WP User Data encryption

Hi guys. Looking to pickup some brains for seems to be impossible task. Got a project with a lot of users and crazy requirements about security so… AWS RDS encryption is not enough – we need to encrypt user’s table and user meta.

Now everything is beautiful, wp_signon has wp_authenticate filter so I thought I’m in heaven and then I hit the rocks with wp_metadata that has neither hooks nor is pluggable:
https://github.com/WordPress/WordPress/blob/master/wp-includes/meta.php#L461

So I can encrypt data on the way in, on login but not on the way out… Any smart move for workaround or is it just the end