The Mangler Function: 
This is reversible using the inverse keys.

Decryption Keys:
     (K49)-1   -(K50)   -(K51)    (K52)-1   K47    K48     (K43)-1    -(K44)  ....

Advanced  Encryption Standard (AES):

Developed with the help of NIST as an efficient, flexible, secure and
unencumbered (free to implement) standard  for protecting
sensitive non classified, U.S. government information.
NIST selected an algorithm called Rijndael (named after two Belgium cryptographers).
It uses a variety of block and key sizes (mainly 128, 192 and 256)
and the standards are named: AES-128, AES-192, AES-256!
(block sizes are fixed in all to 128 bits).
It is similar to DES and IDEA in that there is rounds and key expansion.


Multiple Encryption DES