A wireless charging system and method resistant to side channel attacks

Abstract

The present invention discloses a wireless charging system and method that is resistant to side-channel attacks, comprising a core controller and a hardware encryption module, an active communication function module, a feedback module, and a current limiting module. The core controller and hardware encryption module are used to encrypt transmitted data, the active communication function module is used to obtain information about the wireless charging transmitter and the wireless charging receiver, and transmit the information to the core controller and the hardware encryption module to implement the encryption process, the feedback module is used to collect the transmission current of the wireless charging transmitter and feed it back to the core controller and the hardware encryption module, dividing the charging process into a constant current charging stage, a constant voltage charging stage, and other stages; the current limiting module is used to be enabled when the wireless charging is in the constant voltage charging stage and other stages, reducing the information in the wireless charging energy transmission. The present invention proposes a method of limiting the current at the wireless charging receiver to suppress changes in the wireless charging current, thereby preventing wireless charging energy trajectory side-channel attacks caused by leakage of the user's energy trajectory.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless charging, and in particular to a wireless charging system and method that are resistant to side channel attacks. Background Art

[0002] In recent years, wireless charging systems have developed rapidly, becoming widely used in mobile devices, electric vehicles, and industrial production processes, greatly facilitating people's lives and travel. With the expansion of wireless charging applications, discussions on wireless charging security have intensified, with a key focus being the cryptographic authentication of wireless charging users. The Wireless Power Consortium (WPC) has announced that the new Qi 1.3 standard will mandate strong cryptographic authentication for wireless charging devices. If authentication fails, the wireless charging system will refuse charging or charge at a lower power. Currently, academics are leaning towards using chaotic encryption to securely authenticate wireless charging user information (G. Kaddoum, "Wireless Chaos-Based Communication Systems: A Comprehensive Survey," IEEE Access, vol. 4, pp. 2621-2648, 2016). Although the principle of chaotic encryption is promising, practical testing of this method is limited, and widespread application requires further verification.

[0003] In addition to user authentication, side-channel attacks on wireless charging have also gradually attracted people's attention. Alexander et al. found that by analyzing the changes in wireless charging current through neural networks, they can obtain information about the web pages visited by users. This is because the energy trajectory when loading different web pages is different (Alexander S.La Cour, Khurram K.Afridi, and G.Edward Suh, "Wireless Charging Power Side-Channel Attacks," arXiv:2105.12266v2[cs.CR]). In constant voltage charging mode, the user side will give priority to using wireless charging energy rather than the energy stored in the phone, so the energy used by the user will be directly exposed to the wireless charging energy trajectory. Therefore, not only the security of the communication channel, but also the information leakage of the energy transmission channel needs to be considered. (Publication No.: CN110768779A ) proposed a side channel protection method for chip power supply, but the wireless charging side channel is different from the chip power supply in many ways, mainly reflected in:

[0004] 1. Wireless charging is a high-power energy transmission method, and its transmission efficiency is an important consideration. The energy attenuation caused by direct filtering will reduce the efficiency of energy transmission.

[0005] 2. Wireless charging side channel information leakage is primarily reflected in current rather than voltage, while chip power supply side channel protection focuses primarily on voltage protection. For these reasons, wireless charging energy side channel protection differs significantly from chip power supply side channel protection.

[0006] Based on the research of the above-mentioned paper, this invention proposes a new encryption protocol based on traditional asymmetric encryption methods, which can effectively protect user identity privacy and prevent unauthenticated users from stealing energy. At the same time, a constant current device is used at the receiving end of the infinite charging energy to limit the current change to a small range to prevent side-channel attacks of wireless charging energy. Summary of the Invention

[0007] The purpose of the present invention is to provide a wireless charging module and a secure software and hardware encryption method, which adopts the national secret SM2 / SM3 algorithm to alleviate the problem that the existing wireless charging system has low security and user information is easily stolen.

