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
  26static u_int32_t ks[12] = {0x01010101, 0x01010101, 0x01010101, 0x01010101,
  27                           0x02020202, 0x02020202, 0x02020202, 0x02020202,
  28                           0x03030303, 0x03030303, 0x03030303, 0x03030303};
  29
  30/*
  31 * +------------------------
  32 * | <parent tfm>
  33 * +------------------------
  34 * | xcbc_tfm_ctx
  35 * +------------------------
  36 * | consts (block size * 2)
  37 * +------------------------
  38 */
  39struct xcbc_tfm_ctx {
  40        struct crypto_cipher *child;
  41        u8 ctx[];
  42};
  43
  44/*
  45 * +------------------------
  46 * | <shash desc>
  47 * +------------------------
  48 * | xcbc_desc_ctx
  49 * +------------------------
  50 * | odds (block size)
  51 * +------------------------
  52 * | prev (block size)
  53 * +------------------------
  54 */
  55struct xcbc_desc_ctx {
  56        unsigned int len;
  57        u8 ctx[];
  58};
  59
  60static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
  61                                     const u8 *inkey, unsigned int keylen)
  62{
  63        unsigned long alignmask = crypto_shash_alignmask(parent);
  64        struct xcbc_tfm_ctx *ctx = crypto_shash_ctx(parent);
  65        int bs = crypto_shash_blocksize(parent);
  66        u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
  67        int err = 0;
  68        u8 key1[bs];
  69
  70        if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen)))
  71                return err;
  72
  73        crypto_cipher_encrypt_one(ctx->child, consts, (u8 *)ks + bs);
  74        crypto_cipher_encrypt_one(ctx->child, consts + bs, (u8 *)ks + bs * 2);
  75        crypto_cipher_encrypt_one(ctx->child, key1, (u8 *)ks);
  76
  77        return crypto_cipher_setkey(ctx->child, key1, bs);
  78
  79}
  80
  81static int crypto_xcbc_digest_init(struct shash_desc *pdesc)
  82{
  83        unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
  84        struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
  85        int bs = crypto_shash_blocksize(pdesc->tfm);
  86        u8 *prev = PTR_ALIGN(&ctx->ctx[0], alignmask + 1) + bs;
  87
  88        ctx->len = 0;
  89        memset(prev, 0, bs);
  90
  91        return 0;
  92}
  93
  94static int crypto_xcbc_digest_update(struct shash_desc *pdesc, const u8 *p,
  95                                     unsigned int len)
  96{
  97        struct crypto_shash *parent = pdesc->tfm;
  98        unsigned long alignmask = crypto_shash_alignmask(parent);
  99        struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
 100        struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
 101        struct crypto_cipher *tfm = tctx->child;
 102        int bs = crypto_shash_blocksize(parent);
 103        u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
 104        u8 *prev = odds + bs;
 105
 106        /* checking the data can fill the block */
 107        if ((ctx->len + len) <= bs) {
 108                memcpy(odds + ctx->len, p, len);
 109                ctx->len += len;
 110                return 0;
 111        }
 112
 113        /* filling odds with new data and encrypting it */
 114        memcpy(odds + ctx->len, p, bs - ctx->len);
 115        len -= bs - ctx->len;
 116        p += bs - ctx->len;
 117
 118        crypto_xor(prev, odds, bs);
 119        crypto_cipher_encrypt_one(tfm, prev, prev);
 120
 121        /* clearing the length */
 122        ctx->len = 0;
 123
 124        /* encrypting the rest of data */
 125        while (len > bs) {
 126                crypto_xor(prev, p, bs);
 127                crypto_cipher_encrypt_one(tfm, prev, prev);
 128                p += bs;
 129                len -= bs;
 130        }
 131
 132        /* keeping the surplus of blocksize */
 133        if (len) {
 134                memcpy(odds, p, len);
 135                ctx->len = len;
 136        }
 137
 138        return 0;
 139}
 140
 141static int crypto_xcbc_digest_final(struct shash_desc *pdesc, u8 *out)
 142{
 143        struct crypto_shash *parent = pdesc->tfm;
 144        unsigned long alignmask = crypto_shash_alignmask(parent);
 145        struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
 146        struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
 147        struct crypto_cipher *tfm = tctx->child;
 148        int bs = crypto_shash_blocksize(parent);
 149        u8 *consts = PTR_ALIGN(&tctx->ctx[0], alignmask + 1);
 150        u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
