diff --git a/wchat/common/Help.php b/wchat/common/Help.php
index 4528ead..2d8799a 100644
--- a/wchat/common/Help.php
+++ b/wchat/common/Help.php
@@ -162,20 +162,18 @@ class Help extends Miniprogarampage
 	 */
 	public static function sign(array $array, $key, $type)
 	{
-		ksort($array, SORT_ASC);
-		$string = [];
-		foreach ($array as $hashKey => $val) {
-			if (empty($val)) {
-				continue;
+		ksort($array);
+		$buff = "";
+		foreach ($array as $k => $v) {
+			if ($k != "sign" && $v != "" && !is_array($v)) {
+				$buff .= $k . "=" . $v . "&";
 			}
-			$string[] = $hashKey . '=' . $val;
 		}
-		$string[] = 'key=' . $key;
-		$string = implode('&', $string);
-		if ($type == 'MD5') {
+		$string = trim($buff, "&") . '&key=' . $key;
+		if (strtoupper($type) == 'MD5') {
 			return strtoupper(md5($string));
 		} else {
-			return hash('sha256', $string);
+			return hash_hmac('sha256', $string, $key);
 		}
 	}