A blockchain based private framework for facilitating digital forensics using IoT

Abstract

Introduction: Images play an essential role as evidence in any forensic analysis of a police investigation. They are a crucial part of the analysis and store important and nuanced information required to guide the analysis in the right direction and then finally lead the investigation to a just conclusion. However, these images are often subject to tampering. Malicious elements of society external or internal entities involved in conducting the investigation, try to tamper with, mend, and destroy pieces of evidence. This change can mislead the direction of the evidence and can benefit the accused. Research Problem: Through the scope of this paper, we will try to tackle this problem and find a solution for it. Methods: The approach proposed to tackle this problem is to implement a blockchain-based, distributed virtual private network (VPN) system. The network consists of devices spread across the internet, connected via a VPN. Only authorized devices are a part of the network and each device has a particular role and key. The image is captured from the IoT device at the crime scene, it is then encrypted using a Mixed Alphabet Cipher substitution algorithm that converts the RGB values to a string at the camera node and then transferred to the main server. It is further decrypted and again encrypted using the key of the main server. Upon encryption, the string is converted to a hash key which is then added to the blockchain. Results: The performance of the proposed network is tested on two different parameters- operating system and image size. It was found that the encryption time of images varies linearly with image size, operating system and image size. The different operating systems are Ubuntu and two variants of MAC OS. The images being tested vary from 200x200 px to 3840x2160px. The encryption and decryption time of different images is recorded, and it was found that the encryption time of images varies linearly with image size. Conclusion: The proposed solution was successfully developed and tested on different sets of images and operating systems. As our solution uses an in-house developed blockchain network, it has a better working cost than using an Ethereum-based blockchain.