Database message cache should be encrypted

[makinde]

For this to be deployed in many environments the message information stored in the database needs to be encrypted. Having it exposed to any user who can see the tables is a security risk at my university.

[Zelest]

Having others accessing the tables is a security risk in my opinion and I don't think this is a job for Roundcube to solve as it's the system administrators job to create a separate user/database for Roundcube and only letting Roundcube have access to it. Saying that it's a security risk because others have access to the database is like saying that postfix (or any other MTA) has a security risk because they don't encrypt the maildirs and someone else have access to the maildir.