Robust and efficient group key agreement method in uav ad hoc networks

Abstract

The application discloses a robust and efficient group key agreement method for unmanned aerial vehicle self-organizing network, which comprises the following steps: calculating the first key contribution quantity and the second key contribution quantity according to the owned and missing key contributions; determining to send the key contribution when the key contribution complementary rate obtained from the first key contribution quantity and the second key contribution quantity is greater than the first random number; determining to send the to-be-sent key contribution when the global key contribution propagation degree obtained from the to-be-sent key contribution is greater than the second random number; performing key contribution aggregation according to the sender group key generation tree to obtain a sender key contribution set; after receiving the sender key contribution set, merging the sender key contribution set to the group key generation tree, and obtaining the final group key according to the merged group key generation tree. The application improves the group key agreement success rate, avoids redundant forwarding, significantly reduces the transmission times, and reduces the bandwidth demand and the delay.

Description

Technical Field

[0001] This invention belongs to the field of group key technology, specifically relating to a robust and efficient group key negotiation method for unmanned aerial vehicle (UAV) self-organizing networks. Background Technology

[0002] In recent years, the rapid development of drone technology has led to its widespread application in key areas such as smart city management, disaster emergency response, traffic management, and tactical communication relay. Adaptive Unmanned Aerial Networks (UANETs), with their advantages of dynamic networking and decentralized collaboration, are gradually becoming an important architecture supporting drone swarm collaborative tasks. In UANETs, ​​drones contribute task data and other information through group communication to collaboratively complete more complex tasks. The security of group communication is directly related to the confidentiality and integrity of the contributed information. Therefore, group key negotiation technology is widely adopted to generate a contribution key for the swarm and encrypt the communication link to resist various security threats such as eavesdropping and tampering.

[0003] Existing group key negotiation schemes can be categorized into asynchronous and synchronous group key negotiation based on their negotiation methods. Asynchronous group key negotiation has the advantage of tolerating offline group members. However, this type of scheme relies on an online central server and is typically used in centralized scenarios such as online meetings and internal enterprise communications, fundamentally conflicting with the distributed nature of UANET. In contrast, synchronous group key negotiation has been extensively studied in scenarios like UANET and is more suitable for decentralized environments.

[0004] In distributed synchronous key negotiation protocols, each drone broadcasts its key contribution and requires all members to collect the complete key contribution set to generate a consistent group key. However, the highly dynamic and unstable wireless communication environment of UANET can lead to the loss of data packets used for exchanging key contributions, discrepancies in the key contribution sets held by each member, and ultimately, inconsistencies in the calculated group key. To address this issue, existing technologies often compensate for message loss through redundant transmission. In this process, each drone, after receiving a message from another member, forwards it to all its neighboring nodes. The main purpose is to increase the probability that each drone receives the message through multiple paths by repeatedly forwarding it, ensuring coverage of more nodes in the network and reducing the risk of message loss. However, while this mechanism effectively improves the success rate of key contribution propagation, its indiscriminate forwarding behavior results in a large amount of redundant data propagating in the network, severely wasting bandwidth and computing resources. This is especially problematic when there are many drones, significantly degrading the overall performance of the UANET. Therefore, how to ensure the effective propagation of key contributions while minimizing redundant propagation and reducing resource consumption has become an urgent problem to be solved. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a robust and efficient group key negotiation method for unmanned aerial vehicle (UAV) self-organizing networks.

[0006] The technical problem to be solved by this invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a robust and efficient group key negotiation method for unmanned aerial vehicle (UAV) self-organizing networks, the method comprising:

[0008] The sending drone calculates its own first key contribution and the receiving drone's second key contribution;

[0009] The sending drone calculates the key contribution complementarity rate based on the first key contribution quantity and the second key contribution quantity. When the key contribution complementarity rate is greater than the first random number, it determines to send a key contribution to the receiving drone.

