Virtual private blockchains

BLockchain technology combines distributed systems, peer-to-peer networking, and cryptography for innovative applications in IoT, Smart Contracts, and Electronic Banking, ensuring security without intermediaries. However, it is not universally suitable. For instance, sensitive and confidential data sharing containing financial transactional metadata does not comply with the original public blockchain functional design. Private blockchains offer a solution, but they demand resources, pose a single point of failure, and challenge decentralisation ideals. This thesis proposes the novel concept of a Virtual Private Blockchain (VPBC) as a mechanism to create a blockchain architecture with properties akin to those of a private blockchain, leveraging existing public blockchain functionality. It is shown how a scheme combining secret sharing with predefined shares and steganography can be used to transmit transactions confidentially and facilitate covert communication on the VPBC. Furthermore, the information-theoretic security of the scheme is proven. An implementation of the VPBC architecture using a real blockchain deployment based on Multichain is reported. This implementation is reposited in an open-source project hosted on GitHub. An evaluation of the VPBC concept and implementation based on a performance and security analysis is reported, showing that the VPBC delivers significantly less computational overhead, robust security and high algorithmic computational speed and reliability compared to the schemes in reviewed literature with related works. Importantly, a case study on a real-world application of the VPBC for a proposed decentralised Higher Education information system is documented. Furthermore, a theoretical security model for the VPBC is established, which could be used as a foundation for future research.