# Development of an Electronic Smart Safe Box Using Private Blockchain Technology
## 4 Results
### Evaluation of Proposed Blockchain System for Smart Safe Box  
To test the performance of the blockchain technology used to secure the transaction in the smart safe box, we considered three different nodes performing the various transaction at different times of the day. Initially, node1 performs the transaction in the smart safe box by adding document1 to it. The transaction is sent to the server connected to the smart safe box via internet access. After some time, node2 performs a transaction by adding a new document to the smart safe box, however, removing some part of the document1. The transaction is recorded and sent to the server. Finally, node1 accessed the smart safe box for document1, which was altered by node2. Node1 checks the transaction of the log stored in the server upon each transaction to the smart safe box. Finally, node1 found that the transaction performed by node2 alters document1 and thus a security breach is identified by checking the previous transactions. The following Figure 7 shows the transaction of the above scenario.  
The concept of the proposed blockchain is based on the consensus algorithm as discussed in Section 3. To implement the concept of private blockchain in the proposed scheme, we have considered a node opening the smart box as a leader and the rest of the subjects as witnesses. To perform a transaction, a leader first generates a transaction  
Figure 6: GPS testing results.  
Figure 7: Generating blocks using the private blockchain technology.  
message and sends it to the witnesses. Unlike the voting-based consensus algorithm, the leader is not randomly selected in our proposed private blockchain solution. However, a node that is interested in the transaction can become a leader and the rest of them a witness. As soon as a witness receives a transaction request from the leader, it starts collecting the signature of the rest of the witness nodes. After collecting the signatures from the rest of the witness nodes, each witness node marks the transaction as a valid transaction. Finally, the signed transaction request is broadcasted to each witness. To test the above-mentioned scenario in the proposed smart safe box, we considered a situation where a transaction is successful only and therefore ignored the situation where a transaction is unsuccessful. In the case of a successful transaction, all the witnesses sign the transaction, and the final copy is broadcast to every witness successfully. Further, we considered all the participating witness nodes connected to the same network. Also, two different results were calculated i.e., the variation in (1) overhead with different transactions per block (t/b) and (2) throughput with transaction per second (t/s) against a different number of nodes. We have noticed that as the non-consensus activities increase, the overheads also increase. It can be seen in Figure 8a, that 70% of the overheads are caused by non-consensus activities, and the remaining 30% are spent on consensus activities. However, as the nodes are connected to the same network, the throughput is high as shown in Figure 8b.  
Figure 8: (a) Overhead and (b) Throughput of proposed private blockchain with a various number of transactions.  
Concluding the practical implementation of the system, we have noticed that the system may be a suitable solution for those who are sharing a common place for securing their important contents. For instance, in a joint family account in a bank, mutual documents, etc. the goal is to protect data from individual access and thus require the authentication of each entity modifying and updating the important things such as jewelry, documents, etc.