Merge pull request #4136 from BitGo/BTC-721-override-signing

feat: add flag to override signing for non-segwit transactions
BitGo · Dec 11, 2023 · b578210 · b578210
2 parents 6e8b84c + 2bcdaf0
commit b578210
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Showing 3 changed files with 38 additions and 6 deletions.
diff --git a/modules/abstract-utxo/src/abstractUtxoCoin.ts b/modules/abstract-utxo/src/abstractUtxoCoin.ts
@@ -247,6 +247,11 @@ type UtxoBaseSignTransactionOptions<TNumber extends number | bigint = number> =
    * When false, creates half-signed transaction with placeholder signatures.
    */
   isLastSignature?: boolean;
+  /**
+   * If true, allows signing a non-segwit input with a witnessUtxo instead requiring a previous
+   * transaction (nonWitnessUtxo)
+   */
+  allowNonSegwitSigningWithoutPrevTx?: boolean;
 };
 
 export type SignTransactionOptions<TNumber extends number | bigint = number> = UtxoBaseSignTransactionOptions<TNumber> &
@@ -1164,13 +1169,21 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
       return signerKeychain;
     };
 
+    const setSignerMusigNonceWithOverride = (
+      psbt: utxolib.bitgo.UtxoPsbt,
+      signerKeychain: utxolib.BIP32Interface,
+      nonSegwitOverride: boolean
+    ) => {
+      utxolib.bitgo.withUnsafeNonSegwit(psbt, () => psbt.setAllInputsMusig2NonceHD(signerKeychain), nonSegwitOverride);
+    };
+
     let signerKeychain: utxolib.BIP32Interface | undefined;
 
     if (tx instanceof bitgo.UtxoPsbt && isTxWithKeyPathSpendInput) {
       switch (params.signingStep) {
         case 'signerNonce':
           signerKeychain = getSignerKeychain();
-          tx.setAllInputsMusig2NonceHD(signerKeychain);
+          setSignerMusigNonceWithOverride(tx, signerKeychain, !!params.allowNonSegwitSigningWithoutPrevTx);
           AbstractUtxoCoin.PSBT_CACHE.set(tx.getUnsignedTx().getId(), tx);
           return { txHex: tx.toHex() };
         case 'cosignerNonce':
@@ -1191,7 +1204,7 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
           // this instance is not an external signer
           assert(txPrebuild.walletId, 'walletId is required for MuSig2 bitgo nonce');
           signerKeychain = getSignerKeychain();
-          tx.setAllInputsMusig2NonceHD(signerKeychain);
+          setSignerMusigNonceWithOverride(tx, signerKeychain, !!params.allowNonSegwitSigningWithoutPrevTx);
           const response = await this.signPsbt(tx.toHex(), txPrebuild.walletId);
           tx.combine(bitgo.createPsbtFromHex(response.psbt, this.network));
           break;
@@ -1214,7 +1227,10 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
 
     let signedTransaction: bitgo.UtxoTransaction<bigint> | bitgo.UtxoPsbt;
     if (tx instanceof bitgo.UtxoPsbt) {
-      signedTransaction = signAndVerifyPsbt(tx, signerKeychain, { isLastSignature });
+      signedTransaction = signAndVerifyPsbt(tx, signerKeychain, {
+        isLastSignature,
+        allowNonSegwitSigningWithoutPrevTx: params.allowNonSegwitSigningWithoutPrevTx,
+      });
     } else {
       if (tx.ins.length !== txPrebuild.txInfo?.unspents?.length) {
         throw new Error('length of unspents array should equal to the number of transaction inputs');

diff --git a/modules/abstract-utxo/src/sign.ts b/modules/abstract-utxo/src/sign.ts
@@ -63,7 +63,10 @@ export class TransactionSigningError<TNumber extends number | bigint = number> e
 export function signAndVerifyPsbt(
   psbt: utxolib.bitgo.UtxoPsbt,
   signerKeychain: utxolib.BIP32Interface,
-  { isLastSignature }: { isLastSignature: boolean }
+  {
+    isLastSignature,
+    allowNonSegwitSigningWithoutPrevTx,
+  }: { isLastSignature: boolean; allowNonSegwitSigningWithoutPrevTx?: boolean }
 ): utxolib.bitgo.UtxoPsbt | utxolib.bitgo.UtxoTransaction<bigint> {
   const txInputs = psbt.txInputs;
   const outputIds: string[] = [];
@@ -83,7 +86,11 @@ export function signAndVerifyPsbt(
       }
 
       try {
-        psbt.signInputHD(inputIndex, signerKeychain);
+        utxolib.bitgo.withUnsafeNonSegwit(
+          psbt,
+          () => psbt.signInputHD(inputIndex, signerKeychain),
+          !!allowNonSegwitSigningWithoutPrevTx
+        );
         debug('Successfully signed input %d of %d', inputIndex + 1, psbt.data.inputs.length);
       } catch (e) {
         return new InputSigningError<bigint>(inputIndex, { id: outputId }, e);
@@ -105,7 +112,13 @@ export function signAndVerifyPsbt(
 
       const outputId = outputIds[inputIndex];
       try {
-        if (!psbt.validateSignaturesOfInputHD(inputIndex, signerKeychain)) {
+        if (
+          !utxolib.bitgo.withUnsafeNonSegwit(
+            psbt,
+            () => psbt.validateSignaturesOfInputHD(inputIndex, signerKeychain),
+            !!allowNonSegwitSigningWithoutPrevTx
+          )
+        ) {
           return new InputSigningError(inputIndex, { id: outputId }, new Error(`invalid signature`));
         }
       } catch (e) {

diff --git a/modules/sdk-core/src/bitgo/wallet/wallet.ts b/modules/sdk-core/src/bitgo/wallet/wallet.ts
@@ -689,6 +689,9 @@ export class Wallet implements IWallet {
         assert(k.pub);
         return k.pub;
       }),
+      // Building PSBTs with the bulk flag does not include the previous transaction for non-segwit inputs.
+      // Manually override the signing and validating to not fail.
+      allowNonSegwitSigningWithoutPrevTx: !!params.bulk,
     };
 
     const txPrebuilds = Array.isArray(buildResponse) ? buildResponse : [buildResponse];