In this chapter, readers have been introduced to the security, confidentiality, and privacy aspects of blockchain technology. Privacy was discussed, which is another major inhibiting factor in adapting public blockchains for various industries. Next, smart contract security, which is a very hot topic currently, was discussed. It is a deep and extensive subject but a brief introduction on various aspects has been given, which should serve as a solid ground for further research in this area.

For example, formal verification on its own is a vast area for research. Furthermore, examples of formal verification have also been provided to give readers an idea of what tools are available. It should be noted that the tools mentioned earlier are under heavy development and lack various desirable features. Also, documentation is quite scarce; therefore, readers are encouraged to keep an eye on developments, especially around formal verification and developments related to the Ethereum mauve paper, as it is going to develop rapidly very soon. The field of blockchain security and especially smart contract security is so ripe now that a whole book can be written on the subject.

There are many experts and researchers in academia and the commercial sector exploring this area and soon there will be many automated tools available for the verification of smart contracts. There is an online tool available already at https://securify.ch which analyses smart contract code to find security vulnerabilities.