2 files changed, 29 insertions, 0 deletions
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index 28dfdecdfc..f9907f5e00 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -234,6 +234,32 @@ bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreato
     return sigdata.complete;
 }
 
+bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& tx, PSBTInput& input, SignatureData& sigdata, int index, int sighash)
+{
+    // if this input has a final scriptsig or scriptwitness, don't do anything with it
+    if (!input.final_script_sig.empty() || !input.final_script_witness.IsNull()) {
+        return true;
+    }
+
+    // Fill SignatureData with input info
+    input.FillSignatureData(sigdata);
+
+    // Get UTXO
+    CTxOut utxo;
+    if (input.non_witness_utxo) {
+        utxo = input.non_witness_utxo->vout[tx.vin[index].prevout.n];
+    } else if (!input.witness_utxo.IsNull()) {
+        utxo = input.witness_utxo;
+    } else {
+        return false;
+    }
+
+    MutableTransactionSignatureCreator creator(&tx, index, utxo.nValue, sighash);
+    bool sig_complete = ProduceSignature(provider, creator, utxo.scriptPubKey, sigdata);
+    input.FromSignatureData(sigdata);
+    return sig_complete;
+}
+
 class SignatureExtractorChecker final : public BaseSignatureChecker
 {
 private:
diff --git a/src/script/sign.h b/src/script/sign.h
index ab2153e3b9..9f0382e257 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -634,6 +634,9 @@ bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreato
 bool SignSignature(const SigningProvider &provider, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, const CAmount& amount, int nHashType);
 bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType);
 
+/** Signs a PSBTInput */
+bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& tx, PSBTInput& input, SignatureData& sigdata, int index, int sighash = 1);
+
 /** Extract signature data from a transaction input, and insert it. */
 SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn, const CTxOut& txout);
 void UpdateInput(CTxIn& input, const SignatureData& data);