[0010] The sending drone obtains the global key contribution propagation degree based on the key contribution to be sent. When the global key contribution propagation degree is greater than the second random number, it determines to send the key contribution to be sent to the receiving drone. The key contribution to be sent is a key contribution that the sending drone owns but the receiving drone does not own.

[0011] The sending drone aggregates key contributions based on the sending group key generation tree and the key contribution to be sent, to obtain the sending key contribution set;

[0012] When the receiving drone receives the sender's key contribution set, it merges the sender's key contribution set into the receiver's group key generation tree, and obtains the final group key based on the merged receiver's group key generation tree.

[0013] Optionally, before the sending drone calculates its own first key contribution count and the receiving drone's second key contribution count, the method further includes:

[0014] Construct the KeyMatrix for both the sending drone and the receiving drone to record the propagation status of key contributions.

[0015] Optionally, the key contribution complementarity rate is calculated as follows:

[0016] ;

[0017] in, Indicates the sending drone and the receiving drone Key contribution complementarity rate, Indicates the sending drone The number of key contributions, Indicates the receiving drone The number of key contributions.

[0018] Optionally, the global key contribution propagation degree is calculated as follows:

[0019] ;

[0020] in, Indicates the sending drone Global key contribution propagation degree, Indicates the sending drone The first in KeyMatrix Line number Column elements, For drone swarms.

[0021] Optionally, the sender group key generation tree and the group key generation tree are Merkle trees, where the value of each child node is obtained based on the corresponding key contribution, each internal node is obtained based on the values ​​of the child nodes on both sides, and the final group key is obtained based on the value of the root node of the merged group key generation tree.

[0022] Optionally, the calculation process for the child node's value is as follows:

[0023] ;

[0024] in, Indicates the sending drone The first in Key contribution The corresponding child nodes The value represents a random string of the same length as the key contribution. This represents a hash function.

[0025] Optionally, the value calculation process for the internal nodes is as follows:

[0026] ;

[0027] in, This represents the value of the internal node. This represents the value of the child node on one side of the internal node. This represents the value of the child node on the other side of the internal node.

[0028] Optionally, the final group key is calculated as follows:

[0029] ;

[0030] in, This refers to the final group key. Derived function for key. This represents the value of the root node.

[0031] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

[0032] In the above technical solution, this invention enables drones to selectively forward key contributions to receiving drones as needed, rather than blindly forwarding them randomly, thereby avoiding unnecessary redundant forwarding. Secondly, each drone can aggregate multiple key contributions into a set for transmission. This not only ensures the availability of key contributions but also significantly reduces the number of key contribution transmissions, lowers bandwidth requirements, and effectively reduces the latency of group key negotiation.

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0034] Figure 1 This is a flowchart of a robust and efficient group key negotiation method for unmanned aerial vehicle (UAV) self-organizing networks provided by an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of a local KeyMatrix for a drone provided in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of a group key generation tree provided in an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of node merging provided in an embodiment of the present invention. Detailed Implementation

[0038] To facilitate understanding of the present invention, a brief description of the prior art and the inventive concept of the present invention will be provided first.

[0039] In this invention, a UAV Ad-hoc Network (UANET) is constructed, consisting of multiple UAVs, each with a fixed identifier. Before executing a mission, the Ground Control Station (GCS) assigns relevant parameters and secret values ​​to each UAV. It is important to emphasize that the GCS does not participate in the group key negotiation process of the UANET during the subsequent mission. Assuming the entire UANET is a connected network, two adjacent UAVs with suitable distances can establish a communication link and mark each other as neighboring nodes. Each UAV can transmit messages to any other UAV in the UANET through multi-hop communication links. Due to the instability of wireless links and the high dynamism of the UANET, there is a certain probability of message loss when UAVs communicate with each other.

[0040] Figure 1 This is a flowchart of a robust and efficient group key negotiation method for unmanned aerial vehicle (UAV) self-organizing networks provided by an embodiment of the present invention, as shown below. Figure 1 As shown, the method may include the following steps:

[0041] S101, The sending drone calculates the number of its own first key contribution and the number of the receiving drone's second key contribution.

