Image logo Bob conference 2018.

Talk: 12:50-13:35 (English)

Formally Specifying Blockchain Protocols using the Psi Calculus

Blockchains are distributed systems, with actors that adhere to agreed-upon protocols. The protocols ensure that the systems performs as desired, even when some of the actors behave dishonestly.

Since the integrity of such a system can protect hundreds of millions of dollars, cryptographers spend great effort on designing the protocols, and proving correctness guarantees under well-specified threat models. The implementation of the actual systems running those protocols is then performed by software engineers. These two activities require different skillsets, as well as different levels of abstraction. Bridging this gap while preserving the correctness guarantees is a non-trivial task.

At IOHK, we use the Psi calculus to translate the cryptographic protocols described in research papers (main protocol here, related papers here) into a formal language, producing a machine-readable, executable specification. This has multiple benefits:

  • It creates a common language for the researchers and engineers.
  • It forces the specification to be complete and unambiguous.
  • It allows simulations, including performance simulations, of the systems before they are fully implemented.

The leap that leads from the research paper to the implementation can then be replaced by a larger number of small steps, each refining the specification and adding more details and design decisions. It is then feasible to show that the implementation matches the paper, by verifying that each of these steps.

Philipp Kant

During his postdoc years in theoretical particle physics, Philipp developed a passion for Haskell, and finally made the switch to software development in 2014. Early in 2017, he joined IOHK, a cryptocurrency research and development company.