diff --git a/lib/bcoin/hd.js b/lib/bcoin/hd.js
index c5497e0e..779a6b2f 100644
--- a/lib/bcoin/hd.js
+++ b/lib/bcoin/hd.js
@@ -821,6 +821,26 @@ HD.isHD = function isHD(obj) {
     || HDPublicKey.isHDPublicKey(obj);
 };
 
+/**
+ * Test whether an object is an HD private key.
+ * @param {Object} obj
+ * @returns {Boolean}
+ */
+
+HD.isPrivate = function isPrivate(obj) {
+  return HDPrivateKey.isHDPrivateKey(obj);
+};
+
+/**
+ * Test whether an object is an HD public key.
+ * @param {Object} obj
+ * @returns {Boolean}
+ */
+
+HD.isPublic = function isPublic(obj) {
+  return HDPublicKey.isHDPublicKey(obj);
+};
+
 /**
  * HDPrivateKey
  * @exports HDPrivateKey
@@ -1223,6 +1243,46 @@ HDPrivateKey.prototype.equal = function equal(obj) {
     && utils.equal(this.privateKey, obj.privateKey);
 };
 
+/**
+ * Compare a key against an object.
+ * @param {Object} obj
+ * @returns {Boolean}
+ */
+
+HDPrivateKey.prototype.compare = function compare(key) {
+  var cmp;
+
+  if (!HDPrivateKey.isHDPrivateKey(key))
+    return 1;
+
+  cmp = this.depth - key.depth;
+
+  if (cmp !== 0)
+    return cmp;
+
+  cmp = utils.cmp(this.parentFingerPrint, key.parentFingerPrint);
+
+  if (cmp !== 0)
+    return cmp;
+
+  cmp = this.childIndex - key.childIndex;
+
+  if (cmp !== 0)
+    return cmp;
+
+  cmp = utils.cmp(this.chainCode, key.chainCode);
+
+  if (cmp !== 0)
+    return cmp;
+
+  cmp = utils.cmp(this.privateKey, key.privateKey);
+
+  if (cmp !== 0)
+    return cmp;
+
+  return 0;
+};
+
 /**
  * Inject properties from seed.
  * @private
@@ -1838,6 +1898,46 @@ HDPublicKey.prototype.equal = function equal(obj) {
     && utils.equal(this.publicKey, obj.publicKey);
 };
 
+/**
+ * Compare a key against an object.
+ * @param {Object} obj
+ * @returns {Boolean}
+ */
+
+HDPublicKey.prototype.compare = function compare(key) {
+  var cmp;
+
+  if (!HDPublicKey.isHDPublicKey(key))
+    return 1;
+
+  cmp = this.depth - key.depth;
+
+  if (cmp !== 0)
+    return cmp;
+
+  cmp = utils.cmp(this.parentFingerPrint, key.parentFingerPrint);
+
+  if (cmp !== 0)
+    return cmp;
+
+  cmp = this.childIndex - key.childIndex;
+
+  if (cmp !== 0)
+    return cmp;
+
+  cmp = utils.cmp(this.chainCode, key.chainCode);
+
+  if (cmp !== 0)
+    return cmp;
+
+  cmp = utils.cmp(this.publicKey, key.publicKey);
+
+  if (cmp !== 0)
+    return cmp;
+
+  return 0;
+};
+
 /**
  * Convert key to a more json-friendly object.
  * @returns {Object}
diff --git a/lib/bcoin/http/rpc.js b/lib/bcoin/http/rpc.js
index 82c9aaa2..6798b5d6 100644
--- a/lib/bcoin/http/rpc.js
+++ b/lib/bcoin/http/rpc.js
@@ -1134,10 +1134,10 @@ RPC.prototype.getrawmempool = function getrawmempool(args, callback) {
   if (args.length > 0)
     verbose = toBool(args[0], false);
 
-  this.mempoolToJSON(verbose, callback);
+  this._mempoolToJSON(verbose, callback);
 };
 