[0042] Understandably, based on its own KeyMatrix, that is... For each neighboring drone Sending drone First, calculate the values ​​of both the drone itself and the receiving drone. The number of key contributions possessed is denoted as the first key contribution number. Second key contribution quantity .

[0043] Optionally, prior to S101, the method further includes: constructing a KeyMatrix for both the sending drone and the receiving drone to record the propagation state of key contributions.

[0044] KeyMatrix is ​​a two-dimensional matrix used to record the propagation state of each key contribution during group key negotiation. Let... Indicated by drones The generated key contribution. Each drone participating in the negotiation. Maintain a separate local KeyMatrix, denoted as Its dimensions are ,in This represents the total number of drones in UANET. Specifically, if the matrix elements... This indicates that from the perspective of the drone, the receiving drone... Successfully received from the sender's drone Key contribution; if This indicates that from the drone From the perspective of the receiving drone Unsuccessfully received from the sender's drone The key contribution. The diagonal elements of KeyMatrix are always set to 1, because each drone must have its own generated key contribution.

[0045] With three drones , , Taking the UANET as an example, Figure 2 This is a schematic diagram of a drone's local KeyMatrix provided in an embodiment of the present invention. Assuming that after several message transmissions, the KeyMatrix maintained locally by each drone is as follows: Figure 2 As shown. For drones For example, the first line of its local KeyMatrix indicates that it has received the drone. Key contribution ( (), but have not yet received the drone. Key contribution ( The second line of KeyMatrix indicates the drone. All key contributions have been successfully received. , , The third line describes the drone. The drone has been received. Key contribution ( ), but not received Key contribution ( ).

[0046] With drones Similarly, drones and The reception status of global drone key contributions can also be obtained through their respective KeyMatrix. It should be noted that due to transmission latency, the perspectives of each drone are not entirely consistent, therefore their respective KeyMatrix may differ. However, this is sufficient to allow drones to obtain a global perspective as much as possible in a distributed scenario, laying the foundation for subsequent targeted key contribution forwarding.

[0047] Before group key negotiation begins, each drone initializes its local KeyMatrix. At this stage, no message exchange or key contribution transmission has occurred; each drone only holds its own generated key contribution. Therefore, the diagonal elements of their KeyMatrix are set to 1, while all other elements are initialized to 0. During the subsequent group key negotiation process, drones exchange key contributions via message exchange. When the sending drone... To the recipient Forwarding key contribution At the same time, it will send its own KeyMatrix.

[0048] Receiving drone Received from the sender's drone Key contribution and Next, it first checks if it possesses the key contribution locally. If not, it saves the key contribution and sets the corresponding element in the local KeyMatrix. Setting it to 1 indicates that it has received a key contribution. Subsequently, the receiving drone Use the following formula With oneself Perform a bitwise AND operation to update the understanding of the global key contribution reception status:

[0049] ;

[0050] in, This update enables the receiving drone Sending drone The perspective of the global key contribution reception state is merged into the local data, thereby obtaining more information about the global state.

[0051] It is worth mentioning that if and only if all elements of a drone's KeyMatrix are 1, it can be determined that all drones in the group have received all key contributions, and the drone then terminates forwarding.

[0052] S102. The sending drone calculates the key contribution complementarity rate based on the first key contribution quantity and the second key contribution quantity. When the key contribution complementarity rate is greater than the first random number, it determines to send the key contribution to the receiving drone.

[0053] Understandably, to avoid redundant transmission and further optimize the transmission efficiency of key contributions in UANET, an adaptive key contribution forwarding strategy is proposed. This strategy dynamically adjusts the forwarding target node and target key contribution based on the key contribution reception status reflected in the KeyMatrix, thereby suppressing redundant transmission.

