Mercurial > projects > hoofbaby
comparison deps/Platinum/ThirdParty/Neptune/ThirdParty/axTLS/crypto/rc4.c @ 0:3425707ddbf6
Initial import (hopefully this mercurial stuff works...)
author | fraserofthenight |
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date | Mon, 06 Jul 2009 08:06:28 -0700 |
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1 /* | |
2 * Copyright (c) 2007, Cameron Rich | |
3 * | |
4 * All rights reserved. | |
5 * | |
6 * Redistribution and use in source and binary forms, with or without | |
7 * modification, are permitted provided that the following conditions are met: | |
8 * | |
9 * * Redistributions of source code must retain the above copyright notice, | |
10 * this list of conditions and the following disclaimer. | |
11 * * Redistributions in binary form must reproduce the above copyright notice, | |
12 * this list of conditions and the following disclaimer in the documentation | |
13 * and/or other materials provided with the distribution. | |
14 * * Neither the name of the axTLS project nor the names of its contributors | |
15 * may be used to endorse or promote products derived from this software | |
16 * without specific prior written permission. | |
17 * | |
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR | |
22 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, | |
23 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, | |
24 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR | |
25 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF | |
26 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING | |
27 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | |
28 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
29 */ | |
30 | |
31 /** | |
32 * An implementation of the RC4/ARC4 algorithm. | |
33 * Originally written by Christophe Devine. | |
34 */ | |
35 | |
36 #include <string.h> | |
37 #include "crypto.h" | |
38 | |
39 /** | |
40 * Get ready for an encrypt/decrypt operation | |
41 */ | |
42 void RC4_setup(RC4_CTX *ctx, const uint8_t *key, int length) | |
43 { | |
44 int i, j = 0, k = 0, a; | |
45 uint8_t *m; | |
46 | |
47 ctx->x = 0; | |
48 ctx->y = 0; | |
49 m = ctx->m; | |
50 | |
51 for (i = 0; i < 256; i++) | |
52 m[i] = i; | |
53 | |
54 for (i = 0; i < 256; i++) | |
55 { | |
56 a = m[i]; | |
57 j = (uint8_t)(j + a + key[k]); | |
58 m[i] = m[j]; | |
59 m[j] = a; | |
60 | |
61 if (++k >= length) | |
62 k = 0; | |
63 } | |
64 } | |
65 | |
66 /** | |
67 * Perform the encrypt/decrypt operation (can use it for either since | |
68 * this is a stream cipher). | |
69 */ | |
70 void RC4_crypt(RC4_CTX *ctx, const uint8_t *msg, uint8_t *out, int length) | |
71 { | |
72 int i; | |
73 uint8_t *m, x, y, a, b; | |
74 out = (uint8_t *)msg; | |
75 | |
76 x = ctx->x; | |
77 y = ctx->y; | |
78 m = ctx->m; | |
79 | |
80 for (i = 0; i < length; i++) | |
81 { | |
82 a = m[++x]; | |
83 y += a; | |
84 m[x] = b = m[y]; | |
85 m[y] = a; | |
86 out[i] ^= m[(uint8_t)(a + b)]; | |
87 } | |
88 | |
89 ctx->x = x; | |
90 ctx->y = y; | |
91 } |