diff --git a/package.json b/package.json
index d418e3e..6d86c04 100644
--- a/package.json
+++ b/package.json
@@ -37,5 +37,8 @@
   "scripts": {
     "test": "istanbul test ./node_modules/.bin/_mocha -- --reporter list test/*.js",
     "compile": "browserify src/index.js -s Bitcoin | uglifyjs > bitcoinjs-min.js"
+  },
+  "dependencies": {
+    "crypto-js": "~3.1.2-2"
   }
 }
diff --git a/src/address.js b/src/address.js
index a4d5168..79720d4 100644
--- a/src/address.js
+++ b/src/address.js
@@ -1,5 +1,4 @@
 var base58 = require('./base58');
-var Crypto = require('./crypto-js/crypto');
 var conv = require('./convert');
 var util = require('./util');
 var mainnet = require('./network').mainnet.addressVersion;
diff --git a/src/base58.js b/src/base58.js
index 5390e7a..ec584c0 100644
--- a/src/base58.js
+++ b/src/base58.js
@@ -2,8 +2,11 @@
 // https://en.bitcoin.it/wiki/Base58Check_encoding
 
 var BigInteger = require('./jsbn/jsbn');
-var Crypto = require('./crypto-js/crypto');
+var Crypto = require('crypto-js');
+var SHA256 = Crypto.SHA256;
+var WordArray = Crypto.lib.WordArray;
 var conv = require('./convert');
+var util = require('./util');
 
 var alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
 var base = BigInteger.valueOf(58);
@@ -80,18 +83,15 @@ module.exports.decode = function (input) {
 
 module.exports.checkEncode = function(input, vbyte) {
     vbyte = vbyte || 0;
-    var front = [vbyte].concat(input);
-    var checksum = Crypto.SHA256(Crypto.SHA256(front, {asBytes: true}), {asBytes: true})
-                        .slice(0,4);
-    return module.exports.encode(front.concat(checksum));
+    var front = [vbyte].concat(input)
+    return module.exports.encode(front.concat(getChecksum(front)));
 }
 
 module.exports.checkDecode = function(input) {
     var bytes = module.exports.decode(input),
         front = bytes.slice(0,bytes.length-4),
         back = bytes.slice(bytes.length-4);
-    var checksum = Crypto.SHA256(Crypto.SHA256(front,{asBytes: true}), {asBytes: true})
-                        .slice(0,4);
+    var checksum = getChecksum(front)
     if (""+checksum != ""+back) {
         throw new Error("Checksum failed");
     }
@@ -99,3 +99,11 @@ module.exports.checkDecode = function(input) {
     o.version = front[0];
     return o;
 }
+
+function getChecksum(bytes) {
+  var wordArray = util.bytesToWordArray(bytes)
+  return conv.hexToBytes(SHA256(SHA256(wordArray)).toString()).slice(0,4);
+}
+
+module.exports.getChecksum = getChecksum
+
diff --git a/src/ecdsa.js b/src/ecdsa.js
index 54fda8b..0b4e3c2 100644
--- a/src/ecdsa.js
+++ b/src/ecdsa.js
@@ -3,7 +3,7 @@ var util = require('./util');
 var SecureRandom = require('./jsbn/rng');
 var BigInteger = require('./jsbn/jsbn');
 var conv = require('./convert')
-var Crypto = require('./crypto-js/crypto.js')
+var HmacSHA256 = require('crypto-js/hmac-sha256');
 
 var ECPointFp = require('./jsbn/ec').ECPointFp;
 
