crypto/tea.c

   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/byteorder.h>
  26 #include <linux/crypto.h>
  27 #include <linux/types.h>
  28
  29 #define TEA_KEY_SIZE            16
  30 #define TEA_BLOCK_SIZE          8
  31 #define TEA_ROUNDS              32
  32 #define TEA_DELTA               0x9e3779b9
  33
  34 #define XTEA_KEY_SIZE           16
  35 #define XTEA_BLOCK_SIZE         8
  36 #define XTEA_ROUNDS             32
  37 #define XTEA_DELTA              0x9e3779b9
  38
  39 struct tea_ctx {
  40         u32 KEY[4];
  41 };
  42
  43 struct xtea_ctx {
  44         u32 KEY[4];
  45 };
  46
  47 static int tea_setkey(struct crypto_tfm *tfm, const u8 *in_key,
  48                       unsigned int key_len)
  49 {
  50         struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
  51         const __le32 *key = (const __le32 *)in_key;
  52
  53         ctx->KEY[0] = le32_to_cpu(key[0]);
  54         ctx->KEY[1] = le32_to_cpu(key[1]);
  55         ctx->KEY[2] = le32_to_cpu(key[2]);
  56         ctx->KEY[3] = le32_to_cpu(key[3]);
  57
  58         return 0;
  59
  60 }
  61
  62 static void tea_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  63 {
  64         u32 y, z, n, sum = 0;
  65         u32 k0, k1, k2, k3;
  66         struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
  67         const __le32 *in = (const __le32 *)src;
  68         __le32 *out = (__le32 *)dst;
  69
  70         y = le32_to_cpu(in[0]);
  71         z = le32_to_cpu(in[1]);
  72
  73         k0 = ctx->KEY[0];
  74         k1 = ctx->KEY[1];
  75         k2 = ctx->KEY[2];
  76         k3 = ctx->KEY[3];
  77
  78         n = TEA_ROUNDS;
  79
  80         while (n-- > 0) {
  81                 sum += TEA_DELTA;
  82                 y += ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1);
  83                 z += ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3);
  84         }
  85
  86         out[0] = cpu_to_le32(y);
  87         out[1] = cpu_to_le32(z);
  88 }
  89
  90 static void tea_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  91 {
  92         u32 y, z, n, sum;
  93         u32 k0, k1, k2, k3;
  94         struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
  95         const __le32 *in = (const __le32 *)src;
  96         __le32 *out = (__le32 *)dst;
  97
  98         y = le32_to_cpu(in[0]);
  99         z = le32_to_cpu(in[1]);
 100
 101         k0 = ctx->KEY[0];
 102         k1 = ctx->KEY[1];
 103         k2 = ctx->KEY[2];
 104         k3 = ctx->KEY[3];
 105
 106         sum = TEA_DELTA << 5;
 107
 108         n = TEA_ROUNDS;
 109
 110         while (n-- > 0) {
 111                 z -= ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3);
 112                 y -= ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1);
 113                 sum -= TEA_DELTA;
 114         }
 115
 116         out[0] = cpu_to_le32(y);
 117         out[1] = cpu_to_le32(z);
 118 }
 119
 120 static int xtea_setkey(struct crypto_tfm *tfm, const u8 *in_key,
 121                        unsigned int key_len)
 122 {
 123         struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);
 124         const __le32 *key = (const __le32 *)in_key;
 125
 126         ctx->KEY[0] = le32_to_cpu(key[0]);
 127         ctx->KEY[1] = le32_to_cpu(key[1]);
 128         ctx->KEY[2] = le32_to_cpu(key[2]);
 129         ctx->KEY[3] = le32_to_cpu(key[3]);
 130
 131         return 0;
 132
 133 }
 134
 135 static void xtea_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
 136 {
 137         u32 y, z, sum = 0;
 138         u32 limit = XTEA_DELTA * XTEA_ROUNDS;
 139         struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);
 140         const __le32 *in = (const __le32 *)src;
 141         __le32 *out = (__le32 *)dst;
 142
 143         y = le32_to_cpu(in[0]);
 144         z = le32_to_cpu(in[1]);
 145
 146         while (sum != limit) {
 147                 y += ((z << 4 ^ z >> 5) + z) ^ (sum + ctx->KEY[sum&3]);
 148                 sum += XTEA_DELTA;
 149                 z += ((y << 4 ^ y >> 5) + y) ^ (sum + ctx->KEY[sum>>11 &3]);
 150         }
 151
 152         out[0] = cpu_to_le32(y);
 153         out[1] = cpu_to_le32(z);
 154 }
 155
 156 static void xtea_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
 157 {
 158         u32 y, z, sum;
 159         struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
 160         const __le32 *in = (const __le32 *)src;
 161         __le32 *out = (__le32 *)dst;
 162
 163         y = le32_to_cpu(in[0]);
 164         z = le32_to_cpu(in[1]);
 165
 166         sum = XTEA_DELTA * XTEA_ROUNDS;
 167
