# Comparative Study of Blockchain Hashing Algorithms with a Proposal for HashLEA
## 1 Introduction
Improper hash function placement may increase the delay of updates within the blockchain and thus not allow the network to be efficient or even available promptly [29]. There are proposed solutions to solve blockchain-based IoT device problems. The proposed suggestions may cover areas like authentication mechanisms, consensus protocols, or establishing lightweight architectures. While these proposed solutions explore lightweight hash function alternatives for blockchain-based IoT devices, they offer little to no evaluation of the selected approach [30]. Rather, they address energy-aware methods or the problem of energy efficiency for hashing, respectively. Hash functions are an important part of blockchain operation, so hashing power must be considered. Toward blockchain applications for IoT devices, while energy efficiency is one performance metric that a hash function should have, other performance metrics such as resource utilization, speed, and throughput should be considered when selecting and evaluating hash functions for IoT devices in blockchain applications [31; 32]. Despite the advancements and application-specific advantages of existing lightweight hash functions, several challenges persist in achieving seamless integration between IoT devices and blockchain systems. These challenges include computational complexity, energy consumption, and compatibility with resource-constrained devices, as discussed in the previous section. Addressing these limitations requires innovative approaches to hashing that prioritize both performance and security while remaining suitable for the unique requirements of IoT environments. To address these challenges, this study introduces a novel hashing algorithm called HashLEA (Hash Lightweight Encryption Algorithm). Designed specifically for IoT-blockchain integration, HashLEA leverages the lightweight LEA cipher and incorporates efficient block processing techniques. Blockchain-based IoT applications, such as supply chain monitoring or smart grid management, require efficient and secure hashing mechanisms to ensure data integrity and performance. The proposed HashLEA algorithm addresses these challenges through its lightweight design and high performance. Figure 1 demonstrates an example of how HashLEA can be practically applied in a supply chain monitoring scenario, ensuring data security and integrity across the entire chain. Further technical details and algorithmic structure are provided in Section 4. This figure illustrates a practical use case of HashLEA in supply chain monitoring. The algorithm ensures secure and efficient data handling across various stages of the supply chain, validating and aggregating information to maintain data integrity. The remainder of the paper is structured as follows. The following section builds upon the literature review. Section 3 provides an overview of blockchain, IoT, and hash functions and their key properties, including a discussion on hash functions. Section 4 describes the detailed structure and design of the proposed HashLEA function. Section 5 presents the security analysis and performance evaluations, comparing HashLEA with existing hash algorithms. Finally, Section 6 concludes the paper and outlines potential directions for future work.