[0008] To achieve the above objectives, the technical solution of the present invention is: a wireless charging system resistant to side channel attacks, the system comprising: a core controller and a hardware encryption module, an active communication function module, a feedback module and a current limiting module;

[0009] The core controller and hardware encryption module are used to encrypt transmission data, and realize wireless charging energy transmission and encrypted identity authentication that are resistant to physical attacks through an encrypted communication protocol; the encrypted communication protocol includes asymmetric encryption and digest calculation methods. Wireless charging energy transmission requires a handshake and two-way authentication between the charging parties before it can proceed;

[0010] The active communication function module is used to communicate with the wireless charging transmitter and the wireless charging receiver, obtain information from the wireless charging transmitter and the wireless charging receiver, and transmit it to the core controller and the hardware encryption module to implement the encryption process. At the same time, the encrypted wireless charging receiver information is forwarded to the wireless charging transmitter and the wireless charging transmitter information is forwarded to the wireless charging receiver, thereby realizing a closed loop of encrypted wireless charging information transmission.

[0011] The feedback module is used to collect the transmission current of the wireless charging transmitter and feed it back to the core controller and the hardware encryption module so that the core controller and the hardware encryption module can perform energy control. According to the size and change of the charging current, the charging process is divided into a constant current charging stage, a constant voltage charging stage and other stages;

[0012] The current limiting module is used to be enabled when the wireless charging is in the constant voltage charging stage and other stages, reducing the change information of the current and voltage in the wireless charging energy transmission to prevent side channel attacks on the wireless energy transmission system.

[0013] Furthermore, the communication between both parties of the wireless charging is carried out in an asymmetric encryption form, and the wireless charging transmitter uses a digest value authentication method to authenticate the identity of the wireless charging receiver.

[0014] Furthermore, the core controller and hardware encryption module are based on the collaborative encryption of software-controlled encryption and hardware-accelerated computing. The software-controlled encryption adopts national secret-level security encryption algorithms, including SM2 and SM3 algorithms. The SM2 algorithm is used for asymmetric encryption of two-way communication, and the SM3 algorithm is used for summary calculation of user identity authentication; the hardware-accelerated computing is asymmetric encryption calculation and summary calculation within the finite field of elliptic curves, and data is transmitted through the AXI bus, which can effectively improve the encryption computing speed and maximum concurrency.

[0015] Furthermore, the wireless charging system also includes a wireless transceiver function module, which is a general term for the wireless charging transmitter and the wireless charging receiver. The wireless charging transmitter includes a transmitter module controller, an inverter module and a transmitter coil connected in sequence. The transmitter coil is connected to the transmitter module controller through a feedback module. The transmitter module controller realizes serial communication with the core controller and the hardware encryption module; the wireless charging receiver includes a receiver module controller, a rectifier module and a receiver coil connected in sequence. The rectifier module is also connected to the receiver coil through a current limiting module; the receiver module controller realizes serial communication with the core controller and the hardware encryption module.

[0016] Furthermore, the current limiting module uses a large load in parallel with a small capacitor, so that when the voltage is within a certain range, the change in current can be ignored, thereby preventing the current jump from leaking the energy information used by the user.

[0017] Furthermore, the core controller and hardware encryption module integrate an improved wireless charging identity authentication and charging configuration protocol. Based on the Qi wireless charging protocol, it adds the client and server two-way authentication and dual certificate authentication content of the national encryption protocol, as well as repeated queries on user fields.

[0018] Furthermore, the wireless transceiver function module includes a transmission frequency described by the Qi wireless charging protocol, and the resonant frequency is controlled within the range of 4.3KHz.

[0019] Furthermore, the core controller and the hardware encryption module also include an external memory, and the certificate chain required for identity authentication will be stored separately in the external memory, and the core controller and the hardware encryption module access it through a bus.

