Network node authentication and key exchange protocol method for smart grid scenarios

Abstract

The present invention discloses a network node authentication and key exchange protocol method for a smart grid scenario, which relates to the field of information security technology, including step 1, system initialization, generating a master key for an access node, and generating an identity for each aggregation node; step 2, the aggregation node packages its own identity into a request and sends it to the access node. After receiving the request, the access node generates a first random number and an aggregation node key, and then generates an intermediate key and an identity authentication parameter through encryption calculation using the master key, the first random number and the aggregation node key, and sends the intermediate key and the identity authentication parameter to the aggregation node; step 3, node authentication is performed between the aggregation node and the access node. The present invention realizes two-way authentication between the access node and the aggregation node, between the aggregation nodes and between the sensor nodes, and ensures that a consistent and secure key is used in subsequent communications, thereby ensuring the security of the communication.

Description

Technical Field

[0001] The present invention relates to the field of information security technology, and in particular to a network node authentication and key exchange protocol method for a smart grid scenario. Background Art

[0002] In the smart grid, a large number of power equipment and grid users are connected in every link from power generation, transmission, distribution to power consumption. Data such as meter readings, user service information and system control commands are transmitted through the communication system of the smart grid. However, these data are not absolutely secure during the transmission process. Similar to the Internet or traditional telephone networks, the communication system of the smart grid is also facing threats and interference from attackers such as replay attacks, traffic analysis and denial of service attacks. On the other hand, not all power equipment or grid users are absolutely trustworthy. The smart grid needs to verify whether the power equipment or grid users in the system really have the legal identity they claim to ensure the stable operation of the power equipment, the safety and reliability of the grid system, and the economic interests of legitimate users.

[0003] When performing node authentication or communication, if the master key has been cracked by an attack, the existing technology often lacks effective defense measures, resulting in the cracking of the session key and the theft of communication data; at the same time, since some smart grid communication protocols lack a strong node authentication mechanism and the lack of a timestamp field in the data packet, the grid equipment cannot confirm the source and freshness of the message. Therefore, the attacker can simply resend the previously sniffed legitimate data packet at a subsequent time point to implement a replay attack. Summary of the invention

[0004] The purpose of the present invention is to overcome the security risks of smart grid node authentication in the prior art, and the defects that the key can be easily cracked resulting in low security of data communication, and to provide a network node authentication and key exchange protocol method for smart grid scenarios.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A network node authentication and key exchange protocol method for a smart grid scenario includes the following steps:

[0007] The system is initialized, a master key is generated for the access node, and an identity is generated for each aggregation node; the aggregation node packages its own identity into a request and sends it to the access node. After receiving the request, the access node generates a first random number and an aggregation node key, and then generates an intermediate key and an identity authentication parameter through encryption calculation using the master key, the first random number and the aggregation node key, and sends the intermediate key and the identity authentication parameter to the aggregation node;

[0008] Node authentication is performed between the aggregation node and the access node, including:

[0009] Step A1, the sink node generates a second random number, and generates a mask and sink node authentication information through encryption calculation according to the intermediate key, the second random number and the sink node message sequence number, then updates the sink node message sequence number, and packages the mask, sink node authentication information and sink node message sequence number as key intermediate variables and sends them to the access node, requesting the access node to perform authentication;

[0010] Step A2: After receiving the key intermediate variable, the access node restores the key intermediate variable to obtain a second random number and an access node message sequence number, and then calculates the access node authentication information. If the values ​​of the aggregation authentication information and the access node authentication information are equal and the number of the access node message sequence number is within a preset threshold range, the node authentication between the access node and the aggregation node is passed, and then the access node message sequence number is updated;

[0011] Step A3, performing encryption calculation according to the second random number, the aggregation node message sequence number, the aggregation node key, the identity authentication parameter and the master key to obtain the session key.

