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
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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