EPFL researchers develop greener bitcoin alternative

A bird's eye view of the EPFL - École polytechnique fédérale de Lausanne (Photo: Facebook/EPFL)

The ecological footprint of the digital currency Bitcoin is huge. The reason is the mechanism that is supposed to ensure the security of transactions, for example, to prevent a Bitcoin unit from being spent more than once. At its core, each transaction must be confirmed by a temporary central controller who controls the entirety of the Bitcoin network and has the authority to add the new transaction to the "blockchain".

For his performance, the central controller receives Bitcoin units, which is why the competition for this role is fierce. The winner is the one who solves a complex mathematical problem - which requires enormous computing power and vast amounts of energy. Experts also refer to this as "mining".

Presumption of innocence as a basis

However, a research team led by Rachid Guerraoui of the Swiss Federal Institute of Technology Lausanne (EPFL) proposes a different, minimalist approach that uses far less energy. "If it's just a question of whether person A is allowed to transfer a bitcoin unit to person B, or if they have already given that unit to person C, D and E, you don't need a central authority controlling the entire network," Guerraoui explained in an interview with the Keystone-SDA news agency. It's a much simpler problem, he said.

Instead of placing all actors under general suspicion, the algorithm developed by Guerraoui and his colleagues, called "Byzantine Reliable Broadcast," assumes the principle of presumption of innocence, EPFL said Monday.

Sampling for assurance

The security of the system can be ensured through communication (or "broadcasting") between participants in the Bitcoin network, the statement continued. Instead of a central controller short-circuiting all participants, the exchange with a sample of other "players" is sufficient.

"If person A wants to pay with bitcoin, the system will not allow person B to accept the payment until it has been ruled out via a random sample of other players that person A has already spent the bitcoin unit," Guerraoui said.

The energy consumption of this approach would be about the same as that of exchanging e-mails, the researcher said. Only a few grams of CO2 would then be emitted for a transaction, compared to an estimated 300 kilograms for a classic Bitcoin transaction.

High security for simple transactions

In terms of transaction security, the new system is in no way inferior to the classic one, EPFL wrote. However, "Byzantine Reliable Broadcast" is not suitable for all applications that are possible with Bitcoin. For example, more complex transactions such as for smart contracts are not possible. Relatively simple applications such as a payment system for a bike-sharing service are conceivable, however.

The EPFL research team has already presented the concept in two publications at professional conferences and received great recognition from experts, according to EPFL. Guerraoui and colleagues plan to make the new algorithm available to the public as open-source code by the end of 2020. (SDA)