Yes, this is possible, but since databases do this in a variety of different ways, it is not terribly straightforward.
The best way to do this is using Tableau's Custom SQL function, where you can pass in a completely custom SQL SELECT statement to the database.
Then, you will use your database's built-in functions to decrypt the data.
With custom SQL, you can pass almost any SELECT statement to the database, so the real limitation is what your database allows you to do!
Hope this helps!
If data security is our primary focus here, this technique would really only work with a live connection correct? If we use the tableau extract, the data would be exposed within the extract
The tde extract is only readable by Tableau, but it would indeed land the data to disk.
Unless stored with the connection on tableau server, the live connection would require a username/password to the DB to pull data.