From 8a1ba9d2402460ccd980a617c0067fd290eaf201 Mon Sep 17 00:00:00 2001
From: Raymond Pan <raymondpan2022@gmail.com>
Date: Wed, 1 May 2024 00:38:38 -0400
Subject: [PATCH] v3

---
 main.py | 101 +++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 60 insertions(+), 41 deletions(-)

diff --git a/main.py b/main.py
index 2b71225..76fdf8f 100644
--- a/main.py
+++ b/main.py
@@ -5,31 +5,22 @@
 # difficulty target: 0000ffff00000000000000000000000000000000000000000000000000000000
 
 # output format:
-# block header
-# serialized coinbase transaction
-# txids of the transactions mined in the block
+# first line: block header
+# second line: serialized coinbase transaction
+# following lines: txids of the transactions mined in the block
+
+# task 1: process the transactions
+# task 2: validate the transactions
+# task 3: put the transactions in a block
+# task 4: mine the block
 
 import json
 import os
 import hashlib
-
+import time
 from ecdsa import VerifyingKey, SECP256k1, BadSignatureError
 from ecdsa.util import sigdecode_der
 
-def serialize_transaction(transaction):
-    prevout = transaction['vin'][0]['prevout']
-    scriptpubkey_type = prevout['scriptpubkey_type']
-
-    if scriptpubkey_type == 'v0_p2wpkh':
-        serialized_tx = f"{prevout['value']}{prevout['scriptpubkey']}"
-    else:
-        serialized_tx = json.dumps(transaction, sort_keys=True)
-
-    return serialized_tx
-
-def double_hash256(data):
-    return hashlib.sha256(hashlib.sha256(data.encode()).digest()).digest()
-
 def load_transactions(mempool_dir):
     transactions = []
     for filename in os.listdir(mempool_dir):
@@ -44,33 +35,59 @@ def load_transactions(mempool_dir):
     return transactions
 
 def validate_transaction(transaction):
-  try:
-    vin = transaction['vin'][0]
-    if 'witness' not in vin or len(vin['witness']) < 2:
-      return False
+    try:
+        vin = transaction['vin'][0]
+        if 'witness' not in vin or len(vin['witness']) < 2:
+            return False
 
-    txid = vin['txid']
-    signature_hex = vin['witness'][0]
-    public_key_hex = vin['witness'][1]
+        signature_hex = vin['witness'][0]
+        public_key_hex = vin['witness'][1]
 
-    sighash_type = signature_hex[-2:]
-    signature_bytes = bytes.fromhex(signature_hex[:-2])
-    
-    serialized_tx = serialize_transaction(transaction)
-    serialized_tx += sighash_type
+        signature_bytes = bytes.fromhex(signature_hex)
+        vk = VerifyingKey.from_string(bytes.fromhex(public_key_hex), curve=SECP256k1)
+        serialized_tx = serialize_transaction(transaction)
+        message_hash = double_hash256(serialized_tx)
+
+        return vk.verify(signature_bytes, message_hash, sigdecode=sigdecode_der)
+    except (KeyError, ValueError, BadSignatureError, IndexError):
+        return False
+
+def serialize_transaction(transaction):
+    # Simplified serialization logic
+    serialized_tx = json.dumps(transaction, sort_keys=True)
+    return serialized_tx
+
+def double_hash256(data):
+    return hashlib.sha256(hashlib.sha256(data.encode()).digest()).digest()
+
+def calculate_merkle_root(transactions):
+    if not transactions:
+        return ''
     
-    message_hash = double_hash256(serialized_tx)
+    tx_hashes = [hashlib.sha256(json.dumps(tx).encode()).hexdigest() for tx in transactions]
+    while len(tx_hashes) > 1:
+        new_level = []
+        for i in range(0, len(tx_hashes), 2):
+            left = tx_hashes[i]
+            right = tx_hashes[i + 1] if (i + 1) < len(tx_hashes) else tx_hashes[i]
+            new_level.append(hashlib.sha256((left + right).encode()).hexdigest())
+        tx_hashes = new_level
     
-    vk = VerifyingKey.from_string(bytes.fromhex(public_key_hex), curve=SECP256k1)
-    return vk.verify(signature_bytes, message_hash, sigdecode=sigdecode_der)
-  except (KeyError, ValueError, BadSignatureError, IndexError):
-    return False
+    return tx_hashes[0]
+
+def create_block_header(transactions, nonce):
+    merkle_root = calculate_merkle_root(transactions)
+    timestamp = int(time.time())
+    previous_block_hash = '0000000000000000000000000000000000000000000000000000000000000000'
+    version = 1
+    bits = '1d00ffff'
+    header = f"{version}{previous_block_hash}{merkle_root}{timestamp}{bits}{nonce}"
+    return header
 
 def mine_block(transactions, difficulty_target):
-    block_data = "".join(tx['id'] for tx in transactions)
     nonce = 0
     while True:
-        block_header = f'{block_data}{nonce}'
+        block_header = create_block_header(transactions, nonce)
         block_hash = hashlib.sha256(block_header.encode()).hexdigest()
         if block_hash < difficulty_target:
             break
@@ -82,15 +99,17 @@ def write_output(block_hash, transactions):
         f.write(f"Block Hash: {block_hash}\n")
         f.write("Serialized Coinbase Transaction\n")
         for tx in transactions:
-            f.write(f"{tx['id']}\n")
+            f.write(f"{tx['txid']}\n")
 
 def main():
-    mempool_dir = "mempool"
+    mempool_dir = "./mempool"
     transactions = load_transactions(mempool_dir)
+    if not transactions:
+        print("No valid transactions found.")
+        return
     difficulty_target = "0000ffff00000000000000000000000000000000000000000000000000000000"
-    _, block_hash = mine_block(transactions, difficulty_target)
+    nonce, block_hash = mine_block(transactions, difficulty_target)
     write_output(block_hash, transactions)
 
 if __name__ == "__main__":
     main()
-    
\ No newline at end of file