Bitmessage Plus: A Blockchain-Based Communication Protocol with High Practicality

Abstract

We are in the Internet era, when protecting the security of personal information is both vital and challenging. As the most commonly used methods of communication, centralized systems cannot meet the increasing need for information security. Blockchain, with its characteristics of openness, decentralization, and tamper resistance, is an innovative technology underlying Bitcoin. There is potential to use blockchain in developing decentralized and transparent communication systems. Bitmessage is a well-known decentralized messaging system that enables users to exchange messages and prevents accidental eavesdropping. Bitmessage achieves anonymity and privacy by relying on the blockchain flooding propagation mechanism and asymmetric encryption algorithm. Unfortunately, Bitmessage uses proof-of-work as the solution to prevent spam, which wastes computational power and makes it inefficient to be used in practice. To address this problem, we improve Bitmessage with a novel antispam mechanism based on proof-of-space, which requires the user to dedicate a certain amount of disk space to send a message. This improvement reduces the time and computing resource costs by eliminating computationally heavy hash operations. Moreover, we achieve a high level of anonymity by using the stealth address as the destination of the delivered message, which can only be identified by the intended receiver. Finally, we improve the protocol's reliability by taking the blockchain as an immutable database to store the delivered messages.