Authentication process

Abstract

Authentication method The present description relates to a method of authenticating (200) a first device (P) to a second device (V), in which a signature of a first analog signal of said first device (P) is used for authentication. Figure for abstract: Fig. 2

Description

Title of the invention: Authentication method Technical field

[0001] The present description relates generally to electronic circuits and devices, and more particularly to the security of electronic circuits and devices. The present description relates more specifically to the implementation of an authentication method allowing, for example, several electronic devices to start a reliable communication. Prior art

[0002] Communication between two electronic devices, or circuits, is often preceded by an authentication phase. During this phase, an authentication process, implemented by the two devices, makes it possible to verify whether these two devices are authorized to communicate with each other.

[0003] Authentication methods are often used during communication between a terminal-type device and peripheral-type electronic equipment or device, for example a consumable or an accessory. The authentication method makes it possible, in this case, to validate the access of the peripheral-type device to the data and / or to functionalities of the terminal-type device. The authentication method is a first means of protection against malicious devices attempting to access data and / or to functionalities of other devices.

[0004] It would be desirable to be able to improve, at least in part, the known authentication methods. Summary of the invention

[0005] There is a need for more secure authentication methods, allowing more reliable authentication of one electronic circuit or device to another electronic circuit or device.

[0006] In particular, there is a need to prevent a clone of an electronic device from being able to authenticate in its place.

[0007] There is a need for electronic circuits and devices implementing more secure authentication methods.

[0008] One embodiment overcomes all or part of the drawbacks of known authentication methods.

[0009] One embodiment provides an authentication method using a signature of an analog signal of an electronic device as an identification means.

[0010] One embodiment provides a method of authenticating a first device to a second device, wherein a signature of a first analog signal of said first device is used for authentication.

[0011] Another embodiment provides a system for authenticating a first device to a second device, in which a signature of a first analog signal of said first device is used for authentication.

[0012] According to one embodiment, said signature corresponds to the temporal evolution of at least one physical quantity associated with said first signal during the implementation of at least one specific operation.

[0013] According to one embodiment, said operation is the implementation of an electronic function or a program.

[0014] According to one embodiment, said signature is obtained by at least one circuit for measuring said analog signal.

[0015] According to one embodiment, said at least one measuring circuit is part of said first device, of said second device, or of a third electronic device external to said first and second devices.

[0016] According to one embodiment, during the implementation of said operation, the first device is in a secure mode.

[0017] According to one embodiment, said second device verifies said signature using at least one signature model.

[0018] According to one embodiment, said second device verifies said signature by comparing it with said at least one signature model.

[0019] According to one embodiment, said second device verifies said signature by extracting data from said signature.

[0020] According to one embodiment, said second device verifies said signature using a neural network.

[0021] According to one embodiment, said neural network has been trained on the basis of data representing signature models.

[0022] According to one embodiment, when said signature is transmitted between the first and second devices, said signature is encrypted.

[0023] According to one embodiment, the authentication method is of the Verifier / Prover type.

[0024] According to one embodiment, the authentication system is of the Verifier / Prover type.

[0025] According to one embodiment, a signature of at least a second analog signal of said first device is used for authentication.

[0026] Another embodiment provides an electronic device adapted to be the first device in the method described above, or in the system described above.

[0027] Another embodiment provides an electronic device adapted to be the second device in the method described above, or in the system described above. Brief description of the drawings

[0028] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0029] [Fig.l] represents an example of an electronic device suitable for implementing the authentication method implementation methods described in relation to Figures 2 and 3;

[0030] [Fig.2] represents a block diagram illustrating a first mode of implementation of a method for authenticating a first device with a second device; and

[0031] [Fig. 3] represents a block diagram illustrating a second mode of implementation of a method for authenticating a first device with a second device. Description of the embodiments

[0032] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0033] For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been represented and are detailed.

[0034] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0035] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made unless otherwise specified to the orientation of the figures.

[0036] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0037] The embodiments described below relate to the implementation of an authentication method for authenticating a first electronic device to a second electronic device, for example, for the purpose of future communication between these first and second devices. These embodiments are, more particularly, authentication methods of the Verifier / Prover type, also called Verifier / Candidate type, in which a verifier device, here the second device, sends data to the prover device, here the first device, so that it can apply a transformation to it. The prover device then returns the result of said transformation to the verifier device so that it can verify it. If the result of the verification is correct, then the prover device is authenticated to the verifier device.

[0038] An authentication system is an electronic system comprising a verification device and a proving device.

[0039] One of the objectives pursued by these embodiments is to propose more secure and more reliable authentication methods, and in particular authentication methods adapted to differentiate an electronic device from one of its clones. A "clone" is an electronic device manufactured to have the same operation / behavior as another device with the aim of taking its place, for example for malicious purposes.

