Merge pull request #6635 from BitGo/BTC-2375

feat(utxo-core): simplify signature process with direct message param

Author: davidkaplanbitgo

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

@@ -1,6 +1,7 @@
-import { Psbt, Transaction, bitgo } from '@bitgo/utxo-lib';
+import { Psbt, bitgo } from '@bitgo/utxo-lib';
 
-import { isTaprootChain } from './utils';
+import { addBip322ProofMessage, isTaprootChain } from './utils';
+import { BIP322_TAG, buildToSpendTransaction } from './toSpend';
 
 export type AddressDetails = {
   redeemScript?: Buffer;
@@ -13,11 +14,14 @@ export type AddressDetails = {
  * Source implementation:
  * https://github.com/bitcoin/bips/blob/master/bip-0322.mediawiki#full
  *
- * @param {string} toSpendTxHex - The hex representation of the `toSpend` transaction.
+ * @param {string} message - The message that is hashed into the `to_spend` transaction.
  * @param {AddressDetails} addressDetails - The details of the address, including redeemScript and/or witnessScript.
- * @returns {string} - The hex representation of the constructed PSBT.
+ * @param {string} [tag=BIP322_TAG] - The tag to use for hashing, defaults to BIP322_TAG.
+ * @returns {Psbt} - The hex representation of the constructed PSBT.
  */
-export function buildToSignPsbt(toSpendTx: Transaction<bigint>, addressDetails: AddressDetails): Psbt {
+export function buildToSignPsbt(message: string, addressDetails: AddressDetails, tag = BIP322_TAG): Psbt {
+  const toSpendTx = buildToSpendTransaction(addressDetails.scriptPubKey, message, tag);
+
   // Create PSBT object for constructing the transaction
   const psbt = new Psbt();
   // Set default value for nVersion and nLockTime
@@ -41,6 +45,9 @@ export function buildToSignPsbt(toSpendTx: Transaction<bigint>, addressDetails:
     psbt.updateInput(0, { witnessScript: addressDetails.witnessScript });
   }
 
+  // Add the message as a proprietary key value to the PSBT so we can verify it later
+  addBip322ProofMessage(psbt as bitgo.UtxoPsbt, 0, Buffer.from(message));
+
   // Set the output
   psbt.addOutput({
     value: BigInt(0), // vout[0].nValue = 0
@@ -50,7 +57,7 @@ export function buildToSignPsbt(toSpendTx: Transaction<bigint>, addressDetails:
 }
 
 export function buildToSignPsbtForChainAndIndex(
-  toSpendTx: Transaction<bigint>,
+  message: string,
   rootWalletKeys: bitgo.RootWalletKeys,
   chain: bitgo.ChainCode,
   index: number
@@ -63,12 +70,7 @@ export function buildToSignPsbtForChainAndIndex(
     bitgo.scriptTypeForChain(chain)
   );
 
-  const toSpendScriptPubKey = toSpendTx.outs[0].script;
-  if (!toSpendScriptPubKey.equals(output.scriptPubKey)) {
-    throw new Error('Output scriptPubKey does not match the expected output script for the chain and index.');
-  }
-
-  return buildToSignPsbt(toSpendTx, {
+  return buildToSignPsbt(message, {
     scriptPubKey: output.scriptPubKey,
     redeemScript: output.redeemScript,
     witnessScript: output.witnessScript,

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

@@ -13,6 +13,6 @@ export const BIP322_FIXTURE_HELLO_WORLD_TOSPEND_TX = buildToSpendTransaction(
   Buffer.from('Hello World')
 );
 
-export const BIP322_FIXTURE_HELLOW_WORLD_TOSIGN_PSBT = buildToSignPsbt(BIP322_FIXTURE_HELLO_WORLD_TOSPEND_TX, {
+export const BIP322_FIXTURE_HELLO_WORLD_TOSIGN_PSBT = buildToSignPsbt('Hello World', {
   scriptPubKey: BIP322_PAYMENT_P2WPKH_FIXTURE.output as Buffer,
 });

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

@@ -23,11 +23,9 @@ describe('BIP322 toSign', function () {
 
     fixtures.forEach(({ message, txid }) => {
       it(`should build a to_sign PSBT for message "${message}"`, function () {
-        const toSpendTx = bip322.buildToSpendTransaction(scriptPubKey, Buffer.from(message));
-        const addressDetails = {
+        const result = bip322.buildToSignPsbt(message, {
           scriptPubKey,
-        };
-        const result = bip322.buildToSignPsbt(toSpendTx, addressDetails);
+        });
         const computedTxid = result
           .signAllInputs(prv, [utxolib.Transaction.SIGHASH_ALL])
           .finalizeAllInputs()
@@ -41,13 +39,6 @@ describe('BIP322 toSign', function () {
   describe('buildToSignPsbtForChainAndIndex', function () {
     const rootWalletKeys = utxolib.testutil.getDefaultWalletKeys();
 
