Of Command Recording Devices (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102016205183.0A DE102016205183A1 (de) | 2016-03-30 | 2016-03-30 | Verfahren zum Erzeugen eines kryptographischen Schlüssels, Vorrichtung und elektrisches System |
PCT/EP2017/051646 WO2017167465A1 (de) | 2016-03-30 | 2017-01-26 | Verfahren zum erzeugen eines kryptographischen schlüssels, vorrichtung und elektrisches system |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3437246A1 true EP3437246A1 (de) | 2019-02-06 |
Family
ID=57944406
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP17702345.4A Withdrawn EP3437246A1 (de) | 2016-03-30 | 2017-01-26 | Verfahren zum erzeugen eines kryptographischen schlüssels, vorrichtung und elektrisches system |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP3437246A1 (de) |
CN (1) | CN108886467A (de) |
DE (1) | DE102016205183A1 (de) |
WO (1) | WO2017167465A1 (de) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN114448613B (zh) * | 2021-12-21 | 2024-01-26 | 北京邮电大学 | 通信***的物理层密钥生成方法、装置和电子设备 |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19963329A1 (de) | 1999-12-27 | 2001-07-12 | Siemens Ag | Sicherung von Sensordaten |
EP1972090B1 (de) * | 2005-12-14 | 2015-08-19 | Nxp B.V. | Onchip-schätzung von schlüsselextraktionsparametern für physische token |
CN101924600B (zh) * | 2010-07-30 | 2013-01-02 | 中国科学院软件研究所 | 检测密码模块抵御能量分析攻击能力的方法 |
CN103583013B (zh) * | 2011-06-02 | 2016-04-13 | 三菱电机株式会社 | 密钥信息生成装置以及密钥信息生成方法 |
DE102011081421A1 (de) * | 2011-08-23 | 2013-02-28 | Siemens Ag | System zur sicheren Übertragung von Daten und Verfahren |
US10216965B2 (en) * | 2014-01-08 | 2019-02-26 | Stc.Unm | Systems and methods for generating physically unclonable functions from non-volatile memory cells |
US9667419B2 (en) * | 2014-01-10 | 2017-05-30 | Robert Bosch Gmbh | System and method for cryptographic key identification |
-
2016
- 2016-03-30 DE DE102016205183.0A patent/DE102016205183A1/de not_active Withdrawn
-
2017
- 2017-01-26 EP EP17702345.4A patent/EP3437246A1/de not_active Withdrawn
- 2017-01-26 WO PCT/EP2017/051646 patent/WO2017167465A1/de active Application Filing
- 2017-01-26 CN CN201780020409.1A patent/CN108886467A/zh active Pending
Also Published As
Publication number | Publication date |
---|---|
DE102016205183A1 (de) | 2017-10-05 |
CN108886467A (zh) | 2018-11-23 |
WO2017167465A1 (de) | 2017-10-05 |
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