add multisig output descriptors

src/main/java/com/craigraw/drongo/ExtendedPublicKey.java

@@ -0,0 +1,185 @@
+package com.craigraw.drongo;
+
+import com.craigraw.drongo.crypto.*;
+import com.craigraw.drongo.protocol.Base58;
+
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+public class ExtendedPublicKey {
+    private static final int bip32HeaderP2PKHXPub = 0x0488B21E; //The 4 byte header that serializes in base58 to "xpub".
+    private static final int bip32HeaderP2PKHYPub = 0x049D7CB2; //The 4 byte header that serializes in base58 to "ypub".
+    private static final int bip32HeaderP2WPKHZPub = 0x04B24746; // The 4 byte header that serializes in base58 to "zpub"
+    private static final int bip32HeaderP2WHSHPub = 0x2AA7ED3; // The 4 byte header that serializes in base58 to "Zpub"
+
+    private int parentFingerprint;
+    private String keyDerivationPath;
+    private DeterministicKey pubKey;
+    private String childDerivationPath;
+    private ChildNumber pubKeyChildNumber;
+
+    private DeterministicHierarchy hierarchy;
+
+    public ExtendedPublicKey(int parentFingerprint, String keyDerivationPath, DeterministicKey pubKey, String childDerivationPath, ChildNumber pubKeyChildNumber) {
+        this.parentFingerprint = parentFingerprint;
+        this.keyDerivationPath = keyDerivationPath;
+        this.pubKey = pubKey;
+        this.childDerivationPath = childDerivationPath;
+        this.pubKeyChildNumber = pubKeyChildNumber;
+
+        this.hierarchy = new DeterministicHierarchy(pubKey);
+    }
+
+    public int getParentFingerprint() {
+        return parentFingerprint;
+    }
+
+    public List<ChildNumber> getKeyDerivation() {
+        return parsePath(keyDerivationPath);
+    }
+
+    public DeterministicKey getPubKey() {
+        return pubKey;
+    }
+
+    public List<ChildNumber> getChildDerivation() {
+        return getChildDerivation(0);
+    }
+
+    public List<ChildNumber> getChildDerivation(int wildCardReplacement) {
+        return getChildDerivation(getPubKey().getChildNumber(), childDerivationPath, wildCardReplacement);
+    }
+
+    public boolean describesMultipleAddresses() {
+        return childDerivationPath.endsWith("/*");
+    }
+
+    public List<ChildNumber> getReceivingDerivation(int wildCardReplacement) {
+        if(describesMultipleAddresses()) {
+            if(childDerivationPath.endsWith("0/*")) {
+                return getChildDerivation(getPubKey().getChildNumber(), childDerivationPath, wildCardReplacement);
+            }
+
+            if(pubKeyChildNumber.num() == 0 && childDerivationPath.endsWith("/*")) {
+                return getChildDerivation(new ChildNumber(0, getPubKey().getChildNumber().isHardened()), childDerivationPath, wildCardReplacement);
+            }
+        }
+
+        throw new IllegalStateException("Cannot derive receiving address from output descriptor " + this.toString());
+    }
+
+    public List<ChildNumber> getChangeDerivation(int wildCardReplacement) {
+        if(describesMultipleAddresses()) {
+            if(childDerivationPath.endsWith("0/*")) {
+                return getChildDerivation(getPubKey().getChildNumber(), childDerivationPath.replace("0/*", "1/*"), wildCardReplacement);
+            }
+
+            if(pubKeyChildNumber.num() == 1 && childDerivationPath.endsWith("/*")) {
+                return getChildDerivation(new ChildNumber(1, getPubKey().getChildNumber().isHardened()), childDerivationPath, wildCardReplacement);
+            }
+        }
+
+        throw new IllegalStateException("Cannot derive change address from output descriptor " + this.toString());
+    }
+
+    private List<ChildNumber> getChildDerivation(ChildNumber firstChild, String derivationPath, int wildCardReplacement) {
+        List<ChildNumber> path = new ArrayList<>();
