## 1 Introduction  
With the rapid development of UAV technology, it has become widely used in various fields. In the military, UAVs can infiltrate the enemy to carry out precise target strikes, reconnaissance patrols and other high-risk tasks; for civilian use, they are widely used in the service industry, agricultural and industrial scenarios, such as UAV express delivery, disaster rescue in complex environments, aerial irrigation of crops, and network relay in communication scenarios [1, 2, 3, 4]. They bring great convenience to people's production and life. Typically, UAVs operate remotely by receiving commands from the GCS, and the information transmitted is essentially highly sensitive and critical [5]. Therefore, security is the top priority in UAVs communication. [PERSON] has designed and developed a set of UAV hijacking scheme, which can make the UAV fly to uncontrollable areas by tampering with GPS data, resulting in unpredictable consequences [6, 7]. Meanwhile, a vulnerability has been discovered in DJI drones, which allowed attackers to intercept users' identity tokens, steal account information, violate users' privacy, and even hijack the drones by logging into DJI forums as a legitimate identity [8]. Therefore, we should design a robust protocol to protect the communication security of UAVs. The current security threats in drones [9, 10, 11, 12, 13] are:* _Eavesdropping attack_: This type of attack is a passive attack. During the execution of the protocol, attackers can listen and obtain communication messages between nodes through an insecure communication channel without interfering with the normal operation of the protocol, and then attackers can analyze the messages to obtain some communication information or key information to carry out further attacks. * _Replay attack_: After attackers intercept the communication message between nodes, they retransmit the intercepted message, causing all nodes in the system to process the message again. If nodes in the system do not judge the expired message, the replayed message may have unpredictable consequences for the network system. * _Message tampering attack_: Attackers intercept the message sent by the node and modify it according to the attack purpose, then send the modified message to the recipient of the original message. In this type of attack, attackers can change the intercepted message in part or in whole in any way desired. * _Man-in-the-middle attack_: This type of attack is usually found in protocols that lack mutual authentication between the two parties. Attackers can submit the question asked by one subject in the protocol to another participant for an answer, and then submit the answer to the subject who asked the question. * _Denial of Service Attack (DoS Attack)_: Attackers make the system network unavailable to other legitimate users by continuously taking up resources on the system network. The rapid relative movement between UAVs easily causes frequent connection and disconnection of communication links, whereas nodes can join or leave the network at any time, which makes the network topology change rapidly and causing frequent changes in the trust relationship between nodes. If the authentication of the leaving nodes or newly joined nodes into the network is too simple, attackers will get the disconnected node's information and then simulate the disconnected nodes to request re-entry authentication, causing security risks to the system. Therefore, the proposed security solution for UAV communications needs to be able to meet the following security objectives [14,15]. * _Session Key Agreement_: The generated session key should be negotiated by both parties, rather than generated and distributed by the other party. Both parties shall contribute equally to the generation of the session key. * _User Anonymity and Untraceability_. The protocol needs to achieve user anonymity and untraceability, which means that attackers cannot get the user's identity.