Comment on Over 2 percent of the US’s electricity generation now goes to bitcoin

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dhork@lemmy.world ⁨9⁩ ⁨months⁩ ago

The whole point of mining is to arrange transactions into blocks, and then generate a cryptographic hash of the block that meets some difficulty criteria. It costs some small amount of computing to do that. But an astonishingly large number of hashes won’t meet that difficulty criteria, which is why miners have to try a gazillion times to find one that works.

However, once a block has a valid hash, it is added to the chain. Then, the hash of that valid block must be used in the next block, which will be equally hard to find.

By “security”, what is really meant is “How can I be sure that a transaction can’t be undone once it is committed”? And it’s because all these blocks are stacked on top of each other, and cryptographically related. Once a transaction appears in a block, and a few blocks get mined on top of it, it becomes extremely difficult to un-do it, because someone would have to put in the computing power to re-authenticate a string of blocks, all while the rest of the network is adding blocks to the valid chain.

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