diff --git a/browser-build.js b/browser-build.js
index 74f545693..ae22766b6 100644
--- a/browser-build.js
+++ b/browser-build.js
@@ -34,13 +34,13 @@ function build(options, callback) {
       "global": true,
       "presets": ["es2015"],
       "plugins": ["transform-runtime"],
-      "only": ['lib/*', 'node_modules/co-gather/*', 'shims/*'],
+      "only": ['lib/*', 'node_modules/co-gather/*', 'shims/*', 'shims/crypto/*'],
     }).transform(aliasify, {
       global: true,
       aliases: {
         'zlib': false,
         'iconv-lite': false,
-        'crypto': './shims/crypto.js',
+        'crypto': './shims/crypto/crypto.js',
       },
       verbose: false
     }).bundle(function(err, data) {
diff --git a/package.json b/package.json
index 333a8685f..44205e1f3 100644
--- a/package.json
+++ b/package.json
@@ -13,7 +13,7 @@
     "mime": "./shims/mime.js",
     "urllib": "./shims/xhr.js",
     "utility": "./shims/utility.js",
-    "crypto": "./shims/crypto.js",
+    "crypto": "./shims/crypto/crypto.js",
     "fs": false,
     "child_process": false
   },
@@ -66,7 +66,6 @@
     "browserify": "^13.3.0",
     "co-fs": "^1.2.0",
     "co-mocha": "^1.2.1",
-    "crypto-browserify": "^1.0.9",
     "crypto-js": "^3.1.9-1",
     "filereader": "^0.10.3",
     "git-pre-hooks": "^1.2.0",
diff --git a/shims/crypto.js b/shims/crypto.js
deleted file mode 100644
index dfd091421..000000000
--- a/shims/crypto.js
+++ /dev/null
@@ -1,2 +0,0 @@
-// use crypto-browserify@1.0.9 to minify dist size
-module.exports = require('crypto-browserify');
diff --git a/shims/crypto/crypto.js b/shims/crypto/crypto.js
new file mode 100644
index 000000000..88968b1c1
--- /dev/null
+++ b/shims/crypto/crypto.js
@@ -0,0 +1,90 @@
+
+var Buffer = require('buffer').Buffer;
+var sha = require('./sha');
+var sha256 = require('./sha256');
+var md5 = require('./md5');
+
+var algorithms = {
+  sha1: sha,
+  sha256: sha256,
+  md5: md5
+};
+
+var blocksize = 64;
+var zeroBuffer = new Buffer(blocksize);
+zeroBuffer.fill(0);
+
+function hmac(fn, key, data) {
+  if(!Buffer.isBuffer(key)) key = new Buffer(key);
+  if(!Buffer.isBuffer(data)) data = new Buffer(data);
+
+  if(key.length > blocksize) {
+    key = fn(key)
+  } else if(key.length < blocksize) {
+    key = Buffer.concat([key, zeroBuffer], blocksize)
+  }
+
+  var ipad = new Buffer(blocksize), opad = new Buffer(blocksize);
+  for(var i = 0; i < blocksize; i++) {
+    ipad[i] = key[i] ^ 0x36
+    opad[i] = key[i] ^ 0x5C
+  }
+
+  var hash = fn(Buffer.concat([ipad, data]))
+  return fn(Buffer.concat([opad, hash]))
+}
+
+function hash(alg, key) {
+  alg = alg || 'sha1';
+  var fn = algorithms[alg];
+  var bufs = [];
+  var length = 0;
+  if(!fn) error('algorithm:', alg, 'is not yet supported');
+  return {
+    update: function (data) {
+      if(!Buffer.isBuffer(data)) data = new Buffer(data);
+
+      bufs.push(data);
+      length += data.length;
+      return this
+    },
+    digest: function (enc) {
+      var buf = Buffer.concat(bufs);
+      var r = key ? hmac(fn, key, buf) : fn(buf);
+      bufs = null;
+      return enc ? r.toString(enc) : r
+    }
+  }
+}
+
+function error () {
+  var m = [].slice.call(arguments).join(' ')
+  throw new Error([
+    m,
+    'we accept pull requests',
+    'http://github.com/dominictarr/crypto-browserify'
+  ].join('\n'))
+}
+
+exports.createHash = function (alg) { return hash(alg) };
+exports.createHmac = function (alg, key) { return hash(alg, key) };
+
+function each(a, f) {
+  for(var i in a)
+    f(a[i], i)
+}
+
+// the least I can do is make error messages for the rest of the node.js/crypto api.
