Proof of Authority (PoA) is a widely adopted consensus algorithm for permissioned blockchain networks, where a group of trusted entities governs the network. PoA is known for achieving rapid consensus with minimal computational and energy requirements. However, existing PoA variants such as Aura and Clique suffer from low transaction throughput in high workload conditions and provide limited randomness in leader selection. They are also vulnerable to time and order manipulation attacks. To overcome these limitations, this paper introduces a novel PoA-based consensus algorithm called Proof of Random Leader (PoRL), which utilizes a verifiable random function to enhance transaction throughput, improve scalability, and ensure fair and unpredictable leader selection. The proposed PoRL algorithm was implemented in Python and evaluated using a network of six consensus nodes with varying computational capabilities. The performance of PoRL was assessed based on key metrics, including security, consistency, availability, fault tolerance, block time, and transaction throughput. Experimental results indicate that PoRL achieves lower consensus times and higher transaction throughput compared to Aura and Clique, making it a more efficient solution for permissioned blockchain networks. The findings of this study provide valuable insights for blockchain practitioners in selecting the most suitable PoA implementation based on their specific network requirements.

There is rising global demand for the deployment of a central bank digital currency (CBDC) system to achieve financial stability. However, striking a balance between privacy, transparency, and auditability in such a system is technically difficult. We propose a CBDC system based on a consortium blockchain that adopts a privacy-preserving, transparent unspent transaction output (UTXO) model. The proposed system satisfies the travel rule of payment, unlike existing cryptocurrencies. Unlike the conventional UTXO approach, users use wallet-linked addresses for transactions rather than their actual wallet addresses. Each transacting address is generated using two keys: a random private key computed by the sender and the recipient's public key. The final private key is known only to the recipient, and it is required to spend the UTXO received using the address. Thus, each user holds only a single authorized public key and address, which eases regulatory compliance in the network without compromising anonymity and privacy. To manage the blockchain, the central bank and several certificate authorities execute the energy-efficient Clique consensus algorithm. Only the central bank supplies money to the network. A prototype of the system was implemented using Python-Flask, and it outperformed the state-of-the-art systems by providing a smaller transaction size (665 B) and lower verification time (9 ms).

Due to the involvement of a large number of intermediaries across different time zones in the correspondent banking process, existing interbank payment systems cannot provide cost-effective cross-border transactions. They also suffer from lack of transparency and long transaction delays. These issues can be solved by designing a cryptocurrency in an auditable manner using a permissioned blockchain where a group of authorities can govern the network. In this paper, we propose a low-cost, seamless cross-border payment system based on an auditable cryptocurrency that enables unspent transaction output-based transactions in a consortium blockchain network. To manage the blockchain, participating countries execute the energy-efficient proof of authority consensus algorithm with equal rights. Unlike conventional cryptocurrencies, dynamic decentralized identifiers (DIDs) are used as transacting addresses so that self-manageable authentication can be performed on-chain without any interaction with a trusted third party. The identity of transacting parties is known to respective DID issuers only. This approach enables peer-to-peer transactions while protecting user privacy and ensuring transparency without jeopardizing auditability. For user convenience, multi-party computation and multi-signature protocols are also provided. The system was implemented in Python, and the transaction mechanism was tested. This paper can help with ongoing research on blockchain-based cross-border payment solutions worldwide.