feat(utxo-core): add buildToSpendTransactionFromChainAndIndex function

Add function to create BIP322 to_spend transaction by deriving output
script from wallet keys, chain and index. Includes validation to prevent
usage with Taproot script types which are not supported by BIP322.

Co-authored-by: llm-git <[email protected]>

TICKET: BTC-2372

Author: davidkaplanbitgo

modules/utxo-core/src/bip322/toSpend.ts

@@ -1,5 +1,5 @@
 import { Hash } from 'fast-sha256';
-import { Psbt, Transaction } from '@bitgo/utxo-lib';
+import { Psbt, Transaction, bitgo, networks } from '@bitgo/utxo-lib';
 
 export const BIP322_TAG = 'BIP0322-signed-message';
 
@@ -66,3 +66,23 @@ export function buildToSpendTransaction(
   // Return transaction
   return psbt.extractTransaction();
 }
+
+export function buildToSpendTransactionFromChainAndIndex(
+  rootWalletKeys: bitgo.RootWalletKeys,
+  chain: bitgo.ChainCode,
+  index: number,
+  message: string | Buffer,
+  tag = BIP322_TAG
+): Transaction<bigint> {
+  const taprootChains = [...bitgo.chainCodesP2tr, ...bitgo.chainCodesP2trMusig2];
+  if (taprootChains.some((tc) => tc === chain)) {
+    throw new Error('BIP322 is not supported for Taproot script types.');
+  }
+
+  const outputScript = bitgo.outputScripts.createOutputScript2of3(
+    rootWalletKeys.deriveForChainAndIndex(chain, index).publicKeys,
+    bitgo.scriptTypeForChain(chain),
+    networks.bitcoin
+  );
+  return buildToSpendTransaction(outputScript.scriptPubKey, message, tag);
+}

modules/utxo-core/test/bip322/toSpend.ts

@@ -1,6 +1,12 @@
 import assert from 'assert';
 
-import { buildToSpendTransaction, hashMessageWithTag } from '../../src/bip322';
+import { testutil, bitgo } from '@bitgo/utxo-lib';
+
+import {
+  buildToSpendTransaction,
+  hashMessageWithTag,
+  buildToSpendTransactionFromChainAndIndex,
+} from '../../src/bip322';
 
 import { BIP322_PAYMENT_P2WPKH_FIXTURE } from './bip322.utils';
 
@@ -53,4 +59,46 @@ describe('to_spend', function () {
       });
     });
   });
+
+  describe('buildToSpendTransactionFromChainAndIndex', function () {
+    it('should throw an error for Taproot chains', function () {
+      const taprootChains = [...bitgo.chainCodesP2tr, ...bitgo.chainCodesP2trMusig2];
+      taprootChains.forEach((chain) => {
+        assert.throws(() => {
+          buildToSpendTransactionFromChainAndIndex(
+            testutil.getDefaultWalletKeys(),
+            chain,
+            0,
+            Buffer.from('Hello World')
+          );
+        }, /BIP322 is not supported for Taproot script types/);
+      });
+    });
+
+    describe('should build a to_spend transaction for a non-Taproot chain', function () {
+      function run(chain: bitgo.ChainCode) {
+        it(`scriptType: ${bitgo.scriptTypeForChain(chain)}, chain ${chain}`, function () {
+          const tx = buildToSpendTransactionFromChainAndIndex(
+            testutil.getDefaultWalletKeys(),
+            20,
+            0,
+            Buffer.from('Hello World')
+          );
+          const expectedScriptPubKey = bitgo.outputScripts
+            .createOutputScript2of3(testutil.getDefaultWalletKeys().deriveForChainAndIndex(20, 0).publicKeys, 'p2wsh')
+            .scriptPubKey.toString();
+          const scriptPubKeyFromTx = tx.outs[0].script.toString();
+          assert.deepStrictEqual(
+            scriptPubKeyFromTx,
+            expectedScriptPubKey,
+            'ScriptPubKey does not match expected value'
+          );
+        });
+      }
+
+      ([0, 1, 10, 11, 20, 21] as bitgo.ChainCode[]).forEach((chain) => {
+        run(chain);
+      });
+    });
+  });
 });