[Mcrypt-users] RC4 / DES56

[Steve <lor...@ya...>]

Hi

Firstly I know very little about the art of
cryptography. I'm trying to connect to an online
credit card processing system where I need to encrypt
two pieces of data (the amount and order id) using
either a DES56 or RC4 algorthim.  I have access to the
mcrypt libraries via PHP.

My questions. What is DES56 and how does it differ
from DES? Can DES56 be done with the mcrypt libraries?
Can anyone recommend a good tutorial on the web where
I can figure out how to do this? Is RC4 is easier to
implement? I believe that the ECB mode is best for
encrypting text strings, do I have to know what
encryption mode the bank is using? Or do the different
modes end in the same result but go about it in
different ways?

Any help would be greatly appreciated.

cheers
steve

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