linux/crypto/xcbc.c
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   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
  27static 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 */
  40struct 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 */
  56struct xcbc_desc_ctx {
  57        unsigned int len;
  58        u8 ctx[];
  59};
  60
  61static 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
  82static 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
  95static 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
 142static 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
 177static 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
 193static 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
 199static 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) {
 258out_free_inst:
 259                shash_free_instance(shash_crypto_instance(inst));
 260        }
 261
 262out_put_alg:
 263        crypto_mod_put(alg);
 264        return err;
 265}
 266
 267static struct crypto_template crypto_xcbc_tmpl = {
 268        .name = "xcbc",
 269        .create = xcbc_create,
 270        .free = shash_free_instance,
 271        .module = THIS_MODULE,
 272};
 273
 274static int __init crypto_xcbc_module_init(void)
 275{
 276        return crypto_register_template(&crypto_xcbc_tmpl);
 277}
 278
 279static void __exit crypto_xcbc_module_exit(void)
 280{
 281        crypto_unregister_template(&crypto_xcbc_tmpl);
 282}
 283
 284module_init(crypto_xcbc_module_init);
 285module_exit(crypto_xcbc_module_exit);
 286
 287MODULE_LICENSE("GPL");
 288MODULE_DESCRIPTION("XCBC keyed hash algorithm");
 289
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