I'm going to be storing a few sensitive pieces of information (SSN, Bank Accounts, etc) so they'll obviously need to be encrypted. What strategies do you recommend?

Should I do all the encryption/decryption in the web app itself? Should I use something like pgcrypto and have the conversions done on the DB side? Something else entirely?

Also, if you think I should do encryption on the web app side, what Python libraries would you recommend?