• Blockchains Use Massive Amounts of Energy—But There’s a Plan to Fix That - MIT Technology Review
    https://www.technologyreview.com/s/609480/bitcoin-uses-massive-amounts-of-energybut-theres-a-plan-to-fix-it

    Bitcoin guzzles about as much electricity annually as all of Nigeria. Ethereum gulps electrons too, as do most other cryptocurrencies.

    Blockchains get a lot of love, but they are only shared sets of data. What brings cryptocurrencies like Bitcoin and Ethereum to life is the way all the computers in their networks agree, over and over, that what a blockchain says is true. To do this, they use an algorithm called a consensus mechanism. You’ve probably heard it called “mining.” (See: “What Bitcoin Is, and Why It Matters”)

    Cryptocurrency miners do much more than unlock new coins. In the process, they check the blockchain to make sure people aren’t spending coins fraudulently, and they add new lists of transactions—the blocks—to the chain. It’s the second step, meant to secure the blockchain from attacks, that guzzles electricity.

    Ultimately, the miners must transform each list of most recent transactions into a digital signature that can serve as proof that the information is true. All miners can do this, using a cryptographic tool that takes any input and spits out a string of seemingly random characters. But Bitcoin’s creator, Satoshi Nakamoto, made this part particularly difficult.

    This expends an immense amount of energy, signaling to the rest of the network that a miner’s accounting can be trusted.

    But while this particular method of reaching agreement—known as “proof of work”—is the most established, it isn’t the only one. A growing number of technologists are exploring different avenues, and some smaller cryptocurrencies already employ alternative means.

    The one in the best position to supplant proof of work is called “proof of stake.”

    #Monnaie_numérique #Bitcoin #Energie