🚀 go-pugleaf

What follows is the core of the IDEA cipher system.  Starting with a
random key and a random dataIn and then feeding back the dataOut
successively as dataIn, a pretty strong URNG should result.  It generates
16 bytes at a time.  I don't think much is known about its statistical
properties but it is known to be a strong cipher.


/******************************************************************************/
/* encryption and decryption algorithm IDEA                                   */

void  Idea(dataIn, dataOut, key)

u_int16 *dataIn, *dataOut, *key;
{
	register u_int32 round, x0, x1, x2, x3, t0, t1, t2;

  x0 = (u_int32)*(dataIn++);
	x1 = (u_int32)*(dataIn++);
  x2 = (u_int32)*(dataIn++);
	x3 = (u_int32)*(dataIn);
  for (round = nofRound; round > 0; round--)
	{
    x0 = Mul(x0, (u_int32)*(key++));
    x1 = (x1 + (u_int32)*(key++)) & ones;
    x2 = (x2 + (u_int32)*(key++)) & ones;
    x3 = Mul(x3, (u_int32)*(key++));
    t0 = Mul((u_int32)*(key++), x0 ^ x2);      
    t1 = Mul((u_int32)*(key++), (t0 + (x1 ^ x3)) & ones);
    t0 = (t0 + t1) & ones;
    x0 ^= t1;
		x3 ^= t0;
    t0 ^= x1;
		x1 = x2 ^ t1;
		x2 = t0;
  }
  *(dataOut++) = (u_int16)(Mul(x0, (u_int32)*(key++)));
  *(dataOut++) = (u_int16)((x2 + (u_int32)*(key++)) & ones);
  *(dataOut++) = (u_int16)((x1 + (u_int32)*(key++)) & ones);
  *(dataOut) = (u_int16)(Mul(x3, (u_int32)*key));
} /* Idea */
-- 
Bob Cain    rcain@netcom.com   408-358-2007

"There are some strings.  They're just not attached."
                                                    Victoria Roberts


               PGP 1.0 or 2.0 public key available on request.