From 22f0600afe4a10da8b52c82269842b4187fd4363 Mon Sep 17 00:00:00 2001
From: Devrandom <c1.devrandom@niftybox.net>
Date: Sat, 20 Sep 2014 10:27:51 -0700
Subject: [PATCH] Refactor married keychains

* move handling of following keychains into the leading keychain
* move multisig threshold into the leading keychain
* extract MarriedKeyChain from DeterministicKeyChain
---
 .../main/java/org/bitcoinj/core/ECKey.java    |  14 +
 .../main/java/org/bitcoinj/core/Wallet.java   |  56 +--
 .../org/bitcoinj/crypto/DeterministicKey.java |  18 +
 .../store/WalletProtobufSerializer.java       |   8 +-
 .../wallet/DeterministicKeyChain.java         | 284 +++++++++++--
 .../org/bitcoinj/wallet/KeyChainGroup.java    | 324 +++-----------
 .../org/bitcoinj/wallet/MarriedKeyChain.java  | 286 +++++++++++++
 .../main/java/org/bitcoinj/wallet/Protos.java | 396 +++++++++---------
 .../java/org/bitcoinj/core/WalletTest.java    |  12 +-
 .../store/WalletProtobufSerializerTest.java   |  14 +-
 .../bitcoinj/wallet/KeyChainGroupTest.java    |  49 +--
 .../deterministic-wallet-serialization.txt    |   2 +
 .../wallet/watching-wallet-serialization.txt  |   2 +
 core/src/wallet.proto                         |  10 +-
 .../java/org/bitcoinj/tools/WalletTool.java   |   9 +-
 15 files changed, 890 insertions(+), 594 deletions(-)
 create mode 100644 core/src/main/java/org/bitcoinj/wallet/MarriedKeyChain.java

diff --git a/core/src/main/java/org/bitcoinj/core/ECKey.java b/core/src/main/java/org/bitcoinj/core/ECKey.java
index 2df6e7ab..e096529b 100644
--- a/core/src/main/java/org/bitcoinj/core/ECKey.java
+++ b/core/src/main/java/org/bitcoinj/core/ECKey.java
@@ -1134,4 +1134,18 @@ public class ECKey implements EncryptableItem, Serializable {
         helper.add("isEncrypted", isEncrypted());
         return helper.toString();
     }
+
+    public void formatKeyWithAddress(boolean includePrivateKeys, StringBuilder builder, NetworkParameters params) {
+        final Address address = toAddress(params);
+        builder.append("  addr:");
+        builder.append(address.toString());
+        builder.append("  hash160:");
+        builder.append(Utils.HEX.encode(getPubKeyHash()));
+        builder.append("\n");
+        if (includePrivateKeys) {
+            builder.append("  ");
+            builder.append(toStringWithPrivate());
+            builder.append("\n");
+        }
+    }
 }
diff --git a/core/src/main/java/org/bitcoinj/core/Wallet.java b/core/src/main/java/org/bitcoinj/core/Wallet.java
index c27c0e2d..581eb3a4 100644
--- a/core/src/main/java/org/bitcoinj/core/Wallet.java
+++ b/core/src/main/java/org/bitcoinj/core/Wallet.java
@@ -293,18 +293,10 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
     }
 
     /**
-     * Returns the number of signatures required to spend from this wallet. For a normal non-married wallet this will
-     * always be 1. For a married wallet this will be the N from N-of-M CHECKMULTISIG scripts used in this wallet.
-     * This value is either directly specified during the marriage (see {@link #addFollowingAccountKeys(java.util.List, int)})
-     * or, if not specified, calculated implicitly as a simple majority of keys.
+     * Gets the active keychain via {@link KeyChainGroup#getActiveKeyChain()}
      */
-    public int getSigsRequiredToSpend() {
-        lock.lock();
-        try {
-            return keychain.getSigsRequiredToSpend();
-        } finally {
-            lock.unlock();
-        }
+    public DeterministicKeyChain getActiveKeychain() {
+        return keychain.getActiveKeyChain();
     }
 
     /**
@@ -629,38 +621,18 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
     }
 
     /**
-     * <p>Alias for <code>addFollowingAccountKeys(followingAccountKeys, (followingAccountKeys.size() + 1) / 2 + 1)</code></p>
-     * <p>Creates married wallet requiring majority of keys to spend (2-of-3, 3-of-5 and so on)</p>
-     * <p>IMPORTANT: As of Bitcoin Core 0.9 all multisig transactions which require more than 3 public keys are
-     * non-standard and such spends won't be processed by peers with default settings, essentially making such
-     * transactions almost nonspendable</p>
+     * Add a pre-configured keychain to the wallet.  Useful for setting up a complex keychain,
+     * such as for a married wallet.  For example:
+     * <pre>
+     * MarriedKeyChain chain = MarriedKeyChain.builder()
+     *     .random(new SecureRandom())
+     *     .followingKeys(followingKeys)
+     *     .threshold(2).build();
+     * wallet.addAndActivateHDChain(chain);
+     * </p>
      */
-    public void addFollowingAccountKeys(List<DeterministicKey> followingAccountKeys) {
-        lock.lock();
-        try {
-            keychain.addFollowingAccountKeys(followingAccountKeys);
-        } finally {
-            lock.unlock();
-        }
-    }
-
-    /**
-     * Makes given account keys follow the account key of the active keychain. After that you will be able
-     * to get P2SH addresses to receive coins to. Given threshold value specifies how many signatures required to
-     * spend transactions for this married wallet. This value should not exceed total number of keys involved
-     * (one followed key plus number of following keys).</p>
-     * <p>IMPORTANT: As of Bitcoin Core 0.9 all multisig transactions which require more than 3 public keys are
-     * non-standard and such spends won't be processed by peers with default settings, essentially making such
-     * transactions almost nonspendable</p>
-     * This method should be called only once before key rotation, otherwise it will throw an IllegalStateException.
-     */
-    public void addFollowingAccountKeys(List<DeterministicKey> followingAccountKeys, int threshold) {
-        lock.lock();
-        try {
-            keychain.addFollowingAccountKeys(followingAccountKeys, threshold);
-        } finally {
-            lock.unlock();
-        }
+    public void addAndActivateHDChain(DeterministicKeyChain chain) {
+        keychain.addAndActivateHDChain(chain);
     }
 
     /** See {@link org.bitcoinj.wallet.DeterministicKeyChain#setLookaheadSize(int)} for more info on this. */
diff --git a/core/src/main/java/org/bitcoinj/crypto/DeterministicKey.java b/core/src/main/java/org/bitcoinj/crypto/DeterministicKey.java
index 451ed139..26875d19 100644
--- a/core/src/main/java/org/bitcoinj/crypto/DeterministicKey.java
+++ b/core/src/main/java/org/bitcoinj/crypto/DeterministicKey.java
@@ -448,4 +448,22 @@ public class DeterministicKey extends ECKey {
             helper.add("creationTimeSeconds", creationTimeSeconds);
         return helper.toString();
     }
+
+    @Override
+    public void formatKeyWithAddress(boolean includePrivateKeys, StringBuilder builder, NetworkParameters params) {
+        final Address address = toAddress(params);
+        builder.append("  addr:");
+        builder.append(address.toString());
+        builder.append("  hash160:");
+        builder.append(Utils.HEX.encode(getPubKeyHash()));
+        builder.append("  (");
+        builder.append(getPathAsString());
+        builder.append(")");
+        builder.append("\n");
+        if (includePrivateKeys) {
+            builder.append("  ");
+            builder.append(toStringWithPrivate());
+            builder.append("\n");
+        }
+    }
 }
diff --git a/core/src/main/java/org/bitcoinj/store/WalletProtobufSerializer.java b/core/src/main/java/org/bitcoinj/store/WalletProtobufSerializer.java
index fb8984cc..341aaee3 100644
--- a/core/src/main/java/org/bitcoinj/store/WalletProtobufSerializer.java
+++ b/core/src/main/java/org/bitcoinj/store/WalletProtobufSerializer.java
@@ -205,8 +205,6 @@ public class WalletProtobufSerializer {
             walletBuilder.addTransactionSigners(protoSigner);
         }
 
-        walletBuilder.setSigsRequiredToSpend(wallet.getSigsRequiredToSpend());
-
         // Populate the wallet version.
         walletBuilder.setVersion(wallet.getVersion());
 
@@ -410,16 +408,14 @@ public class WalletProtobufSerializer {
         if (!walletProto.getNetworkIdentifier().equals(params.getId()))
             throw new UnreadableWalletException.WrongNetwork();
 
-        int sigsRequiredToSpend = walletProto.getSigsRequiredToSpend();
-
         // Read the scrypt parameters that specify how encryption and decryption is performed.
         KeyChainGroup chain;
         if (walletProto.hasEncryptionParameters()) {
             Protos.ScryptParameters encryptionParameters = walletProto.getEncryptionParameters();
             final KeyCrypterScrypt keyCrypter = new KeyCrypterScrypt(encryptionParameters);
-            chain = KeyChainGroup.fromProtobufEncrypted(params, walletProto.getKeyList(), sigsRequiredToSpend, keyCrypter);
+            chain = KeyChainGroup.fromProtobufEncrypted(params, walletProto.getKeyList(), keyCrypter);
         } else {
-            chain = KeyChainGroup.fromProtobufUnencrypted(params, walletProto.getKeyList(), sigsRequiredToSpend);
+            chain = KeyChainGroup.fromProtobufUnencrypted(params, walletProto.getKeyList());
         }
         Wallet wallet = factory.create(params, chain);
 
diff --git a/core/src/main/java/org/bitcoinj/wallet/DeterministicKeyChain.java b/core/src/main/java/org/bitcoinj/wallet/DeterministicKeyChain.java
index 9fe5bf31..fdd80f04 100644
--- a/core/src/main/java/org/bitcoinj/wallet/DeterministicKeyChain.java
+++ b/core/src/main/java/org/bitcoinj/wallet/DeterministicKeyChain.java
@@ -18,10 +18,14 @@ package org.bitcoinj.wallet;
 
 import org.bitcoinj.core.BloomFilter;
 import org.bitcoinj.core.ECKey;
+import org.bitcoinj.core.NetworkParameters;
 import org.bitcoinj.core.Utils;
 import org.bitcoinj.crypto.*;
+import org.bitcoinj.script.Script;
 import org.bitcoinj.store.UnreadableWalletException;
 import org.bitcoinj.utils.Threading;
+
+import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableList;
 import com.google.protobuf.ByteString;
 import org.slf4j.Logger;
@@ -37,6 +41,7 @@ import java.util.concurrent.Executor;
 import java.util.concurrent.locks.ReentrantLock;
 
 import static com.google.common.base.Preconditions.*;
+import static com.google.common.collect.Lists.newArrayList;
 import static com.google.common.collect.Lists.newLinkedList;
 
 /**
@@ -87,11 +92,12 @@ import static com.google.common.collect.Lists.newLinkedList;
  * But even when you are requesting the 33rd key, you will still be looking 100 keys ahead.
  * </p>
  */
+@SuppressWarnings("PublicStaticCollectionField")
 public class DeterministicKeyChain implements EncryptableKeyChain {
     private static final Logger log = LoggerFactory.getLogger(DeterministicKeyChain.class);
     public static final String DEFAULT_PASSPHRASE_FOR_MNEMONIC = "";
 
-    private final ReentrantLock lock = Threading.lock("DeterministicKeyChain");
+    protected final ReentrantLock lock = Threading.lock("DeterministicKeyChain");
 
     private DeterministicHierarchy hierarchy;
     @Nullable private DeterministicKey rootKey;
@@ -114,11 +120,11 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
     // yet. For new chains it's set to whatever the default is, unless overridden by setLookaheadSize. For deserialized
     // chains, it will be calculated on demand from the number of loaded keys.
     private static final int LAZY_CALCULATE_LOOKAHEAD = -1;
-    private int lookaheadSize = 100;
+    protected int lookaheadSize = 100;
     // The lookahead threshold causes us to batch up creation of new keys to minimize the frequency of Bloom filter
     // regenerations, which are expensive and will (in future) trigger chain download stalls/retries. One third
     // is an efficiency tradeoff.
-    private int lookaheadThreshold = calcDefaultLookaheadThreshold();
+    protected int lookaheadThreshold = calcDefaultLookaheadThreshold();
 
     private int calcDefaultLookaheadThreshold() {
         return lookaheadSize / 3;
@@ -144,6 +150,99 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
     // If set this chain is following another chain in a married KeyChainGroup
     private boolean isFollowing;
 
+    // holds a number of signatures required to spend. It's the N from N-of-M CHECKMULTISIG script for P2SH transactions
+    // and always 1 for other transaction types
+    protected int sigsRequiredToSpend = 1;
+
+
+    public static class Builder<T extends Builder<T>> {
+        protected SecureRandom random;
+        protected int bits = 128;
+        protected String passphrase;
+        protected long seedCreationTimeSecs;
+        protected byte[] entropy;
+        protected DeterministicSeed seed;
+
+        protected Builder() {
+        }
+
+        @SuppressWarnings("unchecked")
+        protected T self() {
+            return (T)this;
+        }
+
+        /**
+         * Creates a deterministic key chain starting from the given entropy. All keys yielded by this chain will be the same
+         * if the starting entropy is the same. You should provide the creation time in seconds since the UNIX epoch for the
+         * seed: this lets us know from what part of the chain we can expect to see derived keys appear.
+         */
+        public T entropy(byte[] entropy) {
+            this.entropy = entropy;
+            return self();
+        }
+
+        /**
+         * Creates a deterministic key chain starting from the given seed. All keys yielded by this chain will be the same
+         * if the starting seed is the same.
+         */
+        public T seed(DeterministicSeed seed) {
+            this.seed = seed;
+            return self();
+        }
+
+        /**
+         * Generates a new key chain with entropy selected randomly from the given {@link java.security.SecureRandom}
+         * object and of the requested size in bits.  The derived seed is further protected with a user selected passphrase
+         * (see BIP 39).
+         * @param random the random number generator - use new SecureRandom().
+         * @param bits The number of bits of entropy to use when generating entropy.  Either 128 (default), 192 or 256.
+         */
+        public T random(SecureRandom random, int bits) {
+            this.random = random;
+            this.bits = bits;
+            return self();
+        }
+
+        /**
+         * Generates a new key chain with 128 bits of entropy selected randomly from the given {@link java.security.SecureRandom}
+         * object.  The derived seed is further protected with a user selected passphrase
+         * (see BIP 39).
+         * @param random the random number generator - use new SecureRandom().
+         */
+        public T random(SecureRandom random) {
+            this.random = random;
+            return self();
+        }
+
+        /** The passphrase to use with the generated mnemonic, or null. Currently must be empty. */
+        public T passphrase(String passphrase) {
+            // FIXME support non-empty passphrase
+            this.passphrase = passphrase;
+            return self();
+        }
+
+
+        public DeterministicKeyChain build() {
+            checkState(random != null || entropy != null || seed != null, "Must provide either entropy or random");
+            checkState(passphrase == null || seed == null, "Passphrase must not be specified with seed");
+            DeterministicKeyChain chain;
+
+            if (random != null) {
+                chain = new DeterministicKeyChain(random, bits, passphrase, seedCreationTimeSecs);
+            } else if (entropy != null) {
+                chain = new DeterministicKeyChain(entropy, passphrase, seedCreationTimeSecs);
+            } else {
+                chain = new DeterministicKeyChain(seed);
+            }
+
+            return chain;
+        }
+    }
+
+    public static Builder<?> builder() {
+        return new Builder();
+    }
+
     /**
      * Generates a new key chain with entropy selected randomly from the given {@link java.security.SecureRandom}
      * object and the default entropy size.
@@ -170,7 +269,7 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
     }
 
