column level encryption and SQL performance

[tom...@gmail.com]

Hello

We are being asked about encrypting SSNs and see that a simple sql such as

select id from t_contact where ssn = '350507267'

goes from lightning quick on returning a result and using an existing index to becoming very slow and doing a table scan to return a row after encryption (looks like it must be un-encrypting all rows to get to the one needed)

SELECT id FROM t_contact WHERE decrypt_char(ssn, 'XXXXXXXXXXXX') = '350507267'

what are the options to quicken the return result - or are there none?

thanks