+        path.add(firstChild);
+        path.addAll(parsePath(derivationPath, wildCardReplacement));
+
+        return path;
+    }
+
+    public DeterministicKey getKey(List<ChildNumber> path) {
+        return hierarchy.get(path);
+    }
+
+    public static List<ChildNumber> parsePath(String path) {
+        return parsePath(path, 0);
+    }
+
+    public static List<ChildNumber> parsePath(String path, int wildcardReplacement) {
+        String[] parsedNodes = path.replace("M", "").split("/");
+        List<ChildNumber> nodes = new ArrayList<>();
+
+        for (String n : parsedNodes) {
+            n = n.replaceAll(" ", "");
+            if (n.length() == 0) continue;
+            boolean isHard = n.endsWith("H") || n.endsWith("h") || n.endsWith("'");
+            if (isHard) n = n.substring(0, n.length() - 1);
+            if (n.equals("*")) n = Integer.toString(wildcardReplacement);
+            int nodeNumber = Integer.parseInt(n);
+            nodes.add(new ChildNumber(nodeNumber, isHard));
+        }
+
+        return nodes;
+    }
+
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        builder.append(getExtendedPublicKey());
+        builder.append(childDerivationPath);
+        return builder.toString();
+    }
+
+    public String getExtendedPublicKey() {
+        return Base58.encodeChecked(getExtendedPublicKeyBytes());
+    }
+
+    public byte[] getExtendedPublicKeyBytes() {
+        ByteBuffer buffer = ByteBuffer.allocate(78);
+        buffer.putInt(bip32HeaderP2PKHXPub);
+
+        List<ChildNumber> childPath = parsePath(childDerivationPath);
+        int depth = 5 - childPath.size();
+        buffer.put((byte)depth);
+
+        buffer.putInt(parentFingerprint);
+
+        buffer.putInt(pubKeyChildNumber.i());
+
+        buffer.put(pubKey.getChainCode());
+        buffer.put(pubKey.getPubKey());
+
+        return buffer.array();
+    }
+
+    static ExtendedPublicKey fromDescriptor(String keyDerivationPath, String extPubKey, String childDerivationPath) {
+        byte[] serializedKey = Base58.decodeChecked(extPubKey);
+        ByteBuffer buffer = ByteBuffer.wrap(serializedKey);
+        int header = buffer.getInt();
+        if(!(header == bip32HeaderP2PKHXPub || header == bip32HeaderP2PKHYPub || header == bip32HeaderP2WPKHZPub || header == bip32HeaderP2WHSHPub)) {
+            throw new IllegalArgumentException("Unknown header bytes: " + DeterministicKey.toBase58(serializedKey).substring(0, 4));
+        }
+
+        int depth = buffer.get() & 0xFF; // convert signed byte to positive int since depth cannot be negative
+        final int parentFingerprint = buffer.getInt();
+        final int i = buffer.getInt();
+        ChildNumber childNumber;
+        List<ChildNumber> path;
+
+        if(depth == 0) {
+            //Poorly formatted extended public key, add first child path element
+            childNumber = new ChildNumber(0, false);
+        } else if ((i & ChildNumber.HARDENED_BIT) != 0) {
+            childNumber = new ChildNumber(i ^ ChildNumber.HARDENED_BIT, true); //already hardened
+        } else {
+            childNumber = new ChildNumber(i, false);
+        }
+        path = Collections.unmodifiableList(new ArrayList<>(Arrays.asList(childNumber)));
+
+        byte[] chainCode = new byte[32];
+        buffer.get(chainCode);
+        byte[] data = new byte[33];
+        buffer.get(data);
+        if(buffer.hasRemaining()) {
+            throw new IllegalArgumentException("Found unexpected data in key");
+        }
+
+        DeterministicKey pubKey = new DeterministicKey(path, chainCode, new LazyECPoint(ECKey.CURVE.getCurve(), data), depth, parentFingerprint);
+        return new ExtendedPublicKey(parentFingerprint, keyDerivationPath, pubKey, childDerivationPath, childNumber);
+    }
+}