[0020] The present invention also provides a wireless charging method resistant to side channel attacks, the method comprising the following steps:

[0021] S1, the core controller and the hardware encryption module actively search for external devices to be charged until a stop search instruction is received or at least one device to be charged is found;

[0022] S2. After step S1 is completed, if the core controller and the hardware encryption module search for at least one device to be charged, they actively send an identity authentication request through the active communication function module to request the identity information and charging configuration information of the device to be charged. This information is encrypted using the private key d in the core controller and the hardware encryption module;

[0023] S3. The device to be charged calculates its identity information through a hash value, encrypts it with the charging configuration information using the public key Q, and sends it to the core controller and hardware encryption module. After the core controller and hardware encryption module pass the identity authentication, they can configure the charging power and charging mode.

[0024] S4. The core controller and hardware encryption module complete configuration and perform wireless charging energy transmission according to the configured power. During the charging process, the transmission current of the wireless charging transmitter is collected through the feedback module and fed back to the core controller and hardware encryption module. Based on the size and change of the charging current, the charging process is divided into a constant current charging stage, a constant voltage charging stage, and other stages. When the wireless charging is in the constant voltage charging stage and other stages, the current limiting module reduces the information in the wireless charging energy transmission to prevent side channel attacks on the wireless energy transmission system.

[0025] Furthermore, when a wireless charging is completed, the core controller and the hardware encryption module will record: the public key encryption result of the identity hash value of the device to be charged during this encrypted communication process. If the same device to be charged performs multiple identity authentication and charging requests in a short period of time, the encryption results in each request should be different, otherwise the core controller and the hardware encryption module will regard the encryption as a failure.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This paper proposes an improved wireless charging encryption protocol based on a combination of software and hardware encryption. This protocol, based on the existing one, enables more concise implementation of confidential user authentication and wireless charging parameter configuration, while also providing some protection against external attacks.

[0028] 2. The present invention proposes a method of current limiting at the wireless charging receiving end to suppress changes in wireless charging current, thereby preventing wireless charging energy trajectory side channel attacks caused by user energy trajectory leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 This is a schematic diagram of the core controller and hardware encryption module;

[0031] Figure 2 This is a schematic diagram of the software and hardware collaborative encryption of the core controller and hardware encryption module;

[0032] Figure 3 This is a communication flow chart of the wireless charging system;

[0033] Figure 4 This is a flow chart of the wireless charging protocol;

[0034] Figure 5 Flowchart for wireless charging identity authentication;

[0035] Figure 6 Schematic diagram of the structure of the wireless charging system resistant to side channel attacks of the present invention;

[0036] Figure 7 Schematic diagram of the current limiting module. DETAILED DESCRIPTION

[0037] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0038] like Figure 1 and Figure 6 As shown, the present invention provides a wireless charging system that is resistant to side channel attacks, the system comprising: a core controller and a hardware encryption module, an active communication function module, a feedback module and a current limiting module;

[0039] The core controller and hardware encryption module are used to encrypt transmission data and realize wireless charging energy transmission and encrypted identity authentication that are resistant to physical attacks through an encrypted communication protocol; the encrypted communication protocol includes asymmetric encryption and digest calculation methods. Wireless charging energy transmission requires a handshake and two-way authentication between the charging parties before it can be carried out;

[0040] The core controller and hardware encryption module include an encryption interval setting unit for setting the encryption interval; a random number unit for generating random numbers for use in the encryption process; a clock unit for providing a standard clock; a signal generating unit for generating the communication signals required by the core processor; a serial communication interface for serial communication between the core processor and the outside world; a certificate storage unit for storing the server certificate identity storage unit used in the encryption project for storing the authenticated user identity in the current system; a program storage unit for storing the core program; and a power supply unit for supplying power between multiple modules of the system and supporting low-power consumption mode.