[0054] Assume the sending drone The local key contribution set is Its neighboring drones are When the sending drone When forwarding key contributions, it selects a subset of neighboring drones as forwarding targets. For any drone... , The receiver's drone can be inferred based on its own local KeyMatrix. Locally owned key contribution set .

[0055] Key Contribution Complement Rate indicates the sending drone's... The key contribution is beneficial to the receiving drone. The degree of complementarity. Key contribution complementarity rate. Defined as the sending drone The owner and the receiver of the drone The key contribution complementarity rate is calculated as follows: (The percentage of missing key contributions relative to the total number of key contributions held by both parties is used to determine the key contribution complementarity rate.)

[0056] ;

[0057] in, Indicates the sending drone and the receiving drone Key contribution complementarity rate, Indicates the sending drone The number of key contributions, Indicates the receiving drone The number of key contributions.

[0058] For example, when the group size is 4, if the drone The key contribution is , have ,but It is 0.25.

[0059] The core idea of ​​key contribution complementarity is that the probability of a drone choosing a forwarding target is proportional to its key contribution complementarity with that target node. When forwarding key contributions, the drone prioritizes neighboring nodes that currently lack more key contributions than it possesses. By selecting nodes with stronger complementarity, redundant distribution can be minimized, avoiding sending the same key contribution to nodes it already owns, thereby optimizing bandwidth and energy efficiency.

[0060] S103. The sending drone obtains the global key contribution propagation degree based on the key contribution to be sent. When the global key contribution propagation degree is greater than the second random number, it determines to send the key contribution to be sent to the receiving drone. The key contribution to be sent is a key contribution that the sending drone owns but the receiving drone does not own.

[0061] Understandably, Key Contribution Propagation Degree measures the breadth of a key contribution's propagation within the UANET. Global Key Contribution Forwarding Degree Defined as having received key contributions The proportion of the number of nodes in the global key contribution propagation degree to the total number of nodes. The calculation method for global key contribution propagation degree is as follows:

[0062] ;

[0063] in, Indicates the sending drone Global key contribution propagation degree, Indicates the sending drone The first in KeyMatrix Line number Column elements, For drone swarms, .

[0064] The core idea of ​​key contribution propagation is that key contribution... The forwarding probability should be inversely proportional to the number of drones in the UANET that have received the contribution. If a key contribution has been received by most drones, its forwarding probability should be reduced to avoid redundancy; conversely, if many nodes have not yet received the key contribution, its forwarding probability should be increased to speed up its propagation and ensure that more nodes can receive the key contribution in a timely manner.

[0065] Therefore, by comprehensively considering the key contribution complementarity rate and the global key contribution propagation degree, each drone can dynamically adjust the probability of forwarding different key contributions to its neighboring nodes. Specifically, when the sending drone... To its neighboring receiving drone When forwarding key contributions, the strategy includes the following steps:

[0066] Based on the sending drone Its own For each neighboring drone Sending drone First, calculate the values ​​of both the drone itself and the receiving drone. The number of key contributions possessed is denoted as follows: and ,as well as That is, the sending drone The owner and the receiver of the drone The number of missing key contributions is used to calculate the key contribution complementarity rate. Subsequently, the sending drone Generate a second random number If the first random number Then it was decided to send the drone to the recipient. Forwarding key contribution.

[0067] Then regarding the sending drone The drone is owned by the user, while the receiving drone is... Each key contribution not owned Through statistics No. The number of 1s in the column is used to further calculate the global key contribution propagation degree. Subsequently, the sending drone Generate a second random number, if the second random number Then it is further determined that the key contribution should be made. Forwarded to the recipient drone .

[0068] S104. The sending drone aggregates key contributions based on the sending group key spanning tree and the key contributions to be sent, to obtain the sending key contribution set.

