diff --git a/src/main/scala/gitbucket/core/util/StringUtil.scala b/src/main/scala/gitbucket/core/util/StringUtil.scala
index fa66729..bbbe5b4 100644
--- a/src/main/scala/gitbucket/core/util/StringUtil.scala
+++ b/src/main/scala/gitbucket/core/util/StringUtil.scala
@@ -13,7 +13,7 @@
 object StringUtil {
 
   private lazy val BlowfishKey = {
-    UUID.randomUUID().toString
+    UUID.randomUUID().toString.substring(0, 16)
   }
 
   def sha1(value: String): String =