1 /* 2 * Cryptographic API. 3 * 4 * TEA, XTEA, and XETA crypto alogrithms 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 * Due to the order of evaluation in XTEA many people have incorrectly 10 * implemented it. XETA (XTEA in the wrong order), exists for 11 * compatibility with these implementations. 12 * 13 * Copyright (c) 2004 Aaron Grothe ajgrothe@yahoo.com 14 * 15 * This program is free software; you can redistribute it and/or modify 16 * it under the terms of the GNU General Public License as published by 17 * the Free Software Foundation; either version 2 of the License, or 18 * (at your option) any later version. 19 * 20 */ 21 22 #include <linux/init.h> 23 #include <linux/module.h> 24 #include <linux/mm.h> 25 #include <asm/scatterlist.h> 26 #include <linux/crypto.h> 27 28 #define TEA_KEY_SIZE 16 29 #define TEA_BLOCK_SIZE 8 30 #define TEA_ROUNDS 32 31 #define TEA_DELTA 0x9e3779b9 32 33 #define XTEA_KEY_SIZE 16 34 #define XTEA_BLOCK_SIZE 8 35 #define XTEA_ROUNDS 32 36 #define XTEA_DELTA 0x9e3779b9 37 38 #define u32_in(x) le32_to_cpu(*(const __le32 *)(x)) 39 #define u32_out(to, from) (*(__le32 *)(to) = cpu_to_le32(from)) 40 41 struct tea_ctx { 42 u32 KEY[4]; 43 }; 44 45 struct xtea_ctx { 46 u32 KEY[4]; 47 }; 48 49 static int tea_setkey(void *ctx_arg, const u8 *in_key, 50 unsigned int key_len, u32 *flags) 51 { 52 53 struct tea_ctx *ctx = ctx_arg; 54 55 if (key_len != 16) 56 { 57 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; 58 return -EINVAL; 59 } 60 61 ctx->KEY[0] = u32_in (in_key); 62 ctx->KEY[1] = u32_in (in_key + 4); 63 ctx->KEY[2] = u32_in (in_key + 8); 64 ctx->KEY[3] = u32_in (in_key + 12); 65 66 return 0; 67 68 } 69 70 static void tea_encrypt(void *ctx_arg, u8 *dst, const u8 *src) 71 { 72 u32 y, z, n, sum = 0; 73 u32 k0, k1, k2, k3; 74 75 struct tea_ctx *ctx = ctx_arg; 76 77 y = u32_in (src); 78 z = u32_in (src + 4); 79 80 k0 = ctx->KEY[0]; 81 k1 = ctx->KEY[1]; 82 k2 = ctx->KEY[2]; 83 k3 = ctx->KEY[3]; 84 85 n = TEA_ROUNDS; 86 87 while (n-- > 0) { 88 sum += TEA_DELTA; 89 y += ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1); 90 z += ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3); 91 } 92 93 u32_out (dst, y); 94 u32_out (dst + 4, z); 95 } 96 97 static void tea_decrypt(void *ctx_arg, u8 *dst, const u8 *src) 98 { 99 u32 y, z, n, sum; 100 u32 k0, k1, k2, k3; 101 102 struct tea_ctx *ctx = ctx_arg; 103 104 y = u32_in (src); 105 z = u32_in (src + 4); 106 107 k0 = ctx->KEY[0]; 108 k1 = ctx->KEY[1]; 109 k2 = ctx->KEY[2]; 110 k3 = ctx->KEY[3]; 111 112 sum = TEA_DELTA << 5; 113 114 n = TEA_ROUNDS; 115 116 while (n-- > 0) { 117 z -= ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3); 118 y -= ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1); 119 sum -= TEA_DELTA; 120 } 121 122 u32_out (dst, y); 123 u32_out (dst + 4, z); 124 125 } 126 127 static int xtea_setkey(void *ctx_arg, const u8 *in_key, 128 unsigned int key_len, u32 *flags) 129 { 130 131 struct xtea_ctx *ctx = ctx_arg; 132 133 if (key_len != 16) 134 { 135 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; 136 return -EINVAL; 137 } 138 139 ctx->KEY[0] = u32_in (in_key); 140 ctx->KEY[1] = u32_in (in_key + 4); 141 ctx->KEY[2] = u32_in (in_key + 8); 142 ctx->KEY[3] = u32_in (in_key + 12); 143 144 return 0; 145 146 } 147 148 static void xtea_encrypt(void *ctx_arg, u8 *dst, const u8 *src) 149 { 150 151 u32 y, z, sum = 0; 152 u32 limit = XTEA_DELTA * XTEA_ROUNDS; 153 154 struct xtea_ctx *ctx = ctx_arg; 155 156 y = u32_in (src); 157 z = u32_in (src + 4); 158 159 while (sum != limit) { 160 y += ((z << 4 ^ z >> 5) + z) ^ (sum + ctx->KEY[sum&3]); 161 sum += XTEA_DELTA; 162 z += ((y << 4 ^ y >> 5) + y) ^ (sum + ctx->KEY[sum>>11 &3]); 163 } 164 165 u32_out (dst, y); 166 u32_out (dst + 4, z); 167 168 } 169 170 