[0069] optional , Figure 3 This is a schematic diagram of a group key generation tree provided in an embodiment of the present invention, as shown below. Figure 3As shown, the tree is a Merkle tree. Both the sender's group key generation tree and the group key generation tree are Merkle trees. The value of each child node is derived from its corresponding key contribution, and each internal node is derived from the values ​​of its two adjacent child nodes. Through bottom-up hash calculation, these key contributions are gradually aggregated. The final group key is derived from the value of the root node of the merged group key generation tree. The group key is generated at the root node using a Key Derivation Function (KDF). It is important to note that all drone contributions participating in group key negotiation belong to the same tree structure. Specifically, the group key generation tree... Follow these rules:

[0070] Each child node Corresponding to the sending drone The unique key contribution provided Based on the structural characteristics of a Merkle tree, the total number of child nodes should be... ,in, Represents the group key spanning tree The depth. If the actual group size is smaller than... If no key contribution is made, the child nodes will be filled with the default value. . A random string of the same length as the key contribution is provided and is known to all group members. Formally, the calculation process for the child node values ​​is represented as follows:

[0071] ;

[0072] in, Indicates the sending drone The first in Key contribution The value of the corresponding child node, Represents a random string of the same length as the key contribution. This represents a hash function.

[0073] Each internal node The value is obtained by concatenating the values ​​of its left and right child nodes and then hashing them using a hash function. The calculation process for the values ​​of internal nodes is as follows:

[0074] ;

[0075] in, Indicates the value of the internal node. This represents the value of the child nodes on one side of an internal node. This represents the value of the child node on the other side of the internal node.

[0076] S105. After the receiving drone receives the sender's key contribution set, it merges the sender's key contribution set into the receiver's group key generation tree, and obtains the final group key based on the merged receiver's group key generation tree.

[0077] Understandably, by performing a bottom-up hash calculation, the value of the root node, containing all drone key contributions, is obtained. The final group key is calculated as follows:

[0078] ;

[0079] in, Indicates the final group key. This is a key derivation function. This represents the value of the root node.

[0080] Based on the structure of a group key generation tree, when the sending drone Requires a set of transmission key contributions In such cases, these key contributions can be aggregated to reduce communication overhead. The specific process is as follows:

[0081] Before contributing the transmission key, the drone first generates a local group key tree. Aggregate all key contributions it possesses. Specifically, starting from the child nodes: if the drone Having a key contribution corresponding to a certain child node Then, the value of the child node is calculated according to the above formula. For each internal node in the tree, if the child nodes on both sides have been calculated, the sending drone... The value of the internal node is then calculated according to the above formula. This process iterates from bottom to top until either of the following occurs: (1) the child nodes on both sides of the internal node are missing, making it impossible to calculate its value; (2) the bottom-up iteration reaches the root node, indicating that the final group key can be calculated.

[0082] Subsequently, for each key contribution in the set of key contributions to be sent, the sending drone... In the group key generation tree The corresponding child nodes are located within the group key generation tree. According to the structure of the group key generation tree, higher-level ancestor nodes are obtained by concatenating and hashing the values ​​of all their descendant nodes; therefore, they implicitly contain the key contributions of all their descendant child nodes. When multiple key contributions to be sent share the same ancestor node, they can be replaced by the value of that ancestor node, thus aggregating multiple key contributions into one. Finally, the sender's key contribution set is obtained, denoted as […]. .

[0083] When the receiving drone Received sender key contribution set Then, it merges these key contributions into the local group key generation tree. In detail, for each received node value representing the key contribution... , Perform the following operations: 1) If If the receiver already contains the node itself or any of its ancestor nodes, then the receiver is considered to be in a different state. The corresponding key contribution is already available, no further action is required; 2) Otherwise, insert the node into The corresponding position.

[0084] Example, Figure 4 This is a schematic diagram of node merging provided in an embodiment of the present invention, as shown below. Figure 4 As shown, suppose the drone needs to contribute a set of keys. Send to the recipient drone Corresponding to the group key generation tree child nodes .according to The structure, , and Contributing to the same ancestor node Therefore, the sending drone It can be used replace ,and This remains unchanged. The final aggregated set of key contributions to be sent is: .

