commit
f03d28f8ad
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@ -1,6 +1,7 @@
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import hashlib
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import json
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from time import time
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from typing import Any, Dict, List, Optional
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from urllib.parse import urlparse
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from uuid import uuid4
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@ -8,32 +9,31 @@ import requests
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from flask import Flask, jsonify, request
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class Blockchain(object):
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class Blockchain:
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def __init__(self):
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self.current_transactions = []
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self.chain = []
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self.nodes = set()
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# Create the genesis block
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self.new_block(previous_hash=1, proof=100)
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self.new_block(previous_hash='1', proof=100)
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def register_node(self, address):
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def register_node(self, address: str) -> None:
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"""
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Add a new node to the list of nodes
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:param address: <str> Address of node. Eg. 'http://192.168.0.5:5000'
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:return: None
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:param address: Address of node. Eg. 'http://192.168.0.5:5000'
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"""
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parsed_url = urlparse(address)
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self.nodes.add(parsed_url.netloc)
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def valid_chain(self, chain):
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def valid_chain(self, chain: List[Dict[str, Any]]) -> bool:
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"""
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Determine if a given blockchain is valid
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:param chain: <list> A blockchain
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:return: <bool> True if valid, False if not
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:param chain: A blockchain
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:return: True if valid, False if not
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"""
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last_block = chain[0]
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@ -57,12 +57,12 @@ class Blockchain(object):
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return True
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def resolve_conflicts(self):
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def resolve_conflicts(self) -> bool:
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"""
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This is our consensus algorithm, it resolves conflicts
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by replacing our chain with the longest one in the network.
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:return: <bool> True if our chain was replaced, False if not
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:return: True if our chain was replaced, False if not
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"""
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neighbours = self.nodes
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@ -91,13 +91,13 @@ class Blockchain(object):
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return False
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def new_block(self, proof, previous_hash=None):
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def new_block(self, proof: int, previous_hash: Optional[str]) -> Dict[str, Any]:
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"""
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Create a new Block in the Blockchain
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:param proof: <int> The proof given by the Proof of Work algorithm
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:param previous_hash: (Optional) <str> Hash of previous Block
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:return: <dict> New Block
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:param proof: The proof given by the Proof of Work algorithm
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:param previous_hash: Hash of previous Block
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:return: New Block
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"""
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block = {
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@ -114,14 +114,14 @@ class Blockchain(object):
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self.chain.append(block)
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return block
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def new_transaction(self, sender, recipient, amount):
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def new_transaction(self, sender: str, recipient: str, amount: int) -> int:
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"""
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Creates a new transaction to go into the next mined Block
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:param sender: <str> Address of the Sender
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:param recipient: <str> Address of the Recipient
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:param amount: <int> Amount
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:return: <int> The index of the Block that will hold this transaction
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:param sender: Address of the Sender
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:param recipient: Address of the Recipient
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:param amount: Amount
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:return: The index of the Block that will hold this transaction
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"""
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self.current_transactions.append({
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'sender': sender,
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@ -132,30 +132,26 @@ class Blockchain(object):
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return self.last_block['index'] + 1
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@property
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def last_block(self):
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def last_block(self) -> Dict[str: Any]:
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return self.chain[-1]
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@staticmethod
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def hash(block):
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def hash(block: Dict[str, Any]) -> str:
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"""
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Creates a SHA-256 hash of a Block
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:param block: <dict> Block
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:return: <str>
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:param block: Block
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"""
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# We must make sure that the Dictionary is Ordered, or we'll have inconsistent hashes
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block_string = json.dumps(block, sort_keys=True).encode()
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return hashlib.sha256(block_string).hexdigest()
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def proof_of_work(self, last_proof):
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def proof_of_work(self, last_proof: int) -> int:
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"""
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Simple Proof of Work Algorithm:
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- Find a number p' such that hash(pp') contains leading 4 zeroes, where p is the previous p'
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- p is the previous proof, and p' is the new proof
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:param last_proof: <int>
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:return: <int>
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"""
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proof = 0
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@ -165,13 +161,13 @@ class Blockchain(object):
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return proof
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@staticmethod
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def valid_proof(last_proof, proof):
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def valid_proof(last_proof: int, proof: int) -> bool:
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"""
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Validates the Proof
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:param last_proof: <int> Previous Proof
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:param proof: <int> Current Proof
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:return: <bool> True if correct, False if not.
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:param last_proof: Previous Proof
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:param proof: Current Proof
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:return: True if correct, False if not.
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"""
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guess = f'{last_proof}{proof}'.encode()
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