Battery cell protection method and battery system

Abstract

The embodiment of the invention discloses a battery unit protection method and a battery system, and the battery unit protection method comprises the following steps: a host converts a first signal into a first ciphertext according to a symmetric encryption algorithm and a temporary shared key, and sends the first ciphertext to a first chip, the first signal is configured to be a signal generated according to a random number and a plaintext including a first command; and the first chip receives the first ciphertext and converts the first ciphertext into a plaintext comprising a first command according to the symmetric encryption algorithm and the temporary shared key, and the first chip executes the first command to enter a first working mode. According to the battery unit protection method disclosed by the invention, the command sent to the first chip by the host is at least encrypted, so that the first command cannot be directly acquired, the information related to the battery in the first chip is protected from being changed, and an unofficial battery is prevented from being misjudged as an official battery.

Description

Technical Field

[0001] The present invention relates to the field of power electronics, and more particularly to a battery unit protection method and a battery system. Background Art

[0002] Most electronic products on the market, such as mobile phones, tablets, laptops, etc., will have poor battery performance after a period of use, and thus require replacement. Since officially certified legal batteries are relatively expensive, many third parties on the market provide uncertified illegal batteries.

[0003] In the existing battery cell protection scheme, the main control module (i.e., host) of the electronic product only identifies whether the fuel gauge chip is legitimate. After authentication, the information transmission between the host and the fuel gauge chip is completely exposed on the communication cable. Therefore, a third party can successfully deceive the host by replacing only the battery cell of the original battery but retaining the motherboard including the fuel gauge chip in the original battery, and by capturing the information on the communication cable, modify the parameters of the fuel gauge chip, such as the number of charging cycles, so that the illegal battery provided by the third party can be used in the above-mentioned electronic products.

[0004] Although illegal batteries provided by third parties are cheap, they pose safety risks. Therefore, a new battery cell protection method is needed to prevent illegal batteries that only replace battery cells from being misjudged as legal batteries. Summary of the invention

[0005] In view of this, the present invention proposes a battery unit protection method and a battery system to solve the technical problem in the prior art that an illegal battery that only replaces the cells in the battery unit is misjudged as a legal battery.

[0006] An embodiment of the present invention provides a battery cell protection method, comprising: when a first chip in the battery cell matches a host, the host converts a first signal into a first ciphertext according to a symmetric encryption algorithm and a temporary shared key, and sends the first ciphertext to the first chip, wherein the first signal is configured as a signal generated according to a random number and a plaintext including a first command; and the first chip receives the first ciphertext and converts the first ciphertext into a plaintext including a first command according to the symmetric encryption algorithm and the temporary shared key, and the first chip executes the first command to enter a first working mode.

[0007] In one embodiment, the battery cell protection method also includes: the host concatenating the random number and the plain text including the first command to generate a second signal; calculating the second signal using a verification algorithm to generate a third signal; and concatenating the second signal and the third signal to generate the first signal.

[0008] In one embodiment, each time the host needs to request the first chip to enter the first working mode, the host generates a first ciphertext and sends it to the first chip, so as to encrypt and transmit the plaintext including the first command.

[0009] In one embodiment, the battery cell protection method also includes: the host and the first chip respectively generate random numbers as their own temporary private keys; the host and the first chip respectively calculate their own public keys based on an asymmetric encryption algorithm and their own temporary private keys; the host and the first chip exchange public keys; and the host and the first chip respectively obtain their own temporary shared keys based on the key interaction algorithm corresponding to the asymmetric encryption algorithm, the other party's public key and their own temporary private key.

[0010] In one embodiment, the battery cell protection method further includes: determining whether the first chip matches the host according to a digital signature algorithm based on an asymmetric encryption algorithm.

[0011] In one embodiment, each time the system is powered on or restarted, it is necessary to determine whether the first chip in the battery unit matches the host.

