use php's hash() function for do_hash() helper
diff --git a/system/helpers/security_helper.php b/system/helpers/security_helper.php
index e05e947..16dfb0d 100644
--- a/system/helpers/security_helper.php
+++ b/system/helpers/security_helper.php
@@ -87,7 +87,7 @@
 {
 	function do_hash($str, $type = 'sha1')
 	{
-		return ($type === 'sha1') ? sha1($str) : md5($str);
+		return hash($type, $str);
 	}
 }