PostgreSQL has a nice encryption (and hashing) module called pgcrypto which is easy to use. Using a provided key, you can quickly encrypt a column which contains sensitive information.
While the setup is fast and the usage is simple, there could be some disadvantages in some contexts:
- be careful how you send the encryption key to the database server (if public, use SSL for transport, else keep it in a private network at least)
- data is encrypted/decrypted in the database, so the transport is in plain (watch out for memory dump attacks)
- some queries are very slow, as the decrypt operation is performed on the entire table if you want to sort or filter by encrypted columns