Root/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
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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