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1da177e4 LT |
1 | /* |
2 | * Cryptographic API. | |
3 | * | |
4 | * TEA and Xtended TEA Algorithms | |
5 | * | |
6 | * The TEA and Xtended TEA algorithms were developed by David Wheeler | |
7 | * and Roger Needham at the Computer Laboratory of Cambridge University. | |
8 | * | |
9 | * Copyright (c) 2004 Aaron Grothe ajgrothe@yahoo.com | |
10 | * | |
11 | * This program is free software; you can redistribute it and/or modify | |
12 | * it under the terms of the GNU General Public License as published by | |
13 | * the Free Software Foundation; either version 2 of the License, or | |
14 | * (at your option) any later version. | |
15 | * | |
16 | */ | |
17 | ||
18 | #include <linux/init.h> | |
19 | #include <linux/module.h> | |
20 | #include <linux/mm.h> | |
21 | #include <asm/scatterlist.h> | |
22 | #include <linux/crypto.h> | |
23 | ||
24 | #define TEA_KEY_SIZE 16 | |
25 | #define TEA_BLOCK_SIZE 8 | |
26 | #define TEA_ROUNDS 32 | |
27 | #define TEA_DELTA 0x9e3779b9 | |
28 | ||
29 | #define XTEA_KEY_SIZE 16 | |
30 | #define XTEA_BLOCK_SIZE 8 | |
31 | #define XTEA_ROUNDS 32 | |
32 | #define XTEA_DELTA 0x9e3779b9 | |
33 | ||
34 | #define u32_in(x) le32_to_cpu(*(const __le32 *)(x)) | |
35 | #define u32_out(to, from) (*(__le32 *)(to) = cpu_to_le32(from)) | |
36 | ||
37 | struct tea_ctx { | |
38 | u32 KEY[4]; | |
39 | }; | |
40 | ||
41 | struct xtea_ctx { | |
42 | u32 KEY[4]; | |
43 | }; | |
44 | ||
45 | static int tea_setkey(void *ctx_arg, const u8 *in_key, | |
46 | unsigned int key_len, u32 *flags) | |
47 | { | |
48 | ||
49 | struct tea_ctx *ctx = ctx_arg; | |
50 | ||
51 | if (key_len != 16) | |
52 | { | |
53 | *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; | |
54 | return -EINVAL; | |
55 | } | |
56 | ||
57 | ctx->KEY[0] = u32_in (in_key); | |
58 | ctx->KEY[1] = u32_in (in_key + 4); | |
59 | ctx->KEY[2] = u32_in (in_key + 8); | |
60 | ctx->KEY[3] = u32_in (in_key + 12); | |
61 | ||
62 | return 0; | |
63 | ||
64 | } | |
65 | ||
66 | static void tea_encrypt(void *ctx_arg, u8 *dst, const u8 *src) | |
67 | { | |
68 | u32 y, z, n, sum = 0; | |
69 | u32 k0, k1, k2, k3; | |
70 | ||
71 | struct tea_ctx *ctx = ctx_arg; | |
72 | ||
73 | y = u32_in (src); | |
74 | z = u32_in (src + 4); | |
75 | ||
76 | k0 = ctx->KEY[0]; | |
77 | k1 = ctx->KEY[1]; | |
78 | k2 = ctx->KEY[2]; | |
79 | k3 = ctx->KEY[3]; | |
80 | ||
81 | n = TEA_ROUNDS; | |
82 | ||
83 | while (n-- > 0) { | |
84 | sum += TEA_DELTA; | |
85 | y += ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1); | |
86 | z += ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3); | |
87 | } | |
88 | ||
89 | u32_out (dst, y); | |
90 | u32_out (dst + 4, z); | |
91 | } | |
92 | ||
93 | static void tea_decrypt(void *ctx_arg, u8 *dst, const u8 *src) | |
94 | { | |
95 | u32 y, z, n, sum; | |
96 | u32 k0, k1, k2, k3; | |
97 | ||
98 | struct tea_ctx *ctx = ctx_arg; | |
99 | ||
100 | y = u32_in (src); | |
101 | z = u32_in (src + 4); | |
102 | ||
103 | k0 = ctx->KEY[0]; | |
104 | k1 = ctx->KEY[1]; | |
105 | k2 = ctx->KEY[2]; | |
106 | k3 = ctx->KEY[3]; | |
107 | ||
108 | sum = TEA_DELTA << 5; | |
109 | ||
110 | n = TEA_ROUNDS; | |
111 | ||
112 | while (n-- > 0) { | |
113 | z -= ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3); | |
114 | y -= ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1); | |
115 | sum -= TEA_DELTA; | |
116 | } | |
117 | ||
118 | u32_out (dst, y); | |
119 | u32_out (dst + 4, z); | |
120 | ||
121 | } | |
122 | ||
123 | static int xtea_setkey(void *ctx_arg, const u8 *in_key, | |
124 | unsigned int key_len, u32 *flags) | |