[0012] In one embodiment, judging whether the first chip matches the host according to a digital signature algorithm based on an asymmetric encryption algorithm includes: the host obtaining the public key of the first chip in the certificate of the first chip; the host generating a random number and sending the random number to the first chip; the first chip using its own private key and a digital signature algorithm based on an asymmetric encryption algorithm to sign the received random number to generate a first result, and sending the first result to the host; the host using the obtained public key of the first chip and a digital signature algorithm based on an asymmetric encryption algorithm to verify the received first result to judge whether the first chip in the battery unit matches the host.

[0013] In one embodiment, the host obtains the public key of the first chip in the certificate of the first chip, including: the host sends a command to obtain the certificate to the first chip; the first chip sends its own certificate to the host; the host verifies the certificate with its own public key and a digital signature algorithm based on an asymmetric encryption algorithm, and if the verification is successful, obtains the public key of the first chip in the certificate.

[0014] In one embodiment, after the first chip operates in the first operating mode for a first time, it exits the first operating mode and enters the second operating mode.

[0015] In one embodiment, in the first working mode, if after a first period of time, neither the host nor the first chip sends or receives information, the first chip exits the first working mode to enter the second working mode.

[0016] An embodiment of the present invention provides a battery system, comprising: a host and a battery cell; the battery system protects its own battery cell by using any one of the above-mentioned battery cell protection methods.

[0017] Compared with the prior art, the technical solution of the present invention has the following advantages: the battery cell protection method of the present invention comprises: the host converts the first signal into a first ciphertext according to a symmetric encryption algorithm and a temporary shared key, and sends the first ciphertext to the first chip, wherein the first signal is configured as a signal generated according to a random number and a plaintext including a first command; and the first chip receives the first ciphertext, and converts the first ciphertext into a plaintext including a first command according to the symmetric encryption algorithm and the temporary shared key, and the first chip executes the first command to enter a first working mode. The battery cell protection method of the present invention protects the battery-related information in the first chip from being changed by at least encrypting the command sent by the host to the first chip so that the first command itself cannot be directly obtained, thereby preventing unofficial batteries from being misjudged as official batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0019] Figure 1 is a schematic diagram of a method for switching the working mode of the first chip of the present invention;

[0020] Figure 2 is a flow chart of a battery cell protection method of the present invention;

[0021] Figure 3 A schematic flow chart of a method for determining whether a first chip matches a host according to the present invention;

[0022] Figure 4 A schematic flow chart of a method for encrypting information according to the present invention;

[0023] Figure 5 A schematic diagram of a method for generating a first ciphertext according to the present invention;

[0024] Figure 6 A schematic diagram of a method for decrypting a first ciphertext according to the present invention. DETAILED DESCRIPTION

[0025] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the detailed description of the present invention below, some specific details are described in detail. It is possible for a person skilled in the art to fully understand the present invention without the description of these details. In order to avoid confusing the essence of the present invention, known methods, processes, flows, components and circuits are not described in detail.

[0026] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0027] At the same time, it should be understood that in the following description, "circuit" refers to a conductive loop composed of at least one element or subcircuit through electrical connection or electromagnetic connection. When an element or circuit is said to be "connected to" another element or an element / circuit is said to be "connected between" two nodes, it can be directly coupled or connected to another element or there can be an intermediate element, and the connection between the elements can be physical, logical, or a combination thereof. On the contrary, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0028] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include", "comprising" and similar words should be interpreted in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to".

[0029] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0030] Figure 1 is a schematic diagram of a method for switching the working mode of the first chip of the present invention; Figure 1 As shown, when the first chip in the battery unit receives the first command D1 issued by the host, the working mode of the first chip is switched from the second working mode to the first working mode; when the first chip receives the second command D2, the working mode of the first chip is switched from the first working mode to the second working mode. Optionally, the second command D2 is issued by the host. The second working mode is the default working mode of the first chip. The authority of the first working mode is greater than that of the second working mode. When the first chip works in the first working mode, the host is allowed to modify the battery-related information in the first chip, such as the number of charge and discharge cycles and other information.

