= Migrating from 3.4.0 to 3.5.0

:Notice: Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at. http://www.apache.org/licenses/LICENSE-2.0 . Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR  CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
:page-partial:

== Encrypted Bookmarks for view models

This release automatically encrypts the bookmarks for view models so that they are not susceptible to forgery or serialization attacks.

The encyrption is performed using an instance of `HmacAuthority`.
By default, the framework creates a random instance each time it is started, meaning that any bookmarks (for view models, not entities) become invalid if the application is restarted, using the following code:

[source,java]
----
@Configuration
class EnableHmacAuthority {
    @Bean
    public HmacAuthority hmacAuthority() {
        return HmacAuthority.HmacSHA256.randomInstance();
    }
}
----

To override this behaviour (so that bookmarks are not invalidated), provide your own instance of this bean.
It's up to you how you choose to keep the seed value secret.