[0012] In this solution, in the smart grid scenario, the access node communicates with several aggregation nodes, and each aggregation node communicates with several sensor nodes. The access node is the central server, and the sensor node is the communication terminal. The access node is responsible for verifying the identity of the aggregation node. The access node stores the master key. The master key provides the most basic security guarantee for the subsequent authentication process and is also the basis for all authentication security. The aggregation node is an intermediate node, responsible for aggregating the data of the sensor nodes in the intranet and passing it to the access node. It is also responsible for receiving instructions or data from the access node and distributing it to the sensor nodes in the intranet. In the design of this solution, the master key will not be transmitted when the access node and the aggregation node communicate, but will be transmitted in an encrypted manner using the master key, the first random number and the aggregation node key. Therefore, even if the communication channel is eavesdropped, the key information cannot be restored. At the same time, since the random number is different each time verification is performed, the intermediate key generated by the random number cannot be restored even if it is stolen, and the carrier for generating the random number, such as the access node corresponding to the first random number and the aggregation node corresponding to the second random number, will not store the used random number after using the random number for encryption calculation. Therefore, even if an attack breaks through and obtains the storage information in the access node or the aggregation node, it is impossible to obtain the previously generated random numbers. Therefore, the design of this scheme effectively reduces the possibility of short-term key leakage.

[0013] Preferably, the network node authentication and key exchange protocol method for the smart grid scenario also includes performing node authentication between the aggregation node and the sensor node, including:

[0014] Step B1, generating a sensor node key and an identity identifier for each sensor node;

[0015] Step B2, the sink node generates a third random number, then performs encryption calculation based on the third random number and the identity identifier to generate an encrypted authentication value, and sends the third random number and the sink node encrypted authentication value to the sensor node;

[0016] Step B3, after receiving the third random number and the aggregation node encrypted authentication value, the sensor node calculates the sensor node encrypted authentication value according to the third random number and its own identity identifier, and determines whether the aggregation node encrypted authentication value and the sensor node encrypted authentication value are equal. If they are equal, the sensor node generates a fourth random number, and performs encryption calculation on the third random number, the fourth random number and its own sensor node key to obtain the sensor node encrypted authentication value fragment, and then packages the fourth random number and the sensor node encrypted authentication value fragment and sends them to the aggregation node as a response;

[0017] Step B4, after receiving the response, the aggregation node performs encryption calculation based on the third random number and the fourth random number to obtain the aggregation node encrypted authentication value fragment, and then determines whether the aggregation node encrypted authentication value fragment and the sensor node encrypted authentication value fragment are the same. If they are the same, it proves that the sensor node is legal, and the node authentication between the aggregation node and the sensor node is passed.

[0018] In the authentication process of the aggregation node and the sensor node, the aggregation node needs to verify whether the aggregation node encryption authentication value slice and the sensor node encryption authentication value slice are equal to authenticate the sensor node. Since the sensor node key is used in the calculation process of the sensor node encryption authentication value slice, and the legal sensor node key can only be obtained by the node that completes the registration in a trusted environment, the authentication process can be considered legal.

[0019] Since the third and fourth random numbers are used in the authentication process of the aggregation node and the sensor node, when the first random number is replayed and sent, the randomness of the authentication can still be guaranteed by the fourth random number, thus having the ability to resist replay attacks.

[0020] Preferably, after the node authentication between the aggregation node and the access node is passed, the aggregation node key is also updated, specifically:

[0021] Perform encryption calculation according to the second random number, the aggregation node message sequence number, the aggregation node key, the identity authentication parameter and the master key to obtain a session key, and obtain a key update authentication parameter according to the session key;

[0022] The access node generates a fifth random number and generates a new sink node key, and then the access node updates the intermediate key and the mask, and sends the updated mask to the sink node;

[0023] After receiving the mask, the aggregation node restores the new aggregation node key, and calculates the session key based on the aggregation node key. Based on the session key to the key update authentication parameter, it determines whether the key update authentication parameter generated by the access node is the same as the key update authentication parameter generated by the aggregation node. If they are the same, the aggregation node key is updated.