src/main/java/com/craigraw/drongo/OutputDescriptor.java

@@ -1,115 +1,116 @@
 package com.craigraw.drongo;
 
-import com.craigraw.drongo.address.Address;
+import com.craigraw.drongo.address.*;
-import com.craigraw.drongo.address.P2PKHAddress;
-import com.craigraw.drongo.address.P2SHAddress;
-import com.craigraw.drongo.address.P2WPKHAddress;
 import com.craigraw.drongo.crypto.ChildNumber;
 import com.craigraw.drongo.crypto.DeterministicKey;
-import com.craigraw.drongo.crypto.ECKey;
-import com.craigraw.drongo.crypto.LazyECPoint;
-import com.craigraw.drongo.protocol.Base58;
 import com.craigraw.drongo.protocol.Script;
-import org.slf4j.Logger;
+import com.craigraw.drongo.protocol.ScriptChunk;
-import org.slf4j.LoggerFactory;
+import com.craigraw.drongo.protocol.ScriptOpCodes;
 
-import java.nio.ByteBuffer;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.StringJoiner;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 public class OutputDescriptor {
-    private static final Logger log = LoggerFactory.getLogger(OutputDescriptor.class);
+    private static final Pattern XPUB_PATTERN = Pattern.compile("(\\[[^\\]]+\\])?(.pub[^/\\)]+)(/[/\\d*']+)?");
-
+    private static final Pattern MULTI_PATTERN = Pattern.compile("multi\\(([\\d+])");
-    private static final int bip32HeaderP2PKHXPub = 0x0488B21E; //The 4 byte header that serializes in base58 to "xpub".
-    private static final int bip32HeaderP2PKHYPub = 0x049D7CB2; //The 4 byte header that serializes in base58 to "ypub".
-    private static final int bip32HeaderP2WPKHZPub = 0x04B24746; // The 4 byte header that serializes in base58 to "zpub"
-
-    private static final Pattern DESCRIPTOR_PATTERN = Pattern.compile("(.+)\\((\\[[^\\]]+\\])?(xpub[^/\\)]+)(/[/\\d*']+)?\\)\\)?");
 
     private String script;
-    private int parentFingerprint;
+    private int multisigThreshold;
-    private String keyDerivationPath;
+    private List<ExtendedPublicKey> extendedPublicKeys;
-    private DeterministicKey pubKey;
-    private String childDerivationPath;
-    private ChildNumber pubKeyChildNumber;
 
-    public OutputDescriptor(String script, int parentFingerprint, String keyDerivationPath, DeterministicKey pubKey, String childDerivationPath, ChildNumber pubKeyChildNumber) {
+    public OutputDescriptor(String script, ExtendedPublicKey extendedPublicKey) {
+        this(script, Collections.singletonList(extendedPublicKey));
+    }
+
+    public OutputDescriptor(String script, List<ExtendedPublicKey> extendedPublicKeys) {
+        this(script, 0, extendedPublicKeys);
+    }
+
+    public OutputDescriptor(String script, int multisigThreshold, List<ExtendedPublicKey> extendedPublicKeys) {
         this.script = script;
-        this.parentFingerprint = parentFingerprint;
+        this.multisigThreshold = multisigThreshold;
-        this.keyDerivationPath = keyDerivationPath;
+        this.extendedPublicKeys = extendedPublicKeys;
-        this.pubKey = pubKey;
+    }
-        this.childDerivationPath = childDerivationPath;
+
-        this.pubKeyChildNumber = pubKeyChildNumber;
+    public List<ExtendedPublicKey> getExtendedPublicKeys() {
+        return extendedPublicKeys;
+    }
+
+    public boolean isMultisig() {
+        return extendedPublicKeys.size() > 1;
+    }
+
+    public ExtendedPublicKey getSingletonExtendedPublicKey() {
+        if(isMultisig()) {
+            throw new IllegalStateException("Output descriptor contains multiple public keys but singleton requested");
+        }
+
+        return extendedPublicKeys.get(0);
     }
 
     public String getScript() {
         return script;
     }
 
-    public int getParentFingerprint() {
+    public boolean describesMultipleAddresses() {
-        return parentFingerprint;
+        for(ExtendedPublicKey pubKey : extendedPublicKeys) {
+            if(!pubKey.describesMultipleAddresses()) {
+                return false;
+            }
         }
 
-    public List<ChildNumber> getKeyDerivation() {
+        return true;
-        return parsePath(keyDerivationPath);
-    }
-
-    public DeterministicKey getPubKey() {
-        return pubKey;
     }
 
     public List<ChildNumber> getChildDerivation() {
-        return getChildDerivation(0);
+        List<ChildNumber> lastDerivation = null;
+        for(ExtendedPublicKey pubKey : extendedPublicKeys) {
+            List<ChildNumber> derivation = pubKey.getChildDerivation();
+            if(lastDerivation != null && !lastDerivation.subList(1, lastDerivation.size()).equals(derivation.subList(1, derivation.size()))) {
+                throw new IllegalStateException("Cannot determine multisig derivation: constituent derivations do not match");
+            }
+            lastDerivation = derivation;
         }
 
-    public List<ChildNumber> getChildDerivation(int wildCardReplacement) {
+        return lastDerivation;
-        return getChildDerivation(new ChildNumber(0, getPubKey().getChildNumber().isHardened()), childDerivationPath, wildCardReplacement);
-    }
-
-    public boolean describesMultipleAddresses() {
-        return childDerivationPath.endsWith("/*");
     }
 
     public List<ChildNumber> getReceivingDerivation(int wildCardReplacement) {
-        if(describesMultipleAddresses()) {
+        if(isMultisig()) {
-            if(childDerivationPath.endsWith("0/*")) {
+            List<ChildNumber> path = new ArrayList<>();
-                return getChildDerivation(new ChildNumber(0, getPubKey().getChildNumber().isHardened()), childDerivationPath, wildCardReplacement);
+            path.add(new ChildNumber(0));
+            path.add(new ChildNumber(wildCardReplacement));
+            return path;
         }
 
