Storing Social Security Numbers

Question

The HR department at the company that I am currently working for has requested that I provide a system for storing employee social security numbers in our company database. The

Answer 1

I'm not sure if you can do this in MySQL, but you could have an insert / update trigger on the table that encrypts the data as it's saved to the database, and then have a view on the table that automatically decrypts the SSN.

Note that this only deals with encrypting the data on disk; you'd want to look into transport-layer encryption as well to protect the data on the wire (again, if MySQL supports that).

Edited to add: After reading Marcin's answer, I realized that I didn't mention the key management issue. Anyone who has access to the trigger or view definitions also has access to the encryption key, so if MySQL has the ability to hide trigger and view definitions, you'd want to look into that as well. Of course, including the encryption key with the encrypted data is inherently insecure in the first place, so this isn't a perfect solution.