     /**
-     * Creates a deterministic key chain starting from the given seed. All keys yielded by this chain will be the same
+     * Creates a deterministic key chain starting from the given entropy. All keys yielded by this chain will be the same
      * if the starting seed is the same. You should provide the creation time in seconds since the UNIX epoch for the
      * seed: this lets us know from what part of the chain we can expect to see derived keys appear.
      */
@@ -209,7 +308,7 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
      * some other keychain. In a married wallet following keychain represents "spouse's" keychain.</p>
      * <p>Watch key has to be an account key.</p>
      */
-    private DeterministicKeyChain(DeterministicKey watchKey, boolean isFollowing) {
+    protected DeterministicKeyChain(DeterministicKey watchKey, boolean isFollowing) {
         this(watchKey, Utils.currentTimeSeconds());
         this.isFollowing = isFollowing;
     }
@@ -581,49 +680,61 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
     //
     //////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
+    protected void beforeSerializeToProtobuf(List<Protos.Key> result) {
+    }
+
     @Override
     public List<Protos.Key> serializeToProtobuf() {
+        List<Protos.Key> result = newArrayList();
         lock.lock();
         try {
-            // Most of the serialization work is delegated to the basic key chain, which will serialize the bulk of the
-            // data (handling encryption along the way), and letting us patch it up with the extra data we care about.
-            LinkedList<Protos.Key> entries = newLinkedList();
-            if (seed != null) {
-                Protos.Key.Builder mnemonicEntry = BasicKeyChain.serializeEncryptableItem(seed);
-                mnemonicEntry.setType(Protos.Key.Type.DETERMINISTIC_MNEMONIC);
-                serializeSeedEncryptableItem(seed, mnemonicEntry);
-                entries.add(mnemonicEntry.build());
-            }
-            Map<ECKey, Protos.Key.Builder> keys = basicKeyChain.serializeToEditableProtobufs();
-            for (Map.Entry<ECKey, Protos.Key.Builder> entry : keys.entrySet()) {
-                DeterministicKey key = (DeterministicKey) entry.getKey();
-                Protos.Key.Builder proto = entry.getValue();
-                proto.setType(Protos.Key.Type.DETERMINISTIC_KEY);
-                final Protos.DeterministicKey.Builder detKey = proto.getDeterministicKeyBuilder();
-                detKey.setChainCode(ByteString.copyFrom(key.getChainCode()));
-                for (ChildNumber num : key.getPath())
-                    detKey.addPath(num.i());
-                if (key.equals(externalKey)) {
-                    detKey.setIssuedSubkeys(issuedExternalKeys);
-                    detKey.setLookaheadSize(lookaheadSize);
-                } else if (key.equals(internalKey)) {
-                    detKey.setIssuedSubkeys(issuedInternalKeys);
-                    detKey.setLookaheadSize(lookaheadSize);
-                }
-                // Flag the very first key of following keychain.
-                if (entries.isEmpty() && isFollowing()) {
-                    detKey.setIsFollowing(true);
-                }
-                if (key.getParent() != null) {
-                    // HD keys inherit the timestamp of their parent if they have one, so no need to serialize it.
-                    proto.clearCreationTimestamp();
-                }
-                entries.add(proto.build());
-            }
-            return entries;
+            beforeSerializeToProtobuf(result);
+            result.addAll(serializeMyselfToProtobuf());
         } finally {
             lock.unlock();
         }
+        return result;
+    }
+
+    protected List<Protos.Key> serializeMyselfToProtobuf() {
+        // Most of the serialization work is delegated to the basic key chain, which will serialize the bulk of the
+        // data (handling encryption along the way), and letting us patch it up with the extra data we care about.
+        LinkedList<Protos.Key> entries = newLinkedList();
+        if (seed != null) {
+            Protos.Key.Builder mnemonicEntry = BasicKeyChain.serializeEncryptableItem(seed);
+            mnemonicEntry.setType(Protos.Key.Type.DETERMINISTIC_MNEMONIC);
+            serializeSeedEncryptableItem(seed, mnemonicEntry);
+            entries.add(mnemonicEntry.build());
+        }
+        Map<ECKey, Protos.Key.Builder> keys = basicKeyChain.serializeToEditableProtobufs();
+        for (Map.Entry<ECKey, Protos.Key.Builder> entry : keys.entrySet()) {
+            DeterministicKey key = (DeterministicKey) entry.getKey();
+            Protos.Key.Builder proto = entry.getValue();
+            proto.setType(Protos.Key.Type.DETERMINISTIC_KEY);
+            final Protos.DeterministicKey.Builder detKey = proto.getDeterministicKeyBuilder();
+            detKey.setChainCode(ByteString.copyFrom(key.getChainCode()));
+            for (ChildNumber num : key.getPath())
+                detKey.addPath(num.i());
+            if (key.equals(externalKey)) {
+                detKey.setIssuedSubkeys(issuedExternalKeys);
+                detKey.setLookaheadSize(lookaheadSize);
+                detKey.setSigsRequiredToSpend(getSigsRequiredToSpend());
+            } else if (key.equals(internalKey)) {
+                detKey.setIssuedSubkeys(issuedInternalKeys);
+                detKey.setLookaheadSize(lookaheadSize);
+                detKey.setSigsRequiredToSpend(getSigsRequiredToSpend());
+            }
+            // Flag the very first key of following keychain.
+            if (entries.isEmpty() && isFollowing()) {
+                detKey.setIsFollowing(true);
+            }
+            if (key.getParent() != null) {
+                // HD keys inherit the timestamp of their parent if they have one, so no need to serialize it.
+                proto.clearCreationTimestamp();
+            }
+            entries.add(proto.build());
+        }
+        return entries;
     }
 
     /**
@@ -636,12 +747,15 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
         DeterministicKeyChain chain = null;
 
         int lookaheadSize = -1;
+        int sigsRequiredToSpend = 1;
+
         for (Protos.Key key : keys) {
             final Protos.Key.Type t = key.getType();
             if (t == Protos.Key.Type.DETERMINISTIC_MNEMONIC) {
                 if (chain != null) {
                     checkState(lookaheadSize >= 0);
                     chain.setLookaheadSize(lookaheadSize);
+                    chain.setSigsRequiredToSpend(sigsRequiredToSpend);
                     chain.maybeLookAhead();
                     chains.add(chain);
                     chain = null;
@@ -693,6 +807,7 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
                     if (chain != null) {
                         checkState(lookaheadSize >= 0);
                         chain.setLookaheadSize(lookaheadSize);
+                        chain.setSigsRequiredToSpend(sigsRequiredToSpend);
                         chain.maybeLookAhead();
                         chains.add(chain);
                         chain = null;
@@ -701,15 +816,23 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
                     isFollowingKey = true;
                 }
                 if (chain == null) {
+                    // If this is not a following chain and previous was, this must be married
+                    boolean isMarried = !isFollowingKey && !chains.isEmpty() && chains.get(chains.size() - 1).isFollowing();
                     if (seed == null) {
                         DeterministicKey accountKey = new DeterministicKey(immutablePath, chainCode, pubkey, null, null);
                         if (!accountKey.getPath().equals(ACCOUNT_ZERO_PATH))
                             throw new UnreadableWalletException("Expecting account key but found key with path: " +
                                     HDUtils.formatPath(accountKey.getPath()));
-                        chain = new DeterministicKeyChain(accountKey, isFollowingKey);
+                        if (isMarried)
+                            chain = new MarriedKeyChain(accountKey);
+                        else
+                            chain = new DeterministicKeyChain(accountKey, isFollowingKey);
                         isWatchingAccountKey = true;
                     } else {
-                        chain = new DeterministicKeyChain(seed, crypter);
+                        if (isMarried)
+                            chain = new MarriedKeyChain(seed, crypter);
+                        else
+                            chain = new DeterministicKeyChain(seed, crypter);
                         chain.lookaheadSize = LAZY_CALCULATE_LOOKAHEAD;
                         // If the seed is encrypted, then the chain is incomplete at this point. However, we will load
                         // it up below as we parse in the keys. We just need to check at the end that we've loaded
@@ -759,6 +882,7 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
                             chain.externalKey = detkey;
                             chain.issuedExternalKeys = key.getDeterministicKey().getIssuedSubkeys();
                             lookaheadSize = Math.max(lookaheadSize, key.getDeterministicKey().getLookaheadSize());
+                            sigsRequiredToSpend = key.getDeterministicKey().getSigsRequiredToSpend();
                         } else if (detkey.getChildNumber().num() == 1) {
                             chain.internalKey = detkey;
                             chain.issuedInternalKeys = key.getDeterministicKey().getIssuedSubkeys();
@@ -772,6 +896,7 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
         if (chain != null) {
             checkState(lookaheadSize >= 0);
             chain.setLookaheadSize(lookaheadSize);
+            chain.setSigsRequiredToSpend(sigsRequiredToSpend);
             chain.maybeLookAhead();
             chains.add(chain);
         }
@@ -1013,6 +1138,10 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
         return result;
     }
 
+    /** Housekeeping call to call when lookahead might be needed.  Normally called automatically by KeychainGroup. */
+    public void maybeLookAheadScripts() {
+    }
+
     /**
      * Returns number of keys used on external path. This may be fewer than the number that have been deserialized
      * or held in memory, because of the lookahead zone.
@@ -1115,4 +1244,73 @@ public class DeterministicKeyChain implements EncryptableKeyChain {
             lock.unlock();
         }
     }
+
+    /**
+     * Whether the keychain is married.  A keychain is married when it vends P2SH addresses
+     * from multiple keychains in a multisig relationship.
+     * @see org.bitcoinj.wallet.MarriedKeyChain
+     */
+    public boolean isMarried() {
+        return false;
+    }
+
+    /** Get redeem data for a key.  Only applicable to married keychains. */
+    public RedeemData getRedeemData(DeterministicKey followedKey) {
+        throw new UnsupportedOperationException();
+    }
+
+    /** Create a new key and return the matching output script.  Only applicable to married keychains. */
+    public Script freshOutputScript(KeyPurpose purpose) {
+        throw new UnsupportedOperationException();
+    }
+
+    public String toString(boolean includePrivateKeys, NetworkParameters params) {
+        final StringBuilder builder2 = new StringBuilder();
+        if (seed != null) {
+            if (seed.isEncrypted()) {
+                builder2.append(String.format("Seed is encrypted%n"));
+            } else if (includePrivateKeys) {
+                final List<String> words = seed.getMnemonicCode();
+                builder2.append(
+                        String.format("Seed as words: %s%nSeed as hex:   %s%n", Joiner.on(' ').join(words),
+                                seed.toHexString())
+                );
+            }
+            builder2.append(String.format("Seed birthday: %d  [%s]%n", seed.getCreationTimeSeconds(), new Date(seed.getCreationTimeSeconds() * 1000)));
+        }
+        final DeterministicKey watchingKey = getWatchingKey();
+        // Don't show if it's been imported from a watching wallet already, because it'd result in a weird/
+        // unintuitive result where the watching key in a watching wallet is not the one it was created with
+        // due to the parent fingerprint being missing/not stored. In future we could store the parent fingerprint
+        // optionally as well to fix this, but it seems unimportant for now.
+        if (watchingKey.getParent() != null) {
+            builder2.append(String.format("Key to watch:  %s%n", watchingKey.serializePubB58()));
+        }
+        formatAddresses(includePrivateKeys, params, builder2);
+        return builder2.toString();
+    }
+
+    protected void formatAddresses(boolean includePrivateKeys, NetworkParameters params, StringBuilder builder2) {
+        for (ECKey key : getKeys(false))
+            key.formatKeyWithAddress(includePrivateKeys, builder2, params);
+    }
+
+    /** The number of signatures required to spend coins received by this keychain. */
+    public void setSigsRequiredToSpend(int sigsRequiredToSpend) {
+        this.sigsRequiredToSpend = sigsRequiredToSpend;
+    }
+
+    /**
+     * Returns the number of signatures required to spend transactions for this KeyChain. It's the N from
+     * N-of-M CHECKMULTISIG script for P2SH transactions and always 1 for other transaction types.
+     */
+    public int getSigsRequiredToSpend() {
+        return sigsRequiredToSpend;
+    }
+
+    /** Returns the redeem script by its hash or null if this keychain did not generate the script. */
+    @Nullable
+    public RedeemData findRedeemDataByScriptHash(ByteString bytes) {
+        return null;
+    }
 }
diff --git a/core/src/main/java/org/bitcoinj/wallet/KeyChainGroup.java b/core/src/main/java/org/bitcoinj/wallet/KeyChainGroup.java
index 7f1ff2b6..50f6ce99 100644
--- a/core/src/main/java/org/bitcoinj/wallet/KeyChainGroup.java
+++ b/core/src/main/java/org/bitcoinj/wallet/KeyChainGroup.java
@@ -26,6 +26,7 @@ import org.bitcoinj.script.ScriptBuilder;
 import org.bitcoinj.store.UnreadableWalletException;
 import org.bitcoinj.utils.ListenerRegistration;
 import org.bitcoinj.utils.Threading;
+
 import com.google.common.base.Joiner;
 import com.google.common.collect.HashMultimap;
 import com.google.common.collect.ImmutableList;
@@ -67,20 +68,9 @@ public class KeyChainGroup implements KeyBag {
 
     private BasicKeyChain basic;
     private NetworkParameters params;
-    private final List<DeterministicKeyChain> chains;
+    private final LinkedList<DeterministicKeyChain> chains;
     private final EnumMap<KeyChain.KeyPurpose, DeterministicKey> currentKeys;
 
-    // The map keys are the watching keys of the followed chains and values are the following chains
-    private Multimap<DeterministicKey, DeterministicKeyChain> followingKeychains;
-
-    // holds a number of signatures required to spend. It's the N from N-of-M CHECKMULTISIG script for P2SH transactions
-    // and always 1 for other transaction types
-    private int sigsRequiredToSpend;
-
-    // The map holds P2SH redeem script and corresponding ECKeys issued by this KeyChainGroup (including lookahead)
-    // mapped to redeem script hashes.
-    private LinkedHashMap<ByteString, RedeemData> marriedKeysRedeemData;
-
     private EnumMap<KeyChain.KeyPurpose, Address> currentAddresses;
     @Nullable private KeyCrypter keyCrypter;
     private int lookaheadSize = -1;
@@ -88,12 +78,12 @@ public class KeyChainGroup implements KeyBag {
 
