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 "os_port.h"
38 #include "crypto.h"
39
40 /* only used for PKCS12 now */
41 #ifdef CONFIG_SSL_USE_PKCS12
42
43 /**
44 * Get ready for an encrypt/decrypt operation
45 */
RC4_setup(RC4_CTX * ctx,const uint8_t * key,int length)46 void RC4_setup(RC4_CTX *ctx, const uint8_t *key, int length)
47 {
48 int i, j = 0, k = 0, a;
49 uint8_t *m;
50
51 ctx->x = 0;
52 ctx->y = 0;
53 m = ctx->m;
54
55 for (i = 0; i < 256; i++)
56 m[i] = i;
57
58 for (i = 0; i < 256; i++)
59 {
60 a = m[i];
61 j = (uint8_t)(j + a + key[k]);
62 m[i] = m[j];
63 m[j] = a;
64
65 if (++k >= length)
66 k = 0;
67 }
68 }
69
70 /**
71 * Perform the encrypt/decrypt operation (can use it for either since
72 * this is a stream cipher).
73 * NOTE: *msg and *out must be the same pointer (performance tweak)
74 */
RC4_crypt(RC4_CTX * ctx,const uint8_t * msg,uint8_t * out,int length)75 void RC4_crypt(RC4_CTX *ctx, const uint8_t *msg, uint8_t *out, int length)
76 {
77 int i;
78 uint8_t *m, x, y, a, b;
79
80 x = ctx->x;
81 y = ctx->y;
82 m = ctx->m;
83
84 for (i = 0; i < length; i++)
85 {
86 a = m[++x];
87 y += a;
88 m[x] = b = m[y];
89 m[y] = a;
90 out[i] ^= m[(uint8_t)(a + b)];
91 }
92
93 ctx->x = x;
94 ctx->y = y;
95 }
96
97 #endif
98