[0031] The first chip in the battery cell is configured as a chip with a communication function. In one embodiment, the first chip is configured as a fuel gauge chip. In the second working mode, the fuel gauge chip is used to read the information of the battery cell of the battery cell, such as voltage, temperature and other information; in the first working mode, the host is allowed to modify the battery-related information in the fuel gauge chip. Optionally, in the first working mode, the fuel gauge chip can also read the information of the battery cell. In another embodiment, the first chip is configured as a battery passport chip. In the second working mode, the battery passport chip is used to obtain the information of the battery cell of the battery cell, such as voltage, temperature and other information. In the first working mode, the host is allowed to modify the battery-related information in the battery passport chip. Optionally, in the first working mode, the battery passport chip can also be used to obtain the information of the battery cell of the battery cell. In another embodiment, the first chip is configured as a battery management system (BMS) controller chip. In the second working mode, the BMS controller chip is used to read the information of the battery cell of the battery cell, such as voltage, temperature and other information; in the first working mode, the host is allowed to modify the battery-related information in the BMS controller chip. Optionally, in the first working mode, the BMS controller chip can also read the information of the battery cell.

[0032] In one embodiment, the battery unit includes a main board and a battery cell, and the main board includes a first chip. In one embodiment, the battery cell and the first chip are packaged in a battery pack. In another embodiment, the battery cell and the first chip are not packaged together, for example, separated into two modules. In one embodiment, the first chip communicates with the host via an IIC bus or an SMBUS bus.

[0033] When only the battery cell of the battery unit is replaced, if the host does not modify the battery-related information in the first chip, such as the number of charging cycles, the host does not consider the replaced battery cell to be a new battery, which will result in a short battery life and unstable power supply. When the battery limit is reached, the host may have an interface prompt or even shut down unexpectedly. In other words, if only a new battery cell is replaced and the battery-related information in the first chip is not modified, the new battery cell cannot be used normally. Therefore, the implementation of the solution of only replacing the battery cell requires the first chip to enter the first working mode to modify the battery-related information in the first chip.

[0034] In order to prevent an illegal battery (i.e., an unofficial certified battery) that only replaces the battery cell of the battery unit from being mistakenly identified as a legal battery (i.e., an officially certified battery), at least the first command D1 needs to be encrypted so that the first chip in the third-party battery unit cannot enter the first working mode, and the host cannot modify the battery-related information in the first chip, and ultimately the illegal battery that only replaces the battery cell will not be mistakenly identified as a legal battery.

[0035] The battery cell protection method includes: identity authentication and information encryption. Specifically, Figure 2 is a flow chart of the battery cell protection method of the present invention; Figure 2 As shown, optionally, step 21 needs to be performed when the system is powered on or restarted.

[0036] 21 Identity authentication, that is, judging whether the first chip matches the host. If the first chip matches the host, optionally, each time the host requests to enter the first working mode, step 22 is executed. If the host does not request to enter the first working mode, the first chip continues to work in the second working mode. Optionally, if the first chip does not match the host, it is judged that the battery unit is illegal. After the host determines that the battery unit is illegal, the host decides to take corresponding measures according to the product policy. In one embodiment, the corresponding measures are set in advance. In one embodiment, after the host determines that the battery unit is illegal, the first chip does not work. In another embodiment, when the host is a mobile phone, after the host determines that the battery unit is illegal, the mobile phone is black screened. In another embodiment, when the host is a notebook or a tablet, after the host determines that the battery unit is illegal, the battery unit is allowed to discharge but not allowed to charge. In one embodiment, if the first chip matches the host, it indicates that the first chip is an officially certified chip; if the first chip does not match the host, it indicates that the first chip is an unofficial certified chip. Optionally, it is judged whether the first chip matches the host according to a digital signature algorithm based on an asymmetric encryption algorithm. The digital signature algorithm can be based on any asymmetric encryption algorithm, and the present invention does not limit this. Preferably, the digital signature algorithm is based on an ECC algorithm, that is, the digital signature algorithm based on an asymmetric encryption algorithm is configured as an ECDSA algorithm.

[0037] 22 Information encryption is used to prevent the first chip from entering the first working mode, which may cause the battery-related information in the first chip to be illegally tampered with.