[0041] The active communication function module is used to communicate with the wireless charging transmitter and the wireless charging receiver, obtain information from the wireless charging transmitter and the wireless charging receiver, and transmit the information to the core controller and the hardware encryption module to implement the encryption process, thereby assisting the wireless charging transmitter in performing identity authentication of the wireless charging receiver and assisting the wireless charging transmitter in performing identity authentication of the wireless charging receiver; at the same time, the encrypted wireless charging receiver information is forwarded to the wireless charging transmitter and the wireless charging transmitter information is forwarded to the wireless charging receiver, thereby realizing a closed loop of encrypted wireless charging information transmission; the user information verification method adopts the digest verification method, and the communication method between the two parties adopts asymmetric encryption communication;

[0042] The wireless charging system also includes a wireless transceiver function module, which is a general term for a wireless charging transmitter and a wireless charging receiver. The wireless charging transmitter includes a transmitter module controller, an inverter module, and a transmitter coil connected in sequence. The transmitter coil is connected to the transmitter module controller through a feedback module. The transmitter module controller communicates serially with the core controller and the hardware encryption module. The wireless charging receiver includes a receiver module controller, a rectifier module, and a receiver coil connected in sequence. The rectifier module is also connected to the receiver coil through a current limiting module. The receiver module controller communicates serially with the core controller and the hardware encryption module.

[0043] The feedback module is used to collect the transmission current of the wireless charging transmitter and feed it back to the core controller and the hardware encryption module so that the core controller and the hardware encryption module can perform energy control. According to the size and change of the charging current, the charging process is divided into a constant current charging stage, a constant voltage charging stage and other stages;

[0044] The current limiting module is used to be enabled when the wireless charging is in the constant voltage charging stage and other stages, reducing the information in the wireless charging energy transmission to prevent side channel attacks on the wireless energy transmission system.

[0045] In the present invention, the encryption algorithm in the core controller and the hardware encryption module is used to perform asymmetric encryption between the wireless charging user and the core controller, rather than symmetric encryption. This allows only the core controller and the hardware encryption module to decrypt information sent by the user, while information sent by the core controller and the hardware encryption module is public and can be decrypted by any user with a public key.

[0046] like Figure 2 As shown, the core controller and hardware encryption module are based on the collaborative encryption of software-controlled encryption and hardware-accelerated computing, giving full play to the respective advantages of software and hardware. The software encryption algorithm includes SM2 and SM3 national secret algorithms to realize functions such as data summary, encryption, decryption, and identity authentication; among them, the SM2 algorithm is used for asymmetric encryption of two-way communication, and the SM3 algorithm is used for summary calculation of user identity authentication; the hardware accelerated operation is asymmetric encryption calculation and summary calculation within the finite field of elliptic curves, and data is transmitted through the AXI bus, which can effectively improve the encryption operation speed and maximum concurrency.

[0047] Figure 3 The general wireless charging system communication process is shown, which mainly includes the following steps: reading the message, judging the protocol content, initiating a national secret communication request with the subordinate, encrypting the message, passing the ciphertext to the subordinate, and ending the communication. Among them, the specific implementation plan of the message encryption step is as follows Figure 4 and Figure 5 shown.

[0048] Based on the Qi wireless charging protocol, the present invention proposes an improved communication protocol that incorporates the client-server bidirectional authentication of the national secret protocol, as well as dual-certificate authentication content, and supports protection against current side-channel attacks, providing users with diverse security authentication methods. In addition, there is a repeated query for the user field. If the current user's encrypted message is consistent with the recent encrypted message of other users, the user request is rejected to prevent the information transmitted by the user from being stolen. The transmission frequency described in the Qi wireless charging protocol is controlled within the resonant frequency range of 4.3KHz. Wireless charging energy transmission requires a handshake and bidirectional authentication between the charging parties before it can be carried out. The specific protocol process is shown in Figure 4 and Figure 5 .

[0049] In the present invention, the core controller and hardware encryption module control the rectifier and inverter modules in the wireless charging and dynamically adjust the resonant frequency by communicating with the two sub-controllers;

[0050] The feedback module collects the charging current and returns it to the core controller through the A / D converter. The core controller divides the charging process into constant current charging stage, constant voltage charging stage and other stages according to the size and change of the charging current. When the charging process is in the constant voltage charging stage or other stages, the current limiting module of the wireless charging receiver will be activated, and the energy of the wireless charging receiver will be attenuated by the current limiter to prevent the wireless charging energy information from leaking.

