A blockchain security scheme to support fog-based internet of things

This paper proposes a fog-based secure data sharing framework for IoT devices that uses blockchain mechanism for this purpose. Fog computation is a popular paradigm that facilitates computation/storage facilities closer to the users and placed in between cloud environment and the users. Here, the IoT devices share data among each other through a secure mechanism. We propose two software agents: Software agent for Network formation and Monitoring (SAN) and Software agent for Blockchain formation and monitoring (SAB) placed in the fog node where SAN forms/monitors the network of IoT devices and SAB implements the security framework for block chain implementation. Here, three different versions of AES (128/192/256) are used for group key sharing. Group key is used for encryption/decryption of the data present in a block of a blockchain. An AES 128 based Proof of Work (PoW) is used for block addition by an authorized IoT device. SHA 256 is used for implementing hashing in blockchain. Three different systems namely System 1, 2, and 3 are considered for the experiment under different settings of design parameters. A comparison between different settings is depicted in the result section. The execution time (in seconds) is used as an evaluation parameter. The performance is found to be best in case of System 3 configuration. The time requirement is found to be a monotonically increasing function of block size and AES key length.