​A blockchain is a series, or "chain", of distributed data records where each participant possesses a local copy. There are a number of methods that can be employed to ensure that the chain is coherent. However, some of them are more energy efficient than others. A team of researchers that included scientists from CEA Tech institute List set out to prove that the Tendermint consensus algorithm—which offers the advantage of being energy efficient—has been implemented correctly.

In blockchain, consensus-making requires all participants to agree on an item (such as a transaction) before it can be added to the chain. The researchers identified several vulnerabilities that were then corrected by the developers. The corrected consensus algorithm was then validated and its implementation in the Tendermint blockchain was tested. The research also confirmed optimal tolerance of the so-called Byzantine Generals Problem—the biggest threat to blockchain systems. Here, the blockchain can tolerate up to one-third of participants being untrustworthy (either they no longer respond, or they send false information to trick the system).

This first-ever demonstration of a consensus-based blockchain is yet another example of List's leadership in this field, coming after the recent appointment of List researcher Sara Tucci to the French government's Blockchain Taskforce  announced in July by France's Economy and Finance Minister with the goal of developing a national blockchain strategy and promoting communication between the blockchain community and the government.  

*Tendermint consensus is used in the Cosmos blockchain network