Rev 4680 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4680 | right-hear | 1 | /* This code illustrates a sample implementation |
| 2 | * of the Arcfour algorithm |
||
| 3 | * Copyright (c) April 29, 1997 Kalle Kaukonen. |
||
| 4 | * All Rights Reserved. |
||
| 5 | * |
||
| 6 | * Redistribution and use in source and binary forms, with or |
||
| 7 | * without modification, are permitted provided that this copyright |
||
| 8 | * notice and disclaimer are retained. |
||
| 9 | * |
||
| 10 | * THIS SOFTWARE IS PROVIDED BY KALLE KAUKONEN AND CONTRIBUTORS ``AS |
||
| 11 | * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
||
| 12 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
||
| 13 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL KALLE |
||
| 14 | * KAUKONEN OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
||
| 15 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
||
| 16 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
||
| 17 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
||
| 18 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
||
| 19 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
||
| 20 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
||
| 21 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
||
| 22 | */ |
||
| 23 | |||
| 24 | #include "fitz.h" |
||
| 25 | |||
| 26 | void |
||
| 27 | fz_arc4_init(fz_arc4 *arc4, const unsigned char *key, const unsigned keylen) |
||
| 28 | { |
||
| 29 | unsigned int t, u; |
||
| 30 | unsigned int keyindex; |
||
| 31 | unsigned int stateindex; |
||
| 32 | unsigned char *state; |
||
| 33 | unsigned int counter; |
||
| 34 | |||
| 35 | state = arc4->state; |
||
| 36 | |||
| 37 | arc4->x = 0; |
||
| 38 | arc4->y = 0; |
||
| 39 | |||
| 40 | for (counter = 0; counter < 256; counter++) |
||
| 41 | { |
||
| 42 | state[counter] = counter; |
||
| 43 | } |
||
| 44 | |||
| 45 | keyindex = 0; |
||
| 46 | stateindex = 0; |
||
| 47 | |||
| 48 | for (counter = 0; counter < 256; counter++) |
||
| 49 | { |
||
| 50 | t = state[counter]; |
||
| 51 | stateindex = (stateindex + key[keyindex] + t) & 0xff; |
||
| 52 | u = state[stateindex]; |
||
| 53 | |||
| 54 | state[stateindex] = t; |
||
| 55 | state[counter] = u; |
||
| 56 | |||
| 57 | if (++keyindex >= keylen) |
||
| 58 | { |
||
| 59 | keyindex = 0; |
||
| 60 | } |
||
| 61 | } |
||
| 62 | } |
||
| 63 | |||
| 64 | static unsigned char |
||
| 65 | fz_arc4_next(fz_arc4 *arc4) |
||
| 66 | { |
||
| 67 | unsigned int x; |
||
| 68 | unsigned int y; |
||
| 69 | unsigned int sx, sy; |
||
| 70 | unsigned char *state; |
||
| 71 | |||
| 72 | state = arc4->state; |
||
| 73 | |||
| 74 | x = (arc4->x + 1) & 0xff; |
||
| 75 | sx = state[x]; |
||
| 76 | y = (sx + arc4->y) & 0xff; |
||
| 77 | sy = state[y]; |
||
| 78 | |||
| 79 | arc4->x = x; |
||
| 80 | arc4->y = y; |
||
| 81 | |||
| 82 | state[y] = sx; |
||
| 83 | state[x] = sy; |
||
| 84 | |||
| 85 | return state[(sx + sy) & 0xff]; |
||
| 86 | } |
||
| 87 | |||
| 88 | void |
||
| 89 | fz_arc4_encrypt(fz_arc4 *arc4, unsigned char *dest, const unsigned char *src, const unsigned len) |
||
| 90 | { |
||
| 91 | unsigned int i; |
||
| 92 | for (i = 0; i < len; i++) |
||
| 93 | { |
||
| 94 | unsigned char x; |
||
| 95 | x = fz_arc4_next(arc4); |
||
| 96 | dest[i] = src[i] ^ x; |
||
| 97 | } |
||
| 98 | } |