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Linux/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");
289 MODULE_ALIAS_CRYPTO("xcbc");
290 

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