Encrypting Existing Data using SQL SERVER 2016

Question

We have a web application running in PROD with SQL Server 2005 as database. Now, we need to implement data encyption as per the policy and planning to move to SQL 2016.

How to encrypt existing PROD data using SQL Server 2016 without changing the data types of the columns?

 

I need to encrypt selected columns on few tables for the existing data and as well as the encryption for the new records (even with new extension tables).

I don't want to apply the encryption using the symmetric key logic. 

Existing tables have records from the range 80000 to 500000. 

 

Can you please guide me on this? 

Thanks.