     /** Creates a keychain group with no basic chain, and a single, lazily created HD chain. */
     public KeyChainGroup(NetworkParameters params) {
-        this(params, null, new ArrayList<DeterministicKeyChain>(1), null, null, 1, null);
+        this(params, null, new ArrayList<DeterministicKeyChain>(1), null, null);
     }
 
     /** Creates a keychain group with no basic chain, and an HD chain initialized from the given seed. */
     public KeyChainGroup(NetworkParameters params, DeterministicSeed seed) {
-        this(params, null, ImmutableList.of(new DeterministicKeyChain(seed)), null, null, 1, null);
+        this(params, null, ImmutableList.of(new DeterministicKeyChain(seed)), null, null);
     }
 
     /**
@@ -101,7 +91,7 @@ public class KeyChainGroup implements KeyBag {
      * This HAS to be an account key as returned by {@link DeterministicKeyChain#getWatchingKey()}.
      */
     public KeyChainGroup(NetworkParameters params, DeterministicKey watchKey) {
-        this(params, null, ImmutableList.of(DeterministicKeyChain.watch(watchKey)), null, null, 1, null);
+        this(params, null, ImmutableList.of(DeterministicKeyChain.watch(watchKey)), null, null);
     }
 
     /**
@@ -110,115 +100,36 @@ public class KeyChainGroup implements KeyBag {
      * This HAS to be an account key as returned by {@link DeterministicKeyChain#getWatchingKey()}.
      */
     public KeyChainGroup(NetworkParameters params, DeterministicKey watchKey, long creationTimeSecondsSecs) {
-        this(params, null, ImmutableList.of(DeterministicKeyChain.watch(watchKey, creationTimeSecondsSecs)), null, null, 1, null);
-    }
-
-    /**
-     * Creates a keychain group with no basic chain, with an HD chain initialized from the given seed and being followed
-     * by given list of watch keys. Watch keys have to be account keys.
-     */
-    public KeyChainGroup(NetworkParameters params, DeterministicSeed seed, List<DeterministicKey> followingAccountKeys, int sigsRequiredToSpend) {
-        this(params, seed);
-
-        addFollowingAccountKeys(followingAccountKeys, sigsRequiredToSpend);
-    }
-
-    /**
-     * <p>Alias for <code>addFollowingAccountKeys(followingAccountKeys, (followingAccountKeys.size() + 1) / 2 + 1)</code></p>
-     * <p>Creates married keychain requiring majority of keys to spend (2-of-3, 3-of-5 and so on)</p>
-     * <p>IMPORTANT: As of Bitcoin Core 0.9 all multisig transactions which require more than 3 public keys are non-standard
-     * and such spends won't be processed by peers with default settings, essentially making such transactions almost
-     * nonspendable</p>
-     */
-    public void addFollowingAccountKeys(List<DeterministicKey> followingAccountKeys) {
-        addFollowingAccountKeys(followingAccountKeys, (followingAccountKeys.size() + 1) / 2 + 1);
-    }
-
-    /**
-     * <p>Makes given account keys follow the account key of the active keychain. After that active keychain will be
-     * treated as married and you will be able to get P2SH addresses to receive coins to. Given sigsRequiredToSpend value
-     * specifies how many signatures required to spend transactions for this married keychain. This value should not exceed
-     * total number of keys involved (one followed key plus number of following keys), otherwise IllegalArgumentException
-     * will be thrown.</p>
-     * <p>IMPORTANT: As of Bitcoin Core 0.9 all multisig transactions which require more than 3 public keys are non-standard
-     * and such spends won't be processed by peers with default settings, essentially making such transactions almost
-     * nonspendable</p>
-     * <p>This method will throw an IllegalStateException, if active keychain is already married or already has leaf keys
-     * issued. In future this behaviour may be replaced with key rotation.</p>
-     */
-    public void addFollowingAccountKeys(List<DeterministicKey> followingAccountKeys, int sigsRequiredToSpend) {
-        checkArgument(sigsRequiredToSpend <= followingAccountKeys.size() + 1, "Multisig threshold can't exceed total number of keys");
-        checkState(!isMarried(), "KeyChainGroup is married already");
-        checkState(getActiveKeyChain().numLeafKeysIssued() == 0, "Active keychain already has keys in use");
-
-        this.sigsRequiredToSpend = sigsRequiredToSpend;
-
-        DeterministicKey accountKey = getActiveKeyChain().getWatchingKey();
-        for (DeterministicKey key : followingAccountKeys) {
-            checkArgument(key.getPath().size() == 1, "Following keys have to be account keys");
-            DeterministicKeyChain chain = DeterministicKeyChain.watchAndFollow(key);
-            if (lookaheadSize >= 0)
-                chain.setLookaheadSize(lookaheadSize);
-            if (lookaheadThreshold >= 0)
-                chain.setLookaheadThreshold(lookaheadThreshold);
-            followingKeychains.put(accountKey, chain);
-        }
+        this(params, null, ImmutableList.of(DeterministicKeyChain.watch(watchKey, creationTimeSecondsSecs)), null, null);
     }
 
     // Used for deserialization.
     private KeyChainGroup(NetworkParameters params, @Nullable BasicKeyChain basicKeyChain, List<DeterministicKeyChain> chains,
-                          @Nullable EnumMap<KeyChain.KeyPurpose, DeterministicKey> currentKeys, Multimap<DeterministicKey,
-                          DeterministicKeyChain> followingKeychains, int sigsRequiredToSpend, @Nullable KeyCrypter crypter) {
+                          @Nullable EnumMap<KeyChain.KeyPurpose, DeterministicKey> currentKeys, @Nullable KeyCrypter crypter) {
         this.params = params;
         this.basic = basicKeyChain == null ? new BasicKeyChain() : basicKeyChain;
-        this.chains = new ArrayList<DeterministicKeyChain>(checkNotNull(chains));
+        this.chains = new LinkedList<DeterministicKeyChain>(checkNotNull(chains));
         this.keyCrypter = crypter;
         this.currentKeys = currentKeys == null
                 ? new EnumMap<KeyChain.KeyPurpose, DeterministicKey>(KeyChain.KeyPurpose.class)
                 : currentKeys;
         this.currentAddresses = new EnumMap<KeyChain.KeyPurpose, Address>(KeyChain.KeyPurpose.class);
-        this.followingKeychains = HashMultimap.create();
-        if (followingKeychains != null) {
-            this.followingKeychains.putAll(followingKeychains);
-        }
-        this.sigsRequiredToSpend = sigsRequiredToSpend;
-        marriedKeysRedeemData = new LinkedHashMap<ByteString, RedeemData>();
         maybeLookaheadScripts();
 
-        if (!this.followingKeychains.isEmpty()) {
-            DeterministicKey followedWatchKey = getActiveKeyChain().getWatchingKey();
+        if (isMarried()) {
             for (Map.Entry<KeyChain.KeyPurpose, DeterministicKey> entry : this.currentKeys.entrySet()) {
-                Address address = makeP2SHOutputScript(entry.getValue(), followedWatchKey).getToAddress(params);
+                Address address = makeP2SHOutputScript(entry.getValue(), getActiveKeyChain()).getToAddress(params);
                 currentAddresses.put(entry.getKey(), address);
             }
         }
     }
 
     /**
-     * This keeps {@link #marriedKeysRedeemData} in sync with the number of keys issued
+     * This keeps married redeem data in sync with the number of keys issued
      */
     private void maybeLookaheadScripts() {
-        if (chains.isEmpty())
-            return;
-
-        int numLeafKeys = 0;
         for (DeterministicKeyChain chain : chains) {
-            numLeafKeys += chain.getLeafKeys().size();
-        }
-
-        checkState(marriedKeysRedeemData.size() <= numLeafKeys, "Number of scripts is greater than number of leaf keys");
-        if (marriedKeysRedeemData.size() == numLeafKeys)
-            return;
-
-        for (DeterministicKeyChain chain : chains) {
-            if (isMarried(chain)) {
-                chain.maybeLookAhead();
-                for (DeterministicKey followedKey : chain.getLeafKeys()) {
-                    RedeemData redeemData = getRedeemData(followedKey, chain.getWatchingKey());
-                    Script scriptPubKey = ScriptBuilder.createP2SHOutputScript(redeemData.redeemScript);
-                    marriedKeysRedeemData.put(ByteString.copyFrom(scriptPubKey.getPubKeyHash()), redeemData);
-                }
-            }
+            chain.maybeLookAheadScripts();
         }
     }
 
@@ -226,6 +137,14 @@ public class KeyChainGroup implements KeyBag {
     public void createAndActivateNewHDChain() {
         // We can't do auto upgrade here because we don't know the rotation time, if any.
         final DeterministicKeyChain chain = new DeterministicKeyChain(new SecureRandom());
+        addAndActivateHDChain(chain);
+    }
+
+    /**
+     * Adds an HD chain to the chains list, and make it the default chain (from which keys are issued).
+     * Useful for adding a complex pre-configured keychain, such as a married wallet.
+     */
+    public void addAndActivateHDChain(DeterministicKeyChain chain) {
         log.info("Creating and activating a new HD chain: {}", chain);
         for (ListenerRegistration<KeyChainEventListener> registration : basic.getListeners())
             chain.addEventListener(registration.listener, registration.executor);
@@ -249,7 +168,7 @@ public class KeyChainGroup implements KeyBag {
      */
     public DeterministicKey currentKey(KeyChain.KeyPurpose purpose) {
         DeterministicKeyChain chain = getActiveKeyChain();
-        if (isMarried(chain)) {
+        if (chain.isMarried()) {
             throw new UnsupportedOperationException("Key is not suitable to receive coins for married keychains." +
                                                     " Use freshAddress to get P2SH address instead");
         }
@@ -266,7 +185,7 @@ public class KeyChainGroup implements KeyBag {
      */
     public Address currentAddress(KeyChain.KeyPurpose purpose) {
         DeterministicKeyChain chain = getActiveKeyChain();
-        if (isMarried(chain)) {
+        if (chain.isMarried()) {
             Address current = currentAddresses.get(purpose);
             if (current == null) {
                 current = freshAddress(purpose);
@@ -308,7 +227,7 @@ public class KeyChainGroup implements KeyBag {
      */
     public List<DeterministicKey> freshKeys(KeyChain.KeyPurpose purpose, int numberOfKeys) {
         DeterministicKeyChain chain = getActiveKeyChain();
-        if (isMarried(chain)) {
+        if (chain.isMarried()) {
             throw new UnsupportedOperationException("Key is not suitable to receive coins for married keychains." +
                     " Use freshAddress to get P2SH address instead");
         }
@@ -320,10 +239,10 @@ public class KeyChainGroup implements KeyBag {
      */
     public Address freshAddress(KeyChain.KeyPurpose purpose) {
         DeterministicKeyChain chain = getActiveKeyChain();
-        if (isMarried(chain)) {
-            List<ECKey> marriedKeys = freshMarriedKeys(purpose, chain);
-            Script p2shScript = makeP2SHOutputScript(marriedKeys);
-            Address freshAddress = Address.fromP2SHScript(params, p2shScript);
+        if (chain.isMarried()) {
+            Script outputScript = chain.freshOutputScript(purpose);
+            checkState(outputScript.isPayToScriptHash()); // Only handle P2SH for now
+            Address freshAddress = Address.fromP2SHScript(params, outputScript);
             maybeLookaheadScripts();
             currentAddresses.put(purpose, freshAddress);
             return freshAddress;
@@ -332,28 +251,6 @@ public class KeyChainGroup implements KeyBag {
         }
     }
 
-    private List<ECKey> freshMarriedKeys(KeyChain.KeyPurpose purpose, DeterministicKeyChain followedKeyChain) {
-        DeterministicKey followedKey = followedKeyChain.getKey(purpose);
-        ImmutableList.Builder<ECKey> keys = ImmutableList.<ECKey>builder().add(followedKey);
-        Collection<DeterministicKeyChain> keyChains = followingKeychains.get(followedKeyChain.getWatchingKey());
-        for (DeterministicKeyChain keyChain : keyChains) {
-            DeterministicKey followingKey = keyChain.getKey(purpose);
-            checkState(followedKey.getChildNumber().equals(followingKey.getChildNumber()), "Following keychains should be in sync");
-            keys.add(followingKey);
-        }
-        return keys.build();
-    }
-
-    private List<ECKey> getMarriedKeysWithFollowed(DeterministicKey followedKey, Collection<DeterministicKeyChain> followingChains) {
-        ImmutableList.Builder<ECKey> keys = ImmutableList.builder();
-        for (DeterministicKeyChain keyChain : followingChains) {
-            keyChain.maybeLookAhead();
-            keys.add(keyChain.getKeyByPath(followedKey.getPath()));
-        }
-        keys.add(followedKey);
-        return keys.build();
-    }
-
     /** Returns the key chain that's used for generation of fresh/current keys. This is always the newest HD chain. */
     public DeterministicKeyChain getActiveKeyChain() {
         if (chains.isEmpty()) {
@@ -379,9 +276,6 @@ public class KeyChainGroup implements KeyBag {
         for (DeterministicKeyChain chain : chains) {
             chain.setLookaheadSize(lookaheadSize);
         }
-        for (DeterministicKeyChain chain : followingKeychains.values()) {
-            chain.setLookaheadSize(lookaheadSize);
-        }
     }
 
     /**
@@ -456,7 +350,14 @@ public class KeyChainGroup implements KeyBag {
 
     @Nullable
     public RedeemData findRedeemDataFromScriptHash(byte[] scriptHash) {
-        return marriedKeysRedeemData.get(ByteString.copyFrom(scriptHash));
+        // Iterate in reverse order, since the active keychain is the one most likely to have the hit
+        for (Iterator<DeterministicKeyChain> iter = chains.descendingIterator() ; iter.hasNext() ; ) {
+            DeterministicKeyChain chain = iter.next();
+            RedeemData redeemData = chain.findRedeemDataByScriptHash(ByteString.copyFrom(scriptHash));
+            if (redeemData != null)
+                return redeemData;
+        }
+        return null;
     }
 
     @Nullable
@@ -552,18 +453,12 @@ public class KeyChainGroup implements KeyBag {
     }
 