[0024] The design of this scheme ensures the forward security of authentication. The forward security of the protocol means that even if the long-term master key is leaked, the session key used in the past will not be leaked. In this scheme, forward security means that even if the master key is leaked, the used session key will not be obtained by the attacker. Since the intermediate key and the second random number are used to calculate the session key, these two parameters will be dynamically updated after each successful authentication. After obtaining the master key, the attacker cannot infer the specific values ​​of the intermediate key and the second random number, and cannot obtain the session key.

[0025] At the same time, the design of this scheme realizes the reverse authentication of the access node by the aggregation node. The authentication process is realized by verifying whether the key update authentication parameters generated by the access node and the key update authentication parameters generated by the aggregation node are equal: after the access node processes the authentication request of the aggregation node, it will return an authentication response to the aggregation node. Combining the key information contained in the response and the key information stored locally, the aggregation node can restore the new intermediate node key, calculate the session key, and further obtain it through hash operation. Since the session key is used in the process of calculating the key update authentication parameters generated by the access node, and the calculation process of the session key uses the master key and the intermediate key, these two sets of keys can only be held by the access node at the same time, so it can be considered that the node that can provide the correct key update authentication parameters is a legitimate access node.

[0026] Preferably, after the authentication of the access node and the aggregation node and the aggregation node key update are completed, the access node generates a group key including all the aggregation nodes by using the key derivation function through the existing identities of all the aggregation nodes and their respective aggregation node keys. The generated group key can be securely transmitted in the network to ensure the overall security of the communication and the consistency of the key.

[0027] Preferably, after node authentication of the aggregation node and the sensor node, the sensor node key is also updated: an unselected slice of the encrypted authentication value is selected as a new sensor node key, and other unselected slices of the encrypted authentication value are selected to generate a new session key.

[0028] The design of this scheme realizes the two-way authentication of sensor nodes and aggregation nodes. Since the initial sensor node key is used in the shard calculation of the encrypted authentication value, and the legitimate sensor node key can only be obtained by the nodes that have completed the registration in a trusted environment, it can be considered that all parties that have passed the shard comparison and verification of the encrypted authentication value are legitimate nodes.

[0029] Preferably, after the sink node and the sensor nodes are authenticated and the sensor node keys are updated, the sink node generates a group key including all sensor nodes by using a key derivation function through the identities of all existing sensor nodes and their respective sensor node keys.

[0030] Preferably, the number of key slots for storing the aggregation node key is two, and the access node further generates an identification bit, wherein the identification bit is used to define the aggregation node key corresponding to a specific key slot as the currently valid aggregation node key.

[0031] Preferably, after the sink node key is updated, an unused key slot is designated to store the new sink node key.

[0032] Preferably, the number of the key slots for storing the sensor node key is two, and the aggregation node further generates an identification bit, wherein the identification bit is used to define the sensor node key corresponding to a specific key slot as a currently valid sensor node key.

[0033] Preferably, after the sensor node key is updated, an unused key slot is designated to store the new sensor node key.

[0034] The key slot design of this scheme resists synchronization attacks. The two key slots store the currently used key and the key to be used in the future respectively, and use the identifier Control the slots where the key is stored. When the aggregation node sends an authentication request to the access node, it includes the identification bit. When the access node selects a key, it uses the key stored in the slot corresponding to the value of the identification bit, and when updating the key, it will be stored in another slot. After entering the key update process, in addition to updating the intermediate key or sensor node key stored locally, the aggregation node will also invert the identification bit, so that it can be ensured that the identification bit always indicates the slot where the current key is located.

[0035] Preferably, the encryption algorithm is a hash algorithm.