[0040] The solution provided by the embodiments described below is to use a signature of an analog signal from the first device to authenticate it with the second device. The term "signature of an analog signal" refers to the recording of the temporal evolution of one or more physical quantities associated with said analog signal during the implementation, by the first device, of at least one specific operation, such as the implementation of an electronic function or a program. This quantity may be its amplitude in voltage, in current, its frequency, etc., examples are detailed below. According to the embodiments described, this signature is obtained using one or more measurement circuits forming part of the first device, the second device, or a third device external to the first and second devices.This signature is provided to the second device which verifies it, using, for example, one or more signature models. According to a particular embodiment, the second device can use a neural network to verify, for example classify, or even compare, all or part of the signature provided with the signature model(s).

[0041] The use of such an analog signature makes it possible to differentiate an electronic device from one of its clones. Indeed, the temporal evolution of an analog signal does not only depend on the operation implemented by the device, but also depends on the material reality of the device, such as the arrangement of the components electronic components that compose it, manufacturing processes used, etc. Thus, several electronic devices from the same manufacturer will have very similar, even identical, signatures, but a clone will most certainly have a different signature.

[0042] Furthermore, the embodiments described below are particularly suitable for use in any type of system requiring the authentication of two electronic circuits or devices, such as, for example, a system comprising a terminal type device and a peripheral or consumable type device, or such as, for example, a system formed on the same chip comprising several electronic circuits.

[0043] [Fig.l] is a block diagram representing, very schematically, an architecture of an example of an electronic device 100 adapted to implement an authentication method according to one embodiment. The device 100 may be, indifferently, a verification device or a proving device of said authentication method.

[0044] According to one example, the electronic device 100 comprises a processor 101 (CPU) adapted to implement different processing of data stored in memories and / or provided by other circuits of the device 100. According to one embodiment, the processor 101 is adapted to implement an authentication method.

[0045] According to one example, the electronic device 100 further comprises different types of memories 102 (MEM), including, for example, a non-volatile memory, a volatile memory, and / or a read-only memory. Each memory 102 is adapted to store different types of data.

[0046] According to one example, the electronic device 100 further comprises a secure element 103 (SE) adapted to process sensitive and / or secret data. The secure element 103 may comprise its own processor(s), its own memory(s), etc. According to one embodiment, the secure element 101 is adapted to implement an authentication method.

[0047] According to one example, the electronic device 100 may further comprise interface circuits 104 (IN / OUT) adapted to send and / or receive data originating from outside the device 100. The interface circuits 104 may further be adapted to implement a data display, for example, a display screen.

[0048] According to one example, the electronic device 100 further comprises different circuits 105 (FCT1) and 106 (FCT2) adapted to perform different functions. For example, the circuits 105 and 106 may comprise measurement circuits, data conversion circuits, etc. According to one embodiment, the circuits 105 and 106 may comprise one or more circuits adapted to implement an authentication method. According to a particular embodiment, the circuits 105 may comprise measurement circuits, analog-digital converters, calculation circuits, etc.

[0049] According to one example, the electronic device 100 further comprises one or more data buses 107 adapted to transfer data between its different components.

[0050] According to one embodiment, a system comprising two devices of the type of device 100 can be adapted to implement an authentication method according to one embodiment. Such a system is called an authentication system.

[0051] [Fig.2] is a block diagram illustrating a first mode of implementation of an authentication method 200 making it possible to authenticate a first electronic device P, also called a proving device P, with a second electronic device V, also called a verifying device V. In other words, the authentication method 200 is adapted to be implemented by an authentication system comprising the devices P and V. According to one embodiment, the devices P and V are of the type of the device 100 described in relation to [Fig.l].

[0052] As described previously, the authentication method 200 is a Verifier / Prover type method.

[0053] At an initial step 201 (Send Challenge), the authentication method 200 begins, for this the verifier device V selects a data item C, also called challenge data C (Challenge Data), or challenge C, to send it to the prover device P. According to an example, the challenge C is a set of binary data.

[0054] According to one embodiment, the data C is chosen from a finite group of data making it possible to implement the authentication method 200, according to one embodiment the size of the group is determined by the format of the data that it comprises, for example 128-bit binary data. According to one example, the group may comprise initialization data for the specific operation implemented by the proving device P, for example generated randomly or pseudo-randomly using a leakage model. According to one example, when the specific operation is the use of an AES type encryption algorithm, the data may be pairs of data comprising an input value and an encryption key. According to another example, the group may comprise encrypted data.

[0055] At a step 202 (Receive Challenge), following step 201, the proving device P receives the data C and can begin to implement the authentication method on its side.

