This function decrypts data. Note that the length of the
returned string can in fact be longer then the unencrypted
string, due to the padding of the data.
The above example shows how to check if the data before
the encryption is the same as the data after the decryption.
It is very important to reinitialize the encryption buffer
with mcrypt_generic_init() before you try to
decrypt the data.
The decryption handle should alwayws be initialized with
mcrypt_generic_init() with a key and an IV
before calling this function. Where the encryption is done,
you should free the encryption buffers by calling
mcrypt_generic_deinit(). See
mcrypt_module_open() for an example.
See also mcrypt_generic(),
mcrypt_generic_init() and
mcrypt_generic_deinit().