| 0,0 → 1,98 |
|---|
| /* This code illustrates a sample implementation |
| * of the Arcfour algorithm |
| * Copyright (c) April 29, 1997 Kalle Kaukonen. |
| * All Rights Reserved. |
| * |
| * Redistribution and use in source and binary forms, with or |
| * without modification, are permitted provided that this copyright |
| * notice and disclaimer are retained. |
| * |
| * THIS SOFTWARE IS PROVIDED BY KALLE KAUKONEN AND CONTRIBUTORS ``AS |
| * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL KALLE |
| * KAUKONEN OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "fitz.h" |
| |
| void |
| fz_arc4_init(fz_arc4 *arc4, const unsigned char *key, const unsigned keylen) |
| { |
| unsigned int t, u; |
| unsigned int keyindex; |
| unsigned int stateindex; |
| unsigned char *state; |
| unsigned int counter; |
| |
| state = arc4->state; |
| |
| arc4->x = 0; |
| arc4->y = 0; |
| |
| for (counter = 0; counter < 256; counter++) |
| { |
| state[counter] = counter; |
| } |
| |
| keyindex = 0; |
| stateindex = 0; |
| |
| for (counter = 0; counter < 256; counter++) |
| { |
| t = state[counter]; |
| stateindex = (stateindex + key[keyindex] + t) & 0xff; |
| u = state[stateindex]; |
| |
| state[stateindex] = t; |
| state[counter] = u; |
| |
| if (++keyindex >= keylen) |
| { |
| keyindex = 0; |
| } |
| } |
| } |
| |
| static unsigned char |
| fz_arc4_next(fz_arc4 *arc4) |
| { |
| unsigned int x; |
| unsigned int y; |
| unsigned int sx, sy; |
| unsigned char *state; |
| |
| state = arc4->state; |
| |
| x = (arc4->x + 1) & 0xff; |
| sx = state[x]; |
| y = (sx + arc4->y) & 0xff; |
| sy = state[y]; |
| |
| arc4->x = x; |
| arc4->y = y; |
| |
| state[y] = sx; |
| state[x] = sy; |
| |
| return state[(sx + sy) & 0xff]; |
| } |
| |
| void |
| fz_arc4_encrypt(fz_arc4 *arc4, unsigned char *dest, const unsigned char *src, const unsigned len) |
| { |
| unsigned int i; |
| for (i = 0; i < len; i++) |
| { |
| unsigned char x; |
| x = fz_arc4_next(arc4); |
| dest[i] = src[i] ^ x; |
| } |
| } |