###### Abstract  
This paper demonstrates a broad exploration of existing authentication and secure communication of unmanned aerial vehicles (UAVs) in a '6G network'. We begin with an overview of existing surveys that deal with UAV authentication in 6G and beyond communications, standardization, applications and security. In order to highlight the impact of blockchain and UAV authentication in 'UAV networks' in future communication systems, we categorize the groups in this review into two comprehensive groups. The first group, named the Performance Group (PG), comprises the performance-related needs on data rates, latency, reliability and massive connectivity. Meanwhile, the second group, named the Specifications Group (SG), is included in the authentication-related needs on non-reputability, data integrity and audit ability. In the 6G network, with blockchain and UAV authentication, the network decentralization and resource sharing would minimize resource under-utilization thereby facilitating PG targets. Furthermore, through an appropriate selection of blockchain type and consensus algorithms, the SG's needs of UAV authentication in 6G network applications can also be readily addressed. In this study, the combination of blockchain and UAV authentication in 6G network emergence is reviewed as a detailed review for secure and universal future communication. Finally, we conclude on the critical identification of challenges and future research directions on the subject. 6G; unmanned aerial vehicles; network; security; topology; authentication; cryptography 2023 13 277. 10.390/app1301207202202  
5G and beyond networks. This figure symbolizes future employment of UAVs in numerous applications in advanced network environments. Blockchain could be a disseminated record innovation where cryptography and hash capacities are utilized to make a chain of information [3]. Blockchain, as it was initially utilized in crypto currencies is presently being utilized in other applications such as keen lattice, associated vehicles and Internet of Things [4; 5; 6]. The demanding prerequisites of these applications will require bolster of advances such as Reconfigurable Shrewdly Surfaces (RIS), TeraHertz (THz) communication, Artificial Intelligence (AI) and little cell systems. To enable a capable mix of these advances for the game plans of resources to achieve the execution essentials, collaboration and coordination in a straightforward and trustless environment is required [7]. Arranged decentralization will be needed to unravel the coordinate sending. Blockchain will give the required genuineness and verification within the decentralized UAV system in 6G-based UAV arrangements. Blockchain will also give the stern security essentials of the longer-term communication structure due to the built-in security highlights. In order to tweak blockchain by the selection of suitable blockchain rudiments, its application essentials, decentralization, security and features such as adaptability are vital considerations. Blockchain offers relatively simple solutions to major issues of centralized systems. It is a pertinent fact that centralized systems have concerns including resilience, safety, scalability and privacy. Blocks chained together by a hash in between them is the simplest concept of blockchain. Genesis block is the originating block of blockchain. The key properties such as the number of tokens existing in the system reside in this first block. The last block in blockchain is named tip block. A potential new block must point to tip block. In a blockchain system, all the members that are part of network contribute to consensus and possess a copy of blockchain. In a blockchain system, each block contains a division of information: (i) transactions and account balances, (ii) block hash and (iii) the block ID. Each node in the blockchain requires the validity to be verified of any new transaction, that is added to the blockchain.