-            if(pubKeyChildNumber.num() == 0 && childDerivationPath.endsWith("/*")) {
+        return getSingletonExtendedPublicKey().getReceivingDerivation(wildCardReplacement);
-                return getChildDerivation(new ChildNumber(0, getPubKey().getChildNumber().isHardened()), childDerivationPath, wildCardReplacement);
-            }
-        }
-
-        throw new IllegalStateException("Cannot derive receiving address from output descriptor " + this.toString());
     }
 
     public List<ChildNumber> getChangeDerivation(int wildCardReplacement) {
-        if(describesMultipleAddresses()) {
+        if(isMultisig()) {
-            if(childDerivationPath.endsWith("0/*")) {
-                return getChildDerivation(new ChildNumber(0, getPubKey().getChildNumber().isHardened()), childDerivationPath.replace("0/*", "1/*"), wildCardReplacement);
-            }
-
-            if(pubKeyChildNumber.num() == 1 && childDerivationPath.endsWith("/*")) {
-                return getChildDerivation(new ChildNumber(1, getPubKey().getChildNumber().isHardened()), childDerivationPath, wildCardReplacement);
-            }
-        }
-
-        throw new IllegalStateException("Cannot derive change address from output descriptor " + this.toString());
-    }
-
-    private List<ChildNumber> getChildDerivation(ChildNumber firstChild, String derivationPath, int wildCardReplacement) {
             List<ChildNumber> path = new ArrayList<>();
-        path.add(firstChild);
+            path.add(new ChildNumber(1));
-        path.addAll(parsePath(derivationPath, wildCardReplacement));
+            path.add(new ChildNumber(wildCardReplacement));
-
             return path;
         }
 
+        return getSingletonExtendedPublicKey().getChangeDerivation(wildCardReplacement);
+    }
+
+    public Address getAddress(List<ChildNumber> path) {
+        if(isMultisig()) {
+            Script script = getMultisigScript(path);
+            return getAddress(script);
+        }
+
+        DeterministicKey childKey = getSingletonExtendedPublicKey().getKey(path);
+        return getAddress(childKey);
+    }
+
     public Address getAddress(DeterministicKey childKey) {
         Address address = null;
         if(script.equals("pkh")) {
@@ -127,105 +128,110 @@ public class OutputDescriptor {
         return address;
     }
 
+    private Address getAddress(Script multisigScript) {
+        Address address = null;
+        if(script.equals("sh(multi")) {
+            address = P2SHAddress.fromProgram(multisigScript.getProgram());
+        } else if(script.equals("wsh(multi")) {
+            address = P2WSHAddress.fromProgram(multisigScript.getProgram());
+        } else {
+            throw new IllegalStateException("Cannot determine address for multisig script " + script);
+        }
+
+        return address;
+    }
+
+    private Script getMultisigScript(List<ChildNumber> path) {
+        List<ScriptChunk> chunks = new ArrayList<>();
+        chunks.add(new ScriptChunk(Script.encodeToOpN(multisigThreshold), null));
+
+        for(ExtendedPublicKey pubKey : extendedPublicKeys) {
+            List<ChildNumber> keyPath = null;
+            if(path.get(0).num() == 0) {
+                keyPath = pubKey.getReceivingDerivation(path.get(1).num());
+            } else if(path.get(0).num() == 1) {
+                keyPath = pubKey.getChangeDerivation(path.get(1).num());
+            } else {
+                keyPath = pubKey.getChildDerivation(path.get(1).num());
+            }
+
+            byte[] pubKeyBytes = pubKey.getKey(keyPath).getPubKey();
+            chunks.add(new ScriptChunk(pubKeyBytes.length, pubKeyBytes));
+        }
+
+        chunks.add(new ScriptChunk(Script.encodeToOpN(extendedPublicKeys.size()), null));
+        chunks.add(new ScriptChunk(ScriptOpCodes.OP_CHECKMULTISIG, null));
+
+        return new Script(chunks);
+    }
+
     // See https://github.com/bitcoin/bitcoin/blob/master/doc/descriptors.md
     public static OutputDescriptor getOutputDescriptor(String descriptor) {
-        String script;
+        if(descriptor.startsWith("pkh") || descriptor.startsWith("xpub")) {
+            return new OutputDescriptor("pkh", getExtendedPublicKeys(descriptor));
+        } else if(descriptor.startsWith("wpkh") || descriptor.startsWith("zpub")) {
+            return new OutputDescriptor("wpkh", getExtendedPublicKeys(descriptor));
+        } else if(descriptor.startsWith("sh(wpkh") || descriptor.startsWith("ypub")) {
+            return new OutputDescriptor("sh(wpkh", getExtendedPublicKeys(descriptor));
+        } else if(descriptor.startsWith("sh(multi") || descriptor.startsWith("Ypub")) {
+            return new OutputDescriptor("sh(multi", getMultsigThreshold(descriptor), getExtendedPublicKeys(descriptor));
+        } else if(descriptor.startsWith("wsh(multi") || descriptor.startsWith("Zpub")) {
+            return new OutputDescriptor("wsh(multi", getMultsigThreshold(descriptor), getExtendedPublicKeys(descriptor));
+        } else {
+            throw new IllegalArgumentException("Could not parse output descriptor:" + descriptor);
+        }
+    }
+
+    private static int getMultsigThreshold(String descriptor) {
+        Matcher matcher = MULTI_PATTERN.matcher(descriptor);
+        if(matcher.find()) {
+            String threshold = matcher.group(1);
+            return Integer.parseInt(threshold);
+        } else {
+            throw new IllegalArgumentException("Could not find multisig threshold in output descriptor:" + descriptor);
+        }
+    }
+
+    private static List<ExtendedPublicKey> getExtendedPublicKeys(String descriptor) {
+        List<ExtendedPublicKey> keys = new ArrayList<>();
+        Matcher matcher = XPUB_PATTERN.matcher(descriptor);
+        while(matcher.find()) {
             String keyDerivationPath ="";
             String extPubKey = null;
             String childDerivationPath = "/0/*";
 
