crypto/xcbc.c

   1 /*
   2  * Copyright (C)2006 USAGI/WIDE Project
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17  *
  18  * Author:
  19  *      Kazunori Miyazawa <miyazawa@linux-ipv6.org>
  20  */
  21
  22 #include <crypto/internal/hash.h>
  23 #include <linux/err.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26
  27 static u_int32_t ks[12] = {0x01010101, 0x01010101, 0x01010101, 0x01010101,
  28                            0x02020202, 0x02020202, 0x02020202, 0x02020202,
  29                            0x03030303, 0x03030303, 0x03030303, 0x03030303};
  30
  31 /*
  32  * +------------------------
  33  * | <parent tfm>
  34  * +------------------------
  35  * | xcbc_tfm_ctx
  36  * +------------------------
  37  * | consts (block size * 2)
  38  * +------------------------
  39  */
  40 struct xcbc_tfm_ctx {
  41         struct crypto_cipher *child;
  42         u8 ctx[];
  43 };
  44
  45 /*
  46  * +------------------------
  47  * | <shash desc>
  48  * +------------------------
  49  * | xcbc_desc_ctx
  50  * +------------------------
  51  * | odds (block size)
  52  * +------------------------
  53  * | prev (block size)
  54  * +------------------------
  55  */
  56 struct xcbc_desc_ctx {
  57         unsigned int len;
  58         u8 ctx[];
  59 };
  60
  61 static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
  62                                      const u8 *inkey, unsigned int keylen)
  63 {
  64         unsigned long alignmask = crypto_shash_alignmask(parent);
  65         struct xcbc_tfm_ctx *ctx = crypto_shash_ctx(parent);
  66         int bs = crypto_shash_blocksize(parent);
  67         u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
  68         int err = 0;
  69         u8 key1[bs];
  70
  71         if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen)))
  72                 return err;
  73
  74         crypto_cipher_encrypt_one(ctx->child, consts, (u8 *)ks + bs);
  75         crypto_cipher_encrypt_one(ctx->child, consts + bs, (u8 *)ks + bs * 2);
  76         crypto_cipher_encrypt_one(ctx->child, key1, (u8 *)ks);
  77
  78         return crypto_cipher_setkey(ctx->child, key1, bs);
  79
  80 }
  81
  82 static int crypto_xcbc_digest_init(struct shash_desc *pdesc)
  83 {
  84         unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
  85         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
  86         int bs = crypto_shash_blocksize(pdesc->tfm);
  87         u8 *prev = PTR_ALIGN(&ctx->ctx[0], alignmask + 1) + bs;
  88
  89         ctx->len = 0;
  90         memset(prev, 0, bs);
  91
  92         return 0;
  93 }
  94
  95 static int crypto_xcbc_digest_update(struct shash_desc *pdesc, const u8 *p,
  96                                      unsigned int len)
  97 {
  98         struct crypto_shash *parent = pdesc->tfm;
  99         unsigned long alignmask = crypto_shash_alignmask(parent);
 100         struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
 101         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
 102         struct crypto_cipher *tfm = tctx->child;
 103         int bs = crypto_shash_blocksize(parent);
 104         u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
 105         u8 *prev = odds + bs;
 106
 107         /* checking the data can fill the block */
 108         if ((ctx->len + len) <= bs) {
 109                 memcpy(odds + ctx->len, p, len);
 110                 ctx->len += len;
 111                 return 0;
 112         }
 113
 114         /* filling odds with new data and encrypting it */
 115         memcpy(odds + ctx->len, p, bs - ctx->len);
 116         len -= bs - ctx->len;
 117         p += bs - ctx->len;
 118
 119         crypto_xor(prev, odds, bs);
 120         crypto_cipher_encrypt_one(tfm, prev, prev);
 121
 122         /* clearing the length */
 123         ctx->len = 0;
 124
 125         /* encrypting the rest of data */
 126         while (len > bs) {
 127                 crypto_xor(prev, p, bs);
 128                 crypto_cipher_encrypt_one(tfm, prev, prev);
 129                 p += bs;
 130                 len -= bs;
 131         }
 132
 133         /* keeping the surplus of blocksize */
 134         if (len) {
 135                 memcpy(odds, p, len);
 136                 ctx->len = len;
 137         }
 138
 139         return 0;
 140 }
 141
 142 static int crypto_xcbc_digest_final(struct shash_desc *pdesc, u8 *out)
 143 {
 144         struct crypto_shash *parent = pdesc->tfm;
 145         unsigned long alignmask = crypto_shash_alignmask(parent);
 146         struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
 147         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
 148         struct crypto_cipher *tfm = tctx->child;