[0038] Figure 3 FIG. 1 is a schematic flow chart of a method for determining whether a first chip matches a host according to the present invention. Figure 3 As shown, judging whether the first chip matches the host according to a digital signature algorithm based on an asymmetric encryption algorithm includes the following steps:

[0039] 3.1 The host obtains the public key of the first chip from the certificate of the first chip;

[0040] Specifically, the host sends a command to obtain a certificate to the first chip; the first chip sends its own certificate to the host; the host verifies the certificate with its own public key and a digital signature algorithm based on an asymmetric encryption algorithm, and if the verification is successful, obtains the public key of the first chip in the certificate.

[0041] The certificate mentioned here is also called a public key certificate, which is a digital certificate used to verify the identity of the holder and associate its public key to ensure the security of communication and data exchange. The certificate is signed by a CA (certificate authority, a trusted third party), and the certificate content includes the holder's public key and related information.

[0042] 3.2 The host generates a random number and sends the random number to the first chip;

[0043] 3.3 The first chip signs the received random number using its own private key and a digital signature algorithm based on an asymmetric encryption algorithm to generate a first result, and sends the first result to the host;

[0044] 3.4 The host uses the acquired public key of the first chip and a digital signature algorithm based on an asymmetric encryption algorithm to verify the received first result to determine whether the first chip in the battery unit matches the host.

[0045] Furthermore, if the signature verification is successful, it indicates that the first chip matches the host, and if the signature verification is unsuccessful, it indicates that the first chip does not match the host.

[0046] Figure 4 A schematic flow chart of the information encryption method of the present invention; Figure 4 As shown, the information encryption method includes the following steps:

[0047] 4.0 Key Exchange

[0048] Specifically, the host and the first chip respectively generate random numbers as their own temporary private keys; the host and the first chip respectively calculate their own public keys according to the asymmetric encryption algorithm and their own temporary private keys; the host and the first chip exchange public keys; and the host and the first chip obtain their own temporary shared keys according to the key interaction algorithm corresponding to the asymmetric encryption algorithm, the other party's public key and their own temporary private key. Preferably, the temporary shared key of the host is equal to the temporary shared key of the first chip. Preferably, in the key exchange stage, the asymmetric encryption algorithm is configured as an ECC algorithm, and the key interaction algorithm corresponding to the asymmetric encryption algorithm is configured as an ECDH algorithm.

[0049] 4.1 The host converts the first signal into a first ciphertext according to a symmetric encryption algorithm and a temporary shared key, and sends the first ciphertext to the first chip, wherein the first signal is configured as a signal generated according to a random number and a plaintext including a first command; preferably, the symmetric encryption algorithm is configured as an AES algorithm.

[0050] The host concatenates the random number and the plain text including the first command to generate a second signal; calculates the second signal using a check algorithm to generate a third signal; and concatenates the second signal and the third signal to generate the first signal. Preferably, the check algorithm is configured as a CRC16 algorithm. Optionally, the check algorithm is an MD3 (Message-Digest Algorithm 3) or MD5 (Message-Digest Algorithm 5) algorithm, etc.

[0051] Specifically, Figure 5 As shown, a schematic diagram of the method for generating the first ciphertext of the present invention is given. The host generates a 128-bit random number K

[128] , and splits the random number K

[128] into the first 64-bit length data K1

[64] and the second 64-bit length data K2

[64] ; the plaintext M including the first command and the split random number are first spliced ​​according to a preset format to generate a second signal M1=K1

[64] |M|K2

[64] ; the second signal M1 is calculated using the CRC16 algorithm to ensure the integrity of the information, and a third signal C is generated; the third signal C is spliced ​​to the end of the second signal M1 to generate the first signal M'=M1|C. Then, the host uses the AES algorithm and a temporary shared key to convert the first signal into the first ciphertext.

[0052] 4.2 The first chip receives the first ciphertext and converts the first ciphertext into plaintext including a first command according to the symmetric encryption algorithm and the temporary shared key, and the first chip executes the first command to enter the first working mode. Preferably, the symmetric encryption algorithm is configured as an AES algorithm.

