diff --git a/app/common.php b/app/common.php
index 44e2c5f12..d74c47d1c 100755
--- a/app/common.php
+++ b/app/common.php
@@ -2608,7 +2608,8 @@ function Authcode($string, $operation = 'DECODE', $key = '', $expiry = 0)
         // substr($result, 0, 10) - time() > 0 验证数据有效性
         // substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16) 验证数据完整性
         // 验证数据有效性，请看未加密明文的格式
-        if((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16)) {
+        if($result !== '' && $result !== null && (substr($result, 0, 10) == 0 || intval(substr($result, 0, 10)) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16))
+        {
             return substr($result, 26);
         } else {
             return '';