-RPC.prototype.mempoolToJSON = function mempoolToJSON(verbose, callback) {
+RPC.prototype._mempoolToJSON = function _mempoolToJSON(verbose, callback) {
   var out = {};
   var i, hashes, hash, entry;
 
@@ -3239,7 +3239,6 @@ RPC.prototype._listReceived = function _listReceived(minconf, empty, account, ca
 
     for (i = 0; i < paths.length; i++) {
       path = paths[i];
-      hash = new Buffer(path.hash, 'hex');
       map[path.hash] = {
         involvesWatchonly: false,
         address: path.toAddress().toBase58(self.network),
diff --git a/lib/bcoin/keyring.js b/lib/bcoin/keyring.js
index 26155e87..86417085 100644
--- a/lib/bcoin/keyring.js
+++ b/lib/bcoin/keyring.js
@@ -246,13 +246,12 @@ KeyRing.fromAccount = function fromAccount(account, key, keys, change, index) {
 KeyRing.prototype.addKey = function addKey(key) {
   assert(Buffer.isBuffer(key));
 
-  if (utils.indexOf(this.keys, key) !== -1)
-    return;
+  utils.binaryInsert(this.keys, key, utils.cmp, true);
 
-  if (this.keys.length === this.n)
+  if (this.keys.length > this.n) {
+    utils.binaryRemove(this.keys, key, utils.cmp);
     throw new Error('Cannot add more keys.');
-
-  utils.binaryInsert(this.keys, key, utils.cmp);
+  }
 };
 
 /**
@@ -612,25 +611,12 @@ KeyRing.prototype.ownOutput = function ownOutput(tx, index) {
  * @returns {Number} Total number of scripts built.
  */
 
-KeyRing.prototype.scriptInputs = function scriptInputs(tx, index) {
+KeyRing.prototype.scriptInputs = function scriptInputs(tx) {
   var total = 0;
   var i, input;
 
-  if (index && typeof index === 'object')
-    index = tx.inputs.indexOf(index);
-
   for (i = 0; i < tx.inputs.length; i++) {
     input = tx.inputs[i];
-
-    if (index != null && index !== i)
-      continue;
-
-    if (!input.coin)
-      continue;
-
-    if (!this.ownOutput(input.coin))
-      continue;
-
     if (tx.scriptInput(i, this))
       total++;
   }
@@ -643,32 +629,16 @@ KeyRing.prototype.scriptInputs = function scriptInputs(tx, index) {
  * to build/sign inputs that are redeemable by this address.
  * @param {MTX} tx
  * @param {HDPrivateKey|KeyPair|Buffer} key - Private key.
- * @param {Number?} index - Index of input. If not present,
- * it will attempt to build and sign all redeemable inputs.
- * @param {SighashType?} type
  * @returns {Number} Total number of inputs scripts built and signed.
  */
 
-KeyRing.prototype.sign = function sign(tx, key, index, type) {
+KeyRing.prototype.sign = function sign(tx, key) {
   var total = 0;
   var i, input;
 
-  if (index && typeof index === 'object')
-    index = tx.inputs.indexOf(index);
-
   for (i = 0; i < tx.inputs.length; i++) {
     input = tx.inputs[i];
-
-    if (index != null && index !== i)
-      continue;
-
-    if (!input.coin)
-      continue;
-
-    if (!this.ownOutput(input.coin))
-      continue;
-
-    if (tx.sign(i, this, key, type))
+    if (tx.sign(i, this, key))
       total++;
   }
 
diff --git a/lib/bcoin/mtx.js b/lib/bcoin/mtx.js
index b5c11382..621ad484 100644
--- a/lib/bcoin/mtx.js
+++ b/lib/bcoin/mtx.js
@@ -220,15 +220,13 @@ MTX.prototype.addOutput = function addOutput(options, value) {
 MTX.prototype.scriptInput = function scriptInput(index, ring) {
   var input, prev, n, i, vector, redeemScript, witnessScript;
 