 168         while (sum) {
 169                 z -= ((y << 4 ^ y >> 5) + y) ^ (sum + ctx->KEY[sum>>11 & 3]);
 170                 sum -= XTEA_DELTA;
 171                 y -= ((z << 4 ^ z >> 5) + z) ^ (sum + ctx->KEY[sum & 3]);
 172         }
 173
 174         out[0] = cpu_to_le32(y);
 175         out[1] = cpu_to_le32(z);
 176 }
 177
 178
 179 static void xeta_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
 180 {
 181         u32 y, z, sum = 0;
 182         u32 limit = XTEA_DELTA * XTEA_ROUNDS;
 183         struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);
 184         const __le32 *in = (const __le32 *)src;
 185         __le32 *out = (__le32 *)dst;
 186
 187         y = le32_to_cpu(in[0]);
 188         z = le32_to_cpu(in[1]);
 189
 190         while (sum != limit) {
 191                 y += (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum&3];
 192                 sum += XTEA_DELTA;
 193                 z += (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 &3];
 194         }
 195
 196         out[0] = cpu_to_le32(y);
 197         out[1] = cpu_to_le32(z);
 198 }
 199
 200 static void xeta_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
 201 {
 202         u32 y, z, sum;
 203         struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
 204         const __le32 *in = (const __le32 *)src;
 205         __le32 *out = (__le32 *)dst;
 206
 207         y = le32_to_cpu(in[0]);
 208         z = le32_to_cpu(in[1]);
 209
 210         sum = XTEA_DELTA * XTEA_ROUNDS;
 211
 212         while (sum) {
 213                 z -= (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 & 3];
 214                 sum -= XTEA_DELTA;
 215                 y -= (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum & 3];
 216         }
 217
 218         out[0] = cpu_to_le32(y);
 219         out[1] = cpu_to_le32(z);
 220 }
 221
 222 static struct crypto_alg tea_algs[3] = { {
 223         .cra_name               =       "tea",
 224         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 225         .cra_blocksize          =       TEA_BLOCK_SIZE,
 226         .cra_ctxsize            =       sizeof (struct tea_ctx),
 227         .cra_alignmask          =       3,
 228         .cra_module             =       THIS_MODULE,
 229         .cra_u                  =       { .cipher = {
 230         .cia_min_keysize        =       TEA_KEY_SIZE,
 231         .cia_max_keysize        =       TEA_KEY_SIZE,
 232         .cia_setkey             =       tea_setkey,
 233         .cia_encrypt            =       tea_encrypt,
 234         .cia_decrypt            =       tea_decrypt } }
 235 }, {
 236         .cra_name               =       "xtea",
 237         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 238         .cra_blocksize          =       XTEA_BLOCK_SIZE,
 239         .cra_ctxsize            =       sizeof (struct xtea_ctx),
 240         .cra_alignmask          =       3,
 241         .cra_module             =       THIS_MODULE,
 242         .cra_u                  =       { .cipher = {
 243         .cia_min_keysize        =       XTEA_KEY_SIZE,
 244         .cia_max_keysize        =       XTEA_KEY_SIZE,
 245         .cia_setkey             =       xtea_setkey,
 246         .cia_encrypt            =       xtea_encrypt,
 247         .cia_decrypt            =       xtea_decrypt } }
 248 }, {
 249         .cra_name               =       "xeta",
 250         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 251         .cra_blocksize          =       XTEA_BLOCK_SIZE,
 252         .cra_ctxsize            =       sizeof (struct xtea_ctx),
 253         .cra_alignmask          =       3,
 254         .cra_module             =       THIS_MODULE,
 255         .cra_u                  =       { .cipher = {
 256         .cia_min_keysize        =       XTEA_KEY_SIZE,
 257         .cia_max_keysize        =       XTEA_KEY_SIZE,
 258         .cia_setkey             =       xtea_setkey,
 259         .cia_encrypt            =       xeta_encrypt,
 260         .cia_decrypt            =       xeta_decrypt } }
 261 } };
 262
 263 static int __init tea_mod_init(void)
 264 {
 265         return crypto_register_algs(tea_algs, ARRAY_SIZE(tea_algs));
 266 }
 267
 268 static void __exit tea_mod_fini(void)
 269 {
 270         crypto_unregister_algs(tea_algs, ARRAY_SIZE(tea_algs));
 271 }
 272
 273 MODULE_ALIAS_CRYPTO("tea");
 274 MODULE_ALIAS_CRYPTO("xtea");
 275 MODULE_ALIAS_CRYPTO("xeta");
 276
 277 module_init(tea_mod_init);
 278 module_exit(tea_mod_fini);
 279
 280 MODULE_LICENSE("GPL");
 281 MODULE_DESCRIPTION("TEA, XTEA & XETA Cryptographic Algorithms");