@@ -39,16 +39,21 @@ function implShamirsTrick(P, k, Q, l)
 };
 
 function deterministicGenerateK(hash,key) {
-    var v = [];
-    var k = [];
-    for (var i = 0;i < 32;i++) v.push(1);
-    for (var i = 0;i < 32;i++) k.push(0);
-    k = Crypto.HMAC(Crypto.SHA256,v.concat([0]).concat(key).concat(hash),k,{ asBytes: true  })
-    v = Crypto.HMAC(Crypto.SHA256,v,k,{ asBytes: true  })
-    k = Crypto.HMAC(Crypto.SHA256,v.concat([1]).concat(key).concat(hash),k,{ asBytes: true  })
-    v = Crypto.HMAC(Crypto.SHA256,v,k,{ asBytes: true  })
-    v = Crypto.HMAC(Crypto.SHA256,v,k,{ asBytes: true  })
-    return BigInteger.fromByteArrayUnsigned(v);
+    var vArr = [];
+    var kArr = [];
+    for (var i = 0;i < 32;i++) vArr.push(1);
+    for (var i = 0;i < 32;i++) kArr.push(0);
+    var v = util.bytesToWordArray(vArr)
+    var k = util.bytesToWordArray(kArr)
+
+    k = HmacSHA256(util.bytesToWordArray(vArr.concat([0]).concat(key).concat(hash)), k)
+    v = HmacSHA256(v, k)
+    vArr = util.wordArrayToBytes(v)
+    k = HmacSHA256(util.bytesToWordArray(vArr.concat([1]).concat(key).concat(hash)), k)
+    v = HmacSHA256(v,k)
+    v = HmacSHA256(v,k)
+    vArr = util.wordArrayToBytes(v)
+    return BigInteger.fromByteArrayUnsigned(vArr);
 }
 
 var ECDSA = {
diff --git a/src/eckey.js b/src/eckey.js
index f6b907f..a729d89 100644
--- a/src/eckey.js
+++ b/src/eckey.js
@@ -1,7 +1,6 @@
 var BigInteger = require('./jsbn/jsbn');
 var sec = require('./jsbn/sec');
 var base58 = require('./base58');
-var Crypto = require('./crypto-js/crypto');
 var util = require('./util');
 var conv = require('./convert');
 var Address = require('./address');
diff --git a/src/hdwallet.js b/src/hdwallet.js
index 8a65b1a..10d5a6b 100644
--- a/src/hdwallet.js
+++ b/src/hdwallet.js
@@ -3,7 +3,8 @@ var base58 = require('./base58.js')
 var assert = require('assert')
 var format = require('util').format
 var util = require('./util.js')
-var Crypto = require('./crypto-js/crypto.js')
+var Crypto = require('crypto-js');
+var HmacSHA512 = Crypto.HmacSHA512
 var ECKey = require('./eckey.js').ECKey
 var ECPubKey = require('./eckey.js').ECPubKey
 var Address = require('./address.js')
@@ -12,7 +13,8 @@ var Network = require('./network')
 var HDWallet = module.exports = function(seed, network) {
     if (seed === undefined) return
 
-    var I = Crypto.HMAC(Crypto.SHA512, seed, 'Bitcoin seed', { asBytes: true })
+    var seedWords = util.bytesToWordArray(convert.stringToBytes(seed))
+    var I = util.wordArrayToBytes(HmacSHA512(seedWords, 'Bitcoin seed'))
     this.chaincode = I.slice(32)
     this.network = network || 'mainnet'
     if(!Network.hasOwnProperty(this.network)) {
@@ -32,10 +34,7 @@ function arrayEqual(a, b) {
     return !(a < b || a > b)
 }
 
-HDWallet.getChecksum = function(buffer) {
-    assert.equal(buffer.length, HDWallet.LENGTH)
-    return Crypto.SHA256(Crypto.SHA256(buffer, { asBytes: true }), { asBytes: true }).slice(0, 4)
-}
+HDWallet.getChecksum = base58.getChecksum;
 