     /**
-     * Returns true if the given keychain is being followed by at least one another keychain
-     */
-    public boolean isMarried(DeterministicKeyChain keychain) {
-        DeterministicKey watchingKey = keychain.getWatchingKey();
-        return followingKeychains.containsKey(watchingKey) && followingKeychains.get(watchingKey).size() > 0;
-    }
-
-    /**
-     * An alias for {@link #isMarried(DeterministicKeyChain)} called for the active keychain
+     * Whether the active keychain is married.  A keychain is married when it vends P2SH addresses
+     * from multiple keychains in a multisig relationship.
+     * @see org.bitcoinj.wallet.MarriedKeyChain
      */
     public boolean isMarried() {
-        return isMarried(getActiveKeyChain());
+        return !chains.isEmpty() && getActiveKeyChain().isMarried();
     }
 
     /**
@@ -638,12 +533,7 @@ public class KeyChainGroup implements KeyBag {
     public int getBloomFilterElementCount() {
         int result = basic.numBloomFilterEntries();
         for (DeterministicKeyChain chain : chains) {
-            if (isMarried(chain)) {
-                chain.maybeLookAhead();
-                result += chain.getLeafKeys().size() * 2;
-            } else {
-                result += chain.numBloomFilterEntries();
-            }
+            result += chain.numBloomFilterEntries();
         }
         return result;
     }
@@ -653,15 +543,8 @@ public class KeyChainGroup implements KeyBag {
         if (basic.numKeys() > 0)
             filter.merge(basic.getFilter(size, falsePositiveRate, nTweak));
 
-        for (Map.Entry<ByteString, RedeemData> entry : marriedKeysRedeemData.entrySet()) {
-            filter.insert(entry.getKey().toByteArray());
-            filter.insert(entry.getValue().redeemScript.getProgram());
-        }
-
         for (DeterministicKeyChain chain : chains) {
-            if (!isMarried(chain)) {
-                filter.merge(chain.getFilter(size, falsePositiveRate, nTweak));
-            }
+            filter.merge(chain.getFilter(size, falsePositiveRate, nTweak));
         }
         return filter;
     }
@@ -671,22 +554,8 @@ public class KeyChainGroup implements KeyBag {
         throw new UnsupportedOperationException();   // Unused.
     }
 
-    private Script makeP2SHOutputScript(List<ECKey> marriedKeys) {
-        return ScriptBuilder.createP2SHOutputScript(makeRedeemScript(marriedKeys));
-    }
-
-    private Script makeP2SHOutputScript(DeterministicKey followedKey, DeterministicKey followedAccountKey) {
-        return ScriptBuilder.createP2SHOutputScript(getRedeemData(followedKey, followedAccountKey).redeemScript);
-    }
-
-    private RedeemData getRedeemData(DeterministicKey followedKey, DeterministicKey followedAccountKey) {
-        Collection<DeterministicKeyChain> followingChains = followingKeychains.get(followedAccountKey);
-        List<ECKey> marriedKeys = getMarriedKeysWithFollowed(followedKey, followingChains);
-        return RedeemData.of(marriedKeys, makeRedeemScript(marriedKeys));
-    }
-
-    private Script makeRedeemScript(List<ECKey> marriedKeys) {
-        return ScriptBuilder.createRedeemScript(sigsRequiredToSpend, marriedKeys);
+    private Script makeP2SHOutputScript(DeterministicKey followedKey, DeterministicKeyChain chain) {
+        return ScriptBuilder.createP2SHOutputScript(chain.getRedeemData(followedKey).redeemScript);
     }
 
     /** Adds a listener for events that are run when keys are added, on the user thread. */
@@ -719,41 +588,31 @@ public class KeyChainGroup implements KeyBag {
         else
             result = Lists.newArrayList();
         for (DeterministicKeyChain chain : chains) {
-            // prepend each chain with it's following chains if any
-            for (DeterministicKeyChain followingChain : followingKeychains.get(chain.getWatchingKey())) {
-                result.addAll(followingChain.serializeToProtobuf());
-            }
             List<Protos.Key> protos = chain.serializeToProtobuf();
             result.addAll(protos);
         }
         return result;
     }
 
-    public static KeyChainGroup fromProtobufUnencrypted(NetworkParameters params, List<Protos.Key> keys, int sigsRequiredToSpend) throws UnreadableWalletException {
-        checkArgument(sigsRequiredToSpend > 0);
+    public static KeyChainGroup fromProtobufUnencrypted(NetworkParameters params, List<Protos.Key> keys) throws UnreadableWalletException {
         BasicKeyChain basicKeyChain = BasicKeyChain.fromProtobufUnencrypted(keys);
         List<DeterministicKeyChain> chains = DeterministicKeyChain.fromProtobuf(keys, null);
         EnumMap<KeyChain.KeyPurpose, DeterministicKey> currentKeys = null;
         if (!chains.isEmpty())
             currentKeys = createCurrentKeysMap(chains);
-        Multimap<DeterministicKey, DeterministicKeyChain> followingKeychains = extractFollowingKeychains(chains);
-        if (sigsRequiredToSpend < 2 && followingKeychains.size() > 0)
-            throw new IllegalArgumentException("Married KeyChainGroup requires multiple signatures to spend");
-        return new KeyChainGroup(params, basicKeyChain, chains, currentKeys, followingKeychains, sigsRequiredToSpend, null);
+        extractFollowingKeychains(chains);
+        return new KeyChainGroup(params, basicKeyChain, chains, currentKeys, null);
     }
 
-    public static KeyChainGroup fromProtobufEncrypted(NetworkParameters params, List<Protos.Key> keys, int sigsRequiredToSpend, KeyCrypter crypter) throws UnreadableWalletException {
-        checkArgument(sigsRequiredToSpend > 0);
+    public static KeyChainGroup fromProtobufEncrypted(NetworkParameters params, List<Protos.Key> keys, KeyCrypter crypter) throws UnreadableWalletException {
         checkNotNull(crypter);
         BasicKeyChain basicKeyChain = BasicKeyChain.fromProtobufEncrypted(keys, crypter);
         List<DeterministicKeyChain> chains = DeterministicKeyChain.fromProtobuf(keys, crypter);
         EnumMap<KeyChain.KeyPurpose, DeterministicKey> currentKeys = null;
         if (!chains.isEmpty())
             currentKeys = createCurrentKeysMap(chains);
-        Multimap<DeterministicKey, DeterministicKeyChain> followingKeychains = extractFollowingKeychains(chains);
-        if (sigsRequiredToSpend < 2 && followingKeychains.size() > 0)
-            throw new IllegalArgumentException("Married KeyChainGroup requires multiple signatures to spend");
-        return new KeyChainGroup(params, basicKeyChain, chains, currentKeys, followingKeychains, sigsRequiredToSpend, crypter);
+        extractFollowingKeychains(chains);
+        return new KeyChainGroup(params, basicKeyChain, chains, currentKeys, crypter);
     }
 
     /**
@@ -848,111 +707,42 @@ public class KeyChainGroup implements KeyBag {
         return currentKeys;
     }
 
-    private static Multimap<DeterministicKey, DeterministicKeyChain> extractFollowingKeychains(List<DeterministicKeyChain> chains) {
+    private static void extractFollowingKeychains(List<DeterministicKeyChain> chains) {
         // look for following key chains and map them to the watch keys of followed keychains
         Multimap<DeterministicKey, DeterministicKeyChain> followingKeychains = HashMultimap.create();
-        List<DeterministicKeyChain> followingChains = new ArrayList<DeterministicKeyChain>();
+        List<DeterministicKeyChain> followingChains = Lists.newArrayList();
         for (Iterator<DeterministicKeyChain> it = chains.iterator(); it.hasNext(); ) {
             DeterministicKeyChain chain = it.next();
             if (chain.isFollowing()) {
                 followingChains.add(chain);
                 it.remove();
             } else if (!followingChains.isEmpty()) {
-                followingKeychains.putAll(chain.getWatchingKey(), followingChains);
-                followingChains.clear();
+                if (!(chain instanceof MarriedKeyChain))
+                    throw new IllegalStateException();
+                ((MarriedKeyChain)chain).setFollowingKeyChains(followingChains);
+                followingChains = Lists.newArrayList();
             }
         }
-        return followingKeychains;
     }
 
     public String toString(boolean includePrivateKeys) {
         final StringBuilder builder = new StringBuilder();
         if (basic != null) {
             for (ECKey key : basic.getKeys())
-                formatKeyWithAddress(includePrivateKeys, key, builder);
+                key.formatKeyWithAddress(includePrivateKeys, builder, params);
         }
         List<String> chainStrs = Lists.newLinkedList();
         for (DeterministicKeyChain chain : chains) {
-            final StringBuilder builder2 = new StringBuilder();
-            DeterministicSeed seed = chain.getSeed();
-            if (seed != null) {
-                if (seed.isEncrypted()) {
-                    builder2.append(String.format("Seed is encrypted%n"));
-                } else if (includePrivateKeys) {
-                    final List<String> words = seed.getMnemonicCode();
-                    builder2.append(
-                            String.format("Seed as words: %s%nSeed as hex:   %s%n", Joiner.on(' ').join(words),
-                                    seed.toHexString())
-                    );
-                }
-                builder2.append(String.format("Seed birthday: %d  [%s]%n", seed.getCreationTimeSeconds(), new Date(seed.getCreationTimeSeconds() * 1000)));
-            }
-            final DeterministicKey watchingKey = chain.getWatchingKey();
-            // Don't show if it's been imported from a watching wallet already, because it'd result in a weird/
-            // unintuitive result where the watching key in a watching wallet is not the one it was created with
-            // due to the parent fingerprint being missing/not stored. In future we could store the parent fingerprint
-            // optionally as well to fix this, but it seems unimportant for now.
-            if (watchingKey.getParent() != null) {
-                builder2.append(String.format("Key to watch:  %s%n", watchingKey.serializePubB58()));
-            }
-            if (isMarried(chain)) {
-                Collection<DeterministicKeyChain> followingChains = followingKeychains.get(chain.getWatchingKey());
-                for (DeterministicKeyChain followingChain : followingChains) {
-                    builder2.append(String.format("Following chain:  %s%n", followingChain.getWatchingKey().serializePubB58()));
-                }
-                builder2.append(String.format("%n"));
-                for (RedeemData redeemData : marriedKeysRedeemData.values())
-                    formatScript(ScriptBuilder.createP2SHOutputScript(redeemData.redeemScript), builder2);
-            } else {
-                for (ECKey key : chain.getKeys(false))
-                    formatKeyWithAddress(includePrivateKeys, key, builder2);
-            }
-            chainStrs.add(builder2.toString());
+            chainStrs.add(chain.toString(includePrivateKeys, params));
         }
         builder.append(Joiner.on(String.format("%n")).join(chainStrs));
         return builder.toString();
     }
 
