diff --git a/crypto_secretbox.js b/crypto_secretbox.js
new file mode 100644
index 0000000..d33b8f5
--- /dev/null
+++ b/crypto_secretbox.js
@@ -0,0 +1,93 @@
+var { crypto_stream, crypto_stream_xor } = require('./crypto_stream')
+var { crypto_onetimeauth, crypto_onetimeauth_verify } = require('./crypto_onetimeauth')
+
+var crypto_secretbox_KEYBYTES = 32,
+    crypto_secretbox_NONCEBYTES = 24,
+    crypto_secretbox_ZEROBYTES = 32,
+    crypto_secretbox_BOXZEROBYTES = 16,
+    crypto_secretbox_MACBYTES = 16
+
+module.exports = {
+  crypto_secretbox,
+  crypto_secretbox_open,
+  crypto_secretbox_detached,
+  crypto_secretbox_open_detached,
+  crypto_secretbox_easy,
+  crypto_secretbox_open_easy,
+  crypto_secretbox_KEYBYTES,
+  crypto_secretbox_NONCEBYTES,
+  crypto_secretbox_ZEROBYTES,
+  crypto_secretbox_BOXZEROBYTES,
+  crypto_secretbox_MACBYTES
+}
+
+function crypto_secretbox(c,m,d,n,k) {
+  var i;
+  if (d < 32) return -1;
+  crypto_stream_xor(c,0,m,0,d,n,k);
+  crypto_onetimeauth(c, 16, c, 32, d - 32, c);
+  for (i = 0; i < 16; i++) c[i] = 0;
+  return 0;
+}
+
+function crypto_secretbox_open(m,c,d,n,k) {
+  var i;
+  var x = new Uint8Array(32);
+  if (d < 32) return -1;
+  crypto_stream(x,0,32,n,k);
+  if (crypto_onetimeauth_verify(c, 16,c, 32,d - 32,x) !== 0) return -1;
+  crypto_stream_xor(m,0,c,0,d,n,k);
+  for (i = 0; i < 32; i++) m[i] = 0;
+  return 0;
+}
+
+function crypto_secretbox_detached (o, mac, msg, n, k) {
+  check(mac, crypto_secretbox_MACBYTES)
+  var tmp = new Uint8Array(msg.length + mac.length)
+  crypto_secretbox_easy(tmp, msg, n, k)
+  o.set(tmp.subarray(0, msg.length))
+  mac.set(tmp.subarray(msg.length))
+}
+
+function crypto_secretbox_open_detached (msg, o, mac, n, k) {
+  check(mac, crypto_secretbox_MACBYTES)
+  var tmp = new Uint8Array(o.length + mac.length)
+  tmp.set(o)
+  tmp.set(mac, msg.length)
+  return crypto_secretbox_open_easy(msg, tmp, n, k)
+}
+
+function crypto_secretbox_easy(o, msg, n, k) {
+  check(msg, 0)
+  check(o, msg.length + crypto_secretbox_MACBYTES)
+  check(n, crypto_secretbox_NONCEBYTES)
+  check(k, crypto_secretbox_KEYBYTES)
+
+  var i
+  var m = new Uint8Array(crypto_secretbox_ZEROBYTES + msg.length);
+  var c = new Uint8Array(m.length);
+  for (i = 0; i < msg.length; i++) m[i+crypto_secretbox_ZEROBYTES] = msg[i];
+  crypto_secretbox(c, m, m.length, n, k);
+  for (i = crypto_secretbox_BOXZEROBYTES; i < c.length; i++) o[i - crypto_secretbox_BOXZEROBYTES] = c[i]
+}
+
+function crypto_secretbox_open_easy(msg, box, n, k) {
+  check(box, crypto_secretbox_MACBYTES)
+  check(msg, box.length - crypto_secretbox_MACBYTES)
+  check(n, crypto_secretbox_NONCEBYTES)
+  check(k, crypto_secretbox_KEYBYTES)
+
+  var i
+  var c = new Uint8Array(crypto_secretbox_BOXZEROBYTES + box.length);
+  var m = new Uint8Array(c.length);
+  for (i = 0; i < box.length; i++) c[i+crypto_secretbox_BOXZEROBYTES] = box[i];
+  if (c.length < 32) return false;
+  if (crypto_secretbox_open(m, c, c.length, n, k) !== 0) return false;
+
+  for (i = crypto_secretbox_ZEROBYTES; i < m.length; i++) msg[i - crypto_secretbox_ZEROBYTES] = m[i]
+  return true
+}
+
+function check (buf, len) {
+  if (!buf || (len && buf.length < len)) throw new Error('Argument must be a buffer' + (len ? ' of length ' + len : ''))
+}
diff --git a/index.js b/index.js
index 639bb33..1e23bf6 100644
--- a/index.js
+++ b/index.js
@@ -45,75 +45,9 @@ function crypto_onetimeauth_verify(h, hpos, m, mpos, n, k) {
   return crypto_verify_16(h,hpos,x,0);
 }
 
