Blockchains are permissionless distributed databases. They have the permissionless property of the Internet network where anyone can setup an entry point, connect it to other nodes and sell access to the services present on the web. They also have the replication capabilities of the cloud where multiple users can access nearby nodes, connect to a “service” and modify its “state” in a consistent way across nodes.

Replication in open distributed databases was believed to be impossible until Satoshi Nakamoto introduced Bitcoin, which is at the same time the first blockchain and a currency used to circumvent the algorithmic limitations of closed database replication algorithms.

Solving the open-network replication problem with an internal currency creates many challenges for the system : financial grade security requirements, interoperability with other systems via “proofs of proper operation”, attack vectors via the VM and the programming languages, privacy protection, etc. We will review the technical challenges posed to the blockchain and the solutions that are being explored to solve them.

Diego Olivier Fernandez Pons started his career in mathematical optimization applying linear and constraint programming to industrial problems. He worked for ILOG and IBM in supply chain optimization solutions. He has advised Tezos in functional programming and formal verification since its inception. He was a founding board member of the Tezos Foundation. He is today scientific advisor of Tezos Southeast Asia and director of Tezos Korea Foundation