static void xtea_decrypt(void *ctx_arg, u8 *dst, const u8 *src) 171 { 172 173 u32 y, z, sum; 174 struct tea_ctx *ctx = ctx_arg; 175 176 y = u32_in (src); 177 z = u32_in (src + 4); 178 179 sum = XTEA_DELTA * XTEA_ROUNDS; 180 181 while (sum) { 182 z -= ((y << 4 ^ y >> 5) + y) ^ (sum + ctx->KEY[sum>>11 & 3]); 183 sum -= XTEA_DELTA; 184 y -= ((z << 4 ^ z >> 5) + z) ^ (sum + ctx->KEY[sum & 3]); 185 } 186 187 u32_out (dst, y); 188 u32_out (dst + 4, z); 189 190 } 191 192 193 static void xeta_encrypt(void *ctx_arg, u8 *dst, const u8 *src) 194 { 195 196 u32 y, z, sum = 0; 197 u32 limit = XTEA_DELTA * XTEA_ROUNDS; 198 199 struct xtea_ctx *ctx = ctx_arg; 200 201 y = u32_in (src); 202 z = u32_in (src + 4); 203 204 while (sum != limit) { 205 y += (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum&3]; 206 sum += XTEA_DELTA; 207 z += (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 &3]; 208 } 209 210 u32_out (dst, y); 211 u32_out (dst + 4, z); 212 213 } 214 215 static void xeta_decrypt(void *ctx_arg, u8 *dst, const u8 *src) 216 { 217 218 u32 y, z, sum; 219 struct tea_ctx *ctx = ctx_arg; 220 221 y = u32_in (src); 222 z = u32_in (src + 4); 223 224 sum = XTEA_DELTA * XTEA_ROUNDS; 225 226 while (sum) { 227 z -= (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 & 3]; 228 sum -= XTEA_DELTA; 229 y -= (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum & 3]; 230 } 231 232 u32_out (dst, y); 233 u32_out (dst + 4, z); 234 235 } 236 237 static struct crypto_alg tea_alg = { 238 .cra_name = "tea", 239 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 240 .cra_blocksize = TEA_BLOCK_SIZE, 241 .cra_ctxsize = sizeof (struct tea_ctx), 242 .cra_module = THIS_MODULE, 243 .cra_list = LIST_HEAD_INIT(tea_alg.cra_list), 244 .cra_u = { .cipher = { 245 .cia_min_keysize = TEA_KEY_SIZE, 246 .cia_max_keysize = TEA_KEY_SIZE, 247 .cia_setkey = tea_setkey, 248 .cia_encrypt = tea_encrypt, 249 .cia_decrypt = tea_decrypt } } 250 }; 251 252 static struct crypto_alg xtea_alg = { 253 .cra_name = "xtea", 254 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 255 .cra_blocksize = XTEA_BLOCK_SIZE, 256 .cra_ctxsize = sizeof (struct xtea_ctx), 257 .cra_module = THIS_MODULE, 258 .cra_list = LIST_HEAD_INIT(xtea_alg.cra_list), 259 .cra_u = { .cipher = { 260 .cia_min_keysize = XTEA_KEY_SIZE, 261 .cia_max_keysize = XTEA_KEY_SIZE, 262 .cia_setkey = xtea_setkey, 263 .cia_encrypt = xtea_encrypt, 264 .cia_decrypt = xtea_decrypt } } 265 }; 266 267 static struct crypto_alg xeta_alg = { 268 .cra_name = "xeta", 269 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 270 .cra_blocksize = XTEA_BLOCK_SIZE, 271 .cra_ctxsize = sizeof (struct xtea_ctx), 272 .cra_module = THIS_MODULE, 273 .cra_list = LIST_HEAD_INIT(xtea_alg.cra_list), 274 .cra_u = { .cipher = { 275 .cia_min_keysize = XTEA_KEY_SIZE, 276 .cia_max_keysize = XTEA_KEY_SIZE, 277 .cia_setkey = xtea_setkey, 278 .cia_encrypt = xeta_encrypt, 279 .cia_decrypt = xeta_decrypt } } 280 }; 281 282 static int __init init(void) 283 { 284 int ret = 0; 285 286 ret = crypto_register_alg(&tea_alg); 287 if (ret < 0) 288 goto out; 289 290 ret = crypto_register_alg(&xtea_alg); 291 if (ret < 0) { 292 crypto_unregister_alg(&tea_alg); 293 goto out; 294 } 295 296 ret = crypto_register_alg(&xeta_alg); 297 if (ret < 0) { 298 crypto_unregister_alg(&tea_alg); 299 crypto_unregister_alg(&xtea_alg); 300 goto out; 301 } 302 303 out: 304 return ret; 305 } 306 307 static void __exit fini(void) 308 { 309 crypto_unregister_alg(&tea_alg); 310 crypto_unregister_alg(&xtea_alg); 311 crypto_unregister_alg(&xeta_alg); 312 } 313 314 MODULE_ALIAS("xtea"); 315 MODULE_ALIAS("xeta"); 316 317 module_init(init); 318 module_exit(fini); 319 320 MODULE_LICENSE("GPL"); 321 MODULE_DESCRIPTION("TEA, XTEA & XETA Cryptographic Algorithms"); 322