Blockchain I & II

Pipfile

@@ -9,6 +9,7 @@ flake8 = "*"
 [packages]
 requests = ">=2.20.0"
 flask = ">=1.0.0"
+flask-cors = "*"
 
 [requires]
 python_version = "3.7"

basic_block_gp/blockchain.py

@@ -12,7 +12,7 @@ def __init__(self):
         self.current_transactions = []
 
         # Create the genesis block
-        self.new_block(previous_hash=1, proof=100)
+        self.new_block(previous_hash="I'm a teapot", proof=100)
 
     def new_block(self, proof, previous_hash=None):
         """
@@ -31,15 +31,21 @@ def new_block(self, proof, previous_hash=None):
         """
 
         block = {
-            # TODO
+            'index': len(self.chain) + 1,
+            'timestamp': time(),
+            'transactions': self.current_transactions,
+            'proof': proof,
+            'previous_hash': previous_hash or self.hash(self.chain[-1])
         }
 
         # Reset the current list of transactions
+        self.current_transactions = []
         # Append the chain to the block
+        self.chain.append(block)
         # Return the new block
-        pass
+        return block
 
-    def hash(block):
+    def hash(self, block):
         """
         Creates a SHA-256 hash of a Block
 
@@ -56,8 +62,14 @@ def hash(block):
         # or we'll have inconsistent hashes
 
         # TODO: Create the block_string
+        #  stringifys json                  # keys in same order for hashes
+        string_object = json.dumps(block, sort_keys=True)
+        #  strip metadata from string
+        block_string = string_object.encode()
 
         # TODO: Hash this string using sha256
+        raw_hash = hashlib.sha256(block_string)
+        hex_hash = raw_hash.hexdigest()
 
         # By itself, the sha256 function returns the hash in a raw string
         # that will likely include escaped characters.
@@ -66,7 +78,7 @@ def hash(block):
         # easier to work with and understand
 
         # TODO: Return the hashed block string in hexadecimal format
-        pass
+        return hex_hash
 
     @property
     def last_block(self):
@@ -80,9 +92,12 @@ def proof_of_work(self, block):
         in an effort to find a number that is a valid proof
         :return: A valid proof for the provided block
         """
-        # TODO
-        pass
-        # return proof
+        block_string = json.dumps(block, sort_keys=True)
+        proof = 0
+        while self.valid_proof(block_string, proof) is False:
+            proof += 1
+
+        return proof
 
     @staticmethod
     def valid_proof(block_string, proof):
@@ -96,10 +111,10 @@ def valid_proof(block_string, proof):
         correct number of leading zeroes.
         :return: True if the resulting hash is a valid proof, False otherwise
         """
-        # TODO
-        pass
-        # return True or False
+        guess = f'{block_string}{proof}'.encode()
+        guess_hash = hashlib.sha256(guess).hexdigest()
 
+        return guess_hash[:3] == "000"
 
 # Instantiate our Node
 app = Flask(__name__)
@@ -109,16 +124,21 @@ def valid_proof(block_string, proof):
 
 # Instantiate the Blockchain
 blockchain = Blockchain()
+print(blockchain.chain)
+print(blockchain.hash(blockchain.last_block))
 
 
 @app.route('/mine', methods=['GET'])
 def mine():
     # Run the proof of work algorithm to get the next proof
-
+    proof = blockchain.proof_of_work(blockchain.last_block)
     # Forge the new Block by adding it to the chain with the proof
+    previous_hash = blockchain.hash(blockchain.last_block)
+    new_block = blockchain.new_block(proof, previous_hash)
 
     response = {
         # TODO: Send a JSON response with the new block
+        "block": new_block
     }
 
     return jsonify(response), 200
@@ -128,6 +148,8 @@ def mine():
 def full_chain():
     response = {
         # TODO: Return the chain and its current length
+        'chain': blockchain.chain,
+        'length': len(blockchain.chain),
     }
     return jsonify(response), 200