-    private void formatScript(Script script, StringBuilder builder) {
-        builder.append("  addr:");
-        builder.append(script.getToAddress(params));
-        builder.append("  hash160:");
-        builder.append(Utils.HEX.encode(script.getPubKeyHash()));
-        builder.append("\n");
-    }
-
-    private void formatKeyWithAddress(boolean includePrivateKeys, ECKey key, StringBuilder builder) {
-        final Address address = key.toAddress(params);
-        builder.append("  addr:");
-        builder.append(address.toString());
-        builder.append("  hash160:");
-        builder.append(Utils.HEX.encode(key.getPubKeyHash()));
-        if (key instanceof DeterministicKey) {
-            builder.append("  (");
-            builder.append((((DeterministicKey) key).getPathAsString()));
-            builder.append(")");
-        }
-        builder.append("\n");
-        if (includePrivateKeys) {
-            builder.append("  ");
-            builder.append(key.toStringWithPrivate());
-            builder.append("\n");
-        }
-    }
-
     /** Returns a copy of the current list of chains. */
     public List<DeterministicKeyChain> getDeterministicKeyChains() {
         return new ArrayList<DeterministicKeyChain>(chains);
     }
-
-    /**
-     * Returns the number of signatures required to spend transactions for this KeyChainGroup. It's the N from
-     * N-of-M CHECKMULTISIG script for P2SH transactions and always 1 for other transaction types.
-     */
-    public int getSigsRequiredToSpend() {
-        return sigsRequiredToSpend;
-    }
-
     /**
      * Returns a counter that increases (by an arbitrary amount) each time new keys have been calculated due to
      * lookahead and thus the Bloom filter that was previously calculated has become stale.
diff --git a/core/src/main/java/org/bitcoinj/wallet/MarriedKeyChain.java b/core/src/main/java/org/bitcoinj/wallet/MarriedKeyChain.java
new file mode 100644
index 00000000..739b561f
--- /dev/null
+++ b/core/src/main/java/org/bitcoinj/wallet/MarriedKeyChain.java
@@ -0,0 +1,286 @@
+/**
+ * Copyright 2013 The bitcoinj developers.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.bitcoinj.wallet;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Lists;
+import com.google.protobuf.ByteString;
+
+import org.bitcoinj.core.BloomFilter;
+import org.bitcoinj.core.ECKey;
+import org.bitcoinj.core.NetworkParameters;
+import org.bitcoinj.core.Utils;
+import org.bitcoinj.crypto.DeterministicKey;
+import org.bitcoinj.crypto.KeyCrypter;
+import org.bitcoinj.script.Script;
+import org.bitcoinj.script.ScriptBuilder;
+
+import java.security.SecureRandom;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+import javax.annotation.Nullable;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkState;
+
+/**
+ * <p>A multi-signature keychain using synchronized HD keys (a.k.a HDM)</p>
+ * <p>This keychain keeps track of following keychains that follow the account key of this keychain.
+ * You can get P2SH addresses to receive coins to from this chain. The threshold - sigsRequiredToSpend
+ * specifies how many signatures required to spend transactions for this married keychain. This value should not exceed
+ * total number of keys involved (one followed key plus number of following keys), otherwise IllegalArgumentException
+ * will be thrown.</p>
+ * <p>IMPORTANT: As of Bitcoin Core 0.9 all multisig transactions which require more than 3 public keys are non-standard
+ * and such spends won't be processed by peers with default settings, essentially making such transactions almost
+ * nonspendable</p>
+ * <p>This method will throw an IllegalStateException, if the keychain is already married or already has leaf keys
+ * issued.</p>
+ */
+public class MarriedKeyChain extends DeterministicKeyChain {
+    // The map holds P2SH redeem script and corresponding ECKeys issued by this KeyChainGroup (including lookahead)
+    // mapped to redeem script hashes.
+    private LinkedHashMap<ByteString, RedeemData> marriedKeysRedeemData = new LinkedHashMap<ByteString, RedeemData>();
+
+    private List<DeterministicKeyChain> followingKeyChains;
+
+    /** Builds a {@link MarriedKeyChain} */
+    public static class Builder<T extends Builder<T>> extends DeterministicKeyChain.Builder<T> {
+        private List<DeterministicKey> followingKeys;
+        private int threshold;
+
+        protected Builder() {
+        }
+
+        public T followingKeys(List<DeterministicKey> followingKeys) {
+            this.followingKeys = followingKeys;
+            return self();
+        }
+
+        public T followingKeys(DeterministicKey followingKey, DeterministicKey ...followingKeys) {
+            this.followingKeys = Lists.asList(followingKey, followingKeys);
+            return self();
+        }
+
+        /**
+         * Threshold, or <code>(followingKeys.size() + 1) / 2 + 1)</code> (majority) if unspecified.</p>
+         * <p>IMPORTANT: As of Bitcoin Core 0.9 all multisig transactions which require more than 3 public keys are non-standard
+         * and such spends won't be processed by peers with default settings, essentially making such transactions almost
+         * nonspendable</p>
+         */
+        public T threshold(int threshold) {
+            this.threshold = threshold;
+            return self();
+        }
+
+        public MarriedKeyChain build() {
+            checkState(random != null || entropy != null || seed != null, "Must provide either entropy or random");
+            checkNotNull(followingKeys, "followingKeys must be provided");
+            MarriedKeyChain chain;
+            if (threshold == 0)
+                threshold = (followingKeys.size() + 1) / 2 + 1;
+            if (random != null) {
+                chain = new MarriedKeyChain(random, bits, passphrase, seedCreationTimeSecs);
+            } else if (entropy != null) {
+                chain = new MarriedKeyChain(entropy, passphrase, seedCreationTimeSecs);
+            } else {
+                chain = new MarriedKeyChain(seed);
+            }
+            chain.addFollowingAccountKeys(followingKeys, threshold);
+            return chain;
+        }
+    }
+
+    public static Builder<?> builder() {
+        return new Builder();
+    }
+
+    // Protobuf deserialization constructors
+    MarriedKeyChain(DeterministicKey accountKey) {
+        super(accountKey, false);
+    }
+
+    MarriedKeyChain(DeterministicSeed seed, KeyCrypter crypter) {
+        super(seed, crypter);
+    }
+
+    // Builder constructors
+    private MarriedKeyChain(SecureRandom random, int bits, String passphrase, long seedCreationTimeSecs) {
+        super(random, bits, passphrase, seedCreationTimeSecs);
+    }
+
+    private MarriedKeyChain(byte[] entropy, String passphrase, long seedCreationTimeSecs) {
+        super(entropy, passphrase, seedCreationTimeSecs);
+    }
+
+    private MarriedKeyChain(DeterministicSeed seed) {
+        super(seed);
+    }
+
+    void setFollowingKeyChains(List<DeterministicKeyChain> followingKeyChains) {
+        checkArgument(!followingKeyChains.isEmpty());
+        this.followingKeyChains = followingKeyChains;
+    }
+
+    @Override
+    public boolean isMarried() {
+        return true;
+    }
+
+    /** Create a new married key and return the matching output script */
+    @Override
+    public Script freshOutputScript(KeyPurpose purpose) {
+        DeterministicKey followedKey = getKey(purpose);
+        ImmutableList.Builder<ECKey> keys = ImmutableList.<ECKey>builder().add(followedKey);
+        for (DeterministicKeyChain keyChain : followingKeyChains) {
+            DeterministicKey followingKey = keyChain.getKey(purpose);
+            checkState(followedKey.getChildNumber().equals(followingKey.getChildNumber()), "Following keychains should be in sync");
+            keys.add(followingKey);
+        }
+        List<ECKey> marriedKeys = keys.build();
+        Script redeemScript = ScriptBuilder.createRedeemScript(sigsRequiredToSpend, marriedKeys);
+        return ScriptBuilder.createP2SHOutputScript(redeemScript);
+    }
+
+    private List<ECKey> getMarriedKeysWithFollowed(DeterministicKey followedKey) {
+        ImmutableList.Builder<ECKey> keys = ImmutableList.builder();
+        for (DeterministicKeyChain keyChain : followingKeyChains) {
+            keyChain.maybeLookAhead();
+            keys.add(keyChain.getKeyByPath(followedKey.getPath()));
+        }
+        keys.add(followedKey);
+        return keys.build();
+    }
+
+    /** Get the redeem data for a key in this married chain */
+    @Override
+    public RedeemData getRedeemData(DeterministicKey followedKey) {
+        checkState(isMarried());
+        List<ECKey> marriedKeys = getMarriedKeysWithFollowed(followedKey);
+        Script redeemScript = ScriptBuilder.createRedeemScript(sigsRequiredToSpend, marriedKeys);
+        return RedeemData.of(marriedKeys, redeemScript);
+    }
+
+    private void addFollowingAccountKeys(List<DeterministicKey> followingAccountKeys, int sigsRequiredToSpend) {
+        checkArgument(sigsRequiredToSpend <= followingAccountKeys.size() + 1, "Multisig threshold can't exceed total number of keys");
+        checkState(numLeafKeysIssued() == 0, "Active keychain already has keys in use");
+        checkState(followingKeyChains == null);
+
+        List<DeterministicKeyChain> followingKeyChains = Lists.newArrayList();
+
+        for (DeterministicKey key : followingAccountKeys) {
+            checkArgument(key.getPath().size() == 1, "Following keys have to be account keys");
+            DeterministicKeyChain chain = DeterministicKeyChain.watchAndFollow(key);
+            if (lookaheadSize >= 0)
+                chain.setLookaheadSize(lookaheadSize);
+            if (lookaheadThreshold >= 0)
+                chain.setLookaheadThreshold(lookaheadThreshold);
+            followingKeyChains.add(chain);
+        }
+
+        this.sigsRequiredToSpend = sigsRequiredToSpend;
+        this.followingKeyChains = followingKeyChains;
+    }
+
+    @Override
+    public void setLookaheadSize(int lookaheadSize) {
+        lock.lock();
+        try {
+            super.setLookaheadSize(lookaheadSize);
+            if (followingKeyChains != null) {
+                for (DeterministicKeyChain followingChain : followingKeyChains) {
+                    followingChain.setLookaheadSize(lookaheadSize);
+                }
+            }
+        } finally {
+            lock.unlock();
+        }
+    }
+
+    @Override
+    protected void beforeSerializeToProtobuf(List<Protos.Key> result) {
+        super.beforeSerializeToProtobuf(result);
+        for (DeterministicKeyChain chain : followingKeyChains) {
+            result.addAll(chain.serializeMyselfToProtobuf());
+        }
+    }
+
+    @Override
+    protected void formatAddresses(boolean includePrivateKeys, NetworkParameters params, StringBuilder builder2) {
+        for (DeterministicKeyChain followingChain : followingKeyChains) {
+            builder2.append(String.format("Following chain:  %s%n", followingChain.getWatchingKey().serializePubB58()));
+        }
+        builder2.append(String.format("%n"));
+        for (RedeemData redeemData : marriedKeysRedeemData.values())
+            formatScript(ScriptBuilder.createP2SHOutputScript(redeemData.redeemScript), builder2, params);
+    }
+
+    private void formatScript(Script script, StringBuilder builder, NetworkParameters params) {
+        builder.append("  addr:");
+        builder.append(script.getToAddress(params));
+        builder.append("  hash160:");
+        builder.append(Utils.HEX.encode(script.getPubKeyHash()));
+        builder.append("\n");
+    }
+
+    @Override
+    public void maybeLookAheadScripts() {
+        super.maybeLookAheadScripts();
+        int numLeafKeys = getLeafKeys().size();
+
+        checkState(marriedKeysRedeemData.size() <= numLeafKeys, "Number of scripts is greater than number of leaf keys");
+        if (marriedKeysRedeemData.size() == numLeafKeys)
+            return;
+
+        maybeLookAhead();
+        for (DeterministicKey followedKey : getLeafKeys()) {
+            RedeemData redeemData = getRedeemData(followedKey);
+            Script scriptPubKey = ScriptBuilder.createP2SHOutputScript(redeemData.redeemScript);
+            marriedKeysRedeemData.put(ByteString.copyFrom(scriptPubKey.getPubKeyHash()), redeemData);
+        }
+    }
+
+    @Nullable
+    @Override
+    public RedeemData findRedeemDataByScriptHash(ByteString bytes) {
+        return marriedKeysRedeemData.get(bytes);
+    }
+
+    @Override
+    public BloomFilter getFilter(int size, double falsePositiveRate, long tweak) {
+        lock.lock();
+        BloomFilter filter;
+        try {
+            filter = new BloomFilter(size, falsePositiveRate, tweak);
+            for (Map.Entry<ByteString, RedeemData> entry : marriedKeysRedeemData.entrySet()) {
+                filter.insert(entry.getKey().toByteArray());
+                filter.insert(entry.getValue().redeemScript.getProgram());
+            }
+        } finally {
+            lock.unlock();
+        }
+        return filter;
+    }
+
+    @Override
+    public int numBloomFilterEntries() {
+        maybeLookAhead();
+        return getLeafKeys().size() * 2;
+    }
+}
diff --git a/core/src/main/java/org/bitcoinj/wallet/Protos.java b/core/src/main/java/org/bitcoinj/wallet/Protos.java
index 75eba3b4..f10b447f 100644
--- a/core/src/main/java/org/bitcoinj/wallet/Protos.java
+++ b/core/src/main/java/org/bitcoinj/wallet/Protos.java
@@ -1269,6 +1269,26 @@ public final class Protos {
      * </pre>
      */
     boolean getIsFollowing();
+
+    // optional uint32 sigsRequiredToSpend = 6 [default = 1];
+    /**
+     * <code>optional uint32 sigsRequiredToSpend = 6 [default = 1];</code>
+     *
+     * <pre>
+     * Number of signatures required to spend. This field is needed only for married keychains to reconstruct KeyChain
+     * and represents the N value from N-of-M CHECKMULTISIG script. For regular single keychains it will always be 1.
+     * </pre>
+     */
+    boolean hasSigsRequiredToSpend();
+    /**
+     * <code>optional uint32 sigsRequiredToSpend = 6 [default = 1];</code>
+     *
+     * <pre>
+     * Number of signatures required to spend. This field is needed only for married keychains to reconstruct KeyChain
+     * and represents the N value from N-of-M CHECKMULTISIG script. For regular single keychains it will always be 1.
+     * </pre>
+     */
+    int getSigsRequiredToSpend();
   }
   /**
    * Protobuf type {@code wallet.DeterministicKey}
@@ -1367,6 +1387,11 @@ public final class Protos {
               isFollowing_ = input.readBool();
               break;
             }
+            case 48: {
+              bitField0_ |= 0x00000010;
+              sigsRequiredToSpend_ = input.readUInt32();
+              break;
+            }
           }
         }
       } catch (com.google.protobuf.InvalidProtocolBufferException e) {
@@ -1554,12 +1579,39 @@ public final class Protos {
       return isFollowing_;
     }
 
+    // optional uint32 sigsRequiredToSpend = 6 [default = 1];
+    public static final int SIGSREQUIREDTOSPEND_FIELD_NUMBER = 6;
+    private int sigsRequiredToSpend_;
+    /**
+     * <code>optional uint32 sigsRequiredToSpend = 6 [default = 1];</code>
+     *
+     * <pre>
+     * Number of signatures required to spend. This field is needed only for married keychains to reconstruct KeyChain
+     * and represents the N value from N-of-M CHECKMULTISIG script. For regular single keychains it will always be 1.
+     * </pre>
+     */
+    public boolean hasSigsRequiredToSpend() {
+      return ((bitField0_ & 0x00000010) == 0x00000010);
+    }
+    /**
+     * <code>optional uint32 sigsRequiredToSpend = 6 [default = 1];</code>
+     *
+     * <pre>
+     * Number of signatures required to spend. This field is needed only for married keychains to reconstruct KeyChain
+     * and represents the N value from N-of-M CHECKMULTISIG script. For regular single keychains it will always be 1.
+     * </pre>
+     */
+    public int getSigsRequiredToSpend() {
+      return sigsRequiredToSpend_;
+    }
+
     private void initFields() {
       chainCode_ = com.google.protobuf.ByteString.EMPTY;
       path_ = java.util.Collections.emptyList();
       issuedSubkeys_ = 0;
       lookaheadSize_ = 0;
       isFollowing_ = false;
+      sigsRequiredToSpend_ = 1;
     }
     private byte memoizedIsInitialized = -1;
     public final boolean isInitialized() {
@@ -1592,6 +1644,9 @@ public final class Protos {
       if (((bitField0_ & 0x00000008) == 0x00000008)) {
         output.writeBool(5, isFollowing_);
       }
+      if (((bitField0_ & 0x00000010) == 0x00000010)) {
+        output.writeUInt32(6, sigsRequiredToSpend_);
+      }
       getUnknownFields().writeTo(output);
     }
 
@@ -1626,6 +1681,10 @@ public final class Protos {
         size += com.google.protobuf.CodedOutputStream
           .computeBoolSize(5, isFollowing_);
       }
+      if (((bitField0_ & 0x00000010) == 0x00000010)) {
+        size += com.google.protobuf.CodedOutputStream
+          .computeUInt32Size(6, sigsRequiredToSpend_);
+      }
       size += getUnknownFields().getSerializedSize();
       memoizedSerializedSize = size;
       return size;
@@ -1757,6 +1816,8 @@ public final class Protos {
         bitField0_ = (bitField0_ & ~0x00000008);
         isFollowing_ = false;
         bitField0_ = (bitField0_ & ~0x00000010);
+        sigsRequiredToSpend_ = 1;
+        bitField0_ = (bitField0_ & ~0x00000020);
         return this;
       }
 
@@ -1806,6 +1867,10 @@ public final class Protos {
           to_bitField0_ |= 0x00000008;
         }
         result.isFollowing_ = isFollowing_;
+        if (((from_bitField0_ & 0x00000020) == 0x00000020)) {
+          to_bitField0_ |= 0x00000010;
+        }
+        result.sigsRequiredToSpend_ = sigsRequiredToSpend_;
         result.bitField0_ = to_bitField0_;
         onBuilt();
         return result;
@@ -1844,6 +1909,9 @@ public final class Protos {
         if (other.hasIsFollowing()) {
           setIsFollowing(other.getIsFollowing());
         }
+        if (other.hasSigsRequiredToSpend()) {
+          setSigsRequiredToSpend(other.getSigsRequiredToSpend());
+        }
         this.mergeUnknownFields(other.getUnknownFields());
         return this;
       }
@@ -2195,6 +2263,59 @@ public final class Protos {
         return this;
       }
 
