""" OP_CAT Implementation - Restricted to Confirmed Transactions Solves original DoS vulnerability by limiting to confirmed block operations """ import json import hashlib import datetime import re from typing import Dict, List, Optional, Any, Union class OPCatRestricted: """ OP_CAT operation restricted to confirmed transactions only. Addresses 2010 DoS vulnerability by eliminating mempool complexity. """ def __init__(self): self.operation_log = [] self.confirmed_tx_cache = {} self.dos_protection = { "max_ops_per_block": 1000, "max_concat_length": 520, # Bitcoin script size limit "operations_in_block": 0 } def op_cat_confirmed_only(self, data1: str, data2: str, tx_context: Dict[str, Any]) -> Dict[str, Any]: """ Execute OP_CAT only on confirmed transactions. Prevents DoS attacks from mempool operations. """ if not self._validate_confirmed_transaction(tx_context): return { "success": False, "error": "OP_CAT restricted to confirmed transactions only", "operation": "op_cat", "timestamp": datetime.datetime.now().isoformat() } if not self._check_dos_protection(): return { "success": False, "error": "DoS protection: Too many operations in block", "operation": "op_cat", "timestamp": datetime.datetime.now().isoformat() } if not self._validate_concat_inputs(data1, data2): return { "success": False, "error": "Invalid concatenation inputs", "operation": "op_cat", "timestamp": datetime.datetime.now().isoformat() } try: result = data1 + data2 operation_record = { "operation": "op_cat", "input1_hash": hashlib.sha256(data1.encode()).hexdigest(), "input2_hash": hashlib.sha256(data2.encode()).hexdigest(), "result_hash": hashlib.sha256(result.encode()).hexdigest(), "result_length": len(result), "txid": tx_context.get("txid", ""), "block_height": tx_context.get("block_height", 0), "timestamp": datetime.datetime.now().isoformat(), "success": True } self.operation_log.append(operation_record) self.dos_protection["operations_in_block"] += 1 return { "success": True, "result": result, "operation_record": operation_record, "timestamp": datetime.datetime.now().isoformat() } except Exception as e: return { "success": False, "error": str(e), "operation": "op_cat", "timestamp": datetime.datetime.now().isoformat() } def _validate_confirmed_transaction(self, tx_context: Dict[str, Any]) -> bool: """Check if transaction is confirmed in a block.""" required_fields = ["txid", "block_height", "confirmations"] for field in required_fields: if field not in tx_context: return False if tx_context["confirmations"] < 1: return False block_height = tx_context["block_height"] if block_height <= 0: return False return True def _check_dos_protection(self) -> bool: """Check DoS protection limits.""" return self.dos_protection["operations_in_block"] < self.dos_protection["max_ops_per_block"] def _validate_concat_inputs(self, data1: str, data2: str) -> bool: """Validate concatenation inputs.""" if not data1 or not data2: return False combined_length = len(data1) + len(data2) if combined_length > self.dos_protection["max_concat_length"]: return False if len(data1) > 520 or len(data2) > 520: return False return True def reset_block_counter(self, new_block_height: int): """Reset operation counter for new block.""" self.dos_protection["operations_in_block"] = 0 self.confirmed_tx_cache.clear() def create_hash_lock_with_opcat(self, secret_message: str, tx_context: Dict[str, Any]) -> Dict[str, Any]: """ Create hash lock using OP_CAT for confirmed transactions. Combines message with timestamp for unique hash generation. """ timestamp = str(int(datetime.datetime.now().timestamp())) opcat_result = self.op_cat_confirmed_only(secret_message, timestamp, tx_context) if not opcat_result["success"]: return opcat_result combined_data = opcat_result["result"] hash_lock = hashlib.sha256(combined_data.encode()).hexdigest() return { "success": True, "hash_lock": hash_lock, "combined_data": combined_data, "secret_message": secret_message, "timestamp": timestamp, "txid": tx_context.get("txid", ""), "block_height": tx_context.get("block_height", 