sign_psbt.py

Author: JAGADISHSUNILPEDNEKAR

examples/sign_psbt.py

@@ -0,0 +1,85 @@
+# Copyright (C) 2025 The python-bitcoin-utils developers
+#
+# This file is part of python-bitcoin-utils
+#
+# It is subject to the license terms in the LICENSE file found in the top-level
+# directory of this distribution.
+#
+# No part of python-bitcoin-utils, including this file, may be copied,
+# modified, propagated, or distributed except according to the terms contained
+# in the LICENSE file.
+
+"""
+Sign a specific input of a PSBT (Partially Signed Bitcoin Transaction) using a WIF private key.
+
+This script allows targeted signing of one input in a PSBT, which is useful for multisig setups,
+hardware wallet integrations, or step-by-step signing processes.
+
+Features:
+- Loads a PSBT from a base64-encoded string
+- Signs a specified input using a provided WIF-formatted private key
+- Supports multiple script types: P2PKH, P2SH, P2WPKH, P2WSH, P2TR
+- Allows optional SIGHASH type customization (default: SIGHASH_ALL)
+
+Usage:
+    python sign_psbt.py <psbt_base64> <private_key_wif> <input_index> [sighash_type]
+
+Arguments:
+    psbt_base64       The PSBT in base64 encoding
+    private_key_wif   The private key in Wallet Import Format (WIF)
+    input_index       Index of the input to sign (0-based)
+    sighash_type      (Optional) Bitcoin SIGHASH flag (e.g., SIGHASH_ALL, SIGHASH_SINGLE)
+
+Returns:
+    Updated PSBT with the input partially signed and printed as base64
+"""
+
+
+import sys
+from bitcoinutils.setup import setup
+from bitcoinutils.keys import PrivateKey
+from bitcoinutils.psbt import PSBT
+from bitcoinutils.constants import SIGHASH_ALL
+
+
+def main():
+    """Main function for signing PSBT example."""
+    # Always call setup() first
+    setup('testnet')
+    
+    # Parse command line arguments
+    if len(sys.argv) < 4:
+        print("Usage: python sign_psbt.py <psbt_base64> <private_key_wif> <input_index> [sighash_type]")
+        print("\nExample:")
+        print("python sign_psbt.py <psbt> cTALNpTpRbbxTCJ2A5Vq88UxT44w1PE2cYqiB3n4hRvzyCev1Wwo 0")
+        sys.exit(1)
+    
+    psbt_base64 = sys.argv[1]
+    private_key_wif = sys.argv[2]
+    input_index = int(sys.argv[3])
+    sighash_type = int(sys.argv[4]) if len(sys.argv) > 4 else SIGHASH_ALL
+    
+    try:
+        # Load PSBT from base64
+        psbt = PSBT.from_base64(psbt_base64)
+        
+        # Load private key
+        private_key = PrivateKey.from_wif(private_key_wif)
+        
+        # Sign the specified input
+        success = psbt.sign_input(input_index, private_key, sighash_type)
+        
+        if success:
+            # Output the updated PSBT
+            print(psbt.to_base64())
+        else:
+            print("Failed to sign input", file=sys.stderr)
+            sys.exit(1)
+            
+    except Exception as e:
+        print(f"Error: {str(e)}", file=sys.stderr)
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()