-  if (typeof index !== 'number')
-    index = this.inputs.indexOf(index);
-
   // Get the input
   input = this.inputs[index];
   assert(input);
 
   // We should have previous outputs by now.
-  assert(input.coin, 'Coins are not available for scripting.');
+  if (!input.coin)
+    return false;
 
   // Optimization: Don't bother with any below
   // calculation if the output is already templated.
@@ -391,11 +389,8 @@ MTX.prototype.scriptInput = function scriptInput(index, ring) {
 MTX.prototype.createSignature = function createSignature(index, prev, key, type, version) {
   var hash;
 
-  if (typeof index !== 'number')
-    index = this.inputs.indexOf(index);
-
   if (type == null)
-    type = 'all';
+    type = constants.hashType.ALL;
 
   if (typeof type === 'string')
     type = constants.hashType[type.toUpperCase()];
@@ -423,15 +418,20 @@ MTX.prototype.signInput = function signInput(index, ring, key, type) {
   var input, prev, signature, keyIndex, signatures, i;
   var len, m, n, keys, vector, version;
 
-  if (typeof index !== 'number')
-    index = this.inputs.indexOf(index);
-
   // Get the input
   input = this.inputs[index];
   assert(input);
 
   // We should have previous outputs by now.
-  assert(input.coin, 'Coins are not available for signing.');
+  if (!input.coin)
+    return false;
+
+  // Optimization: test output against the
+  // address map to avoid unnecessary calculation.
+  // A hash table lookup may be faster than all
+  // the nonsense below.
+  if (!ring.ownOutput(input.coin))
+    return false;
 
   // Get the previous output's script
   prev = input.coin.script;
@@ -712,12 +712,7 @@ MTX.prototype.isSigned = function isSigned() {
  */
 
 MTX.prototype.sign = function sign(index, ring, key, type) {
-  var input;
-
-  if (index && typeof index === 'object')
-    index = this.inputs.indexOf(index);
-
-  input = this.inputs[index];
+  var input = this.inputs[index];
   assert(input);
 
   // Build script for input
diff --git a/lib/bcoin/txdb.js b/lib/bcoin/txdb.js
index dcfacd6c..a1edc1aa 100644
--- a/lib/bcoin/txdb.js
+++ b/lib/bcoin/txdb.js
@@ -1393,10 +1393,10 @@ TXDB.prototype.filterLocked = function filterLocked(coins) {
   for (i = 0; i < coins.length; i++) {
     coin = coins[i];
     if (!this.isLocked(coin))
-      out.push(coins);
+      out.push(coin);
   }
 
-  return coins;
+  return out;
 };
 
 /**
diff --git a/lib/bcoin/utils.js b/lib/bcoin/utils.js
index 5b7f82be..f27d4db3 100644
--- a/lib/bcoin/utils.js
+++ b/lib/bcoin/utils.js
@@ -2256,14 +2256,21 @@ utils.binarySearch = function binarySearch(items, key, compare, insert) {
  * @returns {Number} index
  */
 
-utils.binaryInsert = function binaryInsert(items, item, compare) {
+utils.binaryInsert = function binaryInsert(items, item, compare, uniq) {
   var i = utils.binarySearch(items, item, compare, true);
+
+  if (uniq && i < items.length) {
+    if (compare(items[i], item) === 0)
+      return -1;
+  }
+
   if (i === 0)
     items.unshift(item);
   else if (i === items.length)
     items.push(item);
   else
     items.splice(i, 0, item);
+
   return i;
 };
 
