diff --git a/lib/xxtea.js b/lib/xxtea.js
index 4f95e7a..8a331a7 100755
--- a/lib/xxtea.js
+++ b/lib/xxtea.js
@@ -288,26 +288,26 @@ function toString(bytes) {
         toLongString(bytes, n));
 }
 
-function encrypt(data, key) {
+function encrypt(data, key, includeLength = true) {
     if (typeof data === 'string') data = toBytes(data);
     if (typeof key === 'string') key = toBytes(key);
     if (data === undefined || data === null || data.length === 0) {
         return data;
     }
-    return toUint8Array(encryptUint32Array(toUint32Array(data, true), toUint32Array(fixk(key), false)), false);
+    return toUint8Array(encryptUint32Array(toUint32Array(data, includeLength), toUint32Array(fixk(key), false)), false);
 }
 
 function encryptToString(data, key) {
     return new Buffer(encrypt(data, key)).toString('base64');
 }
 
-function decrypt(data, key) {
+function decrypt(data, key, includeLength = true) {
     if (typeof data === 'string') data = new Buffer(data, 'base64');
     if (typeof key === 'string') key = toBytes(key);
     if (data === undefined || data === null || data.length === 0) {
         return data;
     }
-    return toUint8Array(decryptUint32Array(toUint32Array(data, false), toUint32Array(fixk(key), false)), true);
+    return toUint8Array(decryptUint32Array(toUint32Array(data, false), toUint32Array(fixk(key), false)), includeLength);
 }
 
 function decryptToString(data, key) {