finalize_psbt.py

Author: JAGADISHSUNILPEDNEKAR

examples/finalize_psbt.py

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+#!/usr/bin/env python3
+"""
+Finalize a PSBT (Partially Signed Bitcoin Transaction) to produce a broadcastable Bitcoin transaction.
+
+This script serves as the finalizer step (as defined in BIP-174), assembling signatures and scripts
+into a complete transaction ready for broadcast.
+
+Features:
+- Loads a base64-encoded PSBT from string or file
+- Finalizes all inputs by constructing scriptSig/scriptWitness
+- Optionally validates that all inputs are fully signed before finalization
+- Outputs the raw hex-encoded Bitcoin transaction
+
+Usage:
+    python finalize_psbt.py <psbt_base64_string>
+    python finalize_psbt.py --file <psbt_file.txt>
+    python finalize_psbt.py --file <psbt_file.txt> --validate
+
+Arguments:
+    <psbt_base64_string>        PSBT data as a base64-encoded string
+    --file <psbt_file.txt>      Load PSBT from a file
+    --validate                  (Optional) Enforce validation before finalizing
+
+Returns:
+    Hex-encoded, fully signed Bitcoin transaction ready for broadcast
+"""
+
+
+import argparse
+import base64
+import sys
+from bitcoinutils.setup import setup
+from bitcoinutils.psbt import PSBT
+
+
+def main():
+    """
+    Main function for PSBT finalization.
+    
+    Usage:
+        python finalize_psbt.py <psbt_base64_string>
+        python finalize_psbt.py --file <psbt_file.txt>
+        python finalize_psbt.py --file <psbt_file.txt> --validate
+    """
+    parser = argparse.ArgumentParser(description='Finalize a PSBT and create a transaction.')
+    parser.add_argument('psbt', nargs='?', help='Base64-encoded PSBT string')
+    parser.add_argument('--file', help='Text file containing base64 PSBT')
+    parser.add_argument('--validate', action='store_true', help='Validate finalized transaction')
+    parser.add_argument('--network', choices=['mainnet', 'testnet'], default='testnet', 
+                       help='Bitcoin network (default: testnet)')
+    
+    args = parser.parse_args()
+    
+    # Setup the library for specified network
+    setup(args.network)
+    
+    try:
+        # Load PSBT from input
+        if args.file:
+            with open(args.file, 'r') as f:
+                psbt_b64 = f.read().strip()
+        elif args.psbt:
+            psbt_b64 = args.psbt
+        else:
+            print("Error: Provide either base64 string or --file option.")
+            print("Use --help for usage information.")
+            return 1
+        
+        # Create PSBT object
+        psbt = PSBT.from_base64(psbt_b64)
+        
+        # Finalize the PSBT
+        if args.validate:
+            final_tx, validation = psbt.finalize(validate=True)
+            
+            print("Finalized Transaction (Hex):")
+            print(final_tx.serialize())
+            
+            print("\nValidation Report:")
+            print(f"Valid: {validation['valid']}")
+            print(f"Transaction ID: {validation['txid']}")
+            print(f"Size: {validation['size']} bytes")
+            print(f"Virtual Size: {validation['vsize']} vbytes")
+            
+            if validation['errors']:
+                print("Errors:")
+                for error in validation['errors']:
+                    print(f"  - {error}")
+            
+            if validation['warnings']:
+                print("Warnings:")
+                for warning in validation['warnings']:
+                    print(f"  - {warning}")
+                    
+        else:
+            final_tx = psbt.finalize(validate=False)
+            print("Finalized Transaction (Hex):")
+            print(final_tx.serialize())
+            
+        print(f"\nTransaction ready to broadcast!")
+        print(f"Use 'bitcoin-cli sendrawtransaction {final_tx.serialize()}' to broadcast")
+        
+        return 0
+        
+    except Exception as e:
+        print(f"Error: {str(e)}")
+        return 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())