[0053] Specifically, Figure 6 A schematic diagram of a method for decrypting a first ciphertext according to the present invention is shown in FIG. The first chip receives the first ciphertext, converts the first ciphertext using an AES algorithm and a temporary shared key, and performs a CRC check to generate a plaintext M including a first command.

[0054] It should be noted that Figure 5 and Figure 6 The generation and decryption process of the first ciphertext is given only as an illustration of the present invention, and the present invention is not limited thereto.

[0055] In the present invention, only the first command is encrypted. In another embodiment, the second command may also be encrypted, which is not limited by the present invention.

[0056] The battery protection method of the present invention can not only prevent illegal batteries (i.e., unofficial certified batteries) whose battery cells are only replaced from being misjudged as legal batteries (i.e., officially certified batteries), but also prevent illegal batteries whose battery cells are replaced as a whole from being misjudged as legal batteries.

[0057] In the present invention, during identity authentication, based on the ECC (Elliptic curve cryptography) algorithm, the digital signature ECDSA (Elliptic curve digital signature algorithm) algorithm is used to implement signature and verification. Specifically, through the random number challenge initiated by the host, the first chip signs the random number, and the host obtains the signature result and verifies the signature to prove that the first chip is officially certified. The adopted ECC algorithm is safer than the previous SHA256 algorithm. After the host confirms through identity authentication that the first chip is an officially certified chip, the host wants to enter the first working mode of the first chip to change the relevant information of the battery in the first chip. In the prior art, the communication commands and communication information between the host and the first chip are exposed in plain text on the communication cable, which is easy to be obtained and forged by a third party. Therefore, the present invention also provides information encryption, and generates a temporary key through the ECDH (Elliptic curve Diffie-Hellman) algorithm. This method can reduce the workload of chip key management, and then use a symmetric encryption algorithm, such as AES (Advanced encryption standard) to quickly encrypt and decrypt the communication commands and communication information. At the same time, in order to ensure that the same plain text produces different ciphertexts, a random number can be introduced into the plain text, and then the AES algorithm (i.e., a salted symmetric encryption algorithm) is used for encryption. The combined use of the ECDH key interaction algorithm and the salted symmetric encryption algorithm makes it possible to generate different ciphertexts even if the same valid plain text is used, that is, the transmission of communication information or commands on the communication line is different each time, which effectively hinders replay attacks, greatly increases the difficulty of cracking, and improves security. It should be noted that the random number challenge, random number key and random number salting must all rely on hardware true randomness, otherwise they can be easily cracked.

[0058] In the present invention, the ECC public key encryption algorithm is used to improve the security of identity authentication. By at least encrypting the command sent by the host to the first chip, the first command itself is protected from being directly obtained, and the battery-related information in the first chip is further protected from being changed, such as the number of battery charge and discharge cycles and battery health. Information such as is not modified increases the difficulty of cracking by a third party and hinders the introduction of unofficial batteries.

[0059] In one embodiment, the implementation of information encryption requires the addition of additional modules inside the first chip, such as an ECDSA algorithm module (whose formula is based on the ECC algorithm), an ECDH algorithm module, an AES algorithm, etc. The additional modules are integrated inside the first chip to reduce the additional cost of the dedicated chip. Whether it is when proving the legitimacy of the first chip or when protecting its data from being tampered with, integration on one chip is more conducive to protecting the first chip itself and increasing the security of this solution.

[0060] Preferably, each time the host needs to request the first chip to enter the first working mode, information encryption is required, that is, the host generates a first ciphertext and sends it to the first chip to encrypt and transmit the plaintext including the first command.

[0061] Preferably, each time the system is powered on or restarted, it is necessary to determine whether the first chip in the battery unit matches the host.

[0062] Preferably, after the first chip operates in the first operating mode for a first time, that is, stays in this mode for a long time, it exits the first operating mode and enters the second operating mode.

[0063] Preferably, in the first working mode, if after a first period of time, neither the host nor the first chip sends or receives information, that is, the communication line is not operated for a long time, the first chip exits the first working mode and enters the second working mode.