125 | { | |
126 | ||
127 | struct xtea_ctx *ctx = ctx_arg; | |
128 | ||
129 | if (key_len != 16) | |
130 | { | |
131 | *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; | |
132 | return -EINVAL; | |
133 | } | |
134 | ||
135 | ctx->KEY[0] = u32_in (in_key); | |
136 | ctx->KEY[1] = u32_in (in_key + 4); | |
137 | ctx->KEY[2] = u32_in (in_key + 8); | |
138 | ctx->KEY[3] = u32_in (in_key + 12); | |
139 | ||
140 | return 0; | |
141 | ||
142 | } | |
143 | ||
144 | static void xtea_encrypt(void *ctx_arg, u8 *dst, const u8 *src) | |
145 | { | |
146 | ||
147 | u32 y, z, sum = 0; | |
148 | u32 limit = XTEA_DELTA * XTEA_ROUNDS; | |
149 | ||
150 | struct xtea_ctx *ctx = ctx_arg; | |
151 | ||
152 | y = u32_in (src); | |
153 | z = u32_in (src + 4); | |
154 | ||
155 | while (sum != limit) { | |
156 | y += (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum&3]; | |
157 | sum += XTEA_DELTA; | |
158 | z += (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 &3]; | |
159 | } | |
160 | ||
161 | u32_out (dst, y); | |
162 | u32_out (dst + 4, z); | |
163 | ||
164 | } | |
165 | ||
166 | static void xtea_decrypt(void *ctx_arg, u8 *dst, const u8 *src) | |
167 | { | |
168 | ||
169 | u32 y, z, sum; | |
170 | struct tea_ctx *ctx = ctx_arg; | |
171 | ||
172 | y = u32_in (src); | |
173 | z = u32_in (src + 4); | |
174 | ||
175 | sum = XTEA_DELTA * XTEA_ROUNDS; | |
176 | ||
177 | while (sum) { | |
178 | z -= (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 & 3]; | |
179 | sum -= XTEA_DELTA; | |
180 | y -= (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum & 3]; | |
181 | } | |
182 | ||
183 | u32_out (dst, y); | |
184 | u32_out (dst + 4, z); | |
185 | ||
186 | } | |
187 | ||
188 | static struct crypto_alg tea_alg = { | |
189 | .cra_name = "tea", | |
190 | .cra_flags = CRYPTO_ALG_TYPE_CIPHER, | |
191 | .cra_blocksize = TEA_BLOCK_SIZE, | |
192 | .cra_ctxsize = sizeof (struct tea_ctx), | |
193 | .cra_module = THIS_MODULE, | |
194 | .cra_list = LIST_HEAD_INIT(tea_alg.cra_list), | |
195 | .cra_u = { .cipher = { | |
196 | .cia_min_keysize = TEA_KEY_SIZE, | |
197 | .cia_max_keysize = TEA_KEY_SIZE, | |
198 | .cia_setkey = tea_setkey, | |
199 | .cia_encrypt = tea_encrypt, | |
200 | .cia_decrypt = tea_decrypt } } | |
201 | }; | |
202 | ||
203 | static struct crypto_alg xtea_alg = { | |
204 | .cra_name = "xtea", | |
205 | .cra_flags = CRYPTO_ALG_TYPE_CIPHER, | |
206 | .cra_blocksize = XTEA_BLOCK_SIZE, | |
207 | .cra_ctxsize = sizeof (struct xtea_ctx), | |
208 | .cra_module = THIS_MODULE, | |
209 | .cra_list = LIST_HEAD_INIT(xtea_alg.cra_list), | |
210 | .cra_u = { .cipher = { | |
211 | .cia_min_keysize = XTEA_KEY_SIZE, | |
212 | .cia_max_keysize = XTEA_KEY_SIZE, | |
213 | .cia_setkey = xtea_setkey, | |
214 | .cia_encrypt = xtea_encrypt, | |
215 | .cia_decrypt = xtea_decrypt } } | |
216 | }; | |
217 | ||
218 | static int __init init(void) | |
219 | { | |
220 | int ret = 0; | |
221 | ||
222 | ret = crypto_register_alg(&tea_alg); | |
223 | if (ret < 0) | |
224 | goto out; | |
225 | ||
226 | ret = crypto_register_alg(&xtea_alg); | |
227 | if (ret < 0) { | |
228 | crypto_unregister_alg(&tea_alg); | |
229 | goto out; | |
230 | } | |
231 | ||
232 | out: | |
233 | return ret; | |
234 | } | |
235 | ||
236 | static void __exit fini(void) | |
237 | { | |
238 | crypto_unregister_alg(&tea_alg); | |
239 | crypto_unregister_alg(&xtea_alg); | |
240 | } | |
241 | ||
242 | MODULE_ALIAS("xtea"); | |
243 | ||
244 | module_init(init); | |
245 | module_exit(fini); | |
246 | ||
247 | MODULE_LICENSE("GPL"); | |
248 | MODULE_DESCRIPTION("TEA & XTEA Cryptographic Algorithms"); |