blockchain.py

import hashlib

class Block:
    prev_hash = None
    nonce = -1

    data = None

    current_hash = None

    def __init__(self, prev_hash, data):
        self.prev_hash = prev_hash
        self.data = data

    def __repr__(self):
        return "Block {0} (prev. {1})".format(
            self.current_hash,
            self.prev_hash
        )

    @property
    def block_string(self):
        return "{0}-{1}-{2}".format(
            self.prev_hash,
            self.data,
            self.nonce
        )

    def hash(self):
        return hashlib.sha256(bytes(self.block_string, "utf-8")).hexdigest()

    def mine(self, difficulty):
        found = False
        while not found:
            self.nonce += 1
            self.current_hash = self.hash()
            if self.current_hash[0:difficulty] == "0" * difficulty:
                found = True


class Blockchain:
    blocks = []
    difficulty = 4

    def add(self, block):
        block.mine(self.difficulty)
        self.blocks.append(block)

    @property
    def last_block(self):
        return self.blocks[-1] if len(self.blocks) else None

    def build_block(self, data):
        if self.last_block:
            block = Block(self.last_block.current_hash, data)
            self.add(block)
        else:
            raise Exception("Missing Genesis block")




f = open("test.txt", "w")


chain = Blockchain()

init = "initialisation"

init_Block = Block(None, init)

chain.add(init_Block)

n = 0
while  n < 10:

    n = n + 1
    test = "test"

    a_Block = Block(init_Block, test)

    chain.add(a_Block)




    for b in chain.blocks:
        f.write(str(b) + "\n")