signing fixes

src/main/java/com/sparrowwallet/drongo/protocol/TransactionWitness.java

@@ -24,8 +24,9 @@ public class TransactionWitness extends ChildMessage {
     public TransactionWitness(Transaction transaction, List<TransactionSignature> signatures, Script witnessScript) {
         setParent(transaction);
         this.pushes = new ArrayList<>();
+        //If a multisig witness script, add a zero byte witness element to handle the multisig off by one bug
         if(ScriptType.MULTISIG.isScriptType(witnessScript)) {
-            pushes.add(new byte[] { ScriptOpCodes.OP_0 });
+            pushes.add(new byte[0]);
         }
         for(TransactionSignature signature : signatures) {
             pushes.add(signature.encodeToBitcoin());
@@ -95,7 +96,7 @@ public class TransactionWitness extends ChildMessage {
 
     protected void bitcoinSerializeToStream(OutputStream stream) throws IOException {
         stream.write(new VarInt(pushes.size()).encode());
-        for (int i = 0; i < pushes.size(); i++) {
+        for(int i = 0; i < pushes.size(); i++) {
             byte[] push = pushes.get(i);
             if(push.length == 1 && push[0] == 0) {
                 stream.write(push);

src/main/java/com/sparrowwallet/drongo/psbt/PSBTInput.java

@@ -386,7 +386,7 @@ public class PSBTInput {
                 //All partial sigs are already verified
                 int reqSigs = getSigningScript().getNumRequiredSignatures();
                 int sigs = getPartialSignatures().size();
-                return sigs == reqSigs;
+                return sigs >= reqSigs;
             } catch(NonStandardScriptException e) {
                 return false;
             }
@@ -457,6 +457,31 @@ public class PSBTInput {
         return false;
     }
 
+    public ScriptType getScriptType() {
+        Script signingScript = getUtxo().getScript();
+
+        boolean p2sh = false;
+        if(P2SH.isScriptType(signingScript)) {
+            p2sh = true;
+
+            if(getRedeemScript() != null) {
+                signingScript = getRedeemScript();
+            } else if(getFinalScriptSig() != null) {
+                signingScript = getFinalScriptSig().getFirstNestedScript();
+            } else {
+                return null;
+            }
+        }
+
+        if(P2WPKH.isScriptType(signingScript)) {
+            return p2sh ? P2SH_P2WPKH : P2WPKH;
+        } else if(P2WSH.isScriptType(signingScript)) {
+            return p2sh ? P2SH_P2WSH : P2WSH;
+        }
+
+        return ScriptType.getType(signingScript);
+    }
+
     public Script getSigningScript() {
         Script signingScript = getUtxo().getScript();
 

src/main/java/com/sparrowwallet/drongo/wallet/FinalizingPSBTWallet.java

@@ -1,9 +1,12 @@
 package com.sparrowwallet.drongo.wallet;
 
+import com.sparrowwallet.drongo.KeyPurpose;
 import com.sparrowwallet.drongo.crypto.ECKey;
 import com.sparrowwallet.drongo.policy.Miniscript;
 import com.sparrowwallet.drongo.policy.Policy;
 import com.sparrowwallet.drongo.policy.PolicyType;
+import com.sparrowwallet.drongo.protocol.NonStandardScriptException;
+import com.sparrowwallet.drongo.protocol.Script;
 import com.sparrowwallet.drongo.protocol.ScriptType;
 import com.sparrowwallet.drongo.protocol.TransactionSignature;
 import com.sparrowwallet.drongo.psbt.PSBT;
@@ -15,7 +18,7 @@ import java.util.stream.IntStream;
 
 /**
  * This is a special wallet that is used solely to finalize a fully signed PSBT by reading from the partial signatures and UTXO scriptPubKey
- *
+ * It is used when the normal wallet is not available.
  */
 public class FinalizingPSBTWallet extends Wallet {
     private final Map<PSBTInput, WalletNode> signedInputNodes = new LinkedHashMap<>();
@@ -25,15 +28,43 @@ public class FinalizingPSBTWallet extends Wallet {
     public FinalizingPSBTWallet(PSBT psbt) {
         super("Finalizing PSBT Wallet");
 