diff --git a/lib/bcoin/wallet.js b/lib/bcoin/wallet.js
index 4fae1249..a6171ec5 100644
--- a/lib/bcoin/wallet.js
+++ b/lib/bcoin/wallet.js
@@ -1360,8 +1360,6 @@ Wallet.prototype.getRedeem = function getRedeem(hash, callback) {
  * sign, only creates signature slots). Only builds scripts
  * for inputs that are redeemable by this wallet.
  * @param {MTX} tx
- * @param {Number?} index - Index of input. If not present,
- * it will attempt to sign all redeemable inputs.
  * @param {Function} callback - Returns [Error, Number]
  * (total number of scripts built).
  */
@@ -1386,16 +1384,13 @@ Wallet.prototype.scriptInputs = function scriptInputs(tx, callback) {
  * to build/sign inputs that are redeemable by this wallet.
  * @param {MTX} tx
  * @param {Object|String|Buffer} options - Options or passphrase.
- * @param {Number?} options.index - Index of input. If not present,
- * it will attempt to build and sign all redeemable inputs.
- * @param {SighashType?} options.type
  * @param {Function} callback - Returns [Error, Number] (total number
  * of inputs scripts built and signed).
  */
 
 Wallet.prototype.sign = function sign(tx, options, callback) {
   var self = this;
-  var passphrase, timeout, index, type;
+  var passphrase, timeout;
 
   if (typeof options === 'function') {
     callback = options;
@@ -1407,8 +1402,6 @@ Wallet.prototype.sign = function sign(tx, options, callback) {
 
   passphrase = options.passphrase;
   timeout = options.timeout;
-  index = options.index;
-  type = options.type;
 
   this.deriveInputs(tx, function(err, rings) {
     if (err)
@@ -1418,34 +1411,11 @@ Wallet.prototype.sign = function sign(tx, options, callback) {
       if (err)
         return callback(err);
 
-      self._sign(rings, master, tx, index, type, callback);
+      self.signAsync(rings, master, tx, callback);
     });
   });
 };
 
-/**
- * Sign a transaction.
- * @param {KeyRing[]} rings
- * @param {HDPrivateKey} master
- * @param {MTX} tx
- * @param {Number?} index
- * @param {SighashType?} type
- */
-
-Wallet.sign = function sign(rings, master, tx, index, type) {
-  var total = 0;
-  var i, ring, key;
-
-  for (i = 0; i < rings.length; i++) {
-    ring = rings[i];
-    key = ring.derive(master);
-    assert(utils.equal(key.getPublicKey(), ring.key));
-    total += ring.sign(tx, key, index, type);
-  }
-
-  return total;
-};
-
 /**
  * Sign a transaction asynchronously.
  * @param {KeyRing[]} rings
@@ -1457,20 +1427,43 @@ Wallet.sign = function sign(rings, master, tx, index, type) {
  * of inputs scripts built and signed).
  */
 
-Wallet.prototype._sign = function _sign(rings, master, tx, index, type, callback) {
+Wallet.prototype.signAsync = function signAsync(rings, master, tx, callback) {
   var result;
 
   if (!this.workerPool) {
     callback = utils.asyncify(callback);
     try {
-      result = Wallet.sign(rings, master, tx, index, type);
+      result = Wallet.sign(rings, master, tx);
     } catch (e) {
       return callback(e);
     }
     return callback(null, result);
   }
 
-  this.workerPool.sign(rings, master, tx, index, type, callback);
+  this.workerPool.sign(rings, master, tx, callback);
+};
+
+/**
+ * Sign a transaction.
+ * @param {KeyRing[]} rings
+ * @param {HDPrivateKey} master
+ * @param {MTX} tx
+ * @param {Number?} index
+ * @param {SighashType?} type
+ */
+
+Wallet.sign = function sign(rings, master, tx) {
+  var total = 0;
+  var i, ring, key;
+
+  for (i = 0; i < rings.length; i++) {
+    ring = rings[i];
+    key = ring.derive(master);
+    assert(utils.equal(key.getPublicKey(), ring.key));
+    total += ring.sign(tx, key);
+  }
+
+  return total;
 };
 
 /**
@@ -2216,8 +2209,6 @@ Account.prototype.fromOptions = function fromOptions(options) {
   if (!this.name)
     this.name = this.accountIndex + '';
 