 HDWallet.fromMasterHex = function(hex) {
     var bytes = convert.hexToBytes(hex)
@@ -188,6 +187,7 @@ HDWallet.prototype.derive = function(i) {
     , iBytes = util.numToBytes(i, 4).reverse()
     , cPar = this.chaincode
     , usePriv = i >= HDWallet.HIGHEST_BIT
+    , SHA512 = Crypto.algo.SHA512
 
     if (usePriv) {
         assert(this.priv, 'Private derive on public key')
@@ -195,12 +195,12 @@ HDWallet.prototype.derive = function(i) {
         // If 1, private derivation is used:
         // let I = HMAC-SHA512(Key = cpar, Data = 0x00 || kpar || i) [Note:]
         var kPar = this.priv.toBytes().slice(0, 32)
-        I = Crypto.HMAC(Crypto.SHA512, [0].concat(kPar, iBytes), cPar, { asBytes: true })
+        I = util.HmacFromBytesToBytes(SHA512, [0].concat(kPar, iBytes), cPar)
     } else {
         // If 0, public derivation is used:
         // let I = HMAC-SHA512(Key = cpar, Data = χ(kpar*G) || i)
         var KPar = this.pub.toBytes(true)
-        I = Crypto.HMAC(Crypto.SHA512, KPar.concat(iBytes), cPar, { asBytes: true })
+        I = util.HmacFromBytesToBytes(SHA512, KPar.concat(iBytes), cPar)
     }
 
     // Split I = IL || IR into two 32-byte sequences, IL and IR.
@@ -239,3 +239,4 @@ HDWallet.prototype.getKeyVersion = function() {
 }
 
 HDWallet.prototype.toString = HDWallet.prototype.toBase58
+
diff --git a/src/index.js b/src/index.js
index 2aa97ee..375244f 100644
--- a/src/index.js
+++ b/src/index.js
@@ -31,7 +31,7 @@ module.exports = {
     ECPubKey: Key.ECPubKey,
     Message: require('./message'),
     BigInteger: require('./jsbn/jsbn'),
-    Crypto: require('./crypto-js/crypto'),
+    Crypto: require('crypto-js'), //should we expose this at all?
     Script: require('./script'),
     Opcode: require('./opcode'),
     Transaction: require('./transaction').Transaction,
diff --git a/src/message.js b/src/message.js
index b370f92..2c0f03e 100644
--- a/src/message.js
+++ b/src/message.js
@@ -1,6 +1,6 @@
 /// Implements Bitcoin's feature for signing arbitrary messages.
 
-var Crypto = require('./crypto-js/crypto');
+var SHA256 = require('crypto-js/sha256');
 var ecdsa = require('./ecdsa');
 var conv = require('./convert');
 var util = require('./util');
@@ -24,7 +24,7 @@ Message.makeMagicMessage = function (message) {
 
 Message.getHash = function (message) {
   var buffer = Message.makeMagicMessage(message);
-  return Crypto.SHA256(Crypto.SHA256(buffer, {asBytes: true}), {asBytes: true});
+  return util.wordArrayToBytes(SHA256(SHA256(util.bytesToWordArray(buffer))));
 };
 
 Message.signMessage = function (key, message, compressed) {
diff --git a/src/transaction.js b/src/transaction.js
index 6f7f15b..a9ba2e8 100644
--- a/src/transaction.js
+++ b/src/transaction.js
@@ -2,11 +2,11 @@ var BigInteger = require('./jsbn/jsbn');
 var Script = require('./script');
 var util = require('./util');
 var conv = require('./convert');
-var Crypto = require('./crypto-js/crypto');
 var Wallet = require('./wallet');
 var ECKey = require('./eckey').ECKey;
 var ECDSA = require('./ecdsa');
 var Address = require('./address');
+var Message = require('./message');
 
 var Transaction = function (doc) {
     if (!(this instanceof Transaction)) { return new Transaction(doc); }
@@ -207,9 +207,7 @@ function (connectedScript, inIndex, hashType)
 
   buffer = buffer.concat(util.numToBytes(parseInt(hashType),4));
 
-  var hash1 = Crypto.SHA256(buffer, {asBytes: true});
-
-  return Crypto.SHA256(hash1, {asBytes: true});
+  return Message.getHash(buffer)
 };
 
 /**
@@ -220,7 +218,7 @@ function (connectedScript, inIndex, hashType)
 Transaction.prototype.getHash = function ()
 {
   var buffer = this.serialize();
-  return Crypto.SHA256(Crypto.SHA256(buffer, {asBytes: true}), {asBytes: true}).reverse();
+  return Message.getHash(buffer).reverse()
 };
 