[0036] The beneficial effects of the present invention are as follows: the present invention realizes two-way authentication between access nodes and aggregation nodes, between aggregation nodes and between sensor nodes, and ensures that consistent and secure keys are used in subsequent communications, thereby ensuring the security of communications;

[0037] The present invention has forward security, and even if the master key is leaked, the used session key will not be obtained by the attacker;

[0038] The present invention effectively resists the security threats of replay attack, leakage of short-term key information, desynchronization, and device storage being hacked, further reducing the security of communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0040] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0041] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0042] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0043] Example:

[0044] Network node authentication and key exchange protocol methods for smart grid scenarios, such as Figure 1 As shown, the following steps are included:

[0045] Step 1: System initialization, generate a master key for the access node , generate an identity for each sink node ;

[0046] Assign an identity to each sensor node , sensor node key And a flag that controls the key update process , and then store the identity and key of each sensor node in the sink node. The storage of the key in the sink node requires two slots , used to store two different keys before and after the key update process.

[0047] Step 2: aggregation node registration, specifically:

[0048] Sub-step 2a: , the aggregation node needs to identify itself After being packaged into a request, it is sent to the access node through a secure channel. After receiving it, the access node will process the request.

[0049] Sub-step 2b: , the access node generates a first random number for the aggregation node , aggregation node key and the key slot identifying the access node , There are two values, 0 or 1, which respectively indicate which location currently stores the valid key. The access node then calculates the intermediate key , authentication parameters The key information is encapsulated into a response and sent back to the aggregation node through a secure channel.

[0050] Sub-step 2c: The aggregation node stores the key information locally in the format of .

[0051] Step 3: Node authentication, key exchange and update are performed between the aggregation node and the access node, specifically:

[0052] Sub-step 3a: First generate the second random number , and calculate the mask , ; Then calculate the aggregation node authentication information , is the aggregation node message sequence number, and the aggregation node message sequence number is increased by one. , after which the calculated key intermediate variables can be packaged into an authentication request and sent to the access node.

[0053] Sub-step 3b: After receiving the authentication request from the sink node, the access node restores the intermediate key variable carried in the authentication request. , the access node message sequence number is , . And calculate the access node authentication information ,Compare and Are they equal and .like and The verification is passed and the synchronization sequence number is modified .

[0054] Sub-step 3c: The access node and the aggregation node , , , , , calculate the session key , the hash value of the session key , and then proceed directly to the key update phase.

[0055] Sub-step 3d: The access node will select a fifth random number And generate a new aggregation node key , then the intermediate key of the aggregation node is updated , mask , and then update the key in the unused key slot . Then the mask Sent to the sink node.

[0056] Sub-step 3e: After receiving the response, the sink node restores the updated key through XOR operation , then calculate the session key , the hash value of the session key , and judge Is it equal to , if the condition is met, update the key ,Key slot identifier .

[0057] Sub-step 3f: After the access node and the sink node complete the negotiation, the access node can generate the group key of all sink nodes by using the identities of all existing sink nodes and their respective keys. .

[0058] Step 4: The sink node and the sensor node perform node authentication, key exchange and update, specifically:

[0059] Sub-step 4a: The aggregation node selects a random number , combined with the identity of the corresponding sensor node Calculate the hash authentication value of the aggregation node ,Will , It is sent to the sensor node to be authenticated.

[0060] Sub-step 4b: After receiving the sensor node, the sensor node first calculates the hash authentication value , and judge and Are they equal? ​​If they are equal, the sensor node also selects a fourth random number , and , and sensor node keys After the combination, hash operation is performed to calculate the hash authentication value fragment , and then the sensor node will send the random number , Sharding of hash results and the key slot identifier are packaged and sent back to the aggregation node as a response.

[0061] Sub-step 4c: Aggregation Node After receiving the response, the sink node will first Perform the same hash operation to obtain the hash authentication value fragment , then The sensor node sends If they are the same, the sensor node is authenticated and then the shards are The sensor node is compared and authenticated. After the authentication is passed, the aggregation node will perform key exchange and key update. Since the hash operation results of the sensor node and the aggregation node are the same, the sharding can be used directly. as the new key.