-  this.pushKey(this.accountKey);
-
   if (options.keys) {
     assert(Array.isArray(options.keys));
     for (i = 0; i < options.keys.length; i++)
@@ -2255,7 +2246,7 @@ Account.MAX_LOOKAHEAD = 5;
 
 Account.prototype.init = function init(callback) {
   // Waiting for more keys.
-  if (this.keys.length !== this.n) {
+  if (this.keys.length !== this.n - 1) {
     assert(!this.initialized);
     this.save();
     return callback();
@@ -2292,40 +2283,29 @@ Account.prototype.open = function open(callback) {
  */
 
 Account.prototype.pushKey = function pushKey(key) {
-  var index = -1;
-  var i;
-
-  assert(key, 'Key required.');
-
-  if (key.accountKey)
-    key = key.accountKey;
+  var index;
 
   if (bcoin.hd.isExtended(key))
     key = bcoin.hd.fromBase58(key);
 
-  if (key.hdPublicKey)
-    key = key.hdPublicKey;
-
-  if (!bcoin.hd.isHD(key))
+  if (!bcoin.hd.isPublic(key))
     throw new Error('Must add HD keys to wallet.');
 
   if (!key.isAccount44())
     throw new Error('Must add HD account keys to BIP44 wallet.');
 
-  for (i = 0; i < this.keys.length; i++) {
-    if (this.keys[i].equal(key)) {
-      index = i;
-      break;
-    }
-  }
+  if (key.equal(this.accountKey))
+    throw new Error('Cannot add own key.');
 
-  if (index !== -1)
+  index = utils.binaryInsert(this.keys, key, cmp, true);
+
+  if (index === -1)
     return false;
 
-  if (this.keys.length === this.n)
+  if (this.keys.length > this.n - 1) {
+    utils.binaryRemove(this.keys, key, cmp);
     throw new Error('Cannot add more keys.');
-
-  this.keys.push(key);
+  }
 
   return true;
 };
@@ -2339,42 +2319,22 @@ Account.prototype.pushKey = function pushKey(key) {
  */
 
 Account.prototype.spliceKey = function spliceKey(key) {
-  var index = -1;
-  var i;
-
-  assert(key, 'Key required.');
-
-  if (key.accountKey)
-    key = key.accountKey;
-
   if (bcoin.hd.isExtended(key))
     key = bcoin.hd.fromBase58(key);
 
-  if (key.hdPublicKey)
-    key = key.hdPublicKey;
-
-  if (!bcoin.hd.isHD(key))
+  if (!bcoin.hd.isHDPublicKey(key))
     throw new Error('Must add HD keys to wallet.');
 
   if (!key.isAccount44())
     throw new Error('Must add HD account keys to BIP44 wallet.');
 
-  for (i = 0; i < this.keys.length; i++) {
-    if (this.keys[i].equal(key)) {
-      index = i;
-      break;
-    }
-  }
+  if (key.equal(this.accountKey))
+    throw new Error('Cannot remove own key.');
 
-  if (index === -1)
-    return false;
-
-  if (this.keys.length === this.n)
+  if (this.keys.length === this.n - 1)
     throw new Error('Cannot remove key.');
 
-  this.keys.splice(index, 1);
-
-  return true;
+  return utils.binaryRemove(this.keys, key, cmp);
 };
 
 /**
@@ -2426,7 +2386,7 @@ Account.prototype._checkKeys = function _checkKeys(callback) {
   if (this.initialized || this.type !== keyTypes.MULTISIG)
     return callback(null, false);
 
-  if (this.keys.length !== this.n)
+  if (this.keys.length !== this.n - 1)
     return callback(null, false);
 
   ring = this.deriveReceive(0);
@@ -2708,7 +2668,7 @@ Account.prototype.toJSON = function toJSON() {
  */
 