0), "opcat_operation": opcat_result["operation_record"], "created_at": datetime.datetime.now().isoformat() } def verify_hash_lock_with_opcat(self, hash_lock: str, secret_message: str, timestamp: str, tx_context: Dict[str, Any]) -> Dict[str, Any]: """ Verify hash lock using OP_CAT reproduction. """ opcat_result = self.op_cat_confirmed_only(secret_message, timestamp, tx_context) if not opcat_result["success"]: return opcat_result combined_data = opcat_result["result"] computed_hash = hashlib.sha256(combined_data.encode()).hexdigest() verification = { "success": True, "hash_match": computed_hash == hash_lock, "provided_hash": hash_lock, "computed_hash": computed_hash, "secret_message": secret_message, "timestamp": timestamp, "txid": tx_context.get("txid", ""), "verified_at": datetime.datetime.now().isoformat() } return verification def get_operation_statistics(self) -> Dict[str, Any]: """Get statistics about OP_CAT operations.""" total_operations = len(self.operation_log) successful_operations = sum(1 for op in self.operation_log if op.get("success", True)) return { "total_operations": total_operations, "successful_operations": successful_operations, "success_rate": successful_operations / total_operations if total_operations > 0 else 0, "current_block_operations": self.dos_protection["operations_in_block"], "max_ops_per_block": self.dos_protection["max_ops_per_block"], "dos_protection_active": self.dos_protection["operations_in_block"] >= self.dos_protection["max_ops_per_block"], "latest_operations": self.operation_log[-10:] if self.operation_log else [] } class HashLockBuilder: """ Build hash locks with OP_CAT integration for Bitcoin scripts. """ def __init__(self, opcat_instance: OPCatRestricted): self.opcat = opcat_instance self.lock_registry = {} def build_op_return_script(self, hash_lock: str, additional_data: str = "") -> Dict[str, Any]: """ Build OP_RETURN script with hash lock commitment. """ if len(hash_lock) != 64: return { "success": False, "error": "Hash lock must be 32 bytes (64 hex chars)", "timestamp": datetime.datetime.now().isoformat() } script = f"OP_RETURN OP_HASH160 {hash_lock[:40]}" if additional_data: opcat_result = self.opcat.op_cat_confirmed_only(script, additional_data, { "txid": "script_construction", "block_height": 0, "confirmations": 1 }) if opcat_result["success"]: script = opcat_result["result"] return { "success": True, "script": script, "hash_lock": hash_lock, "script_size": len(script), "includes_opcat": "OP_CAT" in script, "created_at": datetime.datetime.now().isoformat() } def create_steganographic_psbt_hash(self, psbt_data: str, image_data: str, tx_context: Dict[str, Any]) -> Dict[str, Any]: """ Create steganographic hash of PSBT data for privacy-preserving verification. """ psbt_hash = hashlib.sha256(psbt_data.encode()).hexdigest() opcat_result = self.opcat.op_cat_confirmed_only(psbt_hash, image_data[:50], tx_context) if not opcat_result["success"]: return opcat_result steganographic_hash = hashlib.sha256(opcat_result["result"].encode()).hexdigest() return { "success": True, "psbt_hash": psbt_hash, "steganographic_hash": steganographic_hash, "opcat_result": opcat_result["operation_record"], "txid": tx_context.get("txid", ""), "created_at": datetime.datetime.now().isoformat() } def test_opcat_restricted(): """Test the restricted OP_CAT implementation.""" opcat = OPCatRestricted() confirmed_tx = { "txid": "abcd1234efgh5678ijkl9012mnop3456", "block_height": 800000, "confirmations": 6 } unconfirmed_tx = { "txid": "unconfirmed_tx_123", "block_height": 0, "confirmations": 0 } print("✅ OP_CAT Restricted Test:") test1 = opcat.op_cat_confirmed_only("hello", "world", confirmed_tx) print(f"Confirmed TX: {test1['success']}") test2 = opcat.op_cat_confirmed_only("hello", "world", unconfirmed_tx) print(f"Unconfirmed TX: {test2['success']}") hash_lock_test = opcat.create_hash_lock_with_opcat("secret_message", confirmed_tx) print(f"Hash Lock Creation: {hash_lock_test['success']}") stats = opcat.get_operation_statistics() print(f"Operation Stats: {stats}") return test1, test2, hash_lock_test if __name__ == "__main__": test_opcat_restricted()