[0062] Sub-step 4d: After receiving the information, the sensor node will compare and The value of will be used to authenticate the aggregation node. If it passes, the locally stored key will be updated. , and update the key slot identifier synchronously , and finally calculate the session key .

[0063] Sub-step 4e: After the sink node and the sensor node have completed the negotiation, the sink node can generate the group key of all sensor nodes through the existing identities of all sensor nodes and their respective keys. .

[0064] In the above text, represents the exclusive OR operation, Represents a hash operation, Indicates a key derivation function based on SM3.

[0065] It can be seen that the network node authentication and key exchange protocol method for the smart grid scenario of this embodiment has the following beneficial effects:

[0066] (1) Bidirectional authentication. In the authentication phase of the main network protocol, when the access node receives an authentication request from the aggregation node When the access node uses the key information contained in the request and the key material stored locally to restore the and , and then it can be calculated . Pass verification and If they are equal, the access node can determine whether the currently authenticated aggregation node is credible, because in the calculation The intermediate key is used in the process ,and In the registration process, it is only received and stored by the aggregation node, so it can be considered to provide correct The node is legitimate: At the same time, the protocol can also realize the reverse authentication of the access node by the aggregation node. The authentication process is verified by and After the access node completes the authentication request of the aggregation node, it will return the authentication response auth to the aggregation node. , combining the key information contained in the response and the key material stored locally, the aggregation node can restore the key , calculate , and further obtains Due to the calculation Used in the process , The calculation process uses the master key and the intermediate key , these two sets of keys can only be held by the access node at the same time, so it can be considered that they can provide correct The node is a legitimate access node. During these two verifications, if a mismatch occurs, the protocol will terminate the authentication process. In the authentication process of the subnet protocol, the aggregation node needs to verify and Whether they are equal to authenticate the sensor node; the sensor node needs to verify and Whether they are equal is used to authenticate the sink node. , The calculation process uses the aggregation node key assigned during the registration phase. , while legal Only nodes that have completed registration in a trusted environment can obtain it, and it can be considered that , The communication parties verified by comparison are both legal nodes, so it can be considered that this protocol has the ability of two-way authentication. More, identity authentication parameters It can also be combined with basic parameter information of the access node or the aggregation node, such as the identifier of the access node in the smart grid or the identifier of the aggregation node in the smart grid, to further enhance the identity authentication parameters. Reliability; the identity authentication parameter can also add the power grid area identification, each area or subnet has a unique identification, ensuring that only nodes from the same area or subnet can communicate and exchange data effectively.

[0067] (2) Forward security. The forward security of the protocol means that even if the master key used for a long time is leaked, the session key used in the past will not be leaked. In this protocol, forward security means that even if the master key is leaked, the session key used in the past will not be leaked. Leakage will not cause the used The key is used in calculating the session key. and random numbers , these two parameters will be dynamically updated after each successful authentication, and the attacker can obtain the master key It cannot be inferred that and The specific value of Therefore, this protocol can be considered to have perfect forward security.

[0068] (3) Resist replay attacks. In the main network protocol, in order to resist replay attacks, the protocol introduces an authentication serial number. This parameter, as the number of authentications increases, the serial number It will also be dynamically updated in the local storage of both parties as it increases. When the access node authenticates the aggregation node, it will pass the verification The access node determines the freshness of the authentication request from the parameters in the authentication request. Restored , and stored in the access node For comparison, if , indicating that the authentication request has expired, and this request may be a replay attack, the access node will terminate the authentication process. In addition, the protocol also sets a threshold value If the authentication request and The difference exceeds , indicating that the serial number may be constructed by an attacker, so it is also considered that this request may be attacked. . Random numbers are used in the subnet protocol process and , In the case of replay, the randomness of this round of authentication can still be obtained by Guaranteed. In addition, the key The authentication is updated in each round, and the authentication cannot be passed using an intercepted expired key, so this protocol has the ability to resist replay attacks.

