1 /* LRW: as defined by Cyril Guyot in
2 * http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
3 *
4 * Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>
5 *
6 * Based om ecb.c
7 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the Free
11 * Software Foundation; either version 2 of the License, or (at your option)
12 * any later version.
13 */
14 /* This implementation is checked against the test vectors in the above
15 * document and by a test vector provided by Ken Buchanan at
16 * http://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html
17 *
18 * The test vectors are included in the testing module tcrypt.[ch] */
19 #include <crypto/algapi.h>
20 #include <linux/err.h>
21 #include <linux/init.h>
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/scatterlist.h>
25 #include <linux/slab.h>
26
27 #include <crypto/b128ops.h>
28 #include <crypto/gf128mul.h>
29
30 struct priv {
31 struct crypto_cipher *child;
32 /* optimizes multiplying a random (non incrementing, as at the
33 * start of a new sector) value with key2, we could also have
34 * used 4k optimization tables or no optimization at all. In the
35 * latter case we would have to store key2 here */
36 struct gf128mul_64k *table;
37 /* stores:
38 * key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
39 * key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
40 * key2*{ 0,0,...1,1,1,1,1 }, etc
41 * needed for optimized multiplication of incrementing values
42 * with key2 */
43 be128 mulinc[128];
44 };
45
46 static inline void setbit128_bbe(void *b, int bit)
47 {
48 __set_bit(bit ^ 0x78, b);
49 }
50
51 static int setkey(struct crypto_tfm *parent, const u8 *key,
52 unsigned int keylen)
53 {
54 struct priv *ctx = crypto_tfm_ctx(parent);
55 struct crypto_cipher *child = ctx->child;
56 int err, i;
57 be128 tmp = { 0 };
58 int bsize = crypto_cipher_blocksize(child);
59
60 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
61 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
62 CRYPTO_TFM_REQ_MASK);
63 if ((err = crypto_cipher_setkey(child, key, keylen - bsize)))
64 return err;
65 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
66 CRYPTO_TFM_RES_MASK);
67
68 if (ctx->table)
69 gf128mul_free_64k(ctx->table);
70
71 /* initialize multiplication table for Key2 */
72 ctx->table = gf128mul_init_64k_bbe((be128 *)(key + keylen - bsize));
73 if (!ctx->table)
74 return -ENOMEM;
75
76 /* initialize optimization table */
77 for (i = 0; i < 128; i++) {
78 setbit128_bbe(&tmp, i);
79 ctx->mulinc[i] = tmp;
80 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
81 }
82
83 return 0;
84 }
85
86 struct sinfo {
87 be128 t;
88 struct crypto_tfm *tfm;
89 void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
90 };
91
92 static inline void inc(be128 *iv)
93 {
94 if (!(iv->b = cpu_to_be64(be64_to_cpu(iv->b) + 1)))
95 iv->a = cpu_to_be64(be64_to_cpu(iv->a) + 1);
96 }
97
98 static inline void lrw_round(struct sinfo *s, void *dst, const void *src)
99 {
100 be128_xor(dst, &s->t, src); /* PP <- T xor P */
101 s->fn(s->tfm, dst, dst); /* CC <- E(Key2,PP) */
102 be128_xor(dst, dst, &s->t); /* C <- T xor CC */
103 }
104
105 /* this returns the number of consequative 1 bits starting
106 * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
107 static inline int get_index128(be128 *block)
108 {
109 int x;
110 __be32 *p = (__be32 *) block;
111
112 for (p += 3, x = 0; x < 128; p--, x += 32) {
113 u32 val = be32_to_cpup(p);
114
115 if (!~val)
116 continue;
117
118 return x + ffz(val);
119 }
120
121 return x;
122 }
123
124 static int crypt(struct blkcipher_desc *d,
125 struct blkcipher_walk *w, struct priv *ctx,
126 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
127 {
128 int err;
129 unsigned int avail;
130 const int bs = crypto_cipher_blocksize(ctx->child);
131 struct sinfo s = {
132 .tfm = crypto_cipher_tfm(ctx->child),
133 .fn = fn
134 };
135 be128 *iv;
136 u8 *wsrc;
137 u8 *wdst;
138
139 err = blkcipher_walk_virt(d, w);
140 if (!(avail = w->nbytes))
141 return err;
142
143 wsrc = w->src.virt.addr;
144 wdst = w->dst.virt.addr;
145
146 /* calculate first value of T */
147 iv = (be128 *)w->iv;
148 s.t = *iv;
149
150 /* T <- I*Key2 */
151 gf128mul_64k_bbe(&s.t, ctx->table);