+      // optional uint32 sigsRequiredToSpend = 6 [default = 1];
+      private int sigsRequiredToSpend_ = 1;
+      /**
+       * <code>optional uint32 sigsRequiredToSpend = 6 [default = 1];</code>
+       *
+       * <pre>
+       * Number of signatures required to spend. This field is needed only for married keychains to reconstruct KeyChain
+       * and represents the N value from N-of-M CHECKMULTISIG script. For regular single keychains it will always be 1.
+       * </pre>
+       */
+      public boolean hasSigsRequiredToSpend() {
+        return ((bitField0_ & 0x00000020) == 0x00000020);
+      }
+      /**
+       * <code>optional uint32 sigsRequiredToSpend = 6 [default = 1];</code>
+       *
+       * <pre>
+       * Number of signatures required to spend. This field is needed only for married keychains to reconstruct KeyChain
+       * and represents the N value from N-of-M CHECKMULTISIG script. For regular single keychains it will always be 1.
+       * </pre>
+       */
+      public int getSigsRequiredToSpend() {
+        return sigsRequiredToSpend_;
+      }
+      /**
+       * <code>optional uint32 sigsRequiredToSpend = 6 [default = 1];</code>
+       *
+       * <pre>
+       * Number of signatures required to spend. This field is needed only for married keychains to reconstruct KeyChain
+       * and represents the N value from N-of-M CHECKMULTISIG script. For regular single keychains it will always be 1.
+       * </pre>
+       */
+      public Builder setSigsRequiredToSpend(int value) {
+        bitField0_ |= 0x00000020;
+        sigsRequiredToSpend_ = value;
+        onChanged();
+        return this;
+      }
+      /**
+       * <code>optional uint32 sigsRequiredToSpend = 6 [default = 1];</code>
+       *
+       * <pre>
+       * Number of signatures required to spend. This field is needed only for married keychains to reconstruct KeyChain
+       * and represents the N value from N-of-M CHECKMULTISIG script. For regular single keychains it will always be 1.
+       * </pre>
+       */
+      public Builder clearSigsRequiredToSpend() {
+        bitField0_ = (bitField0_ & ~0x00000020);
+        sigsRequiredToSpend_ = 1;
+        onChanged();
+        return this;
+      }
+
       // @@protoc_insertion_point(builder_scope:wallet.DeterministicKey)
     }
 
@@ -14291,26 +14412,6 @@ public final class Protos {
      */
     org.bitcoinj.wallet.Protos.TransactionSignerOrBuilder getTransactionSignersOrBuilder(
         int index);
-
-    // optional uint32 sigsRequiredToSpend = 18 [default = 1];
-    /**
-     * <code>optional uint32 sigsRequiredToSpend = 18 [default = 1];</code>
-     *
-     * <pre>
-     * Number of signatures required to spend. This field is needed only for married wallets to reconstruct KeyChainGroup
-     * and represents the N value from N-of-M CHECKMULTISIG script. For regular single wallets it will always be 1.
-     * </pre>
-     */
-    boolean hasSigsRequiredToSpend();
-    /**
-     * <code>optional uint32 sigsRequiredToSpend = 18 [default = 1];</code>
-     *
-     * <pre>
-     * Number of signatures required to spend. This field is needed only for married wallets to reconstruct KeyChainGroup
-     * and represents the N value from N-of-M CHECKMULTISIG script. For regular single wallets it will always be 1.
-     * </pre>
-     */
-    int getSigsRequiredToSpend();
   }
   /**
    * Protobuf type {@code wallet.Wallet}
@@ -14474,11 +14575,6 @@ public final class Protos {
               transactionSigners_.add(input.readMessage(org.bitcoinj.wallet.Protos.TransactionSigner.PARSER, extensionRegistry));
               break;
             }
-            case 144: {
-              bitField0_ |= 0x00000200;
-              sigsRequiredToSpend_ = input.readUInt32();
-              break;
-            }
           }
         }
       } catch (com.google.protobuf.InvalidProtocolBufferException e) {
@@ -15146,32 +15242,6 @@ public final class Protos {
       return transactionSigners_.get(index);
     }
 
-    // optional uint32 sigsRequiredToSpend = 18 [default = 1];
-    public static final int SIGSREQUIREDTOSPEND_FIELD_NUMBER = 18;
-    private int sigsRequiredToSpend_;
-    /**
-     * <code>optional uint32 sigsRequiredToSpend = 18 [default = 1];</code>
-     *
-     * <pre>
-     * Number of signatures required to spend. This field is needed only for married wallets to reconstruct KeyChainGroup
-     * and represents the N value from N-of-M CHECKMULTISIG script. For regular single wallets it will always be 1.
-     * </pre>
-     */
-    public boolean hasSigsRequiredToSpend() {
-      return ((bitField0_ & 0x00000200) == 0x00000200);
-    }
-    /**
-     * <code>optional uint32 sigsRequiredToSpend = 18 [default = 1];</code>
-     *
-     * <pre>
-     * Number of signatures required to spend. This field is needed only for married wallets to reconstruct KeyChainGroup
-     * and represents the N value from N-of-M CHECKMULTISIG script. For regular single wallets it will always be 1.
-     * </pre>
-     */
-    public int getSigsRequiredToSpend() {
-      return sigsRequiredToSpend_;
-    }
-
     private void initFields() {
       networkIdentifier_ = "";
       lastSeenBlockHash_ = com.google.protobuf.ByteString.EMPTY;
@@ -15188,7 +15258,6 @@ public final class Protos {
       keyRotationTime_ = 0L;
       tags_ = java.util.Collections.emptyList();
       transactionSigners_ = java.util.Collections.emptyList();
-      sigsRequiredToSpend_ = 1;
     }
     private byte memoizedIsInitialized = -1;
     public final boolean isInitialized() {
@@ -15293,9 +15362,6 @@ public final class Protos {
       for (int i = 0; i < transactionSigners_.size(); i++) {
         output.writeMessage(17, transactionSigners_.get(i));
       }
-      if (((bitField0_ & 0x00000200) == 0x00000200)) {
-        output.writeUInt32(18, sigsRequiredToSpend_);
-      }
       getUnknownFields().writeTo(output);
     }
 
@@ -15365,10 +15431,6 @@ public final class Protos {
         size += com.google.protobuf.CodedOutputStream
           .computeMessageSize(17, transactionSigners_.get(i));
       }
-      if (((bitField0_ & 0x00000200) == 0x00000200)) {
-        size += com.google.protobuf.CodedOutputStream
-          .computeUInt32Size(18, sigsRequiredToSpend_);
-      }
       size += getUnknownFields().getSerializedSize();
       memoizedSerializedSize = size;
       return size;
@@ -15554,8 +15616,6 @@ public final class Protos {
         } else {
           transactionSignersBuilder_.clear();
         }
-        sigsRequiredToSpend_ = 1;
-        bitField0_ = (bitField0_ & ~0x00008000);
         return this;
       }
 
@@ -15678,10 +15738,6 @@ public final class Protos {
         } else {
           result.transactionSigners_ = transactionSignersBuilder_.build();
         }
-        if (((from_bitField0_ & 0x00008000) == 0x00008000)) {
-          to_bitField0_ |= 0x00000200;
-        }
-        result.sigsRequiredToSpend_ = sigsRequiredToSpend_;
         result.bitField0_ = to_bitField0_;
         onBuilt();
         return result;
@@ -15885,9 +15941,6 @@ public final class Protos {
             }
           }
         }
-        if (other.hasSigsRequiredToSpend()) {
-          setSigsRequiredToSpend(other.getSigsRequiredToSpend());
-        }
         this.mergeUnknownFields(other.getUnknownFields());
         return this;
       }
@@ -18066,59 +18119,6 @@ public final class Protos {
         return transactionSignersBuilder_;
       }
 
-      // optional uint32 sigsRequiredToSpend = 18 [default = 1];
-      private int sigsRequiredToSpend_ = 1;
-      /**
-       * <code>optional uint32 sigsRequiredToSpend = 18 [default = 1];</code>
-       *
-       * <pre>
-       * Number of signatures required to spend. This field is needed only for married wallets to reconstruct KeyChainGroup
-       * and represents the N value from N-of-M CHECKMULTISIG script. For regular single wallets it will always be 1.
-       * </pre>
-       */
-      public boolean hasSigsRequiredToSpend() {
-        return ((bitField0_ & 0x00008000) == 0x00008000);
-      }
-      /**
-       * <code>optional uint32 sigsRequiredToSpend = 18 [default = 1];</code>
-       *
-       * <pre>
-       * Number of signatures required to spend. This field is needed only for married wallets to reconstruct KeyChainGroup
-       * and represents the N value from N-of-M CHECKMULTISIG script. For regular single wallets it will always be 1.
-       * </pre>
-       */
-      public int getSigsRequiredToSpend() {
-        return sigsRequiredToSpend_;
-      }
-      /**
-       * <code>optional uint32 sigsRequiredToSpend = 18 [default = 1];</code>
-       *
-       * <pre>
-       * Number of signatures required to spend. This field is needed only for married wallets to reconstruct KeyChainGroup
-       * and represents the N value from N-of-M CHECKMULTISIG script. For regular single wallets it will always be 1.
-       * </pre>
-       */
-      public Builder setSigsRequiredToSpend(int value) {
-        bitField0_ |= 0x00008000;
-        sigsRequiredToSpend_ = value;
-        onChanged();
-        return this;
-      }
-      /**
-       * <code>optional uint32 sigsRequiredToSpend = 18 [default = 1];</code>
-       *
-       * <pre>
-       * Number of signatures required to spend. This field is needed only for married wallets to reconstruct KeyChainGroup
-       * and represents the N value from N-of-M CHECKMULTISIG script. For regular single wallets it will always be 1.
-       * </pre>
-       */
-      public Builder clearSigsRequiredToSpend() {
-        bitField0_ = (bitField0_ & ~0x00008000);
-        sigsRequiredToSpend_ = 1;
-        onChanged();
-        return this;
-      }
-
       // @@protoc_insertion_point(builder_scope:wallet.Wallet)
     }
 
