A Secure Contactless Payment System with Bidirectional Blockchain and Blake Hash Function

The growth of the Internet of Things (IoT) has led to an increased demand for contactless payment via IoT devices. However, machine-to-machine (M2M) payment in the IoT has been limited by poor centralized transaction management, given the distributed nature of the IoT, which results in massive communication overhead. Blockchain technology provides a promising solution for M2M payments in the IoT, but the current blockchain-based solutions for contactless payment lack security and scalability. To address this, a new customised Committee Member Auction mechanism has been proposed that is both safe and scalable for resource-constrained IoT devices. This mechanism also reduces the block mining time by integrating the BLAKE hashing algorithm, as opposed to SHA-256. The proposed framework was implemented utilizing an ESP32 microcontroller and RC522 RFID reader to record over 100 transactions each for SHA-256 and Blake. The results obtained validate that Blake hashing algorithm along with Bidirectional blockchain outperforms SHA-256 by reducing 30% of mining time. Besides improved mining efficiency, this scheme is also found to be resistant against Long Range Attack, Double Spend Attack and Eclipse attack. The proposed scheme thus offers a more secure and scalable option for contactless payments in IoT systems.