# An Internet of Things Access Control Scheme Based on Permissioned Blockchain and Edge Computing
###### Abstract  
In the IoT (Internet of Things) environment, the existing access control schemes for device resources have some problems, such as poor scalability, high latency, security, and dynamics. Combining the advantages of the permissioned blockchain and edge computing, an access control scheme for the Internet of Things based on the permissioned blockchain and edge computing is proposed. By authenticating the user's identity at the edge, the user's identity is reliable and the response time is improved. In the ABAC (Attribute Based Access Control) model, the blockchain is regarded as a trusted entity, and the access control policy is written into a smart contract and deployed on the blockchain for calling. Most of the existing consensus algorithms have the problems of low throughput and scalability. A Kraft (Kademlia-Raft) consensus algorithm is introduced to solve the above issues. Security analysis and experimental results show that the scheme can achieve fine-grained, dynamic access control, has high throughput and low latency, and ensures security and reliability.  
Internet of Things (IoT); blockchain; access control; smart contract; edge computing +
Footnote †: journal: Applied sciences  
in which only specific users have the right to access any kind of data. Because of a large number of resource-constrained devices in the IoT, edge computing can be combined to achieve low latency. Edge computing refers to an open platform that transfers computing and communication resources from the cloud to the edge nodes of the network in order to provide faster services and computing responses for edge users [11]. Because of the characteristics of the IoT, this paper uses the permissioned blockchain. The permissioned blockchain refers to that of each node participating in the blockchain device to which it is licensed, and the unauthorized node cannot be accessed on the machine [12].  
The resource owner first publishes the access control policy of resources in the blockchain. In order to access data, the resource requester will request access to blockchain data by using smart contract API and whether access permission is granted by the access control policy running in the blockchain. The role of the blockchain in access control is not only to store access control policies and permission transaction information, but also to provide functions such as automatically executed access control policies and grant permissions. The main contributions of this paper are as follows:  
1. A scheme of access control in the IoT environment is proposed, which combines edge computing and license chain, and realizes access control with low delay, fine granularity. and dynamic performance.
2. The solution uses blockchain networks as an interactive medium, smart contracts as the driving force, and the KRaft consensus algorithm as the execution standard to reasonably improve the existing attribute-based access control model, achieving policy implementation goals such as automatic decision-making and authenticity, credibility, transparency, traceability, and auditability.
3. Edge computing is introduced to ensure relatively low computing and communication costs, because the edge side has lower latency and higher availability than the cloud side network, and data will not be attacked during transmission.
4. The security analysis of the scheme is carried out, and the performance of the scheme is compared with other schemes through experimental simulation. Experiments show that the scheme has several strengths, such as throughput and low latency with security and reliability.