Hands-On Blockchain for Python Developers

Proof of work

So, we have three participants in this case: Nelson, Marie, and Sky. But there is another type of participant too: the one who writes into the blockchain is called—in blockchain parlance—the miner. In order to put the transaction into the blockchain, the miner is required to do some work first.

Previously, we had three blocks (block_A, block_B, and block_C), but now we have a candidate block (block_D), which we want to add into the blockchain as follows:

block_D = Block()block_D.id = 4block_D.history = 'Sky loves turtle'block_D.parent_id = block_C.id

But instead of adding block_D to the blockchain just like that, we first require the miner to do some puzzle work. We serialize that block and ask the miner to apply an extra string, ...