[0085] The receiving drone Initial and pending key contribution (Green represents ownership, red represents non-ownership). When it receives the aggregated internal nodes... With child nodes At that time, both will be directly inserted into their local group key generation tree. In the middle. If the receiving drone then... Received again Descendant nodes, because they already have higher-level nodes These nodes will be ignored.

[0086] In the above technical solution, this invention enables drones to selectively forward key contributions to receiving drones as needed, rather than blindly forwarding them randomly, thereby avoiding unnecessary redundant forwarding. Secondly, each drone can aggregate multiple key contributions into a set for transmission. This not only ensures the availability of key contributions but also significantly reduces the number of key contribution transmissions, lowers bandwidth requirements, and effectively reduces the latency of group key negotiation.

[0087] It should be noted that the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention.

[0088] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0089] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings and the disclosure in carrying out the claimed invention. In the description of the invention, the word "comprising" does not exclude other components or steps, "a" or "an" does not exclude a plurality, and "a plurality" means two or more, unless otherwise explicitly specified. Furthermore, while different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce good results.

[0090] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A robust and efficient group key negotiation method for unmanned aerial vehicle (UAV) self-organizing networks, characterized in that, The method includes: The sending drone calculates its own first key contribution and the receiving drone's second key contribution; The sending drone calculates the key contribution complementarity rate based on the first key contribution quantity and the second key contribution quantity. When the key contribution complementarity rate is greater than the first random number, it determines to send a key contribution to the receiving drone. The sending drone obtains the global key contribution propagation degree based on the key contribution to be sent. When the global key contribution propagation degree is greater than the second random number, it determines to send the key contribution to be sent to the receiving drone. The key contribution to be sent is a key contribution that the sending drone owns but the receiving drone does not own. The sending drone aggregates key contributions based on the sending group key generation tree and the key contribution to be sent, to obtain the sending key contribution set; When the receiving drone receives the sender's key contribution set, it merges the sender's key contribution set into the receiver's group key generation tree, and obtains the final group key based on the merged receiver's group key generation tree. Before the sending drone calculates its own first key contribution and the receiving drone's second key contribution, the method further includes: Construct the KeyMatrix for both the sending drone and the receiving drone to record the propagation status of key contributions; The key contribution complementarity rate is calculated as follows: ； in, Indicates the sending drone The key contribution complementarity rate with the receiving drone, Indicates the sending drone The number of key contributions, Indicates the receiving drone The number of key contributions; The calculation method for the global key contribution propagation degree is as follows: ； in, Indicates the sending drone Global key contribution propagation degree, Indicates the sending drone The first in KeyMatrix Line number Column elements, For drone swarms.

2. The robust and efficient group key negotiation method for UAV self-organizing networks according to claim 1, characterized in that, The sender group key generation tree and the group key generation tree are Merkle trees, where the value of each child node is obtained based on the corresponding key contribution, each internal node is obtained based on the values ​​of the child nodes on both sides, and the final group key is obtained based on the value of the root node of the merged receiver group key generation tree.

3. The robust and efficient group key negotiation method for UAV self-organizing networks according to claim 2, characterized in that, The calculation process for the value of the child node is as follows: ； in, Indicates the sending drone The first in Key contribution The value of the corresponding child node, Represents a random string of the same length as the key contribution. This represents a hash function.

4. The robust and efficient group key negotiation method for UAV self-organizing networks according to claim 3, characterized in that, The calculation process for the value of the internal node is as follows: ； in, This represents the value of the internal node. This represents the value of the child node on one side of the internal node. This represents the value of the child node on the other side of the internal node.

5. The robust and efficient group key negotiation method for UAV self-organizing networks according to claim 4, characterized in that, The final group key is calculated as follows: ； in, This refers to the final group key. Derived function for key. This represents the value of the root node.

Images