+each(['createCredentials'
+  , 'createCipher'
+  , 'createCipheriv'
+  , 'createDecipher'
+  , 'createDecipheriv'
+  , 'createSign'
+  , 'createVerify'
+  , 'createDiffieHellman'
+  , 'pbkdf2'], function (name) {
+  exports[name] = function () {
+    error('sorry,', name, 'is not implemented yet')
+  }
+});
\ No newline at end of file
diff --git a/shims/crypto/helpers.js b/shims/crypto/helpers.js
new file mode 100644
index 000000000..4535e6450
--- /dev/null
+++ b/shims/crypto/helpers.js
@@ -0,0 +1,35 @@
+var Buffer = require('buffer').Buffer;
+var intSize = 4;
+var zeroBuffer = new Buffer(intSize); zeroBuffer.fill(0);
+var chrsz = 8;
+
+function toArray(buf, bigEndian) {
+  if ((buf.length % intSize) !== 0) {
+    var len = buf.length + (intSize - (buf.length % intSize));
+    buf = Buffer.concat([buf, zeroBuffer], len);
+  }
+
+  var arr = [];
+  var fn = bigEndian ? buf.readInt32BE : buf.readInt32LE;
+  for (var i = 0; i < buf.length; i += intSize) {
+    arr.push(fn.call(buf, i));
+  }
+  return arr;
+}
+
+function toBuffer(arr, size, bigEndian) {
+  var buf = new Buffer(size);
+  var fn = bigEndian ? buf.writeInt32BE : buf.writeInt32LE;
+  for (var i = 0; i < arr.length; i++) {
+    fn.call(buf, arr[i], i * 4, true);
+  }
+  return buf;
+}
+
+function hash(buf, fn, hashSize, bigEndian) {
+  if (!Buffer.isBuffer(buf)) buf = new Buffer(buf);
+  var arr = fn(toArray(buf, bigEndian), buf.length * chrsz);
+  return toBuffer(arr, hashSize, bigEndian);
+}
+
+module.exports = { hash: hash };
diff --git a/shims/crypto/md5.js b/shims/crypto/md5.js
new file mode 100644
index 000000000..50eeb8949
--- /dev/null
+++ b/shims/crypto/md5.js
@@ -0,0 +1,163 @@
+/*
+ * A JavaScript implementation of the RSA Data Security, Inc. MD5 Message
+ * Digest Algorithm, as defined in RFC 1321.
+ * Version 2.1 Copyright (C) Paul Johnston 1999 - 2002.
+ * Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
+ * Distributed under the BSD License
+ * See http://pajhome.org.uk/crypt/md5 for more info.
