Blockchain example

blockchain.py

import hashlib
import json
from time import time

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

        self.new_block(previous_hash="1234", proof=100)

    def new_block(self, proof, previous_hash=None):
        block = {
            'index': len(self.chain) + 1,
            'timestamp': time(),
            'transactions': self.pending_transactions,
            'proof': proof,
            'previous_hash': previous_hash or self.hash(self.chain[-1])
        }
        self.pending_transactions = []
        self.chain.append(block)
        return block

    def new_transaction(self, sender, recipient, amount):
        transaction = {
            'sender': sender,
            'recipient': recipient,
            'amount': amount
        }
        self.pending_transactions.append(transaction)
        return self.last_block['index'] + 1

    @property
    def last_block(self):
        return self.chain[-1]

    def hash(self, block):
        string_object = json.dumps(block, sort_keys=True)
        block_string = string_object.encode()
        raw_hash = hashlib.sha256(block_string)
        hex_hash = raw_hash.hexdigest()
        return hex_hash


b = Blockchain()
t1 = b.new_transaction("Bob", "Alice", 5)
t2 = b.new_transaction("Alice", "Eve", 3)
t3 = b.new_transaction("Adam", "Bob", 5)
b.new_block(12345)
t4 = b.new_transaction("Max", "Jacob", 25)
t5 = b.new_transaction("Emily", "Joseph", 10)
t6 = b.new_transaction("Naum", "Jaden", 5)
b.new_block(5678)
from pprint import pprint
pprint(b.chain)