 151        u8 *prev = odds + bs;
 152        unsigned int offset = 0;
 153
 154        if (ctx->len != bs) {
 155                unsigned int rlen;
 156                u8 *p = odds + ctx->len;
 157
 158                *p = 0x80;
 159                p++;
 160
 161                rlen = bs - ctx->len -1;
 162                if (rlen)
 163                        memset(p, 0, rlen);
 164
 165                offset += bs;
 166        }
 167
 168        crypto_xor(prev, odds, bs);
 169        crypto_xor(prev, consts + offset, bs);
 170
 171        crypto_cipher_encrypt_one(tfm, out, prev);
 172
 173        return 0;
 174}
 175
 176static int xcbc_init_tfm(struct crypto_tfm *tfm)
 177{
 178        struct crypto_cipher *cipher;
 179        struct crypto_instance *inst = (void *)tfm->__crt_alg;
 180        struct crypto_spawn *spawn = crypto_instance_ctx(inst);
 181        struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 182
 183        cipher = crypto_spawn_cipher(spawn);
 184        if (IS_ERR(cipher))
 185                return PTR_ERR(cipher);
 186
 187        ctx->child = cipher;
 188
 189        return 0;
 190};
 191
 192static void xcbc_exit_tfm(struct crypto_tfm *tfm)
 193{
 194        struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 195        crypto_free_cipher(ctx->child);
 196}
 197
 198static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 199{
 200        struct shash_instance *inst;
 201        struct crypto_alg *alg;
 202        unsigned long alignmask;
 203        int err;
 204
 205        err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
 206        if (err)
 207                return err;
 208
 209        alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
 210                                  CRYPTO_ALG_TYPE_MASK);
 211        if (IS_ERR(alg))
 212                return PTR_ERR(alg);
 213
 214        switch(alg->cra_blocksize) {
 215        case 16:
 216                break;
 217        default:
 218                goto out_put_alg;
 219        }
 220
 221        inst = shash_alloc_instance("xcbc", alg);
 222        err = PTR_ERR(inst);
 223        if (IS_ERR(inst))
 224                goto out_put_alg;
 225
 226        err = crypto_init_spawn(shash_instance_ctx(inst), alg,
 227                                shash_crypto_instance(inst),
 228                                CRYPTO_ALG_TYPE_MASK);
 229        if (err)
 230                goto out_free_inst;
 231
 232        alignmask = alg->cra_alignmask | 3;
 233        inst->alg.base.cra_alignmask = alignmask;
 234        inst->alg.base.cra_priority = alg->cra_priority;
 235        inst->alg.base.cra_blocksize = alg->cra_blocksize;
 236
 237        inst->alg.digestsize = alg->cra_blocksize;
 238        inst->alg.descsize = ALIGN(sizeof(struct xcbc_desc_ctx),
 239                                   crypto_tfm_ctx_alignment()) +
 240                             (alignmask &
 241                              ~(crypto_tfm_ctx_alignment() - 1)) +
 242                             alg->cra_blocksize * 2;
 243
 244        inst->alg.base.cra_ctxsize = ALIGN(sizeof(struct xcbc_tfm_ctx),
 245                                           alignmask + 1) +
 246                                     alg->cra_blocksize * 2;
 247        inst->alg.base.cra_init = xcbc_init_tfm;
 248        inst->alg.base.cra_exit = xcbc_exit_tfm;
 249
 250        inst->alg.init = crypto_xcbc_digest_init;
 251        inst->alg.update = crypto_xcbc_digest_update;
 252        inst->alg.final = crypto_xcbc_digest_final;
 253        inst->alg.setkey = crypto_xcbc_digest_setkey;
 254
 255        err = shash_register_instance(tmpl, inst);
 256        if (err) {
 257out_free_inst:
 258                shash_free_instance(shash_crypto_instance(inst));
 259        }
 260
 261out_put_alg:
 262        crypto_mod_put(alg);
 263        return err;
 264}
 265
 266static struct crypto_template crypto_xcbc_tmpl = {
 267        .name = "xcbc",
 268        .create = xcbc_create,
 269        .free = shash_free_instance,
 270        .module = THIS_MODULE,
 271};
 272
 273static int __init crypto_xcbc_module_init(void)
 274{
 275        return crypto_register_template(&crypto_xcbc_tmpl);
 276}
 277
 278static void __exit crypto_xcbc_module_exit(void)
 279{
 280        crypto_unregister_template(&crypto_xcbc_tmpl);
 281}
 282
 283module_init(crypto_xcbc_module_init);
 284module_exit(crypto_xcbc_module_exit);
 285
 286MODULE_LICENSE("GPL");
 287MODULE_DESCRIPTION("XCBC keyed hash algorithm");
 288
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