-        Matcher matcher = DESCRIPTOR_PATTERN.matcher(descriptor);
+            if(matcher.group(1) != null) {
-        if(matcher.matches()) {
+                keyDerivationPath = matcher.group(1);
-            script = matcher.group(1);
-            if(matcher.group(2) != null) {
-                keyDerivationPath = matcher.group(2);
             }
 
-            extPubKey = matcher.group(3);
+            extPubKey = matcher.group(2);
-            if(matcher.group(4) != null) {
+            if(matcher.group(3) != null) {
-                childDerivationPath = matcher.group(4);
+                childDerivationPath = matcher.group(3);
-            }
-        } else if (descriptor.startsWith("xpub")) {
-            extPubKey = descriptor;
-            script = "pkh";
-        } else if(descriptor.startsWith("ypub")) {
-            extPubKey = descriptor;
-            script = "sh(wpkh";
-        } else if(descriptor.startsWith("zpub")) {
-            extPubKey = descriptor;
-            script = "wpkh";
-        } else {
-            throw new IllegalArgumentException("Could not parse output descriptor:" + descriptor);
             }
 
-        byte[] serializedKey = Base58.decodeChecked(extPubKey);
+            ExtendedPublicKey extendedPublicKey = ExtendedPublicKey.fromDescriptor(keyDerivationPath, extPubKey, childDerivationPath);
-        ByteBuffer buffer = ByteBuffer.wrap(serializedKey);
+            keys.add(extendedPublicKey);
-        int header = buffer.getInt();
-        if(!(header == bip32HeaderP2PKHXPub || header == bip32HeaderP2PKHYPub || header == bip32HeaderP2WPKHZPub)) {
-            throw new IllegalArgumentException("Unknown header bytes: " + DeterministicKey.toBase58(serializedKey).substring(0, 4));
         }
 
-        int depth = buffer.get() & 0xFF; // convert signed byte to positive int since depth cannot be negative
+        return keys;
-        final int parentFingerprint = buffer.getInt();
-        final int i = buffer.getInt();
-        ChildNumber childNumber;
-        List<ChildNumber> path;
-
-        if(depth == 0) {
-            //Poorly formatted extended public key, add first child path element
-            childNumber = new ChildNumber(0, false);
-        } else if ((i & ChildNumber.HARDENED_BIT) != 0) {
-            childNumber = new ChildNumber(i ^ ChildNumber.HARDENED_BIT, true); //already hardened
-        } else {
-            childNumber = new ChildNumber(i, false);
-        }
-        path = Collections.unmodifiableList(new ArrayList<>(Arrays.asList(childNumber)));
-
-        //Remove account level for depth 4 keys
-        if(depth == 4 && (descriptor.startsWith("xpub") || descriptor.startsWith("ypub") || descriptor.startsWith("zpub"))) {
-            log.warn("Output descriptor describes a public key derived at depth 4; change addresses not available");
-            childDerivationPath = "/*";
-        }
-
-        byte[] chainCode = new byte[32];
-        buffer.get(chainCode);
-        byte[] data = new byte[33];
-        buffer.get(data);
-        if(buffer.hasRemaining()) {
-            throw new IllegalArgumentException("Found unexpected data in key");
-        }
-
-        DeterministicKey pubKey = new DeterministicKey(path, chainCode, new LazyECPoint(ECKey.CURVE.getCurve(), data), depth, parentFingerprint);
-        return new OutputDescriptor(script, parentFingerprint, keyDerivationPath, pubKey, childDerivationPath, childNumber);
-    }
-
-    public static List<ChildNumber> parsePath(String path) {
-        return parsePath(path, 0);
-    }
-
-    public static List<ChildNumber> parsePath(String path, int wildcardReplacement) {
-        String[] parsedNodes = path.replace("M", "").split("/");
-        List<ChildNumber> nodes = new ArrayList<>();
-
-        for (String n : parsedNodes) {
-            n = n.replaceAll(" ", "");
-            if (n.length() == 0) continue;
-            boolean isHard = n.endsWith("H") || n.endsWith("h") || n.endsWith("'");
-            if (isHard) n = n.substring(0, n.length() - 1);
-            if (n.equals("*")) n = Integer.toString(wildcardReplacement);
-            int nodeNumber = Integer.parseInt(n);
-            nodes.add(new ChildNumber(nodeNumber, isHard));
-        }
-
-        return nodes;
     }
 