[0056] At a step 203 (Operation), following step 202, the proving device P uses the data C to implement a specific operation. According to a mode of implementation, this operation is the implementation of an electronic function, such as a specific circuit of the device P, or of a program. According to one embodiment, this operation is an operation comprising an operating diagram specific to the proving device P, i.e. dependent on the structure of the proving device P or its manufacturing process. According to one embodiment, this operation is an operation which leaks data. In addition, the use of the data C must have an influence on the operation and / or the result of the operation.

[0057] According to one example, the specific operation consists of the application of a data encryption algorithm, for example by using the data C as an encryption key, or for example by applying this algorithm to the data C. According to a particular example, the specific operation consists of the application of an algorithm of the AES (Advanced Encryption Standard) type.

[0058] According to a particular embodiment, during the implementation of the specific operation, the proving device P is in a secure mode, allowing it to be less sensitive to external attacks.

[0059] In a step 204 (Curve), following step 203, one or more measurement circuits of the proving device P are implemented to obtain a signature Op_Curve of at least one analog signal of the proving device P during the implementation of the specific operation of step 203. Here, the signature of an analog signal is called the temporal evolution of one or more physical quantities associated with said analog signal during a given duration. In the present case, the signature Op_Curve of the analog signal is recorded during the implementation of the specific operation. To obtain such a signature, one or more analog signals can be used, separately or in combination. According to one embodiment, the measurement circuit(s) of the device P can measure the signature of one or more analog signals.

[0060] According to a first example, the analog signal(s) measured by the measuring circuits of the device P may come from analog circuits of the device P, such as amplifiers, oscillators, timing circuits, and / or delay circuits. In this case, the measuring circuits may make it possible to measure the time evolution of the voltage, current, frequency, and / or phase shift of these analog signals. Here is a non-exhaustive list of analog signals that may be used in this case: - an internal supply voltage of the proving device P; - an internal clock signal of the proving device P; - an analog signal from an interface circuit of the proving device P; and / or - an analog signal from a RAM or non-volatile memory of the proving device P.

[0061] According to a second example, the analog signal(s) measured by the measuring circuits of the device P may come from the power supply of the various circuits making up the proving device P. Thus, the power supplies concerned may be the power supplies of a processor (CPU), of one or more memories, or even the general power supply of the device P. In this case, the measuring circuits may make it possible to measure the temporal evolution of the voltage or current of these power supplies.

[0062] According to a third example, the analog signal(s) measured by the measurement circuits of the device P may originate from the activity of transistors included in the circuits making up the device P. Thus, the transistors concerned may be transistors of the processor, transistors of circuits implementing particular functionalities, such as the circuits 105 described in relation to [Fig.l], or even transistors forming part of the chip forming the device P. In this case, the measurement circuits may make it possible to measure the temporal evolution of the emission of photons from these transistors, using, for example, avalanche effect diodes triggered by an individual photon and associated calculation methods.The measuring circuits can, in addition, make it possible to measure the temporal evolution of the electromagnetic emissions of these transistors, using, for example, micro-coils on a metal layer (micro-self on metal layer).

[0063] Once the Op_Curve signature of the analog signal(s) is obtained, the proving device P sends it to the verifying device. According to one embodiment, the proving device P can send said Op_Curve signature securely, for example by encrypting it.

[0064] At a step 205 (Receive Curve), following step 204, the verifier device V receives the signature of the prover device P.

[0065] At a step 206 (SPA), following step 205 and step 207 (Model), the verifier device V verifies the received signature Op_Curve by verifying it using one or more known signature models, for example by comparing it to one of these models, or by extracting data from this signature. This verification can be implemented, for example, by using a simple power or current analysis (SPA - Simple Power Analysis), or, for example, an attack by "behavior models" (Template attacks) for which data extracted from a curve make it possible to find the curve model used. To implement such an attack, curve models are generated by carrying out tests on thousands of reference circuits, and by detecting points of interest on these curves, or by classifying in decreasing order of probability the possible extracted, or leaked, values.

[0066] According to a preferred example, the verification of step 206 can be implemented using artificial intelligence, such as a neural network trained from the model(s). The use of a neural network has the advantage of being more difficult to understand for someone who wishes to understand step 206. Indeed, the analysis of the structure of a circuit implementing a neural network does not make it possible to understand the operation(s) that it executes.

[0067] Furthermore, in step 206, according to a variant, the verification device V can take into account the data C.

[0068] At the end of step 206, the verifier device V obtains a result data R.

[0069] At step 207, preceding step 206, the signature model(s) have been obtained, for example by obtaining signatures with several devices coming from the same manufacturing batch in a factory of several proving devices of the type of device P.

[0070] At a step 208 (BYTE), optional and subsequent to step 206, the result data R is modified, for example by being truncated, into a data item T(R).

[0071] At a step 209 (Ok?), following step 208, the verification device V uses the data T(R) to conclude on the authentication, or not, of the proving device P. In the case where step 208 is not implemented, it is the result data R which is used at step 209.

