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/*
* Copyright © 1999 Bart Massey.
* All Rights Reserved. See the file COPYING in this directory
* for licensing information.
*/
/*
* Implementation of Alleged RC4
*
* Bart 1999/2
*
* Used primarily for PRNG, so interface is not too fancy
*/
namespace ARC4 {
global int[256] state = {};
global int p1, p2;
public void nsetkey(int nn, int k)
/*
* First argument is number of times to iterate the
* initial scramble. 10 seems good for most apps.
* Second argument is integer key: largest useful key is
* 8 * 62 bits.
*/
{
int i, j, n, ii;
int[64] key = {};
key[0] = 13;
key[1] = 17;
for (n = 2; n < 64 && k > 0; n++) {
key[n] = k & 0xff;
k = k >> 8;
}
for (i = 0; i < 256; i++)
state[i] = i;
for (ii = 0; ii < nn; ii++) {
j = 0;
for (i = 0; i < 256; i++) {
j = (j + state[i] + key[i % n]) & 0xff;
int tmp = state[i];
state[i] = state[j];
state[j] = tmp;
}
}
p1 = p2 = 0;
}
public int streambyte()
/*
* Get the next byte from the stream
*/
{
p1 = (p1 + 1) & 0xff;
p2 = (p2 + state[p1]) & 0xff;
int tmp = state[p1];
state[p1] = state[p2];
state[p2] = tmp;
int n = (state[p1] + state[p2]) & 0xff;
return state[n];
}
}
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