     public String toString() {
         StringBuilder builder = new StringBuilder();
         builder.append(script);
         builder.append("(");
-        builder.append(getExtendedPublicKey());
+
-        builder.append(childDerivationPath);
+        if(isMultisig()) {
+            StringJoiner joiner = new StringJoiner(",");
+            joiner.add(Integer.toString(multisigThreshold));
+            for(ExtendedPublicKey pubKey : extendedPublicKeys) {
+                joiner.add(pubKey.toString());
+            }
+            builder.append(joiner.toString());
+        } else {
+            builder.append(getSingletonExtendedPublicKey());
+        }
+
         builder.append(")");
 
         if(script.contains("(")){
@@ -234,26 +240,4 @@ public class OutputDescriptor {
 
         return builder.toString();
     }
-
-    public String getExtendedPublicKey() {
-        return Base58.encodeChecked(getExtendedPublicKeyBytes());
-    }
-
-    public byte[] getExtendedPublicKeyBytes() {
-        ByteBuffer buffer = ByteBuffer.allocate(78);
-        buffer.putInt(bip32HeaderP2PKHXPub);
-
-        List<ChildNumber> childPath = parsePath(childDerivationPath);
-        int depth = 5 - childPath.size();
-        buffer.put((byte)depth);
-
-        buffer.putInt(parentFingerprint);
-
-        buffer.putInt(pubKeyChildNumber.i());
-
-        buffer.put(pubKey.getChainCode());
-        buffer.put(pubKey.getPubKey());
-
-        return buffer.array();
-    }
 }

src/main/java/com/craigraw/drongo/WatchWallet.java

@@ -11,32 +11,30 @@ public class WatchWallet {
 
     private String name;
     private OutputDescriptor outputDescriptor;
-    private DeterministicHierarchy hierarchy;
 
     private HashMap<Address,List<ChildNumber>> addresses = new HashMap<>(LOOK_AHEAD_LIMIT*2);
 
     public WatchWallet(String name, String descriptor) {
         this.name = name;
         this.outputDescriptor = OutputDescriptor.getOutputDescriptor(descriptor);
-        this.hierarchy = new DeterministicHierarchy(outputDescriptor.getPubKey());
     }
 
     public void initialiseAddresses() {
         if(outputDescriptor.describesMultipleAddresses()) {
             for(int index = 0; index <= LOOK_AHEAD_LIMIT; index++) {
                 List<ChildNumber> receivingDerivation = outputDescriptor.getReceivingDerivation(index);
-                Address address = getAddress(receivingDerivation);
+                Address address = getReceivingAddress(index);
                 addresses.put(address, receivingDerivation);
             }
 
             for(int index = 0; index <= LOOK_AHEAD_LIMIT; index++) {
                 List<ChildNumber> changeDerivation = outputDescriptor.getChangeDerivation(index);
-                Address address = getAddress(changeDerivation);
+                Address address = getChangeAddress(index);
                 addresses.put(address, changeDerivation);
             }
         } else {
             List<ChildNumber> derivation = outputDescriptor.getChildDerivation();
-            Address address = getAddress(derivation);
+            Address address = outputDescriptor.getAddress(derivation);
             addresses.put(address, derivation);
         }
     }
@@ -61,8 +59,11 @@ public class WatchWallet {
         return getAddress(outputDescriptor.getChangeDerivation(index));
     }
 
