   AES_ENCRYPT(str,key_str)
   AES_DECRYPT(crypt_str,key_str)
These functions allow encryption and decryption of data using the official
AES (Advanced Encryption Standard) algorithm, previously known as "Rijndael."
Encoding with a 128-bit key length is used, but you can extend it up to
256 bits by modifying the source. We chose 128 bits because it is much
faster and it is usually secure enough.

The input arguments may be any length. If either argument is NULL,
the result of this function is also NULL.

Because AES is a block-level algorithm, padding is used to encode uneven length
strings and so the result string length may be calculated as
16*(trunc(string_length/16)+1).

If AES_DECRYPT() detects invalid data or incorrect padding, it
returns NULL. However, it is possible for AES_DECRYPT()
to return a non-NULL value (possibly garbage) if the input data or
the key is invalid.

You can use the AES functions to store data in an encrypted form by
modifying your queries:
