This is a library of routines that implements the RC2 algorithm, as
described in RFC2268.  It consists of the following routines:

rc2_expand_key(char[] key, int length, int effective_key_length);

This places the given key (consisting of an array of chars of length length)
into the 128 byte key buffer (internal).  The maths is interesting, but the
outcome is that each byte of the expanded key depends on every byte of the
given key.

The effective_key_length specifies how much of the given key to actually
use.  This is a throwback to the underlying algorithm used.  Usually it
should be the same as length.

rc2_encrypt(unsigned short input[4]);

Encrypts the given 8 bytes and places the result in the same place, using
the previously expanded key.

rc2_decrypt(unsigned short input[4]);

The reverse operation from above, again using the previously expanded key.

In short, therefore, the following actions take place to encrypt a piece of
data:

rc2_expand_key();
while (data left to encrypt) {
	rc2_encrypt();
}

And a similar operation for decryption.

An example application, written by myself, is provided.  This program
endeavours to either encrypt or decrypt stdin (depending on how it is
invoked) and print the results to stdout, using the supplied key and other
data.

Any questions, comments, bug reports, can go to moi at the address below,
all flames (for whatever reason) can be happily poured to /dev/null.

------------------
Matthew Palmer
<mjp16@uow.edu.au>