-    private Address getAddress(List<ChildNumber> path) {
+    public OutputDescriptor getOutputDescriptor() {
-        DeterministicKey childKey = hierarchy.get(path);
+        return outputDescriptor;
-        return outputDescriptor.getAddress(childKey);
+    }
+
+    public Address getAddress(List<ChildNumber> path) {
+        return outputDescriptor.getAddress(path);
     }
 }

src/main/java/com/craigraw/drongo/address/P2WSHAddress.java

@@ -0,0 +1,34 @@
+package com.craigraw.drongo.address;
+
+import com.craigraw.drongo.protocol.*;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static com.craigraw.drongo.address.P2WPKHAddress.HRP;
+
+public class P2WSHAddress extends Address {
+    public P2WSHAddress(byte[] pubKeyHash) {
+        super(pubKeyHash);
+    }
+
+    public int getVersion() {
+        return 0;
+    }
+
+    public String getAddress() {
+        return Bech32.encode(HRP, getVersion(), pubKeyHash);
+    }
+
+    public Script getOutputScript() {
+        List<ScriptChunk> chunks = new ArrayList<>();
+        chunks.add(new ScriptChunk(Script.encodeToOpN(getVersion()), null));
+        chunks.add(new ScriptChunk(pubKeyHash.length, pubKeyHash));
+
+        return new Script(chunks);
+    }
+
+    public static P2WSHAddress fromProgram(byte[] program) {
+        return new P2WSHAddress(Sha256Hash.hash(program));
+    }
+}

src/test/java/com/craigraw/drongo/OutputDescriptorTest.java

@@ -13,7 +13,7 @@ public class OutputDescriptorTest {
 
     @Test
     public void iancolemanP2PKH() {
-        OutputDescriptor descriptor = OutputDescriptor.getOutputDescriptor("xpub6EEznxrqoN5HUXfD3QC3B8Vjw8Lj9UnRj17uTzNaBnEYN5xgwe6Un46Z443sSTBP2bzLZuDzygkdD1FtVWSexFmg4yAuCTxE2HxXFtz541z");
+        OutputDescriptor descriptor = OutputDescriptor.getOutputDescriptor("xpub6EEznxrqoN5HUXfD3QC3B8Vjw8Lj9UnRj17uTzNaBnEYN5xgwe6Un46Z443sSTBP2bzLZuDzygkdD1FtVWSexFmg4yAuCTxE2HxXFtz541z/*");
         Assert.assertEquals("pkh(xpub6EEznxrqoN5HUXfD3QC3B8Vjw8Lj9UnRj17uTzNaBnEYN5xgwe6Un46Z443sSTBP2bzLZuDzygkdD1FtVWSexFmg4yAuCTxE2HxXFtz541z/*)", descriptor.toString());
     }
 
@@ -25,7 +25,7 @@ public class OutputDescriptorTest {
 
     @Test
     public void iancolemanP2SHP2WPKH() {
-        OutputDescriptor descriptor = OutputDescriptor.getOutputDescriptor("ypub6Zken22QbjfomRUXki5v4ndP6T1DEtaBhGGZBvR4ocoooM44dFmnF8DyFmvcK76TKnuvdFfaPnicVvTAPdqEcbuEfKEqfnRoUjSkTB4u1os");
+        OutputDescriptor descriptor = OutputDescriptor.getOutputDescriptor("ypub6Zken22QbjfomRUXki5v4ndP6T1DEtaBhGGZBvR4ocoooM44dFmnF8DyFmvcK76TKnuvdFfaPnicVvTAPdqEcbuEfKEqfnRoUjSkTB4u1os/*");
         Assert.assertEquals("sh(wpkh(xpub6EvPUMMVT48Kv8HQvMJHrhXsvUrmJGagn9kLQXXBRcRvkFEqNbcDd4ZqEZy2KCSXv9o7sn51w8N4cdqbfwRDpNDdnyYR5scKD1P74ZAKbGm/*))", descriptor.toString());
     }
 

src/test/java/com/craigraw/drongo/WatchWalletTest.java

@@ -16,7 +16,7 @@ public class WatchWalletTest {
 
     @Test
     public void iancolemanP2PKH() {
-        WatchWallet wallet = new WatchWallet("", "xpub6EEznxrqoN5HUXfD3QC3B8Vjw8Lj9UnRj17uTzNaBnEYN5xgwe6Un46Z443sSTBP2bzLZuDzygkdD1FtVWSexFmg4yAuCTxE2HxXFtz541z");
+        WatchWallet wallet = new WatchWallet("", "xpub6EEznxrqoN5HUXfD3QC3B8Vjw8Lj9UnRj17uTzNaBnEYN5xgwe6Un46Z443sSTBP2bzLZuDzygkdD1FtVWSexFmg4yAuCTxE2HxXFtz541z/*");
 
         Assert.assertEquals("179cMrkiyx6zD2E1sqBAQLg1SQPAS5vjQW", wallet.getReceivingAddress(0).toString());
         Assert.assertEquals("1GdWCzdt5oDYh5n1qeZQCxg5rQKVTuTMJg", wallet.getReceivingAddress(1).toString());
@@ -33,7 +33,7 @@ public class WatchWalletTest {
 