-    it('should fail when scriptPubKey of to_spend is different than to_sign', function () {
-      const toSpendTx = bip322.buildToSpendTransaction(BIP322_PAYMENT_P2WPKH_FIXTURE.output as Buffer, 'Hello World');
-      assert.throws(() => {
-        bip322.buildToSignPsbtForChainAndIndex(toSpendTx, rootWalletKeys, 0, 0);
-      }, /Output scriptPubKey does not match the expected output script for the chain and index./);
-    });
-
     function run(chain: utxolib.bitgo.ChainCode, shouldFail: boolean, index: number) {
       it(`should${
         shouldFail ? ' fail to' : ''
@@ -60,7 +51,7 @@ describe('BIP322 toSign', function () {
           return;
         }
         const toSpendTx = bip322.buildToSpendTransactionFromChainAndIndex(rootWalletKeys, chain, index, message);
-        const toSignPsbt = bip322.buildToSignPsbtForChainAndIndex(toSpendTx, rootWalletKeys, chain, index);
+        const toSignPsbt = bip322.buildToSignPsbtForChainAndIndex(message, rootWalletKeys, chain, index);
 
         const derivedKeys = rootWalletKeys.deriveForChainAndIndex(chain, index);
         const prv1 = derivedKeys.triple[0];

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

@@ -2,45 +2,37 @@ import assert from 'assert';
 
 import * as utxolib from '@bitgo/utxo-lib';
 
-import { addBip322ProofMessage, getBip322ProofInputIndex, psbtIsBip322Proof } from '../../src/bip322';
+import { getBip322ProofInputIndex, psbtIsBip322Proof } from '../../src/bip322';
 
-import { BIP322_FIXTURE_HELLOW_WORLD_TOSIGN_PSBT } from './bip322.utils';
+import { BIP322_FIXTURE_HELLO_WORLD_TOSIGN_PSBT } from './bip322.utils';
 
 describe('BIP322 Proof utils', function () {
   it('should add a BIP322 proof message to a PSBT input', function () {
     const psbt = utxolib.bitgo.createPsbtFromBuffer(
-      BIP322_FIXTURE_HELLOW_WORLD_TOSIGN_PSBT.toBuffer(),
+      BIP322_FIXTURE_HELLO_WORLD_TOSIGN_PSBT.toBuffer(),
       utxolib.networks.bitcoin
     );
-    const inputIndex = 0;
-    const message = Buffer.from('Hello World');
-    addBip322ProofMessage(psbt, inputIndex, message);
 
-    const proprietaryKeyVals = utxolib.bitgo.getPsbtInputProprietaryKeyVals(psbt.data.inputs[inputIndex], {
+    const proprietaryKeyVals = utxolib.bitgo.getPsbtInputProprietaryKeyVals(psbt.data.inputs[0], {
       identifier: utxolib.bitgo.PSBT_PROPRIETARY_IDENTIFIER,
       subtype: utxolib.bitgo.ProprietaryKeySubtype.BIP322_MESSAGE,
     });
 
     assert.ok(proprietaryKeyVals.length === 1);
-    assert.ok(proprietaryKeyVals[0].value.equals(message));
+    assert.ok(proprietaryKeyVals[0].value.equals(Buffer.from('Hello World')));
     assert.ok(proprietaryKeyVals[0].key.keydata.length === 0); // keydata should be empty
     assert.ok(proprietaryKeyVals[0].key.identifier === utxolib.bitgo.PSBT_PROPRIETARY_IDENTIFIER);
     assert.ok(proprietaryKeyVals[0].key.subtype === utxolib.bitgo.ProprietaryKeySubtype.BIP322_MESSAGE);
   });
 
   it('should return the input index of a BIP322 proof message', function () {
     const psbt = utxolib.bitgo.createPsbtFromBuffer(
-      BIP322_FIXTURE_HELLOW_WORLD_TOSIGN_PSBT.toBuffer(),
+      BIP322_FIXTURE_HELLO_WORLD_TOSIGN_PSBT.toBuffer(),
       utxolib.networks.bitcoin
     );
-    assert.ok(!psbtIsBip322Proof(psbt)); // initially should not be a BIP322 proof
-
-    const inputIndex = 0;
-    const message = Buffer.from('Hello World');
-    addBip322ProofMessage(psbt, inputIndex, message);
 
     const resultIndex = getBip322ProofInputIndex(psbt);
-    assert.strictEqual(resultIndex, inputIndex);
+    assert.strictEqual(resultIndex, 0);
     assert.ok(psbtIsBip322Proof(psbt));
   });
 });