-function crypto_secretbox(c,m,d,n,k) {
-  var i;
-  if (d < 32) return -1;
-  crypto_stream_xor(c,0,m,0,d,n,k);
-  crypto_onetimeauth(c, 16, c, 32, d - 32, c);
-  for (i = 0; i < 16; i++) c[i] = 0;
-  return 0;
-}
-
-function crypto_secretbox_open(m,c,d,n,k) {
-  var i;
-  var x = new Uint8Array(32);
-  if (d < 32) return -1;
-  crypto_stream(x,0,32,n,k);
-  if (crypto_onetimeauth_verify(c, 16,c, 32,d - 32,x) !== 0) return -1;
-  crypto_stream_xor(m,0,c,0,d,n,k);
-  for (i = 0; i < 32; i++) m[i] = 0;
-  return 0;
-}
 
 
 
-function crypto_secretbox_detached (o, mac, msg, n, k) {
-  check(mac, sodium.crypto_secretbox_MACBYTES)
-  var tmp = new Uint8Array(msg.length + mac.length)
-  crypto_secretbox_easy(tmp, msg, n, k)
-  o.set(tmp.subarray(0, msg.length))
-  mac.set(tmp.subarray(msg.length))
-}
-
-function crypto_secretbox_open_detached (msg, o, mac, n, k) {
-  check(mac, sodium.crypto_secretbox_MACBYTES)
-  var tmp = new Uint8Array(o.length + mac.length)
-  tmp.set(o)
-  tmp.set(mac, msg.length)
-  return crypto_secretbox_open_easy(msg, tmp, n, k)
-}
-
-function crypto_secretbox_easy(o, msg, n, k) {
-  check(msg, 0)
-  check(o, msg.length + sodium.crypto_secretbox_MACBYTES)
-  check(n, crypto_secretbox_NONCEBYTES)
-  check(k, crypto_secretbox_KEYBYTES)
-
-  var i
-  var m = new Uint8Array(crypto_secretbox_ZEROBYTES + msg.length);
-  var c = new Uint8Array(m.length);
-  for (i = 0; i < msg.length; i++) m[i+crypto_secretbox_ZEROBYTES] = msg[i];
-  crypto_secretbox(c, m, m.length, n, k);
-  for (i = crypto_secretbox_BOXZEROBYTES; i < c.length; i++) o[i - crypto_secretbox_BOXZEROBYTES] = c[i]
-}
-
-function crypto_secretbox_open_easy(msg, box, n, k) {
-  check(box, sodium.crypto_secretbox_MACBYTES)
-  check(msg, box.length - sodium.crypto_secretbox_MACBYTES)
-  check(n, crypto_secretbox_NONCEBYTES)
-  check(k, crypto_secretbox_KEYBYTES)
-
-  var i
-  var c = new Uint8Array(crypto_secretbox_BOXZEROBYTES + box.length);
-  var m = new Uint8Array(c.length);
-  for (i = 0; i < box.length; i++) c[i+crypto_secretbox_BOXZEROBYTES] = box[i];
-  if (c.length < 32) return false;
-  if (crypto_secretbox_open(m, c, c.length, n, k) !== 0) return false;
-
-  for (i = crypto_secretbox_ZEROBYTES; i < m.length; i++) msg[i - crypto_secretbox_ZEROBYTES] = m[i]
-  return true
-}
-
 function crypto_box_keypair(pk, sk) {
   check(pk, crypto_box_PUBLICKEYBYTES)
   check(sk, crypto_box_SECRETKEYBYTES)
@@ -165,10 +99,6 @@ function crypto_box_seal_open(m, c, pk, sk) {
   return crypto_secretbox_open_easy(m, c.subarray(epk.length), n, k)
 }
 
-var crypto_secretbox_KEYBYTES = 32,
-    crypto_secretbox_NONCEBYTES = 24,
-    crypto_secretbox_ZEROBYTES = 32,
-    crypto_secretbox_BOXZEROBYTES = 16,
     crypto_box_PUBLICKEYBYTES = 32,
     crypto_box_SECRETKEYBYTES = 32,
     crypto_box_BEFORENMBYTES = 32,
@@ -189,13 +119,6 @@ forward(require('./randombytes'))
 forward(require('./crypto_stream'))
 
 
-sodium.crypto_secretbox_KEYBYTES = crypto_secretbox_KEYBYTES,
-sodium.crypto_secretbox_NONCEBYTES = crypto_secretbox_NONCEBYTES,
-sodium.crypto_secretbox_MACBYTES = 16
-sodium.crypto_secretbox_easy = crypto_secretbox_easy
-sodium.crypto_secretbox_open_easy = crypto_secretbox_open_easy
-sodium.crypto_secretbox_detached = crypto_secretbox_detached
-sodium.crypto_secretbox_open_detached = crypto_secretbox_open_detached
 
 sodium.crypto_box_PUBLICKEYBYTES = crypto_box_PUBLICKEYBYTES
 sodium.crypto_box_SECRETKEYBYTES = crypto_box_SECRETKEYBYTES
@@ -215,6 +138,7 @@ function cleanup(arr) {
 
 forward(require('./crypto_hash'))
 forward(require('./crypto_scalarmult'))
+forward(require('./crypto_secretbox'))
 forward(require('./crypto_sign'))
 forward(require('./crypto_stream'))