feat(utxo-core): add verification func for to_sign txs

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

@@ -1,3 +1,4 @@
 export * from './toSpend';
 export * from './toSign';
 export * from './utils';
+export * from './verify';

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

@@ -0,0 +1,53 @@
+import assert from 'assert';
+
+import * as utxolib from '@bitgo/utxo-lib';
+
+import { buildToSpendTransaction } from './toSpend';
+
+export type VerificationInfo = {
+  message: string;
+  address: string;
+};
+
+/**
+ *
+ * @param toSignTx
+ * @param verificationInfo
+ * @param network
+ */
+export function verifyFixedScriptToSignTxWithInfo(
+  toSignTx: utxolib.Transaction<bigint>,
+  verificationInfo: VerificationInfo[],
+  network: utxolib.Network
+): void {
+  assert.deepStrictEqual(
+    toSignTx.ins.length,
+    verificationInfo.length,
+    'to_sign transaction must have one input per message'
+  );
+
+  // Verify the transaction structure
+  assert.deepStrictEqual(toSignTx.version, 0, 'to_sign transaction version must be 0');
+  assert.deepStrictEqual(toSignTx.locktime, 0, 'to_sign transaction locktime must be 0');
+  assert.deepStrictEqual(toSignTx.outs.length, 1, 'to_sign transaction must have one output');
+  assert.deepStrictEqual(toSignTx.outs[0].value, BigInt(0), 'to_sign transaction output value must be 0');
+  assert.deepStrictEqual(
+    toSignTx.outs[0].script.toString('hex'),
+    '6a',
+    'to_sign transaction output script must be OP_RETURN'
+  );
+
+  // Verify the messages against the transaction inputs
+  toSignTx.ins.forEach((input, inputIndex) => {
+    // Check that the expected to_spend transaction matches
+    const scriptPubKey = utxolib.address.toOutputScript(verificationInfo[inputIndex].address, network);
+    const toSpendTx = buildToSpendTransaction(scriptPubKey, verificationInfo[inputIndex].message);
+    assert.deepStrictEqual(
+      utxolib.bitgo.getOutputIdForInput(toSignTx.ins[inputIndex]).txid,
+      toSpendTx.getId(),
+      'to_sign transaction input must reference the to_spend transaction'
+    );
+    assert.deepStrictEqual(input.index, 0, `to_sign transaction input ${inputIndex} index must be 0`);
+    assert.deepStrictEqual(input.sequence, 0, `to_sign transaction input ${inputIndex} sequence must be 0`);
+  });
+}

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

@@ -0,0 +1,48 @@
+import assert from 'assert';
+
+import * as utxolib from '@bitgo/utxo-lib';
+
+import * as bip322 from '../../src/bip322';
+import { addBip322InputWithChainAndIndex, VerificationInfo, verifyFixedScriptToSignTxWithInfo } from '../../src/bip322';
+
+describe('Verify BIP322 to_sign transactions', function () {
+  it('should verify a correctly signed BIP322 to_sign transaction with multiple messages', function () {
+    function createMessage(messageBase: string, index: number): string {
+      return messageBase + index.toString();
+    }
+
+    const rootWalletKeys = utxolib.testutil.getDefaultWalletKeys();
+    const network = utxolib.networks.bitcoin;
+    const messageBase = 'I can believe it is not butter ';
+
+    const toSignPsbt = bip322.createBaseToSignPsbt(rootWalletKeys);
+
+    const verificationInfo: VerificationInfo[] = [];
+    utxolib.bitgo.chainCodes
+      .filter((chain) => chain !== 30 && chain !== 31)
+      .forEach((chain, index) => {
+        const message = createMessage(messageBase, index);
+        const walletKeys = rootWalletKeys.deriveForChainAndIndex(chain, index);
+        const address = utxolib.address.fromOutputScript(
+          utxolib.bitgo.outputScripts.createOutputScript2of3(
+            walletKeys.publicKeys,
+            utxolib.bitgo.scriptTypeForChain(chain),
+            network
+          ).scriptPubKey,
+          network
+        );
+        verificationInfo.push({ message, address });
+        addBip322InputWithChainAndIndex(toSignPsbt, message, rootWalletKeys, { chain, index });
+      });
+    toSignPsbt.setAllInputsMusig2NonceHD(rootWalletKeys.user);
+    toSignPsbt.setAllInputsMusig2NonceHD(rootWalletKeys.bitgo);
+    toSignPsbt.signAllInputsHD(rootWalletKeys.user);
+    toSignPsbt.signAllInputsHD(rootWalletKeys.bitgo);
+
+    const tx = toSignPsbt.finalizeAllInputs().extractTransaction();
+
+    assert.doesNotThrow(() => {
+      verifyFixedScriptToSignTxWithInfo(tx, verificationInfo, network);
+    });
+  });
+});