+ */
+
+var helpers = require('./helpers');
+
+/*
+ * Perform a simple self-test to see if the VM is working
+ */
+function md5_vm_test()
+{
+  return hex_md5("abc") == "900150983cd24fb0d6963f7d28e17f72";
+}
+
+/*
+ * Calculate the MD5 of an array of little-endian words, and a bit length
+ */
+function core_md5(x, len)
+{
+  /* append padding */
+  x[len >> 5] |= 0x80 << ((len) % 32);
+  x[(((len + 64) >>> 9) << 4) + 14] = len;
+
+  var a =  1732584193;
+  var b = -271733879;
+  var c = -1732584194;
+  var d =  271733878;
+
+  for(var i = 0; i < x.length; i += 16)
+  {
+    var olda = a;
+    var oldb = b;
+    var oldc = c;
+    var oldd = d;
+
+    a = md5_ff(a, b, c, d, x[i+ 0], 7 , -680876936);
+    d = md5_ff(d, a, b, c, x[i+ 1], 12, -389564586);
+    c = md5_ff(c, d, a, b, x[i+ 2], 17,  606105819);
+    b = md5_ff(b, c, d, a, x[i+ 3], 22, -1044525330);
+    a = md5_ff(a, b, c, d, x[i+ 4], 7 , -176418897);
+    d = md5_ff(d, a, b, c, x[i+ 5], 12,  1200080426);
+    c = md5_ff(c, d, a, b, x[i+ 6], 17, -1473231341);
+    b = md5_ff(b, c, d, a, x[i+ 7], 22, -45705983);
+    a = md5_ff(a, b, c, d, x[i+ 8], 7 ,  1770035416);
+    d = md5_ff(d, a, b, c, x[i+ 9], 12, -1958414417);
+    c = md5_ff(c, d, a, b, x[i+10], 17, -42063);
+    b = md5_ff(b, c, d, a, x[i+11], 22, -1990404162);
+    a = md5_ff(a, b, c, d, x[i+12], 7 ,  1804603682);
+    d = md5_ff(d, a, b, c, x[i+13], 12, -40341101);
+    c = md5_ff(c, d, a, b, x[i+14], 17, -1502002290);
+    b = md5_ff(b, c, d, a, x[i+15], 22,  1236535329);
+
+    a = md5_gg(a, b, c, d, x[i+ 1], 5 , -165796510);
+    d = md5_gg(d, a, b, c, x[i+ 6], 9 , -1069501632);
+    c = md5_gg(c, d, a, b, x[i+11], 14,  643717713);
+    b = md5_gg(b, c, d, a, x[i+ 0], 20, -373897302);
+    a = md5_gg(a, b, c, d, x[i+ 5], 5 , -701558691);
+    d = md5_gg(d, a, b, c, x[i+10], 9 ,  38016083);
+    c = md5_gg(c, d, a, b, x[i+15], 14, -660478335);
+    b = md5_gg(b, c, d, a, x[i+ 4], 20, -405537848);
+    a = md5_gg(a, b, c, d, x[i+ 9], 5 ,  568446438);
+    d = md5_gg(d, a, b, c, x[i+14], 9 , -1019803690);
+    c = md5_gg(c, d, a, b, x[i+ 3], 14, -187363961);
+    b = md5_gg(b, c, d, a, x[i+ 8], 20,  1163531501);
+    a = md5_gg(a, b, c, d, x[i+13], 5 , -1444681467);
+    d = md5_gg(d, a, b, c, x[i+ 2], 9 , -51403784);
+    c = md5_gg(c, d, a, b, x[i+ 7], 14,  1735328473);
+    b = md5_gg(b, c, d, a, x[i+12], 20, -1926607734);
+
+    a = md5_hh(a, b, c, d, x[i+ 5], 4 , -378558);
+    d = md5_hh(d, a, b, c, x[i+ 8], 11, -2022574463);
+    c = md5_hh(c, d, a, b, x[i+11], 16,  1839030562);
+    b = md5_hh(b, c, d, a, x[i+14], 23, -35309556);
+    a = md5_hh(a, b, c, d, x[i+ 1], 4 , -1530992060);
+    d = md5_hh(d, a, b, c, x[i+ 4], 11,  1272893353);
+    c = md5_hh(c, d, a, b, x[i+ 7], 16, -155497632);
+    b = md5_hh(b, c, d, a, x[i+10], 23, -1094730640);
+    a = md5_hh(a, b, c, d, x[i+13], 4 ,  681279174);