 /**
diff --git a/src/util.js b/src/util.js
index 8d64662..bc61ec7 100644
--- a/src/util.js
+++ b/src/util.js
@@ -1,4 +1,8 @@
-var Crypto = require('./crypto-js/crypto');
+var Crypto = require('crypto-js');
+var RIPEMD160 = Crypto.RIPEMD160;
+var SHA256 = Crypto.SHA256;
+var HMAC= Crypto.algo.HMAC;
+var WordArray = Crypto.lib.WordArray;
 
 /**
  * Create a byte array representing a number with the given length
@@ -45,7 +49,15 @@ exports.wordsToBytes = function (words) {
         bytes.push((words[b >>> 5] >>> (24 - b % 32)) & 0xFF);
     }
     return bytes;
-},
+}
+
+exports.bytesToWordArray = function (bytes) {
+  return new WordArray.init(exports.bytesToWords(bytes), bytes.length)
+}
+
+exports.wordArrayToBytes = function (wordArray) {
+  return exports.wordsToBytes(wordArray.words)
+}
 
 /**
  * Calculate RIPEMD160(SHA256(data)).
@@ -54,7 +66,15 @@ exports.wordsToBytes = function (words) {
  * array.
  */
 exports.sha256ripe160 = function (data) {
-    return Crypto.RIPEMD160(Crypto.SHA256(data, {asBytes: true}), {asBytes: true});
+    var wordArray = RIPEMD160(SHA256(exports.bytesToWordArray(data)))
+    return exports.wordArrayToBytes(wordArray)
+}
+
+
+exports.HmacFromBytesToBytes = function (hasher, message, key) {
+  var hmac = HMAC.create(hasher, exports.bytesToWordArray(key))
+  hmac.update(exports.bytesToWordArray(message))
+  return exports.wordArrayToBytes(hmac.finalize())
 }
 
 exports.error = function(msg) {
diff --git a/test/misc.js b/test/misc.js
index 1ed0b8a..e1d0adc 100644
--- a/test/misc.js
+++ b/test/misc.js
@@ -3,13 +3,18 @@ var assert = require('assert');
 var bitcoinjs = require('../');
 var sec = require('../src/jsbn/sec');
 var BigInteger = require('../src/jsbn/jsbn.js');
-var Crypto = require('../src/crypto-js/crypto.js');
+var SHA256 = require('crypto-js/sha256');
 
 var SecureRandom = require('../src/jsbn/rng');
 var rng = new SecureRandom();
 
 var ecparams = sec('secp256k1');
 var ECPointFp = bitcoinjs.ECPointFp;
+var util = require('../src/util');
+
+function sha256FromBytesToBytes(message){
+  return util.wordArrayToBytes(SHA256(util.bytesToWordArray(message)))
+}
 
 it('Keys & Key Management', function () {
     var p1 = bitcoinjs.Key().getPub()['export']('bytes');
@@ -36,9 +41,7 @@ it('Signing and Verifying', function () {
     assert.ok(s1.verify(BigInteger.ZERO, sig_a));
 
     var message = new BigInteger(1024, rng).toByteArrayUnsigned();
-    var hash = Crypto.SHA256(message, {
-        asBytes: true
-    });
+    var hash = sha256FromBytesToBytes(message);
     var sig_b = s1.sign(hash);
     assert.ok(sig_b, 'Sign random string');
     assert.ok(s1.verify(hash, sig_b));
@@ -50,9 +53,7 @@ it('Signing and Verifying', function () {
         '8a33f50d7cefb96a5dab897b5efcb99cbafb0d777cb83fc9b2115b69c0fa' +
         '3d82507b932b84e4');
 
-    var hash2 = Crypto.SHA256(message2, {
-        asBytes: true
-    });
+    var hash2 = sha256FromBytesToBytes(message2);
 
     var sig_c = bitcoinjs.convert.hexToBytes(
         '3044022038d9b8dd5c9fbf330565c1f51d72a59ba869aeb2c2001be959d3' +