crypto/tea.c

   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");