     @Test
     public void iancolemanP2SHP2WPKH() {
-        WatchWallet wallet = new WatchWallet("", "ypub6Zken22QbjfomRUXki5v4ndP6T1DEtaBhGGZBvR4ocoooM44dFmnF8DyFmvcK76TKnuvdFfaPnicVvTAPdqEcbuEfKEqfnRoUjSkTB4u1os");
+        WatchWallet wallet = new WatchWallet("", "ypub6Zken22QbjfomRUXki5v4ndP6T1DEtaBhGGZBvR4ocoooM44dFmnF8DyFmvcK76TKnuvdFfaPnicVvTAPdqEcbuEfKEqfnRoUjSkTB4u1os/*");
 
         Assert.assertEquals("34SgiHwNwJt3nYCVUQcgJWhefVRBZ4aSHf", wallet.getReceivingAddress(0).toString());
         Assert.assertEquals("3MgPnbF6UYM3FBhZWXoL2ebLPEa3zCCXLh", wallet.getReceivingAddress(1).toString());
@@ -55,4 +55,26 @@ public class WatchWalletTest {
         Assert.assertEquals("34TBBnwqv338BT6BVnTKqziFq8HWY6BNbw", wallet.getReceivingAddress(0).toString());
         Assert.assertEquals("35Jhf9LGCpb1ihJjWH7uLZ8othr1diuspS", wallet.getChangeAddress(0).toString());
     }
+
+    @Test
+    public void electrumP2WSHMulti() {
+        WatchWallet wallet = new WatchWallet("", "wsh(multi(2,xpub699B7APGMoPLUrvPsXiBFrJRV8sTHDBHptpHSH36aESP5SLYs4VcEotnX1EvvA5ZoKF2rZ24Wh4U5ALxM21CfL5Kcj6Tu41PjRr2KKMkJTJ/0/*,xpub6Ds1jx5qxAtdczVBnJfHeGgpspzYuxnXHXLCoPZFFyyMoKJ7zzLgcERB1t7eDV1UuBQL1UKNxHFvcMJ7Zj6D2amdaA8gb21cZSXPrpG1bZr/0/*))");
+
+        Assert.assertEquals("bc1q2jxsrw70ug8jgskmhynvs49h3q5h8fglkdl3trvrc6wsde07wuzqfz98z0", wallet.getReceivingAddress(0).toString());
+        Assert.assertEquals("bc1qzw9j02k6l7z598edcgjh5mks507xevhk34rmnerxv45ptsluf0pqyxmyve", wallet.getChangeAddress(0).toString());
+    }
+
+    @Test
+    public void electrumP2WSHMulti2() {
+        WatchWallet wallet = new WatchWallet("", "wsh(multi(2,Zpub6yhnqjTYE82fc2U1UukQW6qEYsCcNoqsyPWPvL6Qi22YopXv8nD1a44zN87aUQcJr4YdE6DJKEA4xuBr5dzBQHZCBsbiUH7NAcFBgPyx3LB/0/*,Zpub74eXjdXzGCRsixpRAZT3U8ssQ15uhUa1dCFdRJvY3L2qo18He71qWUfpxfbL9e2EYuWKe1tH7qzgUSRVTAektLDVRKwCbAtyRW5j2yhqLiD/0/*))");
+
+        Assert.assertEquals("bc1qa842ug2njv36ycnhq8wjcg6wxjv7p7h4v0tnl40u6nfxxxffyjnq409pr9", wallet.getReceivingAddress(0).toString());
+        Assert.assertEquals("bc1q3auk6c8f77dda0w8y9dz4yd3wqhkf4eufzk8x2quszvzzcyjk6rqgz70pd", wallet.getChangeAddress(0).toString());
+    }
+
+    @Test
+    public void electrumP2WSHMultiSingle() {
+        WatchWallet wallet = new WatchWallet("", "wsh(multi(2,xpub699B7APGMoPLUrvPsXiBFrJRV8sTHDBHptpHSH36aESP5SLYs4VcEotnX1EvvA5ZoKF2rZ24Wh4U5ALxM21CfL5Kcj6Tu41PjRr2KKMkJTJ/0/0,xpub6Ds1jx5qxAtdczVBnJfHeGgpspzYuxnXHXLCoPZFFyyMoKJ7zzLgcERB1t7eDV1UuBQL1UKNxHFvcMJ7Zj6D2amdaA8gb21cZSXPrpG1bZr/0/0))");
+        Assert.assertEquals("bc1q2jxsrw70ug8jgskmhynvs49h3q5h8fglkdl3trvrc6wsde07wuzqfz98z0", wallet.getAddress(wallet.getOutputDescriptor().getChildDerivation()).toString());
+    }
 }