A Quantum Signature Validation Algorithm for Efficient Detection of Tampered Transactions in Blockchain

The Quantum Signature Validation Algorithm (QSVA) is introduced as a novel quantum-based approach designed to enhance the detection of tampered transactions in blockchain systems. Leveraging the powerful capabilities of quantum computing, especially within the framework of transaction-based blockchains, the QSVA aims to surpass classical methods in both speed and efficiency. By utilizing a quantum walk approach integrated with PageRank-based search algorithms, QSVA provides a robust mechanism for identifying fraudulent transactions. Our adaptation of the transaction graph representation efficiently verifies transactions by maintaining a current set of unspent transaction outputs (UTXOs) characteristic of models like Bitcoin. The QSVA not only amplifies detection efficacy through a quadratic speedup but also incorporates two competing quantum search algorithms$-$Quantum SearchRank and Randomized SearchRank$-$to explore their effectiveness as foundational components. Our results indicate that Randomized SearchRank, in particular, outperforms its counterpart in aligning with transaction rankings based on the Classical PageRank algorithm, ensuring more consistent detection probabilities. These findings highlight the potential for quantum algorithms to revolutionize blockchain security by improving detection times to $O(\sqrt{N})$. Progress in Distributed Ledger Technologies (DLTs) could facilitate future integration of quantum solutions into more general distributed systems. As quantum technology continues to evolve, the QSVA stands as a promising strategy offering significant advancements in blockchain efficiency and security.