1 | /* |
2 | * An implementation of the ARCFOUR algorithm |
3 | * |
4 | * Copyright The Mbed TLS Contributors |
5 | * SPDX-License-Identifier: Apache-2.0 |
6 | * |
7 | * Licensed under the Apache License, Version 2.0 (the "License"); you may |
8 | * not use this file except in compliance with the License. |
9 | * You may obtain a copy of the License at |
10 | * |
11 | * http://www.apache.org/licenses/LICENSE-2.0 |
12 | * |
13 | * Unless required by applicable law or agreed to in writing, software |
14 | * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
15 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
16 | * See the License for the specific language governing permissions and |
17 | * limitations under the License. |
18 | */ |
19 | /* |
20 | * The ARCFOUR algorithm was publicly disclosed on 94/09. |
21 | * |
22 | * http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0 |
23 | */ |
24 | |
25 | #include "common.h" |
26 | |
27 | #if defined(MBEDTLS_ARC4_C) |
28 | |
29 | #include "mbedtls/arc4.h" |
30 | #include "mbedtls/platform_util.h" |
31 | |
32 | #include <string.h> |
33 | |
34 | #include "mbedtls/platform.h" |
35 | |
36 | #if !defined(MBEDTLS_ARC4_ALT) |
37 | |
38 | void mbedtls_arc4_init(mbedtls_arc4_context *ctx) |
39 | { |
40 | memset(ctx, 0, sizeof(mbedtls_arc4_context)); |
41 | } |
42 | |
43 | void mbedtls_arc4_free(mbedtls_arc4_context *ctx) |
44 | { |
45 | if (ctx == NULL) { |
46 | return; |
47 | } |
48 | |
49 | mbedtls_platform_zeroize(ctx, sizeof(mbedtls_arc4_context)); |
50 | } |
51 | |
52 | /* |
53 | * ARC4 key schedule |
54 | */ |
55 | void mbedtls_arc4_setup(mbedtls_arc4_context *ctx, const unsigned char *key, |
56 | unsigned int keylen) |
57 | { |
58 | int i, j, a; |
59 | unsigned int k; |
60 | unsigned char *m; |
61 | |
62 | ctx->x = 0; |
63 | ctx->y = 0; |
64 | m = ctx->m; |
65 | |
66 | for (i = 0; i < 256; i++) { |
67 | m[i] = (unsigned char) i; |
68 | } |
69 | |
70 | j = k = 0; |
71 | |
72 | for (i = 0; i < 256; i++, k++) { |
73 | if (k >= keylen) { |
74 | k = 0; |
75 | } |
76 | |
77 | a = m[i]; |
78 | j = (j + a + key[k]) & 0xFF; |
79 | m[i] = m[j]; |
80 | m[j] = (unsigned char) a; |
81 | } |
82 | } |
83 | |
84 | /* |
85 | * ARC4 cipher function |
86 | */ |
87 | int mbedtls_arc4_crypt(mbedtls_arc4_context *ctx, size_t length, const unsigned char *input, |
88 | unsigned char *output) |
89 | { |
90 | int x, y, a, b; |
91 | size_t i; |
92 | unsigned char *m; |
93 | |
94 | x = ctx->x; |
95 | y = ctx->y; |
96 | m = ctx->m; |
97 | |
98 | for (i = 0; i < length; i++) { |
99 | x = (x + 1) & 0xFF; a = m[x]; |
100 | y = (y + a) & 0xFF; b = m[y]; |
101 | |
102 | m[x] = (unsigned char) b; |
103 | m[y] = (unsigned char) a; |
104 | |
105 | output[i] = (unsigned char) |
106 | (input[i] ^ m[(unsigned char) (a + b)]); |
107 | } |
108 | |
109 | ctx->x = x; |
110 | ctx->y = y; |
111 | |
112 | return 0; |
113 | } |
114 | |
115 | #endif /* !MBEDTLS_ARC4_ALT */ |
116 | |
117 | #if defined(MBEDTLS_SELF_TEST) |
118 | /* |
119 | * ARC4 tests vectors as posted by Eric Rescorla in sep. 1994: |
120 | * |
121 | * http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0 |
122 | */ |
123 | static const unsigned char arc4_test_key[3][8] = |
124 | { |
125 | { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, |
126 | { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, |
127 | { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } |
128 | }; |
129 | |
130 | static const unsigned char arc4_test_pt[3][8] = |
131 | { |
132 | { 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF }, |
133 | { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }, |
134 | { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } |
135 | }; |
136 | |
137 | static const unsigned char arc4_test_ct[3][8] = |
138 | { |
139 | { 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 }, |
140 | { 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 }, |
141 | { 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A } |
142 | }; |
143 | |
144 | /* |
145 | * Checkup routine |
146 | */ |
147 | int mbedtls_arc4_self_test(int verbose) |
148 | { |
149 | int i, ret = 0; |
150 | unsigned char ibuf[8]; |
151 | unsigned char obuf[8]; |
152 | mbedtls_arc4_context ctx; |
153 | |
154 | mbedtls_arc4_init(&ctx); |
155 | |
156 | for (i = 0; i < 3; i++) { |
157 | if (verbose != 0) { |
158 | mbedtls_printf(" ARC4 test #%d: " , i + 1); |
159 | } |
160 | |
161 | memcpy(ibuf, arc4_test_pt[i], 8); |
162 | |
163 | mbedtls_arc4_setup(&ctx, arc4_test_key[i], 8); |
164 | mbedtls_arc4_crypt(&ctx, 8, ibuf, obuf); |
165 | |
166 | if (memcmp(obuf, arc4_test_ct[i], 8) != 0) { |
167 | if (verbose != 0) { |
168 | mbedtls_printf("failed\n" ); |
169 | } |
170 | |
171 | ret = 1; |
172 | goto exit; |
173 | } |
174 | |
175 | if (verbose != 0) { |
176 | mbedtls_printf("passed\n" ); |
177 | } |
178 | } |
179 | |
180 | if (verbose != 0) { |
181 | mbedtls_printf("\n" ); |
182 | } |
183 | |
184 | exit: |
185 | mbedtls_arc4_free(&ctx); |
186 | |
187 | return ret; |
188 | } |
189 | |
190 | #endif /* MBEDTLS_SELF_TEST */ |
191 | |
192 | #endif /* MBEDTLS_ARC4_C */ |
193 | |