@@ -18995,81 +18995,81 @@ public final class Protos {
       "\nip_address\030\001 \002(\014\022\014\n\004port\030\002 \002(\r\022\020\n\010servi" +
       "ces\030\003 \002(\004\"M\n\rEncryptedData\022\035\n\025initialisa" +
       "tion_vector\030\001 \002(\014\022\035\n\025encrypted_private_k" +
-      "ey\030\002 \002(\014\"y\n\020DeterministicKey\022\022\n\nchain_co" +
-      "de\030\001 \002(\014\022\014\n\004path\030\002 \003(\r\022\026\n\016issued_subkeys" +
-      "\030\003 \001(\r\022\026\n\016lookahead_size\030\004 \001(\r\022\023\n\013isFoll" +
-      "owing\030\005 \001(\010\"\232\003\n\003Key\022\036\n\004type\030\001 \002(\0162\020.wall" +
-      "et.Key.Type\022\024\n\014secret_bytes\030\002 \001(\014\022-\n\016enc" +
-      "rypted_data\030\006 \001(\0132\025.wallet.EncryptedData",
-      "\022\022\n\npublic_key\030\003 \001(\014\022\r\n\005label\030\004 \001(\t\022\032\n\022c" +
-      "reation_timestamp\030\005 \001(\003\0223\n\021deterministic" +
-      "_key\030\007 \001(\0132\030.wallet.DeterministicKey\022\032\n\022" +
-      "deterministic_seed\030\010 \001(\014\022;\n\034encrypted_de" +
-      "terministic_seed\030\t \001(\0132\025.wallet.Encrypte" +
-      "dData\"a\n\004Type\022\014\n\010ORIGINAL\020\001\022\030\n\024ENCRYPTED" +
-      "_SCRYPT_AES\020\002\022\032\n\026DETERMINISTIC_MNEMONIC\020" +
-      "\003\022\025\n\021DETERMINISTIC_KEY\020\004\"5\n\006Script\022\017\n\007pr" +
-      "ogram\030\001 \002(\014\022\032\n\022creation_timestamp\030\002 \002(\003\"" +
-      "\222\001\n\020TransactionInput\022\"\n\032transaction_out_",
-      "point_hash\030\001 \002(\014\022#\n\033transaction_out_poin" +
-      "t_index\030\002 \002(\r\022\024\n\014script_bytes\030\003 \002(\014\022\020\n\010s" +
-      "equence\030\004 \001(\r\022\r\n\005value\030\005 \001(\003\"\177\n\021Transact" +
-      "ionOutput\022\r\n\005value\030\001 \002(\003\022\024\n\014script_bytes" +
-      "\030\002 \002(\014\022!\n\031spent_by_transaction_hash\030\003 \001(" +
-      "\014\022\"\n\032spent_by_transaction_index\030\004 \001(\005\"\211\003" +
-      "\n\025TransactionConfidence\0220\n\004type\030\001 \001(\0162\"." +
-      "wallet.TransactionConfidence.Type\022\032\n\022app" +
-      "eared_at_height\030\002 \001(\005\022\036\n\026overriding_tran" +
-      "saction\030\003 \001(\014\022\r\n\005depth\030\004 \001(\005\022)\n\014broadcas",
-      "t_by\030\006 \003(\0132\023.wallet.PeerAddress\0224\n\006sourc" +
-      "e\030\007 \001(\0162$.wallet.TransactionConfidence.S" +
-      "ource\"O\n\004Type\022\013\n\007UNKNOWN\020\000\022\014\n\010BUILDING\020\001" +
-      "\022\013\n\007PENDING\020\002\022\025\n\021NOT_IN_BEST_CHAIN\020\003\022\010\n\004" +
-      "DEAD\020\004\"A\n\006Source\022\022\n\016SOURCE_UNKNOWN\020\000\022\022\n\016" +
-      "SOURCE_NETWORK\020\001\022\017\n\013SOURCE_SELF\020\002\"\264\005\n\013Tr" +
-      "ansaction\022\017\n\007version\030\001 \002(\005\022\014\n\004hash\030\002 \002(\014" +
-      "\022&\n\004pool\030\003 \001(\0162\030.wallet.Transaction.Pool" +
-      "\022\021\n\tlock_time\030\004 \001(\r\022\022\n\nupdated_at\030\005 \001(\003\022" +
-      "3\n\021transaction_input\030\006 \003(\0132\030.wallet.Tran",
-      "sactionInput\0225\n\022transaction_output\030\007 \003(\013" +
-      "2\031.wallet.TransactionOutput\022\022\n\nblock_has" +
-      "h\030\010 \003(\014\022 \n\030block_relativity_offsets\030\013 \003(" +
-      "\005\0221\n\nconfidence\030\t \001(\0132\035.wallet.Transacti" +
-      "onConfidence\0225\n\007purpose\030\n \001(\0162\033.wallet.T" +
-      "ransaction.Purpose:\007UNKNOWN\022+\n\rexchange_" +
-      "rate\030\014 \001(\0132\024.wallet.ExchangeRate\022\014\n\004memo" +
-      "\030\r \001(\t\"Y\n\004Pool\022\013\n\007UNSPENT\020\004\022\t\n\005SPENT\020\005\022\014" +
-      "\n\010INACTIVE\020\002\022\010\n\004DEAD\020\n\022\013\n\007PENDING\020\020\022\024\n\020P" +
-      "ENDING_INACTIVE\020\022\"\224\001\n\007Purpose\022\013\n\007UNKNOWN",
-      "\020\000\022\020\n\014USER_PAYMENT\020\001\022\020\n\014KEY_ROTATION\020\002\022\034" +
-      "\n\030ASSURANCE_CONTRACT_CLAIM\020\003\022\035\n\031ASSURANC" +
-      "E_CONTRACT_PLEDGE\020\004\022\033\n\027ASSURANCE_CONTRAC" +
-      "T_STUB\020\005\"N\n\020ScryptParameters\022\014\n\004salt\030\001 \002" +
-      "(\014\022\020\n\001n\030\002 \001(\003:\00516384\022\014\n\001r\030\003 \001(\005:\0018\022\014\n\001p\030" +
-      "\004 \001(\005:\0011\"8\n\tExtension\022\n\n\002id\030\001 \002(\t\022\014\n\004dat" +
-      "a\030\002 \002(\014\022\021\n\tmandatory\030\003 \002(\010\" \n\003Tag\022\013\n\003tag" +
-      "\030\001 \002(\t\022\014\n\004data\030\002 \002(\014\"5\n\021TransactionSigne" +
-      "r\022\022\n\nclass_name\030\001 \002(\t\022\014\n\004data\030\002 \001(\014\"\211\005\n\006" +
-      "Wallet\022\032\n\022network_identifier\030\001 \002(\t\022\034\n\024la",
-      "st_seen_block_hash\030\002 \001(\014\022\036\n\026last_seen_bl" +
-      "ock_height\030\014 \001(\r\022!\n\031last_seen_block_time" +
-      "_secs\030\016 \001(\003\022\030\n\003key\030\003 \003(\0132\013.wallet.Key\022(\n" +
-      "\013transaction\030\004 \003(\0132\023.wallet.Transaction\022" +
-      "&\n\016watched_script\030\017 \003(\0132\016.wallet.Script\022" +
-      "C\n\017encryption_type\030\005 \001(\0162\035.wallet.Wallet" +
-      ".EncryptionType:\013UNENCRYPTED\0227\n\025encrypti" +
-      "on_parameters\030\006 \001(\0132\030.wallet.ScryptParam" +
-      "eters\022\022\n\007version\030\007 \001(\005:\0011\022$\n\textension\030\n" +
-      " \003(\0132\021.wallet.Extension\022\023\n\013description\030\013",
-      " \001(\t\022\031\n\021key_rotation_time\030\r \001(\004\022\031\n\004tags\030" +
-      "\020 \003(\0132\013.wallet.Tag\0226\n\023transaction_signer" +
-      "s\030\021 \003(\0132\031.wallet.TransactionSigner\022\036\n\023si" +
-      "gsRequiredToSpend\030\022 \001(\r:\0011\";\n\016Encryption" +
-      "Type\022\017\n\013UNENCRYPTED\020\001\022\030\n\024ENCRYPTED_SCRYP" +
-      "T_AES\020\002\"R\n\014ExchangeRate\022\022\n\ncoin_value\030\001 " +
-      "\002(\003\022\022\n\nfiat_value\030\002 \002(\003\022\032\n\022fiat_currency" +
-      "_code\030\003 \002(\tB\035\n\023org.bitcoinj.walletB\006Prot" +
-      "os"
+      "ey\030\002 \002(\014\"\231\001\n\020DeterministicKey\022\022\n\nchain_c" +
+      "ode\030\001 \002(\014\022\014\n\004path\030\002 \003(\r\022\026\n\016issued_subkey" +
+      "s\030\003 \001(\r\022\026\n\016lookahead_size\030\004 \001(\r\022\023\n\013isFol" +
+      "lowing\030\005 \001(\010\022\036\n\023sigsRequiredToSpend\030\006 \001(" +
+      "\r:\0011\"\232\003\n\003Key\022\036\n\004type\030\001 \002(\0162\020.wallet.Key." +
+      "Type\022\024\n\014secret_bytes\030\002 \001(\014\022-\n\016encrypted_",
+      "data\030\006 \001(\0132\025.wallet.EncryptedData\022\022\n\npub" +
+      "lic_key\030\003 \001(\014\022\r\n\005label\030\004 \001(\t\022\032\n\022creation" +
+      "_timestamp\030\005 \001(\003\0223\n\021deterministic_key\030\007 " +
+      "\001(\0132\030.wallet.DeterministicKey\022\032\n\022determi" +
+      "nistic_seed\030\010 \001(\014\022;\n\034encrypted_determini" +
+      "stic_seed\030\t \001(\0132\025.wallet.EncryptedData\"a" +
+      "\n\004Type\022\014\n\010ORIGINAL\020\001\022\030\n\024ENCRYPTED_SCRYPT" +
+      "_AES\020\002\022\032\n\026DETERMINISTIC_MNEMONIC\020\003\022\025\n\021DE" +
+      "TERMINISTIC_KEY\020\004\"5\n\006Script\022\017\n\007program\030\001" +
+      " \002(\014\022\032\n\022creation_timestamp\030\002 \002(\003\"\222\001\n\020Tra",
+      "nsactionInput\022\"\n\032transaction_out_point_h" +
+      "ash\030\001 \002(\014\022#\n\033transaction_out_point_index" +
+      "\030\002 \002(\r\022\024\n\014script_bytes\030\003 \002(\014\022\020\n\010sequence" +
+      "\030\004 \001(\r\022\r\n\005value\030\005 \001(\003\"\177\n\021TransactionOutp" +
+      "ut\022\r\n\005value\030\001 \002(\003\022\024\n\014script_bytes\030\002 \002(\014\022" +
+      "!\n\031spent_by_transaction_hash\030\003 \001(\014\022\"\n\032sp" +
+      "ent_by_transaction_index\030\004 \001(\005\"\211\003\n\025Trans" +
+      "actionConfidence\0220\n\004type\030\001 \001(\0162\".wallet." +
+      "TransactionConfidence.Type\022\032\n\022appeared_a" +
+      "t_height\030\002 \001(\005\022\036\n\026overriding_transaction",
+      "\030\003 \001(\014\022\r\n\005depth\030\004 \001(\005\022)\n\014broadcast_by\030\006 " +
+      "\003(\0132\023.wallet.PeerAddress\0224\n\006source\030\007 \001(\016" +
+      "2$.wallet.TransactionConfidence.Source\"O" +
+      "\n\004Type\022\013\n\007UNKNOWN\020\000\022\014\n\010BUILDING\020\001\022\013\n\007PEN" +
+      "DING\020\002\022\025\n\021NOT_IN_BEST_CHAIN\020\003\022\010\n\004DEAD\020\004\"" +
+      "A\n\006Source\022\022\n\016SOURCE_UNKNOWN\020\000\022\022\n\016SOURCE_" +
+      "NETWORK\020\001\022\017\n\013SOURCE_SELF\020\002\"\264\005\n\013Transacti" +
+      "on\022\017\n\007version\030\001 \002(\005\022\014\n\004hash\030\002 \002(\014\022&\n\004poo" +
+      "l\030\003 \001(\0162\030.wallet.Transaction.Pool\022\021\n\tloc" +
+      "k_time\030\004 \001(\r\022\022\n\nupdated_at\030\005 \001(\003\0223\n\021tran",
+      "saction_input\030\006 \003(\0132\030.wallet.Transaction" +
+      "Input\0225\n\022transaction_output\030\007 \003(\0132\031.wall" +
+      "et.TransactionOutput\022\022\n\nblock_hash\030\010 \003(\014" +
+      "\022 \n\030block_relativity_offsets\030\013 \003(\005\0221\n\nco" +
+      "nfidence\030\t \001(\0132\035.wallet.TransactionConfi" +
+      "dence\0225\n\007purpose\030\n \001(\0162\033.wallet.Transact" +
+      "ion.Purpose:\007UNKNOWN\022+\n\rexchange_rate\030\014 " +
+      "\001(\0132\024.wallet.ExchangeRate\022\014\n\004memo\030\r \001(\t\"" +
+      "Y\n\004Pool\022\013\n\007UNSPENT\020\004\022\t\n\005SPENT\020\005\022\014\n\010INACT" +
+      "IVE\020\002\022\010\n\004DEAD\020\n\022\013\n\007PENDING\020\020\022\024\n\020PENDING_",
+      "INACTIVE\020\022\"\224\001\n\007Purpose\022\013\n\007UNKNOWN\020\000\022\020\n\014U" +
+      "SER_PAYMENT\020\001\022\020\n\014KEY_ROTATION\020\002\022\034\n\030ASSUR" +
+      "ANCE_CONTRACT_CLAIM\020\003\022\035\n\031ASSURANCE_CONTR" +
+      "ACT_PLEDGE\020\004\022\033\n\027ASSURANCE_CONTRACT_STUB\020" +
+      "\005\"N\n\020ScryptParameters\022\014\n\004salt\030\001 \002(\014\022\020\n\001n" +
+      "\030\002 \001(\003:\00516384\022\014\n\001r\030\003 \001(\005:\0018\022\014\n\001p\030\004 \001(\005:\001" +
+      "1\"8\n\tExtension\022\n\n\002id\030\001 \002(\t\022\014\n\004data\030\002 \002(\014" +
+      "\022\021\n\tmandatory\030\003 \002(\010\" \n\003Tag\022\013\n\003tag\030\001 \002(\t\022" +
+      "\014\n\004data\030\002 \002(\014\"5\n\021TransactionSigner\022\022\n\ncl" +
+      "ass_name\030\001 \002(\t\022\014\n\004data\030\002 \001(\014\"\351\004\n\006Wallet\022",
+      "\032\n\022network_identifier\030\001 \002(\t\022\034\n\024last_seen" +
+      "_block_hash\030\002 \001(\014\022\036\n\026last_seen_block_hei" +
+      "ght\030\014 \001(\r\022!\n\031last_seen_block_time_secs\030\016" +
+      " \001(\003\022\030\n\003key\030\003 \003(\0132\013.wallet.Key\022(\n\013transa" +
+      "ction\030\004 \003(\0132\023.wallet.Transaction\022&\n\016watc" +
+      "hed_script\030\017 \003(\0132\016.wallet.Script\022C\n\017encr" +
+      "yption_type\030\005 \001(\0162\035.wallet.Wallet.Encryp" +
+      "tionType:\013UNENCRYPTED\0227\n\025encryption_para" +
+      "meters\030\006 \001(\0132\030.wallet.ScryptParameters\022\022" +
+      "\n\007version\030\007 \001(\005:\0011\022$\n\textension\030\n \003(\0132\021.",
+      "wallet.Extension\022\023\n\013description\030\013 \001(\t\022\031\n" +
+      "\021key_rotation_time\030\r \001(\004\022\031\n\004tags\030\020 \003(\0132\013" +
+      ".wallet.Tag\0226\n\023transaction_signers\030\021 \003(\013" +
+      "2\031.wallet.TransactionSigner\";\n\016Encryptio" +
+      "nType\022\017\n\013UNENCRYPTED\020\001\022\030\n\024ENCRYPTED_SCRY" +
+      "PT_AES\020\002\"R\n\014ExchangeRate\022\022\n\ncoin_value\030\001" +
+      " \002(\003\022\022\n\nfiat_value\030\002 \002(\003\022\032\n\022fiat_currenc" +
+      "y_code\030\003 \002(\tB\035\n\023org.bitcoinj.walletB\006Pro" +
+      "tos"
     };
     com.google.protobuf.Descriptors.FileDescriptor.InternalDescriptorAssigner assigner =
       new com.google.protobuf.Descriptors.FileDescriptor.InternalDescriptorAssigner() {
@@ -19093,7 +19093,7 @@ public final class Protos {
           internal_static_wallet_DeterministicKey_fieldAccessorTable = new
             com.google.protobuf.GeneratedMessage.FieldAccessorTable(
               internal_static_wallet_DeterministicKey_descriptor,
-              new java.lang.String[] { "ChainCode", "Path", "IssuedSubkeys", "LookaheadSize", "IsFollowing", });
+              new java.lang.String[] { "ChainCode", "Path", "IssuedSubkeys", "LookaheadSize", "IsFollowing", "SigsRequiredToSpend", });
           internal_static_wallet_Key_descriptor =
             getDescriptor().getMessageTypes().get(3);
           internal_static_wallet_Key_fieldAccessorTable = new
@@ -19159,7 +19159,7 @@ public final class Protos {
           internal_static_wallet_Wallet_fieldAccessorTable = new
             com.google.protobuf.GeneratedMessage.FieldAccessorTable(
               internal_static_wallet_Wallet_descriptor,
-              new java.lang.String[] { "NetworkIdentifier", "LastSeenBlockHash", "LastSeenBlockHeight", "LastSeenBlockTimeSecs", "Key", "Transaction", "WatchedScript", "EncryptionType", "EncryptionParameters", "Version", "Extension", "Description", "KeyRotationTime", "Tags", "TransactionSigners", "SigsRequiredToSpend", });
+              new java.lang.String[] { "NetworkIdentifier", "LastSeenBlockHash", "LastSeenBlockHeight", "LastSeenBlockTimeSecs", "Key", "Transaction", "WatchedScript", "EncryptionType", "EncryptionParameters", "Version", "Extension", "Description", "KeyRotationTime", "Tags", "TransactionSigners", });
           internal_static_wallet_ExchangeRate_descriptor =
             getDescriptor().getMessageTypes().get(14);
           internal_static_wallet_ExchangeRate_fieldAccessorTable = new
diff --git a/core/src/test/java/org/bitcoinj/core/WalletTest.java b/core/src/test/java/org/bitcoinj/core/WalletTest.java
index 04a6b77f..c3c82ae4 100644
--- a/core/src/test/java/org/bitcoinj/core/WalletTest.java
+++ b/core/src/test/java/org/bitcoinj/core/WalletTest.java
@@ -111,7 +111,11 @@ public class WalletTest extends TestWithWallet {
                 wallet.addTransactionSigner(new KeyChainTransactionSigner(keyChain));
         }
 
-        wallet.addFollowingAccountKeys(followingKeys, threshold);
+        MarriedKeyChain chain = MarriedKeyChain.builder()
+                .random(new SecureRandom())
+                .followingKeys(followingKeys)
+                .threshold(threshold).build();
+        wallet.addAndActivateHDChain(chain);
     }
 
