# Security Issues in IoT-Based Wireless Sensor Networks: Classifications and Solutions
## 4 Results and Discussion
### In Integrating Blockchain Technology  
The research results show that blockchain is a potential solution to enhance the security of WSNs. In [102], blockchain not only helps protect data from attacks but also optimizes data transmission efficiency and network resource management. In [103], blockchain deployment in WSNs can be widely applied in fields such as environmental monitoring, healthcare, national security, and smart cities. Studies show that blockchain-based security systems help to improve the accuracy of attack detection and maintain service quality in such networks (Table 6). In [104], blockchain can be combined with technologies such as federated machine learning to enhance the detection and classification of security threats in WSNs.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Criteria** & **Ref.** & **Results and Discussion** \\ \hline Improved data security & [90] & Blockchain helps protect data from unauthorized modification \\ and integrity & [90] & thanks to its immutability mechanism and Merkel-tree algorithm. \\  & & This ensures that data in WSN is always authentic and trustworthy. \\ \hline Detection and removal of & [91] & Blockchain creates a distributed ledger that records the history of node operations, combined with smart contracts to automatically discover and eradicate malicious nodes. \\ \hline \hline \end{tabular}
\end{table}
Table 6: Blockchain application in wireless sensor network security.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Criteria** & **Ref.** & **Results and Discussion** \\ \hline Validate Aggregate Results & [84] & Propose a new framework for secure information aggregation, in which some nodes act as aggregators, which aggregate information according to the query requirements. Suitable for large-scale WSNs, but complicated to deploy. \\ \hline Reduce Data Duplication with & [85] & Optimize energy and bandwidth in hierarchical-based sensor networks. Good security when data is not decrypted at the aggregator node. However, this method is only effective when the data has a high degree of duplication. \\ \hline Differential Aggregation of Data & [86] & Suitable for event detection applications, such as fire or abnormality sensors. However, it is necessary to ensure the reference value at the cluster-head to avoid bias in aggregation (the reference data is based on the averaging of previously transmitted data). \\ \hline Validate Aggregation Results & [87] & Propose a data aggregation mechanism based on WDA authentication node for WSNs to ensure the authentication of data sent from the data aggregator nodes to the base station, thereby enhancing data integrity and protecting against modification attacks. \\ \hline Aggregate Encoded Data & [88] & Proposed stream encryption technique that can be performed directly on encrypted data without decryption. This can help protect the integrity and confidentiality of data being transmitted or processed. End-to-end privacy protection and suitable for resource-constrained devices.  
\end{table}
Table 5: Secure data aggregation in wireless sensor network security.  
One restriction of blockchain application in WSN-IoTs is that the system requires complex computation that leads to excessive energy usage. To solve this problem, the authors [105] proposed the use of efficient consensus algorithms such as Proof of Stake (PoS) or Practical Byzantine Fault Tolerance (PBFT) which significantly reduce energy consumption compared to traditional methods such as Proof of Work (PoW). Simulation results show that blockchain systems applying PBFT can maintain high data transmission efficiency without significantly reducing the lifetime of the networks.