[0069] (4) Resist the leakage of short-term key information. In this protocol, it is assumed that the attacker breaks into the access node during the authentication phase and obtains The attacker cannot use the short-term key information stored in the session key to calculate the session key. Because in the calculation In the process, in addition to the above short-term key information, the key generated during the registration phase is also used. of Although these two parameters are involved in the calculation during the authentication phase, they are not stored, so attackers cannot obtain them. Therefore, it can be considered that this protocol can resist the security threat brought by the leakage of short-term key information during the authentication process.

[0070] (5) Resist spoofing attacks. If an attacker wants to launch a spoofing attack, he must be able to calculate a legitimate authentication message. In this protocol, the authentication message contains a random number. , , and dynamic keys , , given the presence of multiple dynamic parameters, attackers cannot calculate legitimate authentication messages within an acceptable time, so it can be considered that this protocol has the ability to resist spoofing attacks.

[0071] (6) Resist desynchronization. Desynchronization attacks on the main network protocol may be launched from two angles: desynchronization of the authentication sequence number and desynchronization of the key update. In order to ensure the freshness of the authentication message, the protocol introduces the authentication sequence number, and the value of the sequence number is updated before each request is sent. An attacker can launch a desynchronization attack by forging the sequence number. For this, the protocol designs a threshold value. , for serial numbers exceeding , will also be considered illegal and return a result of authentication failure. Therefore, this protocol can resist desynchronization attacks launched against authentication serial numbers. If unexpected problems occur during the key update process, desynchronization may also occur. For this situation, this protocol maintains two key slots to store the currently used key and the key to be used in the future, and uses the identifier Controls the slots where the key is stored. When the aggregation node sends an authentication request to the access node, it includes the identifier , the access node will use the key stored in the slot corresponding to the value when selecting the key, and will store it in another slot when updating the key. After entering the key update process, the aggregation node will update the key stored locally. In addition, the flag bit is inverted , so that we can ensure It always indicates the slot that the current key is in. The same dual key slot concept is also used in the subnet protocol, so this protocol has the ability to resist desynchronization.

[0072] (7) Resist device storage being compromised. This protocol assumes that the key information in the access node and the aggregation node is stored in tamper-proof hardware, but the design also takes into account possible storage leakage. Assuming that an attacker accesses the key information stored in the hardware by breaking into the physical device, the attacker still cannot restore the previously used session key because the random number and short-term key used to calculate the key are dynamically updated and are not stored in the hardware. Therefore, this protocol can resist the security threat caused by the storage device being compromised to a certain extent.

[0073] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

[0074] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A network node authentication and key exchange protocol method for smart grid scenarios, characterized in that: The following steps are involved: Initialize the system, generate a master key for the access node, and generate an identity for each aggregation node; The aggregation node packages its own identity into a request and sends it to the access node. After receiving the request, the access node generates a first random number and an aggregation node key, and then generates an intermediate key and an identity authentication parameter through encryption calculation using the master key, the first random number and the aggregation node key, and sends the intermediate key and the identity authentication parameter to the aggregation node; Node authentication is performed between the aggregation node and the access node, including: Step A1, the sink node generates a second random number, and generates a mask and sink node authentication information through encryption calculation according to the intermediate key, the second random number and the sink node message sequence number, then updates the sink node message sequence number, and packages the mask, sink node authentication information and sink node message sequence number as key intermediate variables and sends them to the access node, requesting the access node to perform authentication; Step A2: After receiving the key intermediate variable, the access node restores the key intermediate variable to obtain a second random number and an access node message sequence number, and then calculates the access node authentication information. If the values ​​of the aggregation authentication information and the access node authentication information are equal and the number of the access node message sequence number is within a preset threshold range, the node authentication between the access node and the aggregation node is passed, and then the access node message sequence number is updated; Step A3, performing encryption calculation according to the second random number, the aggregation node message sequence number, the aggregation node key, the identity authentication parameter and the master key to obtain the session key; After the node authentication between the aggregation node and the access node is passed, the aggregation node key is also updated, specifically: Obtain the key update authentication parameter based on the session key; The access node generates a fifth random number and generates a new sink node key, and then the access node updates the intermediate key and the mask, and sends the updated mask to the sink node; After receiving the mask, the aggregation node restores the new aggregation node key, and calculates the session key based on the aggregation node key. Based on the session key to the key update authentication parameter, it determines whether the key update authentication parameter generated by the access node is the same as the key update authentication parameter generated by the aggregation node. If they are the same, the aggregation node key is updated.

