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time data is encrypted, that state is digested and the hash output is
used for the next state. The data to be encrypted is XORed by the
state to create the ciphered text. To retrieve the original data,
the process is applied again. In this mode, the message digest is
independent of the input data, but the pros and cons of that will not
be discussed here. This fact does help us in making a random number
generator. Depending on the block size, the above may have to loop until
and add data until the requested amount of random data has been produced.
In any case, the initial input into the algorithm determines what will
come out after that point.