[0051] In the present invention, the current limiting module refers to the realization idea of ​​the current limiting diode, and the circuit principle diagram is as follows: Figure 7 As shown, a large load is connected in parallel with a small capacitor, so that when the voltage is within a certain range, the current change can be ignored, preventing the current jump from leaking the user's energy information. When the wireless charging is in constant voltage charging mode, the wireless charging energy will directly expose the energy consumed by the user end. Therefore, in constant voltage charging mode, the current limiting module will be activated to constrain the instantaneous change of current to prevent the user from exposing the instantaneous energy consumption;

[0052] like Figure 2 As shown, the core controller and hardware encryption module also include an external memory. The certificate chain required for identity authentication will be stored separately in the external memory. The core controller and hardware encryption module access it through the bus. The external memory ensures that the certificate chain can be replaced or added or deleted in real time, thereby enhancing the flexibility and effectiveness of the system.

[0053] On the other hand, the present invention also provides a wireless charging method for resisting side channel attacks, comprising the following steps:

[0054] S1. The core control module actively searches for external devices until it receives a stop search instruction or has searched for at least one charging device;

[0055] S2. After step S1 is completed, if the core control module searches for at least one charging device, it actively sends an identity authentication request to obtain the device's identity information and charging configuration information. This information is encrypted using the private key d in the core control module. Before identity authentication is completed, wireless charging is only transmitted at a lower transmission power.

[0056] S3. The device to be charged calculates its identity information through a hash value, encrypts it with the public key Q, and sends it to the core control module. After the core control module passes the identity authentication, it can configure the charging power and charging mode. The configuration information is also encrypted by the device to be charged with the public key Q and sent to the core control module.

[0057] S4. The core control module completes configuration and performs wireless charging energy transmission according to the configured power;

[0058] S5. When a wireless charging session is complete, the core control module records the public key encryption result of the user's identity hash value during this encrypted communication. If the same user makes multiple authentication and charging requests within a short period of time, the encryption result must be different in each request; otherwise, the core controller will deem the encryption failure.

[0059] S6. The public key encryption results stored in the core controller have a time / number limit. When the time is too long, the core controller will clear the older records; when the number of encryptions is too many, the core controller will randomly clear some encrypted records.

[0060] S7. If the user identity authentication fails, return to S1.

[0061] The above embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A wireless charging system resistant to side channel attacks, characterized in that: The system includes: a core controller and a hardware encryption module, an active communication function module, a feedback module and a current limiting module; The core controller and hardware encryption module are used to encrypt transmitted data and integrate an improved wireless charging identity authentication and charging configuration protocol. Based on the Qi wireless charging protocol, it incorporates the client and server bidirectional authentication and dual-certificate authentication content of the national encryption protocol, as well as repeated queries on user fields. The core controller and hardware encryption module implement wireless charging energy transmission and encrypted identity authentication that are resistant to physical attacks through an encrypted communication protocol. The encrypted communication protocol includes asymmetric encryption and digest calculation. Wireless charging energy transmission requires a handshake and bidirectional authentication between the charging parties before it can proceed. The active communication function module is used to communicate with the wireless charging transmitter and the wireless charging receiver, obtain information from the wireless charging transmitter and the wireless charging receiver, and transmit it to the core controller and the hardware encryption module to implement the encryption process. At the same time, the encrypted wireless charging receiver information is forwarded to the wireless charging transmitter and the wireless charging transmitter information is forwarded to the wireless charging receiver, thereby realizing a closed loop of encrypted wireless charging information transmission; The feedback module is used to collect the transmission current of the wireless charging transmitter and feed it back to the core controller and the hardware encryption module so that the core controller and the hardware encryption module can perform energy control. According to the size and change of the charging current, the charging process is divided into a constant current charging stage, a constant voltage charging stage and other stages; The current limiting module is used to be enabled when the wireless charging is in the constant voltage charging stage and other stages, reducing the change information of the current and voltage in the wireless charging energy transmission to prevent side channel attacks on the wireless energy transmission system.

