diff --git a/tempest/scenario/test_encrypted_cinder_volumes.py b/tempest/scenario/test_encrypted_cinder_volumes.py
index dcd77ad..1659ebe 100644
--- a/tempest/scenario/test_encrypted_cinder_volumes.py
+++ b/tempest/scenario/test_encrypted_cinder_volumes.py
@@ -53,7 +53,7 @@
         volume_type = self.create_volume_type(name=volume_type)
         self.create_encryption_type(type_id=volume_type['id'],
                                     provider=encryption_provider,
-                                    key_size=512,
+                                    key_size=256,
                                     cipher='aes-xts-plain64',
                                     control_location='front-end')
         return self.create_volume(volume_type=volume_type['name'])