[0064] The present invention also provides a battery system, comprising: a host and a battery cell; the battery system uses any one of the above-mentioned battery cell protection methods to protect its own battery cells to prevent the battery cell as a whole from being illegally replaced or the batteries in the battery cell from being illegally replaced, that is, to provide obstacles for the battery cell as a whole to be illegally replaced or the batteries in the battery cell to be illegally replaced.

[0065] Although the embodiments are described and illustrated separately above, some common technologies are involved. It is the opinion of ordinary technicians in this field that the embodiments can be replaced and integrated. If the content is not clearly recorded in one of the embodiments, reference can be made to another recorded embodiment.

[0066] According to the embodiments of the present invention as described above, these embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made based on the above description. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and the modified use based on the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A battery cell protection method, characterized in that: include: When the first chip in the battery unit matches the host, The host converts the first signal into a first ciphertext according to a symmetric encryption algorithm and a temporary shared key, and sends the first ciphertext to the first chip, wherein the first signal is configured as a signal generated according to a random number and a plaintext including a first command; as well as The first chip receives the first ciphertext, and converts the first ciphertext into plaintext including a first command according to the symmetric encryption algorithm and the temporary shared key, and the first chip executes the first command to enter a first working mode.

2. The battery cell protection method according to claim 1, characterized in that: Also includes: The host concatenates the random number and the plain text including the first command to generate a second signal; Calculating the second signal using a verification algorithm to generate a third signal; as well as The second signal and the third signal are concatenated to generate the first signal.

3. The battery cell protection method according to claim 1, characterized in that: Each time when the first chip needs to be requested to enter the first working mode, the host generates a first ciphertext and sends it to the first chip, so as to encrypt and transmit the plaintext including the first command.

4. The battery cell protection method according to claim 1, characterized in that: Also includes: The host and the first chip respectively generate random numbers as their own temporary private keys; The host and the first chip respectively calculate their own public keys according to an asymmetric encryption algorithm and their own temporary private keys; The host and the first chip exchange public keys; as well as The host and the first chip obtain their own temporary shared keys according to the key interaction algorithm corresponding to the asymmetric encryption algorithm, the other party's public key and their own temporary private key.

5. The battery cell protection method according to claim 1, characterized in that: Also includes: Whether the first chip matches the host is determined according to a digital signature algorithm based on an asymmetric encryption algorithm.

6. The battery cell protection method according to claim 5, characterized in that: Each time the system is powered on or restarted, it is necessary to determine whether the first chip in the battery unit matches the host.

7. The battery cell protection method according to claim 5, characterized in that: Determining whether the first chip matches the host according to a digital signature algorithm based on an asymmetric encryption algorithm includes: The host obtains the public key of the first chip from the certificate of the first chip; The host generates a random number and sends the random number to the first chip; The first chip signs the received random number using its own private key and a digital signature algorithm based on an asymmetric encryption algorithm to generate a first result, and sends the first result to the host; The host uses the acquired public key of the first chip and a digital signature algorithm based on an asymmetric encryption algorithm to verify the received first result to determine whether the first chip in the battery unit matches the host.

8. The battery cell protection method according to claim 7, characterized in that: The host obtaining the public key of the first chip in the certificate of the first chip includes: The host sends a command to obtain a certificate to the first chip; The first chip sends its own certificate to the host; The host verifies the certificate using its own public key and a digital signature algorithm based on an asymmetric encryption algorithm, and if the verification is successful, obtains the public key of the first chip in the certificate.

9. The battery cell protection method according to claim 1, characterized in that: After the first chip operates in the first operating mode for a first period of time, the first chip exits the first operating mode and enters the second operating mode.

10. The battery cell protection method according to claim 1, characterized in that: In the first working mode, if the host and the first chip do not send or receive information within a first period of time, the first chip exits the first working mode and enters the second working mode.

11. A battery system, characterized in that: include: Main unit and battery unit; The battery system protects its own battery cells using any of the above-mentioned battery cell protection methods.

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