 Account.prototype.fromJSON = function fromJSON(json) {
-  var i;
+  var i, key;
 
   assert.equal(json.network, this.network.type);
   assert(utils.isNumber(json.wid));
@@ -2738,8 +2698,10 @@ Account.prototype.fromJSON = function fromJSON(json) {
 
   assert(this.type != null);
 
-  for (i = 0; i < json.keys.length; i++)
-    this.keys.push(bcoin.hd.fromBase58(json.keys[i]));
+  for (i = 0; i < json.keys.length; i++) {
+    key = bcoin.hd.fromBase58(json.keys[i]);
+    this.pushKey(key);
+  }
 
   return this;
 };
@@ -2751,7 +2713,7 @@ Account.prototype.fromJSON = function fromJSON(json) {
 
 Account.prototype.toRaw = function toRaw(writer) {
   var p = new BufferWriter(writer);
-  var i;
+  var i, key;
 
   p.writeU32(this.network.magic);
   p.writeVarString(this.name, 'utf8');
@@ -2766,8 +2728,10 @@ Account.prototype.toRaw = function toRaw(writer) {
   p.writeBytes(this.accountKey.toRaw());
   p.writeU8(this.keys.length);
 
-  for (i = 0; i < this.keys.length; i++)
-    p.writeBytes(this.keys[i].toRaw());
+  for (i = 0; i < this.keys.length; i++) {
+    key = this.keys[i];
+    p.writeBytes(key.toRaw());
+  }
 
   if (!writer)
     p = p.render();
@@ -2784,7 +2748,7 @@ Account.prototype.toRaw = function toRaw(writer) {
 
 Account.prototype.fromRaw = function fromRaw(data) {
   var p = new BufferReader(data);
-  var i, count;
+  var i, count, key;
 
   this.network = bcoin.network.fromMagic(p.readU32());
   this.name = p.readVarString('utf8');
@@ -2802,8 +2766,10 @@ Account.prototype.fromRaw = function fromRaw(data) {
 
   count = p.readU8();
 
-  for (i = 0; i < count; i++)
-    this.keys.push(bcoin.hd.fromRaw(p.readBytes(82)));
+  for (i = 0; i < count; i++) {
+    key = bcoin.hd.fromRaw(p.readBytes(82));
+    this.pushKey(key);
+  }
 
   return this;
 };
@@ -3279,6 +3245,14 @@ MasterKey.isMasterKey = function isMasterKey(obj) {
     && typeof obj.decrypt === 'function';
 };
 
+/*
+ * Helpers
+ */
+
+function cmp(key1, key2) {
+  return key1.compare(key2);
+}
+
 /*
  * Expose
  */
diff --git a/lib/bcoin/workers.js b/lib/bcoin/workers.js
index 6b761087..24bef1a2 100644
--- a/lib/bcoin/workers.js
+++ b/lib/bcoin/workers.js
@@ -245,13 +245,11 @@ Workers.prototype.verify = function verify(tx, flags, callback) {
  * @param {KeyRing[]} rings
  * @param {HDPrivateKey} master
  * @param {MTX} tx
- * @param {Number?} index
- * @param {SighashType?} type
  * @param {Function} callback
  */
 
-Workers.prototype.sign = function sign(rings, master, tx, index, type, callback) {
-  var args = [rings, master, tx, index, type];
+Workers.prototype.sign = function sign(rings, master, tx, callback) {
+  var args = [rings, master, tx];
   var i, input, sig, sigs, total;
 
   this.execute('sign', args, -1, function(err, result) {
@@ -775,12 +773,10 @@ jobs.verify = function verify(tx, flags) {
  * @param {KeyRing[]} rings
  * @param {HDPrivateKey} master
  * @param {MTX} tx
- * @param {Number?} index
- * @param {SighashType?} type
  */
 
-jobs.sign = function sign(rings, master, tx, index, type) {
-  var total = bcoin.wallet.sign(rings, master, tx, index, type);
+jobs.sign = function sign(rings, master, tx) {
+  var total = bcoin.wallet.sign(rings, master, tx);
   var sigs = [];
   var i, input;