152
153 goto first;
154
155 for (;;) {
156 do {
157 /* T <- I*Key2, using the optimization
158 * discussed in the specification */
159 be128_xor(&s.t, &s.t, &ctx->mulinc[get_index128(iv)]);
160 inc(iv);
161
162 first:
163 lrw_round(&s, wdst, wsrc);
164
165 wsrc += bs;
166 wdst += bs;
167 } while ((avail -= bs) >= bs);
168
169 err = blkcipher_walk_done(d, w, avail);
170 if (!(avail = w->nbytes))
171 break;
172
173 wsrc = w->src.virt.addr;
174 wdst = w->dst.virt.addr;
175 }
176
177 return err;
178 }
179
180 static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
181 struct scatterlist *src, unsigned int nbytes)
182 {
183 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
184 struct blkcipher_walk w;
185
186 blkcipher_walk_init(&w, dst, src, nbytes);
187 return crypt(desc, &w, ctx,
188 crypto_cipher_alg(ctx->child)->cia_encrypt);
189 }
190
191 static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
192 struct scatterlist *src, unsigned int nbytes)
193 {
194 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
195 struct blkcipher_walk w;
196
197 blkcipher_walk_init(&w, dst, src, nbytes);
198 return crypt(desc, &w, ctx,
199 crypto_cipher_alg(ctx->child)->cia_decrypt);
200 }
201
202 static int init_tfm(struct crypto_tfm *tfm)
203 {
204 struct crypto_cipher *cipher;
205 struct crypto_instance *inst = (void *)tfm->__crt_alg;
206 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
207 struct priv *ctx = crypto_tfm_ctx(tfm);
208 u32 *flags = &tfm->crt_flags;
209
210 cipher = crypto_spawn_cipher(spawn);
211 if (IS_ERR(cipher))
212 return PTR_ERR(cipher);
213
214 if (crypto_cipher_blocksize(cipher) != 16) {
215 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
216 return -EINVAL;
217 }
218
219 ctx->child = cipher;
220 return 0;
221 }
222
223 static void exit_tfm(struct crypto_tfm *tfm)
224 {
225 struct priv *ctx = crypto_tfm_ctx(tfm);
226 if (ctx->table)
227 gf128mul_free_64k(ctx->table);
228 crypto_free_cipher(ctx->child);
229 }
230
231 static struct crypto_instance *alloc(struct rtattr **tb)
232 {
233 struct crypto_instance *inst;
234 struct crypto_alg *alg;
235 int err;
236
237 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
238 if (err)
239 return ERR_PTR(err);
240
241 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
242 CRYPTO_ALG_TYPE_MASK);
243 if (IS_ERR(alg))
244 return ERR_CAST(alg);
245
246 inst = crypto_alloc_instance("lrw", alg);
247 if (IS_ERR(inst))
248 goto out_put_alg;
249
250 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
251 inst->alg.cra_priority = alg->cra_priority;
252 inst->alg.cra_blocksize = alg->cra_blocksize;
253
254 if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
255 else inst->alg.cra_alignmask = alg->cra_alignmask;
256 inst->alg.cra_type = &crypto_blkcipher_type;
257
258 if (!(alg->cra_blocksize % 4))
259 inst->alg.cra_alignmask |= 3;
260 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
261 inst->alg.cra_blkcipher.min_keysize =
262 alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
263 inst->alg.cra_blkcipher.max_keysize =
264 alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;
265
266 inst->alg.cra_ctxsize = sizeof(struct priv);
267
268 inst->alg.cra_init = init_tfm;
269 inst->alg.cra_exit = exit_tfm;
270
271 inst->alg.cra_blkcipher.setkey = setkey;
272 inst->alg.cra_blkcipher.encrypt = encrypt;
273 inst->alg.cra_blkcipher.decrypt = decrypt;
274
275 out_put_alg:
276 crypto_mod_put(alg);
277 return inst;
278 }
279
280 static void free(struct crypto_instance *inst)
281 {
282 crypto_drop_spawn(crypto_instance_ctx(inst));
283 kfree(inst);
284 }
285
286 static struct crypto_template crypto_tmpl = {
287 .name = "lrw",
288 .alloc = alloc,
289 .free = free,
290 .module = THIS_MODULE,
291 };
292
293 static int __init crypto_module_init(void)
294 {
295 return crypto_register_template(&crypto_tmpl);
296 }
297
298 static void __exit crypto_module_exit(void)
299 {
300 crypto_unregister_template(&crypto_tmpl);
301 }
302
303 module_init(crypto_module_init);
304 module_exit(crypto_module_exit);
305
306 MODULE_LICENSE("GPL");
307 MODULE_DESCRIPTION("LRW block cipher mode");
308
|
This page was automatically generated by the
LXR engine.
|