+    d = md5_hh(d, a, b, c, x[i+ 0], 11, -358537222);
+    c = md5_hh(c, d, a, b, x[i+ 3], 16, -722521979);
+    b = md5_hh(b, c, d, a, x[i+ 6], 23,  76029189);
+    a = md5_hh(a, b, c, d, x[i+ 9], 4 , -640364487);
+    d = md5_hh(d, a, b, c, x[i+12], 11, -421815835);
+    c = md5_hh(c, d, a, b, x[i+15], 16,  530742520);
+    b = md5_hh(b, c, d, a, x[i+ 2], 23, -995338651);
+
+    a = md5_ii(a, b, c, d, x[i+ 0], 6 , -198630844);
+    d = md5_ii(d, a, b, c, x[i+ 7], 10,  1126891415);
+    c = md5_ii(c, d, a, b, x[i+14], 15, -1416354905);
+    b = md5_ii(b, c, d, a, x[i+ 5], 21, -57434055);
+    a = md5_ii(a, b, c, d, x[i+12], 6 ,  1700485571);
+    d = md5_ii(d, a, b, c, x[i+ 3], 10, -1894986606);
+    c = md5_ii(c, d, a, b, x[i+10], 15, -1051523);
+    b = md5_ii(b, c, d, a, x[i+ 1], 21, -2054922799);
+    a = md5_ii(a, b, c, d, x[i+ 8], 6 ,  1873313359);
+    d = md5_ii(d, a, b, c, x[i+15], 10, -30611744);
+    c = md5_ii(c, d, a, b, x[i+ 6], 15, -1560198380);
+    b = md5_ii(b, c, d, a, x[i+13], 21,  1309151649);
+    a = md5_ii(a, b, c, d, x[i+ 4], 6 , -145523070);
+    d = md5_ii(d, a, b, c, x[i+11], 10, -1120210379);
+    c = md5_ii(c, d, a, b, x[i+ 2], 15,  718787259);
+    b = md5_ii(b, c, d, a, x[i+ 9], 21, -343485551);
+
+    a = safe_add(a, olda);
+    b = safe_add(b, oldb);
+    c = safe_add(c, oldc);
+    d = safe_add(d, oldd);
+  }
+  return Array(a, b, c, d);
+
+}
+
+/*
+ * These functions implement the four basic operations the algorithm uses.
+ */
+function md5_cmn(q, a, b, x, s, t)
+{
+  return safe_add(bit_rol(safe_add(safe_add(a, q), safe_add(x, t)), s),b);
+}
+function md5_ff(a, b, c, d, x, s, t)
+{
+  return md5_cmn((b & c) | ((~b) & d), a, b, x, s, t);
+}
+function md5_gg(a, b, c, d, x, s, t)
+{
+  return md5_cmn((b & d) | (c & (~d)), a, b, x, s, t);
+}
+function md5_hh(a, b, c, d, x, s, t)
+{
+  return md5_cmn(b ^ c ^ d, a, b, x, s, t);
+}
+function md5_ii(a, b, c, d, x, s, t)
+{
+  return md5_cmn(c ^ (b | (~d)), a, b, x, s, t);
+}
+
+/*
+ * Add integers, wrapping at 2^32. This uses 16-bit operations internally
+ * to work around bugs in some JS interpreters.
+ */
+function safe_add(x, y)
+{
+  var lsw = (x & 0xFFFF) + (y & 0xFFFF);
+  var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
+  return (msw << 16) | (lsw & 0xFFFF);
+}
+
+/*
+ * Bitwise rotate a 32-bit number to the left.
+ */
+function bit_rol(num, cnt)
+{
+  return (num << cnt) | (num >>> (32 - cnt));
+}
+
+module.exports = function md5(buf) {
+  return helpers.hash(buf, core_md5, 16);
+};
diff --git a/shims/crypto/sha.js b/shims/crypto/sha.js
new file mode 100644
index 000000000..6a4870182
--- /dev/null
+++ b/shims/crypto/sha.js
@@ -0,0 +1,101 @@
+/*
+ * A JavaScript implementation of the Secure Hash Algorithm, SHA-1, as defined
+ * in FIPS PUB 180-1
+ * Version 2.1a Copyright Paul Johnston 2000 - 2002.
+ * Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
+ * Distributed under the BSD License
+ * See http://pajhome.org.uk/crypt/md5 for details.
+ */
+
+var helpers = require('./helpers');
+
+/*
+ * Calculate the SHA-1 of an array of big-endian words, and a bit length
+ */
+function core_sha1(x, len)
+{
+  /* append padding */
+  x[len >> 5] |= 0x80 << (24 - len % 32);
+  x[((len + 64 >> 9) << 4) + 15] = len;
+
+  var w = Array(80);
+  var a =  1732584193;
+  var b = -271733879;
+  var c = -1732584194;
+  var d =  271733878;
+  var e = -1009589776;
+
+  for(var i = 0; i < x.length; i += 16)
+  {
+    var olda = a;
+    var oldb = b;
+    var oldc = c;
+    var oldd = d;
+    var olde = e;
+
+    for(var j = 0; j < 80; j++)
+    {
+      if(j < 16) w[j] = x[i + j];
+      else w[j] = rol(w[j-3] ^ w[j-8] ^ w[j-14] ^ w[j-16], 1);
+      var t = safe_add(safe_add(rol(a, 5), sha1_ft(j, b, c, d)),
+        safe_add(safe_add(e, w[j]), sha1_kt(j)));
+      e = d;
+      d = c;
+      c = rol(b, 30);
+      b = a;
+      a = t;
+    }
+
+    a = safe_add(a, olda);
+    b = safe_add(b, oldb);
+    c = safe_add(c, oldc);
+    d = safe_add(d, oldd);
+    e = safe_add(e, olde);
+  }
+  return Array(a, b, c, d, e);
+
+}
+
+/*
+ * Perform the appropriate triplet combination function for the current
+ * iteration
+ */
+function sha1_ft(t, b, c, d)
+{
+  if(t < 20) return (b & c) | ((~b) & d);
+  if(t < 40) return b ^ c ^ d;
+  if(t < 60) return (b & c) | (b & d) | (c & d);
+  return b ^ c ^ d;
+}
+
+/*
+ * Determine the appropriate additive constant for the current iteration
+ */
+function sha1_kt(t)
+{
+  return (t < 20) ?  1518500249 : (t < 40) ?  1859775393 :
+    (t < 60) ? -1894007588 : -899497514;
+}
+
+/*
+ * Add integers, wrapping at 2^32. This uses 16-bit operations internally
+ * to work around bugs in some JS interpreters.
+ */
+function safe_add(x, y)
+{
+  var lsw = (x & 0xFFFF) + (y & 0xFFFF);
+  var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
+  return (msw << 16) | (lsw & 0xFFFF);
+}
+
+/*
+ * Bitwise rotate a 32-bit number to the left.
+ */
+function rol(num, cnt)
+{
+  return (num << cnt) | (num >>> (32 - cnt));
+}
+
+module.exports = function sha1(buf) {
+  return helpers.hash(buf, core_sha1, 20, true);
+};
diff --git a/shims/crypto/sha256.js b/shims/crypto/sha256.js
new file mode 100644
index 000000000..954d68500
--- /dev/null
+++ b/shims/crypto/sha256.js
@@ -0,0 +1,79 @@
+
+/**
+ * A JavaScript implementation of the Secure Hash Algorithm, SHA-256, as defined
+ * in FIPS 180-2
+ * Version 2.2-beta Copyright Angel Marin, Paul Johnston 2000 - 2009.
+ * Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
+ *
+ */
+
+var helpers = require('./helpers');
+
+var safe_add = function(x, y) {
+  var lsw = (x & 0xFFFF) + (y & 0xFFFF);
+  var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
+  return (msw << 16) | (lsw & 0xFFFF);
+};
+
+var S = function(X, n) {
+  return (X >>> n) | (X << (32 - n));
+};
+
+var R = function(X, n) {
+  return (X >>> n);
+};
+
+var Ch = function(x, y, z) {
+  return ((x & y) ^ ((~x) & z));
+};
+
+var Maj = function(x, y, z) {
+  return ((x & y) ^ (x & z) ^ (y & z));
+};
+
+var Sigma0256 = function(x) {
+  return (S(x, 2) ^ S(x, 13) ^ S(x, 22));
+};
+
+var Sigma1256 = function(x) {
+  return (S(x, 6) ^ S(x, 11) ^ S(x, 25));
+};
+
+var Gamma0256 = function(x) {
+  return (S(x, 7) ^ S(x, 18) ^ R(x, 3));
+};
+
+var Gamma1256 = function(x) {
+  return (S(x, 17) ^ S(x, 19) ^ R(x, 10));
+};
+
+var core_sha256 = function(m, l) {
+  var K = new Array(0x428A2F98,0x71374491,0xB5C0FBCF,0xE9B5DBA5,0x3956C25B,0x59F111F1,0x923F82A4,0xAB1C5ED5,0xD807AA98,0x12835B01,0x243185BE,0x550C7DC3,0x72BE5D74,0x80DEB1FE,0x9BDC06A7,0xC19BF174,0xE49B69C1,0xEFBE4786,0xFC19DC6,0x240CA1CC,0x2DE92C6F,0x4A7484AA,0x5CB0A9DC,0x76F988DA,0x983E5152,0xA831C66D,0xB00327C8,0xBF597FC7,0xC6E00BF3,0xD5A79147,0x6CA6351,0x14292967,0x27B70A85,0x2E1B2138,0x4D2C6DFC,0x53380D13,0x650A7354,0x766A0ABB,0x81C2C92E,0x92722C85,0xA2BFE8A1,0xA81A664B,0xC24B8B70,0xC76C51A3,0xD192E819,0xD6990624,0xF40E3585,0x106AA070,0x19A4C116,0x1E376C08,0x2748774C,0x34B0BCB5,0x391C0CB3,0x4ED8AA4A,0x5B9CCA4F,0x682E6FF3,0x748F82EE,0x78A5636F,0x84C87814,0x8CC70208,0x90BEFFFA,0xA4506CEB,0xBEF9A3F7,0xC67178F2);
+  var HASH = new Array(0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A, 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19);
+    var W = new Array(64);
+    var a, b, c, d, e, f, g, h, i, j;
+    var T1, T2;
+  /* append padding */
+  m[l >> 5] |= 0x80 << (24 - l % 32);
+  m[((l + 64 >> 9) << 4) + 15] = l;
+  for (var i = 0; i < m.length; i += 16) {
+    a = HASH[0]; b = HASH[1]; c = HASH[2]; d = HASH[3]; e = HASH[4]; f = HASH[5]; g = HASH[6]; h = HASH[7];
+    for (var j = 0; j < 64; j++) {
+      if (j < 16) {
+        W[j] = m[j + i];
+      } else {
+        W[j] = safe_add(safe_add(safe_add(Gamma1256(W[j - 2]), W[j - 7]), Gamma0256(W[j - 15])), W[j - 16]);
+      }
+      T1 = safe_add(safe_add(safe_add(safe_add(h, Sigma1256(e)), Ch(e, f, g)), K[j]), W[j]);
+      T2 = safe_add(Sigma0256(a), Maj(a, b, c));
+      h = g; g = f; f = e; e = safe_add(d, T1); d = c; c = b; b = a; a = safe_add(T1, T2);
+    }
+    HASH[0] = safe_add(a, HASH[0]); HASH[1] = safe_add(b, HASH[1]); HASH[2] = safe_add(c, HASH[2]); HASH[3] = safe_add(d, HASH[3]);
+    HASH[4] = safe_add(e, HASH[4]); HASH[5] = safe_add(f, HASH[5]); HASH[6] = safe_add(g, HASH[6]); HASH[7] = safe_add(h, HASH[7]);
+  }
+  return HASH;
+};
+
+module.exports = function sha256(buf) {
+  return helpers.hash(buf, core_sha256, 32, true);
+};