# Development of an Electronic Smart Safe Box Using Private Blockchain Technology
## 2 Literature Review
For instance, in [19], the authors presented the application of blockchain technology to ensure secure transactions to IoT devices and block the tempering of sensitive data using the Hyperledger Fabric blockchain. A scenario is implemented by IoT devices connected to the centralized server for sharing data where each transaction is recorded by implementing a block. Every participating peer keeps a copy of the ledger, and they also check and sustain the blockchain. Likewise, a system is proposed in [20] to ensure a decentralized mechanism to block the cyber security attacks on the system proposed in [19]. This system further enhances the security of the system proposed in [19] by providing a solution for the constrained devices to join the blockchain network efficiently and securely. A blockchain is mainly based on preparing the hash of data and then linking it to each other as a block. Therefore, using this technology always adds many challenges such as requiring high processing systems, high memory, etc. In this regard, a system based on a lightweight consensus algorithm is introduced in [21]. The proposed lightweight blockchain technology efficiently meets the processing requirements required for IoT devices. Therefore, this technology could be an appropriate solution to use in IoT environments. However,as the IoT consists of many different events, employing such technology at multiple phases can increase the speed requirements. Another blockchain solution is presented in [22] where the author introduces a transfer and store concept to IoT devices. Further, this study presents various challenges that can come across in implementing blockchain technology for IoT devices. The authors also mentioned using the Hyperledger Fabric blockchain as stated in [19]. However, the performance evaluation is performed in smart home environments where the requirement of speed is already provided via high-end systems. Therefore, using such a technology for the IoT environments constrained to limited speed may decrease the availability and suitability. In order to avoid the limitation of the system proposed in [22], the authors of the system presented in [23] come up with a system that introduces the concept of smart contract security. The idea of smart contract security is to secure the transaction for IoT products accessed by a group of users such as smart safe boxes in homes. However, the proposed system, which is based on Ethereum smart contracts, poses many challenges to the implement it in IoT environments. As the IoT-based smart homes and cities are rapidly adding new things and, therefore, the security of accessing these things requires sophisticated and lightweight mechanisms. In this regard, a Proof of Concept (PoC)-based blockchain technology is introduced to handle the authorization issue to the things available in smart homes. According to the authors, a smart contract-based solution is implemented to ensure the integrity of the system. As this concept is purely designed for administration access, the practical implementation of such a system requires great care and turning of a wide number of variables. One of the main reasons the authors suggested the use of blockchain is it provides transparency which in turn helps in auditability [24; 25; 26; 27; 28]. Concluding the above literature, it is worth mentioning that so far none of the blockchain technology can work efficiently for protecting smart safe box transactions. We have therefore proposed a system to handle the transactions in a smart safe box using an immutable blockchain technology as stated in Section 3.1. Also, Table 1 shows the most related research works relevant to our proposed work. All these research articles are mainly about the smart safe box, to discover how they are use and what enhancement features there are in the perspective of the IoT.