Concluding Remarks

In this book, we analyzed in detail the security and privacy provisions of Bitcoin and its underlying blockchain. In addition to discussing existing vulnerabilities of Bitcoin and its various related altcoins, we also discussed and proposed a number of effective countermeasures to deter threats and information leakage within the system—some of which have already been incorporated in Bitcoin client releases. Note that proof-of-work (PoW) powered blockchains currently account for more than 90% of the total market capitalization of existing digital currencies. As far as we are aware, this book offers the most comprehensive and detailed analysis of the security and privacy provisions of existing PoW-based blockchains, and of related clones/variants.

Given that Bitcoin emerges as the most successful PoW blockchain instantiation to date, this book extracts essential lessons learned in security and privacy from eight years of research into the system with the aim to motivate the design of secure and privacy-preserving next-generation blockchain technologies. We now summarize the main observations that we made throughout the book.