1 /* LRW: as defined by Cyril Guyot in
2 * http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
4 * Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>
7 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
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)
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
18 * The test vectors are included in the testing module tcrypt.[ch] */
20 #include <crypto/algapi.h>
21 #include <linux/err.h>
22 #include <linux/init.h>
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/scatterlist.h>
26 #include <linux/slab.h>
28 #include <crypto/b128ops.h>
29 #include <crypto/gf128mul.h>
30 #include <crypto/lrw.h>
33 struct crypto_cipher *child;
34 struct lrw_table_ctx table;
37 static inline void setbit128_bbe(void *b, int bit)
39 __set_bit(bit ^ (0x80 -
48 int lrw_init_table(struct lrw_table_ctx *ctx, const u8 *tweak)
54 gf128mul_free_64k(ctx->table);
56 /* initialize multiplication table for Key2 */
57 ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
61 /* initialize optimization table */
62 for (i = 0; i < 128; i++) {
63 setbit128_bbe(&tmp, i);
65 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
70 EXPORT_SYMBOL_GPL(lrw_init_table);
72 void lrw_free_table(struct lrw_table_ctx *ctx)
75 gf128mul_free_64k(ctx->table);
77 EXPORT_SYMBOL_GPL(lrw_free_table);
79 static int setkey(struct crypto_tfm *parent, const u8 *key,
82 struct priv *ctx = crypto_tfm_ctx(parent);
83 struct crypto_cipher *child = ctx->child;
84 int err, bsize = LRW_BLOCK_SIZE;
85 const u8 *tweak = key + keylen - bsize;
87 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
88 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
90 err = crypto_cipher_setkey(child, key, keylen - bsize);
93 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
96 return lrw_init_table(&ctx->table, tweak);
101 struct crypto_tfm *tfm;
102 void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
105 static inline void inc(be128 *iv)
107 be64_add_cpu(&iv->b, 1);
109 be64_add_cpu(&iv->a, 1);
112 static inline void lrw_round(struct sinfo *s, void *dst, const void *src)
114 be128_xor(dst, &s->t, src); /* PP <- T xor P */
115 s->fn(s->tfm, dst, dst); /* CC <- E(Key2,PP) */
116 be128_xor(dst, dst, &s->t); /* C <- T xor CC */
119 /* this returns the number of consequative 1 bits starting
120 * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
121 static inline int get_index128(be128 *block)
124 __be32 *p = (__be32 *) block;
126 for (p += 3, x = 0; x < 128; p--, x += 32) {
127 u32 val = be32_to_cpup(p);
136 * If we get here, then x == 128 and we are incrementing the counter
137 * from all ones to all zeros. This means we must return index 127, i.e.
138 * the one corresponding to key2*{ 1,...,1 }.
143 static int crypt(struct blkcipher_desc *d,
144 struct blkcipher_walk *w, struct priv *ctx,
145 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
149 const int bs = LRW_BLOCK_SIZE;
151 .tfm = crypto_cipher_tfm(ctx->child),
158 err = blkcipher_walk_virt(d, w);
159 if (!(avail = w->nbytes))
162 wsrc = w->src.virt.addr;
163 wdst = w->dst.virt.addr;
165 /* calculate first value of T */
170 gf128mul_64k_bbe(&s.t, ctx->table.table);
176 /* T <- I*Key2, using the optimization
177 * discussed in the specification */
178 be128_xor(&s.t, &s.t,
179 &ctx->table.mulinc[get_index128(iv)]);
183 lrw_round(&s, wdst, wsrc);
187 } while ((avail -= bs) >= bs);
189 err = blkcipher_walk_done(d, w, avail);
190 if (!(avail = w->nbytes))
193 wsrc = w->src.virt.addr;
194 wdst = w->dst.virt.addr;
200 static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
201 struct scatterlist *src, unsigned int nbytes)
203 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
204 struct blkcipher_walk w;
206 blkcipher_walk_init(&w, dst, src, nbytes);
207 return crypt(desc, &w, ctx,
208 crypto_cipher_alg(ctx->child)->cia_encrypt);
211 static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
212 struct scatterlist *src, unsigned int nbytes)
214 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
215 struct blkcipher_walk w;