-        Map<PSBTInput, WalletNode> signingNodes = new LinkedHashMap<>();
+        if(!psbt.isSigned() || psbt.isFinalized()) {
+            throw new IllegalArgumentException("Only a fully signed, unfinalized PSBT can be used");
+        }
+
+        WalletNode purposeNode = getNode(KeyPurpose.RECEIVE);
+        List<WalletNode> signedNodes = new ArrayList<>(purposeNode.getChildren());
+
         for(int i = 0; i < psbt.getPsbtInputs().size(); i++) {
             PSBTInput psbtInput = psbt.getPsbtInputs().get(i);
             Set<ECKey> keys = psbtInput.getPartialSignatures().keySet();
-            WalletNode signedNode = new WalletNode("m/" + i);
+
+            WalletNode signedNode = signedNodes.get(i);
             signedInputNodes.put(psbtInput, signedNode);
             signedNodeKeys.put(signedNode, new ArrayList<>(keys));
-            numSignatures = keys.size();
+
-            setScriptType(ScriptType.getType(psbtInput.getUtxo().getScript()));
+            ScriptType scriptType = psbtInput.getScriptType();
+            if(scriptType == null || (getScriptType() != null && scriptType.equals(getScriptType()))) {
+                throw new IllegalArgumentException("Cannot determine a single script type from the PSBT");
+            } else {
+                setScriptType(scriptType);
+            }
+
+            try {
+                Script signingScript = psbtInput.getSigningScript();
+                int sigsRequired = signingScript.getNumRequiredSignatures();
+                if(numSignatures > 0 && sigsRequired != numSignatures) {
+                    throw new IllegalArgumentException("Different number of signatures required in PSBT inputs");
+                } else {
+                    numSignatures = sigsRequired;
+                }
+
+                if(ScriptType.MULTISIG.isScriptType(signingScript)) {
+                    signedNodeKeys.put(signedNode, Arrays.asList(ScriptType.MULTISIG.getPublicKeysFromScript(signingScript)));
+                }
+            } catch(NonStandardScriptException e) {
+                throw new IllegalArgumentException(e.getMessage());
+            }
         }
 
         setPolicyType(numSignatures == 1 ? PolicyType.SINGLE : PolicyType.MULTI);
@@ -73,4 +104,15 @@ public class FinalizingPSBTWallet extends Wallet {
     public List<ECKey> getPubKeys(WalletNode node) {
         return signedNodeKeys.get(node);
     }
+
+    @Override
+    public Script getOutputScript(WalletNode node) {
+        for(Map.Entry<PSBTInput, WalletNode> entry : signedInputNodes.entrySet()) {
+            if(node.equals(entry.getValue())) {
+                return entry.getKey().getUtxo().getScript();
+            }
+        }
+
+        return new Script(new byte[10]);
+    }
 }

src/main/java/com/sparrowwallet/drongo/wallet/Wallet.java

@@ -637,7 +637,10 @@ public class Wallet {
                 for(Map.Entry<PSBTInput, WalletNode> signingEntry : signingNodes.entrySet()) {
                     ECKey privKey = keystore.getKey(signingEntry.getValue());
                     PSBTInput psbtInput = signingEntry.getKey();
-                    psbtInput.sign(privKey);
+
+                    if(!psbtInput.isSigned()) {
+                        psbtInput.sign(privKey);
+                    }
                 }
             }
         }
@@ -680,8 +683,8 @@ public class Wallet {
                     finalizedTxInput = getScriptType().addSpendingInput(transaction, utxo, pubKey, transactionSignature);
                 } else if(getPolicyType().equals(PolicyType.MULTI)) {
                     List<ECKey> pubKeys = getPubKeys(signingNode);
-                    List<TransactionSignature> signatures = pubKeys.stream().map(psbtInput::getPartialSignature).collect(Collectors.toList());
+                    List<TransactionSignature> signatures = pubKeys.stream().map(psbtInput::getPartialSignature).filter(Objects::nonNull).collect(Collectors.toList());
-                    if(pubKeys.size() != signatures.size()) {
+                    if(signatures.size() < threshold) {
                         throw new IllegalArgumentException("Pubkeys of partial signatures do not match wallet pubkeys");
                     }