diff --git a/src/script.py b/src/script.py index 8c34db3..b62cc79 100644 --- a/src/script.py +++ b/src/script.py @@ -35,16 +35,17 @@ def is_empty(self) -> bool: return len(self._items) == 0 class Script: - def __init__(self, script: bytes, json_transaction: dict = None, input_index: int = 0): + def __init__(self, script: bytes, json_transaction: dict = None, input_index: int = 0, segwit: bool = False): self.script = script self.stack = Stack() self.alt_stack = Stack() self.if_stack: List[bool] = [] self.transaction = json_transaction # Store JSON transaction self.input_index = input_index + self.segwit = segwit def create_signature_hash(self, hash_type: int) -> bytes: - data_signed = serialize_transaction(self.transaction, self.input_index, int(hash_type)) + data_signed = serialize_transaction(self.transaction, self.input_index, int(hash_type), self.segwit) return hashlib.sha256(data_signed).digest() """ Create the signature hash for the transaction based on the hash type. @@ -179,7 +180,7 @@ def execute(self) -> bool: i += self._execute_opcode(op_name) # Script executed successfully if stack is not empty and top value is true - if self.stack.is_empty(): + if self.stack.is_empty(): return False return self.stack.pop() != b'\x00' @@ -191,7 +192,7 @@ def _execute_opcode(self, op_name: str) -> int: """Execute a single opcode and return how many bytes to advance""" # Constants - if op_name == 'OP_0': + if op_name == 'OP_0': self.stack.push(b'\x00') return 1 elif op_name == 'OP_1NEGATE': diff --git a/src/transaction.py b/src/transaction.py index 45d13ba..661fedd 100644 --- a/src/transaction.py +++ b/src/transaction.py @@ -110,7 +110,7 @@ def valid_input(self, vin_idx, vin): elif scriptpubkey_type == "v1_p2tr": pass elif scriptpubkey_type == "v0_p2wpkh": - return self.validate_p2wpkh(vin) + return self.validate_p2wpkh(vin_idx, vin) # Unknown script type. return False @@ -139,5 +139,68 @@ def validate_p2pkh(self, vin_idx, vin): return is_valid - def validate_p2wpkh(self, vin): - return False + def validate_p2wpkh(self, vin_idx, vin): + """ + Validate a Pay-to-Witness-Public-Key-Hash (P2WPKH) transaction input + + Args: + vin_idx (int): Index of the input being validated + vin (dict): Input data containing witness information + + Returns: + bool: True if the P2WPKH input is valid, False otherwise + """ + # Check for witness data + witness = vin.get("witness", []) + if len(witness) != 2: # P2WPKH requires exactly 2 witness items (signature and pubkey) + return False + + # Get witness components + signature = bytes.fromhex(witness[0]) + pubkey = bytes.fromhex(witness[1]) + + # Get previous output's scriptPubKey + prevout = vin.get("prevout", {}) + if not prevout: + return False + + scriptpubkey = bytes.fromhex(prevout.get("scriptpubkey", "")) + + # Verify the script is proper P2WPKH format (OP_0 <20-byte-key-hash>) + if len(scriptpubkey) != 22 or scriptpubkey[0] != 0x00 or scriptpubkey[1] != 0x14: + return False + + # Create P2PKH-style script from witness data + # P2WPKH witness program is executed as if it were P2PKH scriptPubKey + p2pkh_script = ( + bytes([len(signature)]) + # Push signature + signature + + bytes([len(pubkey)]) + # Push pubkey + pubkey + + # Standard P2PKH script operations + bytes([ + 0x76, # OP_DUP + 0xa9, # OP_HASH160 + 0x14 # Push 20 bytes + ]) + + scriptpubkey[2:22] + # 20-byte pubkey hash from witness program + bytes([ + 0x88, # OP_EQUALVERIFY + 0xac # OP_CHECKSIG + ]) + ) + + # Create script object with witness-specific transaction data + script = Script( + p2pkh_script, + json_transaction=self.json_transaction, + input_index=vin_idx, + segwit=True + ) + + # Execute the script + try: + return script.execute() + except Exception as e: + print(f"P2WPKH validation error: {str(e)}") + return False