217 blkcipher_walk_init(&w, dst, src, nbytes);
218 return crypt(desc, &w, ctx,
219 crypto_cipher_alg(ctx->child)->cia_decrypt);
222 int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
223 struct scatterlist *ssrc, unsigned int nbytes,
224 struct lrw_crypt_req *req)
226 const unsigned int bsize = LRW_BLOCK_SIZE;
227 const unsigned int max_blks = req->tbuflen / bsize;
228 struct lrw_table_ctx *ctx = req->table_ctx;
229 struct blkcipher_walk walk;
230 unsigned int nblocks;
231 be128 *iv, *src, *dst, *t;
232 be128 *t_buf = req->tbuf;
235 BUG_ON(max_blks < 1);
237 blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
239 err = blkcipher_walk_virt(desc, &walk);
240 nbytes = walk.nbytes;
244 nblocks = min(walk.nbytes / bsize, max_blks);
245 src = (be128 *)walk.src.virt.addr;
246 dst = (be128 *)walk.dst.virt.addr;
248 /* calculate first value of T */
249 iv = (be128 *)walk.iv;
253 gf128mul_64k_bbe(&t_buf[0], ctx->table);
260 for (i = 0; i < nblocks; i++) {
261 /* T <- I*Key2, using the optimization
262 * discussed in the specification */
263 be128_xor(&t_buf[i], t,
264 &ctx->mulinc[get_index128(iv)]);
270 be128_xor(dst + i, t, src + i);
273 /* CC <- E(Key2,PP) */
274 req->crypt_fn(req->crypt_ctx, (u8 *)dst,
278 for (i = 0; i < nblocks; i++)
279 be128_xor(dst + i, dst + i, &t_buf[i]);
283 nbytes -= nblocks * bsize;
284 nblocks = min(nbytes / bsize, max_blks);
285 } while (nblocks > 0);
287 err = blkcipher_walk_done(desc, &walk, nbytes);
288 nbytes = walk.nbytes;
292 nblocks = min(nbytes / bsize, max_blks);
293 src = (be128 *)walk.src.virt.addr;
294 dst = (be128 *)walk.dst.virt.addr;
299 EXPORT_SYMBOL_GPL(lrw_crypt);
301 static int init_tfm(struct crypto_tfm *tfm)
303 struct crypto_cipher *cipher;
304 struct crypto_instance *inst = (void *)tfm->__crt_alg;
305 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
306 struct priv *ctx = crypto_tfm_ctx(tfm);
307 u32 *flags = &tfm->crt_flags;
309 cipher = crypto_spawn_cipher(spawn);
311 return PTR_ERR(cipher);
313 if (crypto_cipher_blocksize(cipher) != LRW_BLOCK_SIZE) {
314 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
315 crypto_free_cipher(cipher);
323 static void exit_tfm(struct crypto_tfm *tfm)
325 struct priv *ctx = crypto_tfm_ctx(tfm);
327 lrw_free_table(&ctx->table);
328 crypto_free_cipher(ctx->child);
331 static struct crypto_instance *alloc(struct rtattr **tb)
333 struct crypto_instance *inst;
334 struct crypto_alg *alg;
337 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
341 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
342 CRYPTO_ALG_TYPE_MASK);
344 return ERR_CAST(alg);
346 inst = crypto_alloc_instance("lrw", alg);
350 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
351 inst->alg.cra_priority = alg->cra_priority;
352 inst->alg.cra_blocksize = alg->cra_blocksize;
354 if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
355 else inst->alg.cra_alignmask = alg->cra_alignmask;
356 inst->alg.cra_type = &crypto_blkcipher_type;
358 if (!(alg->cra_blocksize % 4))
359 inst->alg.cra_alignmask |= 3;
360 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
361 inst->alg.cra_blkcipher.min_keysize =
362 alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
363 inst->alg.cra_blkcipher.max_keysize =
364 alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;
366 inst->alg.cra_ctxsize = sizeof(struct priv);
368 inst->alg.cra_init = init_tfm;
369 inst->alg.cra_exit = exit_tfm;
371 inst->alg.cra_blkcipher.setkey = setkey;
372 inst->alg.cra_blkcipher.encrypt = encrypt;
373 inst->alg.cra_blkcipher.decrypt = decrypt;
380 static void free_inst(struct crypto_instance *inst)
382 crypto_drop_spawn(crypto_instance_ctx(inst));
386 static struct crypto_template crypto_tmpl = {
390 .module = THIS_MODULE,
393 static int __init crypto_module_init(void)
395 return crypto_register_template(&crypto_tmpl);
398 static void __exit crypto_module_exit(void)
400 crypto_unregister_template(&crypto_tmpl);
403 module_init(crypto_module_init);
404 module_exit(crypto_module_exit);
406 MODULE_LICENSE("GPL");
407 MODULE_DESCRIPTION("LRW block cipher mode");
408 MODULE_ALIAS_CRYPTO("lrw");