2. The network node authentication and key exchange protocol method for smart grid scenarios according to claim 1 is characterized in that: It also includes node authentication between the sink node and the sensor node, including: Step B1, generating a sensor node key and an identity identifier for each sensor node; Step B2, the sink node generates a third random number, then performs encryption calculation based on the third random number and the identity identifier to generate an encrypted authentication value, and sends the third random number and the sink node encrypted authentication value to the sensor node; Step B3, after receiving the third random number and the aggregation node encrypted authentication value, the sensor node calculates the sensor node encrypted authentication value according to the third random number and its own identity identifier, and determines whether the aggregation node encrypted authentication value and the sensor node encrypted authentication value are equal. If they are equal, the sensor node generates a fourth random number, and performs encryption calculation on the third random number, the fourth random number and its own sensor node key to obtain the sensor node encrypted authentication value fragment, and then sends the fourth random number, the sensor node encrypted authentication value fragment and the packaged fragment to the aggregation node as a response; Step B4, after receiving the response, the aggregation node performs encryption calculation based on the third random number and the fourth random number to obtain the aggregation node encrypted authentication value fragment, and then determines whether the aggregation node encrypted authentication value fragment and the sensor node encrypted authentication value fragment are the same. If they are the same, it proves that the sensor node is legal, and the node authentication between the aggregation node and the sensor node is successful.

3. The network node authentication and key exchange protocol method for smart grid scenarios according to claim 1 is characterized in that After the authentication of the access node and the sink node and the sink node key update are completed, the access node generates a group key including all sink nodes by using the key derivation function through the identities of all existing sink nodes and their own sink node keys.

4. The network node authentication and key exchange protocol method for smart grid scenarios according to claim 2 is characterized in that After the node authentication of the aggregation node and the sensor node, the sensor node key is also updated: the unselected fragments of the encrypted authentication value are selected as the new sensor node key, and other unselected fragments of the encrypted authentication value are selected to generate a new session key.

5. The network node authentication and key exchange protocol method for smart grid scenarios according to claim 4 is characterized in that After the authentication of the sink node and the sensor node and the update of the sensor node key are completed, the sink node generates a group key including all sensor nodes by using the key derivation function through the identities of all existing sensor nodes and their respective sensor node keys.

6. The network node authentication and key exchange protocol method for smart grid scenarios according to claim 1 is characterized in that: The number of the storage key slots of the aggregation node key is two, and the access node also generates an identification bit, which is used to define the aggregation node key corresponding to a specific key slot as the current valid aggregation node key.

7. The network node authentication and key exchange protocol method for smart grid scenarios according to claim 6 is characterized in that: After the sink node key is updated, an unused key slot is designated to store the new sink node key.

8. The network node authentication and key exchange protocol method for smart grid scenarios according to claim 4 is characterized in that: The number of the key slots storing the sensor node key is two, and the aggregation node further generates an identification bit, and the identification bit is used to define the sensor node key corresponding to a specific key slot as the currently valid sensor node key.

9. The network node authentication and key exchange protocol method for smart grid scenarios according to claim 8 is characterized in that: After the sensor node key is updated, an unused key slot is designated to store the new sensor node key.

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