[0072] As stated previously, an advantage of using a signature of one or more analog signals of an electronic device to authenticate it is that this can make it possible to differentiate a clone from a genuine device.

[0073] [Fig. 3] is a block diagram illustrating a first mode of implementation of an authentication method 300 making it possible to authenticate a first electronic device P, also called a proving device P, with a second electronic device V, also called a verifying device V. In other words, the authentication method 300 is adapted to be implemented by an authentication system comprising the devices P and V. According to one embodiment, the devices P and V are of the type of the device 100 described in relation to [Fig. 1].

[0074] The authentication method 300 has elements similar to the authentication method 200 described in relation to [Fig. 2]. The elements common to the methods 200 and 300 are not described in detail again below, and only the differences between the devices 200 and 300 are highlighted.

[0075] More particularly, in the authentication method 300, the measurement circuits making it possible to obtain the signature of one or more analog signals from the proving device are not arranged on board the proving device P, but on board the verifying device V.

[0076] Thus the authentication method 300 comprises the following successive steps: - an initial step 301 (Send Challenge) identical to step 201 of method 200; - a step 302 (Receive Challenge) identical to step 202 of method 200; - a step 303 (Operation) similar to step 203 of method 200; - a step 304 (Curve) similar to step 204 of method 200 but implemented by the verification device V; - a step 305 (SPA) identical to step 206 of method 200; - a step 306 (Model) identical to step 207 of method 200; - a step 307 (BYTE) identical to step 208 of method 200; and - a step 308 (Ok?) identical to step 209 of method 200.

[0077] In the case of the method 300, the step 303 further comprises sending data to the verifying device indicating that the operation has been successfully implemented, or, allowing the verifying device V to verify that this operation has been successfully carried out. According to an example, the specific operation of the step 203 may be an operation of encrypting the data C with an encryption key, and the response sent may comprise the encrypted data.

[0078] Various embodiments and variants have been described. The person skilled in the art will understand that certain features of these various embodiments and variants could be combined, and other variants will appear to the person skilled in the art. In particular, the measurement circuits for obtaining the signature Op_Curve may not be part of the proving device P, nor of the verifying device V, but of an external device. This is, for example, the case when the devices V and P are circuits arranged on the same chip, the measurement circuits may be arranged on the same chip without being part of either the device V or the device P.

[0079] In addition, the authentication method could comprise an operation of authenticating the verifier device V with the prover device P before proceeding with sending the challenge data C.

[0080] Finally, the practical implementation of the embodiments and variants described is within the reach of those skilled in the art from the functional indications given above.

Claims

Claims

1. A method of authenticating (200; 300) a first device (P) to a second device (V), wherein a signature of a first analog signal of said first device (P) is used for authentication.

2. Method according to claim 1, in which said signature (Op_Curve) corresponds to the temporal evolution of at least one physical quantity associated with said first signal during the implementation of at least one specific operation comprising an operating diagram specific to the first device (P).

3. A method according to claim 2, wherein said operation is the implementation of an electronic function or a program.

4. Method according to any one of claims 1 to 3, in which said signature (Op_Curve) is obtained by at least one circuit for measuring said analog signal.

5. A method according to claim 4, wherein said at least one measuring circuit is part of said first device (P), said second device (V), or a third electronic device external to said first and second devices (P, V).

6. Method according to any one of claims 1 to 5, wherein, during the implementation of said operation, the first device (P) is in a secure mode.

7. Method according to any one of claims 1 to 6, wherein said second device (V) verifies said signature (Op_Curve) using at least one signature model.

8. Method according to any one of claims 1 to 7, wherein said second device (V) verifies said signature (Op_Curve) by comparing it with said at least one signature model.

9. A method according to any one of claims 1 to 8, wherein said second device (V) verifies said signature (Op_Curve) by extracting data from said signature (Op_Curve).

10. Method according to claim 9, wherein said second device (V) verifies said signature (Op_Curve) using a neural network.

11. The method of claim 10, wherein said neural network has been trained based on data representing signature patterns.

12. A method according to any one of claims 1 to 11, wherein, when said signature (Op_Curve) is transmitted between the first and second devices (P, V), said signature (Op_Curve) is encrypted.

13. Method according to any one of claims 1 to 12, for Verifier / Prover type authentication.

14. Method according to any one of claims 1 to 13, wherein a signature (Op_Curve) of at least a second analog signal of said first device (P) is used for authentication.

15. System for authenticating a first device (P) to a second device (V), in which a signature (Op_Curve) of a first analog signal of said first device (P) is used for authentication.

16. Electronic device adapted to be the first device (P) in the method according to any one of claims 1 to 14.

17. Electronic device adapted to be the second device (V) in the method (200; 300) according to any one of claims 1 to 14.

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