     @Test
@@ -2652,7 +2656,11 @@ public class WalletTest extends TestWithWallet {
             }
         };
         wallet.addTransactionSigner(signer);
-        wallet.addFollowingAccountKeys(ImmutableList.of(partnerKey));
+        MarriedKeyChain chain = MarriedKeyChain.builder()
+                .random(new SecureRandom())
+                .followingKeys(partnerKey)
+                .build();
+        wallet.addAndActivateHDChain(chain);
 
         myAddress = wallet.currentAddress(KeyChain.KeyPurpose.RECEIVE_FUNDS);
         sendMoneyToWallet(wallet, COIN, myAddress, AbstractBlockChain.NewBlockType.BEST_CHAIN);
diff --git a/core/src/test/java/org/bitcoinj/store/WalletProtobufSerializerTest.java b/core/src/test/java/org/bitcoinj/store/WalletProtobufSerializerTest.java
index bed91ac5..67c300cc 100644
--- a/core/src/test/java/org/bitcoinj/store/WalletProtobufSerializerTest.java
+++ b/core/src/test/java/org/bitcoinj/store/WalletProtobufSerializerTest.java
@@ -31,6 +31,8 @@ import org.bitcoinj.wallet.DeterministicKeyChain;
 import org.bitcoinj.wallet.KeyChain;
 import com.google.common.collect.ImmutableList;
 import com.google.protobuf.ByteString;
+
+import org.bitcoinj.wallet.MarriedKeyChain;
 import org.bitcoinj.wallet.Protos;
 import org.junit.Before;
 import org.junit.Test;
@@ -287,16 +289,20 @@ public class WalletProtobufSerializerTest {
     public void testRoundTripMarriedWallet() throws Exception {
         // create 2-of-2 married wallet
         myWallet = new Wallet(params);
-        final DeterministicKeyChain keyChain = new DeterministicKeyChain(new SecureRandom());
-        DeterministicKey partnerKey = DeterministicKey.deserializeB58(null, keyChain.getWatchingKey().serializePubB58());
+        final DeterministicKeyChain partnerChain = new DeterministicKeyChain(new SecureRandom());
+        DeterministicKey partnerKey = DeterministicKey.deserializeB58(null, partnerChain.getWatchingKey().serializePubB58());
+        MarriedKeyChain chain = MarriedKeyChain.builder()
+                .random(new SecureRandom())
+                .followingKeys(partnerKey)
+                .threshold(2).build();
+        myWallet.addAndActivateHDChain(chain);
 
-        myWallet.addFollowingAccountKeys(ImmutableList.of(partnerKey), 2);
         myAddress = myWallet.currentAddress(KeyChain.KeyPurpose.RECEIVE_FUNDS);
 
         Wallet wallet1 = roundTrip(myWallet);
         assertEquals(0, wallet1.getTransactions(true).size());
         assertEquals(Coin.ZERO, wallet1.getBalance());
-        assertEquals(2, wallet1.getSigsRequiredToSpend());
+        assertEquals(2, wallet1.getActiveKeychain().getSigsRequiredToSpend());
         assertEquals(myAddress, wallet1.currentAddress(KeyChain.KeyPurpose.RECEIVE_FUNDS));
     }
 
diff --git a/core/src/test/java/org/bitcoinj/wallet/KeyChainGroupTest.java b/core/src/test/java/org/bitcoinj/wallet/KeyChainGroupTest.java
index 4e0520d7..8629d731 100644
--- a/core/src/test/java/org/bitcoinj/wallet/KeyChainGroupTest.java
+++ b/core/src/test/java/org/bitcoinj/wallet/KeyChainGroupTest.java
@@ -56,14 +56,24 @@ public class KeyChainGroupTest {
     }
 
     private KeyChainGroup createMarriedKeyChainGroup() {
-        byte[] entropy = Sha256Hash.create("don't use a seed like this in real life".getBytes()).getBytes();
-        DeterministicSeed seed = new DeterministicSeed(entropy, "", MnemonicCode.BIP39_STANDARDISATION_TIME_SECS);
-        KeyChainGroup group = new KeyChainGroup(params, seed, ImmutableList.of(watchingAccountKey), 2);
+        KeyChainGroup group = new KeyChainGroup(params);
+        DeterministicKeyChain chain = createMarriedKeyChain();
+        group.addAndActivateHDChain(chain);
         group.setLookaheadSize(LOOKAHEAD_SIZE);
         group.getActiveKeyChain();
         return group;
     }
 
+    private MarriedKeyChain createMarriedKeyChain() {
+        byte[] entropy = Sha256Hash.create("don't use a seed like this in real life".getBytes()).getBytes();
+        DeterministicSeed seed = new DeterministicSeed(entropy, "", MnemonicCode.BIP39_STANDARDISATION_TIME_SECS);
+        MarriedKeyChain chain = MarriedKeyChain.builder()
+                .seed(seed)
+                .followingKeys(watchingAccountKey)
+                .threshold(2).build();
+        return chain;
+    }
+
     @Test
     public void freshCurrentKeys() throws Exception {
         int numKeys = ((group.getLookaheadSize() + group.getLookaheadThreshold()) * 2)   // * 2 because of internal/external
@@ -400,7 +410,7 @@ public class KeyChainGroupTest {
     @Test
     public void serialization() throws Exception {
         assertEquals(INITIAL_KEYS + 1 /* for the seed */, group.serializeToProtobuf().size());
-        group = KeyChainGroup.fromProtobufUnencrypted(params, group.serializeToProtobuf(), 1);
+        group = KeyChainGroup.fromProtobufUnencrypted(params, group.serializeToProtobuf());
         group.freshKey(KeyChain.KeyPurpose.RECEIVE_FUNDS);
         DeterministicKey key1 = group.freshKey(KeyChain.KeyPurpose.RECEIVE_FUNDS);
         DeterministicKey key2 = group.freshKey(KeyChain.KeyPurpose.CHANGE);
@@ -411,13 +421,13 @@ public class KeyChainGroupTest {
         List<Protos.Key> protoKeys2 = group.serializeToProtobuf();
         assertEquals(INITIAL_KEYS + ((LOOKAHEAD_SIZE + 1) * 2) + 1 /* for the seed */ + 2, protoKeys2.size());
 
-        group = KeyChainGroup.fromProtobufUnencrypted(params, protoKeys1, 1);
+        group = KeyChainGroup.fromProtobufUnencrypted(params, protoKeys1);
         assertEquals(INITIAL_KEYS + ((LOOKAHEAD_SIZE + 1)  * 2)  + 1 /* for the seed */ + 1, protoKeys1.size());
         assertTrue(group.hasKey(key1));
         assertTrue(group.hasKey(key2));
         assertEquals(key2, group.currentKey(KeyChain.KeyPurpose.CHANGE));
         assertEquals(key1, group.currentKey(KeyChain.KeyPurpose.RECEIVE_FUNDS));
-        group = KeyChainGroup.fromProtobufUnencrypted(params, protoKeys2, 1);
+        group = KeyChainGroup.fromProtobufUnencrypted(params, protoKeys2);
         assertEquals(INITIAL_KEYS + ((LOOKAHEAD_SIZE + 1) * 2) + 1 /* for the seed */ + 2, protoKeys2.size());
         assertTrue(group.hasKey(key1));
         assertTrue(group.hasKey(key2));
@@ -426,7 +436,7 @@ public class KeyChainGroupTest {
         final KeyParameter aesKey = scrypt.deriveKey("password");
         group.encrypt(scrypt, aesKey);
         List<Protos.Key> protoKeys3 = group.serializeToProtobuf();
-        group = KeyChainGroup.fromProtobufEncrypted(params, protoKeys3, 1, scrypt);
+        group = KeyChainGroup.fromProtobufEncrypted(params, protoKeys3, scrypt);
         assertTrue(group.isEncrypted());
         assertTrue(group.checkPassword("password"));
         group.decrypt(aesKey);
@@ -443,7 +453,7 @@ public class KeyChainGroupTest {
         group.getBloomFilterElementCount();  // Force lookahead.
         List<Protos.Key> protoKeys1 = group.serializeToProtobuf();
         assertEquals(3 + (group.getLookaheadSize() + group.getLookaheadThreshold() + 1) * 2, protoKeys1.size());
-        group = KeyChainGroup.fromProtobufUnencrypted(params, protoKeys1, 1);
+        group = KeyChainGroup.fromProtobufUnencrypted(params, protoKeys1);
         assertEquals(3 + (group.getLookaheadSize() + group.getLookaheadThreshold() + 1) * 2, group.serializeToProtobuf().size());
     }
 
@@ -452,12 +462,12 @@ public class KeyChainGroupTest {
         group = createMarriedKeyChainGroup();
         Address address1 = group.currentAddress(KeyChain.KeyPurpose.RECEIVE_FUNDS);
         assertTrue(group.isMarried());
-        assertEquals(2, group.getSigsRequiredToSpend());
+        assertEquals(2, group.getActiveKeyChain().getSigsRequiredToSpend());
 
         List<Protos.Key> protoKeys = group.serializeToProtobuf();
-        KeyChainGroup group2 = KeyChainGroup.fromProtobufUnencrypted(params, protoKeys, 2);
+        KeyChainGroup group2 = KeyChainGroup.fromProtobufUnencrypted(params, protoKeys);
         assertTrue(group2.isMarried());
-        assertEquals(2, group.getSigsRequiredToSpend());
+        assertEquals(2, group.getActiveKeyChain().getSigsRequiredToSpend());
         Address address2 = group2.currentAddress(KeyChain.KeyPurpose.RECEIVE_FUNDS);
         assertEquals(address1, address2);
     }
@@ -465,23 +475,10 @@ public class KeyChainGroupTest {
     @Test
     public void addFollowingAccounts() throws Exception {
         assertFalse(group.isMarried());
-        group.addFollowingAccountKeys(ImmutableList.of(watchingAccountKey));
+        group.addAndActivateHDChain(createMarriedKeyChain());
         assertTrue(group.isMarried());
     }
 
-    @Test (expected = IllegalStateException.class)
-    public void addFollowingAccountsTwiceShouldFail() {
-        ImmutableList<DeterministicKey> followingKeys = ImmutableList.of(watchingAccountKey);
-        group.addFollowingAccountKeys(followingKeys);
-        group.addFollowingAccountKeys(followingKeys);
-    }
-
-    @Test (expected = IllegalStateException.class)
-    public void addFollowingAccountsForUsedKeychainShouldFail() {
-        group.freshAddress(KeyChain.KeyPurpose.RECEIVE_FUNDS);
-        group.addFollowingAccountKeys(ImmutableList.of(watchingAccountKey));
-    }
-
     @Test
     public void constructFromSeed() throws Exception {
         ECKey key1 = group.freshKey(KeyChain.KeyPurpose.RECEIVE_FUNDS);
@@ -519,7 +516,7 @@ public class KeyChainGroupTest {
         DeterministicSeed seed1 = group.getActiveKeyChain().getSeed();
         assertNotNull(seed1);
 
-        group = KeyChainGroup.fromProtobufUnencrypted(params, protobufs, 1);
+        group = KeyChainGroup.fromProtobufUnencrypted(params, protobufs);
         group.upgradeToDeterministic(0, null);  // Should give same result as last time.
         DeterministicKey dkey2 = group.freshKey(KeyChain.KeyPurpose.RECEIVE_FUNDS);
         DeterministicSeed seed2 = group.getActiveKeyChain().getSeed();
diff --git a/core/src/test/resources/org/bitcoinj/wallet/deterministic-wallet-serialization.txt b/core/src/test/resources/org/bitcoinj/wallet/deterministic-wallet-serialization.txt
index 33b501c1..5e648b16 100644
--- a/core/src/test/resources/org/bitcoinj/wallet/deterministic-wallet-serialization.txt
+++ b/core/src/test/resources/org/bitcoinj/wallet/deterministic-wallet-serialization.txt
@@ -28,6 +28,7 @@ deterministic_key {
   path: 0
   issued_subkeys: 2
   lookahead_size: 10
+  sigsRequiredToSpend: 1
 }
 
 type: DETERMINISTIC_KEY
@@ -39,6 +40,7 @@ deterministic_key {
   path: 1
   issued_subkeys: 1
   lookahead_size: 10
+  sigsRequiredToSpend: 1
 }
 
 type: DETERMINISTIC_KEY
diff --git a/core/src/test/resources/org/bitcoinj/wallet/watching-wallet-serialization.txt b/core/src/test/resources/org/bitcoinj/wallet/watching-wallet-serialization.txt
index d4b79408..8ab174ab 100644
--- a/core/src/test/resources/org/bitcoinj/wallet/watching-wallet-serialization.txt
+++ b/core/src/test/resources/org/bitcoinj/wallet/watching-wallet-serialization.txt
@@ -14,6 +14,7 @@ deterministic_key {
   path: 0
   issued_subkeys: 2
   lookahead_size: 10
+  sigsRequiredToSpend: 1
 }
 
 type: DETERMINISTIC_KEY
@@ -24,6 +25,7 @@ deterministic_key {
   path: 1
   issued_subkeys: 1
   lookahead_size: 10
+  sigsRequiredToSpend: 1
 }
 
 type: DETERMINISTIC_KEY
diff --git a/core/src/wallet.proto b/core/src/wallet.proto
index 4aa4d921..27dad389 100644
--- a/core/src/wallet.proto
+++ b/core/src/wallet.proto
@@ -66,6 +66,10 @@ message DeterministicKey {
    * a single P2SH multisignature address
    */
   optional bool isFollowing = 5;
+
+  // Number of signatures required to spend. This field is needed only for married keychains to reconstruct KeyChain
+  // and represents the N value from N-of-M CHECKMULTISIG script. For regular single keychains it will always be 1.
+  optional uint32 sigsRequiredToSpend = 6 [default = 1];
 }
 
 /**
@@ -379,11 +383,7 @@ message Wallet {
   // transaction signers added to the wallet
   repeated TransactionSigner transaction_signers = 17;
 
-  // Number of signatures required to spend. This field is needed only for married wallets to reconstruct KeyChainGroup
-  // and represents the N value from N-of-M CHECKMULTISIG script. For regular single wallets it will always be 1.
-  optional uint32 sigsRequiredToSpend = 18 [default = 1];
-
-  // Next tag: 19
+  // Next tag: 18
 }
 
 /** An exchange rate between Bitcoin and some fiat currency. */
diff --git a/tools/src/main/java/org/bitcoinj/tools/WalletTool.java b/tools/src/main/java/org/bitcoinj/tools/WalletTool.java
index c255c7c4..084ad256 100644
--- a/tools/src/main/java/org/bitcoinj/tools/WalletTool.java
+++ b/tools/src/main/java/org/bitcoinj/tools/WalletTool.java
@@ -48,6 +48,8 @@ import joptsimple.OptionParser;
 import joptsimple.OptionSet;
 import joptsimple.OptionSpec;
 import joptsimple.util.DateConverter;
+
+import org.bitcoinj.wallet.MarriedKeyChain;
 import org.bitcoinj.wallet.Protos;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -59,6 +61,7 @@ import java.io.*;
 import java.math.BigInteger;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
+import java.security.SecureRandom;
 import java.text.ParseException;
 import java.util.Date;
 import java.util.List;
@@ -428,7 +431,11 @@ public class WalletTool {
         for (String xpubkey : xpubkeys) {
             keys.add(DeterministicKey.deserializeB58(null, xpubkey.trim()));
         }
-        wallet.addFollowingAccountKeys(keys.build());
+        MarriedKeyChain chain = MarriedKeyChain.builder()
+                .random(new SecureRandom())
+                .followingKeys(keys.build())
+                .build();
+        wallet.addAndActivateHDChain(chain);
     }
 
     private static void rotate() throws BlockStoreException {