Oracle has improved the AES encryption/decryption functions in MySQL 5.6.17. They improved it a lot and posted a blog which explains all the details. If you would like to know more about encryption there are two resources I would recommend: The Code Book by Simon Singh. This is about the history of cryptography, but it also includes a lot of information about crypto which is currently in use. This is also a very entertaining read. Crypto 101 , a free/opensource book which gives a intro to crypto. The webpage also has a video of the talk on which the book is based. And if you're going to use the AES encryption functions in MySQL there are some things you should consider: Connections with a UNIX socket (or shared memory on Windows) should be safe. Local TCP/IP connections are also safe in most circumstances. Remote connections which use the AES encryption should use a protected connection (SSL, VPN, etc). Otherwise someone might be able to sniff the network traffice which...