encrypt data in database

Hi,

I have a .net application and i added a code that encrypts data saved in database. However, there is already data in the fields that was entered before this change.
I know need to check if the values in those fields are encrypted and if not i need to encrypt them.
How can I perform such a check and update the relevant data?
I use TrippleDES in .net to encrypt/decrypt the data.

Thanks

Have a look at this article:

http://aspnet.4guysfromrolla.com/articles/081705-1.aspx