blockchain.py

import hashlib

class Block:
    def __init__(self, index, timestamp, data, previousHash = ""):
        self.index = index
        self.previousHash = previousHash
        self.timestamp = timestamp
        self.data = data;
        self.hash = self.calculateHash()

    def calculateHash(self):
        return (hashlib.sha256((str(self.index) + str(self.previousHash) + str(self.timestamp) + str(self.data)).encode('utf-8')).hexdigest())

    def setdict(self):
        d = { "index":self.index, "previousHash":self.previousHash, "timestamp":self.timestamp, "data":self.data, "hash":self.hash}
        return d

class Blockchain:
    def __init__(self):
        self.chain = [self.createGenesisBlock().setdict()]

    def createGenesisBlock(self):
        return Block(0, "2019/01/01", "Genesis block","0")

    def getLatestBlock(self):
        return self.chain[len(self.chain) - 1]

    def addBlock(self, newBlock):
        newBlock.previousHash = self.getLatestBlock()["hash"]
        newBlock.hash = newBlock.calculateHash()
        self.chain.append(newBlock.setdict())

def main():
    coin = Blockchain()

    coin.addBlock(Block(1, "2019/01/02", "Yotaro: 100000"))
    coin.addBlock(Block(2, "2019/01/03", "mayumi: 10000"))
    coin.addBlock(Block(3, "2019/01/04", "Hitoshi: 10000"))

    print("chain:{}\n".format(coin.chain))

if __name__ == '__main__':

    main()