2. The side-channel attack-resistant wireless charging system according to claim 1, wherein: The communication between the two parties of wireless charging is carried out in the form of asymmetric encryption, and the wireless charging transmitter uses a digest value authentication method to authenticate the identity of the wireless charging receiver.

3. The side-channel attack-resistant wireless charging system according to claim 1, wherein: The core controller and hardware encryption module are implemented collaboratively based on software-controlled encryption and hardware-accelerated computing. Software-controlled encryption adopts national-level security encryption algorithms, including SM2 and SM3 algorithms. The SM2 algorithm is used for asymmetric encryption of two-way communication, and the SM3 algorithm is used for summary calculation of user authentication. Hardware-accelerated computing is asymmetric encryption calculation and summary calculation within the finite field of elliptic curves, and data is transmitted through the AXI bus, which can effectively improve the encryption operation speed and maximum concurrency.

4. The side-channel attack-resistant wireless charging system according to claim 1, wherein: The wireless charging system also includes a wireless transceiver function module, which is a general term for a wireless charging transmitter and a wireless charging receiver. The wireless charging transmitter includes a transmitter module controller, an inverter module, and a transmitter coil connected in sequence. The transmitter coil is connected to the transmitter module controller through a feedback module. The transmitter module controller communicates serially with the core controller and the hardware encryption module. The wireless charging receiver includes a receiver module controller, a rectifier module, and a receiver coil connected in sequence. The rectifier module is also connected to the receiver coil through a current limiting module. The receiver module controller communicates serially with the core controller and the hardware encryption module.

5. The side-channel attack-resistant wireless charging system according to claim 1, wherein: The current limiting module uses a large load in parallel with a small capacitor, so that when the voltage is within a certain range, the change in current can be ignored, thereby preventing the current jump from leaking the energy information used by the user.

6. The side-channel attack-resistant wireless charging system according to claim 4, characterized in that: The wireless transceiver function module includes the transmission frequency described by the Qi wireless charging protocol, and the resonant frequency is controlled within the range of 4.3KHz.

7. The side-channel attack-resistant wireless charging system according to claim 1, wherein: The core controller and the hardware encryption module also include an external memory. The certificate chain required for identity authentication will be stored separately in the external memory, and the core controller and the hardware encryption module access it through a bus.

8. A wireless charging method based on a wireless charging system resistant to side channel attacks according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: S1, the core controller and the hardware encryption module actively search for external devices to be charged until a stop search instruction is received or at least one device to be charged is found; S2. After step S1 is completed, if the core controller and the hardware encryption module search for at least one device to be charged, they actively send an identity authentication request through the active communication function module to request identity information and charging configuration information from the device to be charged. The core controller and the hardware encryption module encrypt the identity information and the charging configuration information using the private key d; S3. The device to be charged calculates its identity information through a hash value and encrypts it using the public key Q. The charging configuration information is also encrypted using the public key Q. The two encrypted results are sent to the core controller and the hardware encryption module. After the core controller and the hardware encryption module pass the identity authentication, the charging power and charging mode can be configured. S4, the core controller and the hardware encryption module complete the configuration and perform wireless charging energy transmission according to the configured power; during the charging process, the transmission current of the wireless charging transmitter is collected through the feedback module and fed back to the core controller and the hardware encryption module. According to the size and change of the charging current, the charging process is divided into a constant current charging stage, a constant voltage charging stage and other stages. When the wireless charging is in the constant voltage charging stage and other stages, the current limiting module is used to reduce the information in the wireless charging energy transmission to prevent side channel attacks on the wireless energy transmission system.

9. The wireless charging method according to claim 8, wherein: When a wireless charging session is completed, the core controller and hardware encryption module will record: during this encrypted communication process, the public key encryption result of the identity hash value of the device to be charged. If the same device to be charged performs multiple identity authentication and charging requests in a short period of time, the encryption results in each request should be different. Otherwise, the core controller and hardware encryption module will deem the encryption to have failed.

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