diff --git a/lib/bcoin/hd.js b/lib/bcoin/hd.js
index a7af378f..2be834a8 100644
--- a/lib/bcoin/hd.js
+++ b/lib/bcoin/hd.js
@@ -171,35 +171,24 @@ function HDPrivateKey(options) {
   this.isPrivate = true;
 }
 
-HDPrivateKey.prototype.scan = function scan(options, txByAddress, callback) {
+HDPrivateKey.prototype.scan44 = function scan44(options, txByAddress, callback) {
+  var self = this;
   var keys = [];
-  var purpose, coinType, root;
-
-  if (!callback) {
-    callback = txByAddress;
-    txByAddress = options;
-    options = null;
-  }
-
-  if (!options)
-    options = {};
-
-  purpose = options.purpose;
-  coinType = options.coinType;
-
-  if (purpose == null)
-    purpose = 44;
-
-  if (coinType == null)
-    coinType = network.type === 'main' ? 0 : 1;
-
-  assert(utils.isFinite(purpose));
-  assert(utils.isFinite(coinType));
+  var coinType;
 
   // 0. get the root node
-  root = this
-    .derive(purpose, true)
-    .derive(coinType, true);
+  if (!(this instanceof HDPublicKey)) {
+    coinType = options.coinType;
+
+    if (coinType == null)
+      coinType = network.type === 'main' ? 0 : 1;
+
+    assert(utils.isFinite(coinType));
+
+    root = this
+      .derive(44, true)
+      .derive(coinType, true);
+  }
 
   return (function scanner(accountIndex) {
     var addressIndex = 0;
@@ -207,7 +196,9 @@ HDPrivateKey.prototype.scan = function scan(options, txByAddress, callback) {
     var gap = 0;
 
     // 1. derive the first account's node (index = 0)
-    var account = root.derive(accountIndex, true);
+    var account = (self instanceof HDPublicKey)
+      ? self
+      : root.derive(accountIndex, true);
 
     // 2. derive the external chain node of this account
     var chain = account.derive(0);
@@ -252,54 +243,56 @@ HDPrivateKey.prototype.scan = function scan(options, txByAddress, callback) {
 
         // 5. if there are some transactions, increase
         // the account index and go to step 1
+        if (self instanceof HDPublicKey)
+          return callback(null, keys);
+
         return scanner(accountIndex + 1);
       });
     })();
   })(0);
 };
 
-HDPrivateKey.prototype.deriveBIP44 = function deriveBIP44(options) {
-  var purpose = options.purpose;
+HDPrivateKey.prototype.deriveRoot44 = function deriveRoot44(options) {
   var coinType = options.coinType;
   var accountIndex = options.accountIndex;
-  var chain = options.chain;
-  var addressIndex = options.addressIndex;
-  var child;
 
-  if (purpose == null)
-    purpose = 44;
+  if (this instanceof HDPublicKey)
+    return this;
 
   if (coinType == null)
     coinType = network.type === 'main' ? 0 : 1;
 
+  assert(utils.isFinite(coinType));
+  assert(utils.isFinite(accountIndex));
+
+  return this
+    .derive(44, true)
+    .derive(coinType, true)
+    .derive(accountIndex, true);
+};
+
+HDPrivateKey.prototype.deriveBIP44 = function deriveBIP44(options, isPublic) {
+  var chain = options.chain;
+  var addressIndex = options.addressIndex;
+
   if (chain == null)
     chain = options.change ? 1 : 0;
 
-  assert(utils.isFinite(purpose));
-  assert(utils.isFinite(coinType));
-  assert(utils.isFinite(accountIndex));
   assert(utils.isFinite(chain));
   assert(utils.isFinite(addressIndex));
 
-  child = this
-    .derive(purpose, true)
-    .derive(coinType, true)
-    .derive(accountIndex, true)
+  return this
+    .deriveRoot44(options)
     .derive(chain)
     .derive(addressIndex);
-
-  return child;
-};
-
-HDPrivateKey.prototype.deriveAccount = function deriveAccount(accountIndex) {
-  return this.deriveBIP44({
-    accountIndex: accountIndex,
-    chain: 0,
-    addressIndex: 0
-  });
 };
 
 HDPrivateKey.prototype.deriveChange = function deriveChange(accountIndex, addressIndex) {
+  if (this instanceof HDPublicKey) {
+    addressIndex = accountIndex;
+    accountIndex = null;
+  }
+
   return this.deriveBIP44({
     accountIndex: accountIndex,
     chain: 1,
@@ -308,6 +301,11 @@ HDPrivateKey.prototype.deriveChange = function deriveChange(accountIndex, addres
 };
 
