diff --git a/lib/wallet/masterkey.js b/lib/wallet/masterkey.js
index b7998248..4f1b4b71 100644
--- a/lib/wallet/masterkey.js
+++ b/lib/wallet/masterkey.js
@@ -6,26 +6,20 @@
 
 'use strict';
 
+var assert = require('assert');
 var util = require('../utils/util');
 var Lock = require('../utils/lock');
 var co = require('../utils/co');
 var crypto = require('../crypto/crypto');
-var assert = require('assert');
 var BufferReader = require('../utils/reader');
 var StaticWriter = require('../utils/staticwriter');
 var encoding = require('../utils/encoding');
 var HD = require('../hd/hd');
 
-/*
- * Constants
- */
-
-var BCOIN_SALT = new Buffer('bcoin', 'ascii');
-
 /**
  * Master BIP32 key which can exist
  * in a timed out encrypted state.
- * @exports Master
+ * @exports MasterKey
  * @constructor
  * @param {Object} options
  */
@@ -54,6 +48,14 @@ function MasterKey(options) {
     this.fromOptions(options);
 }
 
+/**
+ * Key derivation salt.
+ * @const {Buffer}
+ * @default
+ */
+
+MasterKey.SALT = new Buffer('bcoin', 'ascii');
+
 /**
  * Key derivation algorithms.
  * @enum {Number}
@@ -72,8 +74,8 @@ MasterKey.alg = {
  */
 
 MasterKey.algByVal = {
-  0: 'pbkdf2',
-  1: 'scrypt'
+  0: 'PBKDF2',
+  1: 'SCRYPT'
 };
 
 /**
@@ -107,7 +109,7 @@ MasterKey.prototype.fromOptions = function fromOptions(options) {
 
   if (options.alg != null) {
     if (typeof options.alg === 'string') {
-      this.alg = MasterKey.alg[options.alg.toLowerCase()];
+      this.alg = MasterKey.alg[options.alg.toUpperCase()];
       assert(this.alg != null, 'Unknown algorithm.');
     } else {
       assert(typeof options.alg === 'number');
@@ -240,19 +242,24 @@ MasterKey.prototype.stop = function stop() {
  * @returns {Promise}
  */
 
-MasterKey.prototype.derive = function derive(passwd) {
+MasterKey.prototype.derive = co(function* derive(passwd) {
+  var salt = MasterKey.SALT;
+  var N = this.N;
+  var r = this.r;
+  var p = this.p;
+
   if (typeof passwd === 'string')
     passwd = new Buffer(passwd, 'utf8');
 
   switch (this.alg) {
     case MasterKey.alg.PBKDF2:
-      return crypto.pbkdf2Async(passwd, BCOIN_SALT, this.N, 32, 'sha256');
+      return yield crypto.pbkdf2Async(passwd, salt, N, 32, 'sha256');
     case MasterKey.alg.SCRYPT:
-      return crypto.scryptAsync(passwd, BCOIN_SALT, this.N, this.r, this.p, 32);
+      return yield crypto.scryptAsync(passwd, salt, N, r, p, 32);
     default:
-      return Promise.reject(new Error('Unknown algorithm: ' + this.alg));
+      throw new Error('Unknown algorithm: ' + this.alg);
   }
-};
+});
 
 /**
  * Encrypt data with in-memory aes key.
@@ -345,10 +352,10 @@ MasterKey.prototype.destroy = co(function* destroy() {
  * @returns {Promise}
  */
 
-MasterKey.prototype.decrypt = co(function* decrypt(passphrase, aes) {
+MasterKey.prototype.decrypt = co(function* decrypt(passphrase, clean) {
   var unlock = yield this.locker.lock();
   try {
-    return yield this._decrypt(passphrase, aes);
+    return yield this._decrypt(passphrase, clean);
   } finally {
     unlock();
   }
@@ -361,7 +368,7 @@ MasterKey.prototype.decrypt = co(function* decrypt(passphrase, aes) {
  * @returns {Promise}
  */
 
-MasterKey.prototype._decrypt = co(function* decrypt(passphrase, aes) {
+MasterKey.prototype._decrypt = co(function* decrypt(passphrase, clean) {
   var key, data;
 
   if (!this.encrypted)
@@ -380,7 +387,7 @@ MasterKey.prototype._decrypt = co(function* decrypt(passphrase, aes) {
   this.iv = null;
   this.ciphertext = null;
 
-  if (!aes) {
+  if (!clean) {
     crypto.cleanse(key);
     return;
   }
@@ -394,10 +401,10 @@ MasterKey.prototype._decrypt = co(function* decrypt(passphrase, aes) {
  * @returns {Promise}
  */
 
-MasterKey.prototype.encrypt = co(function* encrypt(passphrase, aes) {
+MasterKey.prototype.encrypt = co(function* encrypt(passphrase, clean) {
   var unlock = yield this.locker.lock();
   try {
-    return yield this._encrypt(passphrase, aes);
+    return yield this._encrypt(passphrase, clean);
   } finally {
     unlock();
   }
@@ -410,7 +417,7 @@ MasterKey.prototype.encrypt = co(function* encrypt(passphrase, aes) {
  * @returns {Promise}
  */
 
-MasterKey.prototype._encrypt = co(function* encrypt(passphrase, aes) {
+MasterKey.prototype._encrypt = co(function* encrypt(passphrase, clean) {
   var key, data, iv;
 
   if (this.encrypted)
@@ -432,7 +439,7 @@ MasterKey.prototype._encrypt = co(function* encrypt(passphrase, aes) {
   this.iv = iv;
   this.ciphertext = data;
 
-  if (!aes) {
+  if (!clean) {
     crypto.cleanse(key);
     return;
   }
@@ -569,7 +576,7 @@ MasterKey.prototype.toJSON = function toJSON(unsafe) {
       until: this.until,
       iv: this.iv.toString('hex'),
       ciphertext: unsafe ? this.ciphertext.toString('hex') : undefined,
-      algorithm: MasterKey.algByVal[this.alg],
+      algorithm: MasterKey.algByVal[this.alg].toLowerCase(),
       N: this.N,
       r: this.r,
       p: this.p