Cyber security in the banking sector is of high importance nowadays. The rate of cyberattacks is spiking every year, and the implementation of strong cybersecurity models is required to ensure the confidentiality and integrity of data. Since protecting a bank requires a wide range of security practices, this paper focuses on protecting the bank resources from malicious actors and securing the transactions using a blockchain consensus mechanism that uses a zero-trust security approach among the participants in the transaction. In addition to the framework, an algorithm for blockchain-based online transactions was designed to make use of practical implementation in the future. The ideas formulated during the research and literature review were integrated to design the framework and the algorithm. The proposed framework ensures that the security of the banking sector can be enhanced by adopting the zero-trust concept and blockchain technology. The consensus algorithms used for the transaction make it immutable and decentralized. Zero-trust principles adopted in the model ensure the confidentiality and integrity of the banking system.