 HDPrivateKey.prototype.deriveAddress = function deriveAddress(accountIndex, addressIndex) {
+  if (this instanceof HDPublicKey) {
+    addressIndex = accountIndex;
+    accountIndex = null;
+  }
+
   return this.deriveBIP44({
     accountIndex: accountIndex,
     chain: 0,
@@ -315,6 +313,106 @@ HDPrivateKey.prototype.deriveAddress = function deriveAddress(accountIndex, addr
   });
 };
 
+HDPrivateKey.prototype.scan45 = function scan45(options, txByAddress, callback) {
+  var keys = [];
+  var root;
+
+  root = this.deriveRoot45(options);
+
+  return (function chainCheck(chainConstant) {
+    return (function scanner(cosignerIndex) {
+      var addressIndex = 0;
+      var total = 0;
+      var gap = 0;
+
+      var cosigner = root.derive(cosignerIndex);
+      var chain = cosigner.derive(chainConstant);
+
+      return (function next() {
+        var address = chain.derive(addressIndex++);
+        var addr = bcoin.address.hash2addr(
+          bcoin.address.key2hash(address.publicKey),
+          'pubkey');
+
+        return txByAddress(addr, function(err, txs) {
+          var result;
+
+          if (err)
+            return callback(err);
+
+          if (txs) {
+            if (typeof txs === 'boolean')
+              result = txs;
+            else if (Array.isArray(txs))
+              result = txs.length > 0;
+            else
+              result = false;
+          }
+
+          if (result) {
+            keys.push(address);
+            total++;
+            gap = 0;
+            return next();
+          }
+
+          if (++gap < 20)
+            return next();
+
+          if (total === 0) {
+            if (chainConstant === 0)
+              return chainCheck(1);
+            return callback(null, keys);
+          }
+
+          return scanner(accountIndex + 1);
+        });
+      })();
+    })(0);
+  })(0);
+};
+
+HDPrivateKey.prototype.deriveRoot45 = function deriveRoot45(options) {
+  if (this instanceof HDPublicKey)
+    return this;
+  return this.derive(45, true);
+};
+
+HDPrivateKey.prototype.deriveBIP45 = function deriveBIP45(options) {
+  var cosignerIndex = options.cosignerIndex;
+  var chain = options.chain;
+  var addressIndex = options.addressIndex;
+
+  if (chain == null)
+    chain = options.change ? 1 : 0;
+
+  assert(utils.isFinite(cosignerIndex));
+  assert(utils.isFinite(chain));
+  assert(utils.isFinite(addressIndex));
+
+  return this
+    .deriveRoot45(options)
+    .derive(cosignerIndex)
+    .derive(chain)
+    .derive(addressIndex);
+};
+
+HDPrivateKey.prototype.deriveCosignerChange = function deriveCosignerChange(cosignerIndex, addressIndex) {
+  return this.deriveBIP45({
+    cosignerIndex: cosignerIndex,
+    chain: 1,
+    addressIndex: addressIndex
+  });
+};
+
+HDPrivateKey.prototype.deriveCosignerAddress = function deriveCosignerAddress(cosignerIndex, addressIndex) {
+  return this.deriveBIP45({
+    cosignerIndex: cosignerIndex,
+    chain: 0,
+    addressIndex: addressIndex
+  });
+};
+
 HDPrivateKey.getPath = function getPath(options) {
   var purpose, coinType, accountIndex, chain, addressIndex;
 
@@ -666,11 +764,18 @@ function HDPublicKey(options) {
   this.isPublic = true;
 }
 
+HDPublicKey.prototype.scan44 = HDPrivateKey.prototype.scan44;
+HDPublicKey.prototype.deriveRoot44 = HDPrivateKey.prototype.deriveRoot44;
 HDPublicKey.prototype.deriveBIP44 = HDPrivateKey.prototype.deriveBIP44;
-HDPublicKey.prototype.deriveAccount = HDPrivateKey.prototype.deriveAccount;
 HDPublicKey.prototype.deriveChange = HDPrivateKey.prototype.deriveChange;
 HDPublicKey.prototype.deriveAddress = HDPrivateKey.prototype.deriveAddress;
 
+HDPublicKey.prototype.scan45 = HDPrivateKey.prototype.scan45;
+HDPublicKey.prototype.deriveRoot45 = HDPrivateKey.prototype.deriveRoot45;
+HDPublicKey.prototype.deriveBIP45 = HDPrivateKey.prototype.deriveBIP45;
+HDPublicKey.prototype.deriveCosignerChange = HDPrivateKey.prototype.deriveCosignerChange;
+HDPublicKey.prototype.deriveCosignerAddress = HDPrivateKey.prototype.deriveCosignerAddress;
+
 HDPublicKey.isExtended = function isExtended(data) {
   if (typeof data !== 'string')
     return false;