 149         int bs = crypto_shash_blocksize(parent);
 150         u8 *consts = PTR_ALIGN(&tctx->ctx[0], alignmask + 1);
 151         u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
 152         u8 *prev = odds + bs;
 153         unsigned int offset = 0;
 154
 155         if (ctx->len != bs) {
 156                 unsigned int rlen;
 157                 u8 *p = odds + ctx->len;
 158
 159                 *p = 0x80;
 160                 p++;
 161
 162                 rlen = bs - ctx->len -1;
 163                 if (rlen)
 164                         memset(p, 0, rlen);
 165
 166                 offset += bs;
 167         }
 168
 169         crypto_xor(prev, odds, bs);
 170         crypto_xor(prev, consts + offset, bs);
 171
 172         crypto_cipher_encrypt_one(tfm, out, prev);
 173
 174         return 0;
 175 }
 176
 177 static int xcbc_init_tfm(struct crypto_tfm *tfm)
 178 {
 179         struct crypto_cipher *cipher;
 180         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 181         struct crypto_spawn *spawn = crypto_instance_ctx(inst);
 182         struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 183
 184         cipher = crypto_spawn_cipher(spawn);
 185         if (IS_ERR(cipher))
 186                 return PTR_ERR(cipher);
 187
 188         ctx->child = cipher;
 189
 190         return 0;
 191 };
 192
 193 static void xcbc_exit_tfm(struct crypto_tfm *tfm)
 194 {
 195         struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 196         crypto_free_cipher(ctx->child);
 197 }
 198
 199 static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 200 {
 201         struct shash_instance *inst;
 202         struct crypto_alg *alg;
 203         unsigned long alignmask;
 204         int err;
 205
 206         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
 207         if (err)
 208                 return err;
 209
 210         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
 211                                   CRYPTO_ALG_TYPE_MASK);
 212         if (IS_ERR(alg))
 213                 return PTR_ERR(alg);
 214
 215         switch(alg->cra_blocksize) {
 216         case 16:
 217                 break;
 218         default:
 219                 goto out_put_alg;
 220         }
 221
 222         inst = shash_alloc_instance("xcbc", alg);
 223         err = PTR_ERR(inst);
 224         if (IS_ERR(inst))
 225                 goto out_put_alg;
 226
 227         err = crypto_init_spawn(shash_instance_ctx(inst), alg,
 228                                 shash_crypto_instance(inst),
 229                                 CRYPTO_ALG_TYPE_MASK);
 230         if (err)
 231                 goto out_free_inst;
 232
 233         alignmask = alg->cra_alignmask | 3;
 234         inst->alg.base.cra_alignmask = alignmask;
 235         inst->alg.base.cra_priority = alg->cra_priority;
 236         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 237
 238         inst->alg.digestsize = alg->cra_blocksize;
 239         inst->alg.descsize = ALIGN(sizeof(struct xcbc_desc_ctx),
 240                                    crypto_tfm_ctx_alignment()) +
 241                              (alignmask &
 242                               ~(crypto_tfm_ctx_alignment() - 1)) +
 243                              alg->cra_blocksize * 2;
 244
 245         inst->alg.base.cra_ctxsize = ALIGN(sizeof(struct xcbc_tfm_ctx),
 246                                            alignmask + 1) +
 247                                      alg->cra_blocksize * 2;
 248         inst->alg.base.cra_init = xcbc_init_tfm;
 249         inst->alg.base.cra_exit = xcbc_exit_tfm;
 250
 251         inst->alg.init = crypto_xcbc_digest_init;
 252         inst->alg.update = crypto_xcbc_digest_update;
 253         inst->alg.final = crypto_xcbc_digest_final;
 254         inst->alg.setkey = crypto_xcbc_digest_setkey;
 255
 256         err = shash_register_instance(tmpl, inst);
 257         if (err) {
 258 out_free_inst:
 259                 shash_free_instance(shash_crypto_instance(inst));
 260         }
 261
 262 out_put_alg:
 263         crypto_mod_put(alg);
 264         return err;
 265 }
 266
 267 static struct crypto_template crypto_xcbc_tmpl = {
 268         .name = "xcbc",
 269         .create = xcbc_create,
 270         .free = shash_free_instance,
 271         .module = THIS_MODULE,
 272 };
 273
 274 static int __init crypto_xcbc_module_init(void)
 275 {
 276         return crypto_register_template(&crypto_xcbc_tmpl);
 277 }
 278
 279 static void __exit crypto_xcbc_module_exit(void)
 280 {
 281         crypto_unregister_template(&crypto_xcbc_tmpl);
 282 }
 283
 284 module_init(crypto_xcbc_module_init);
 285 module_exit(crypto_xcbc_module_exit);
 286
 287 MODULE_LICENSE("GPL");
 288 MODULE_DESCRIPTION("XCBC keyed hash algorithm");