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] */
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>
27 #include <crypto/b128ops.h>
28 #include <crypto/gf128mul.h>
30 #define LRW_BLOCK_SIZE 16
33 struct crypto_cipher *child;
34 /* optimizes multiplying a random (non incrementing, as at the
35 * start of a new sector) value with key2, we could also have
36 * used 4k optimization tables or no optimization at all. In the
37 * latter case we would have to store key2 here */
38 struct gf128mul_64k *table;
40 * key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
41 * key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
42 * key2*{ 0,0,...1,1,1,1,1 }, etc
43 * needed for optimized multiplication of incrementing values
48 static inline void setbit128_bbe(void *b, int bit)
50 __set_bit(bit ^ (0x80 -
59 static int setkey(struct crypto_tfm *parent, const u8 *key,
62 struct priv *ctx = crypto_tfm_ctx(parent);
63 struct crypto_cipher *child = ctx->child;
66 int bsize = LRW_BLOCK_SIZE;
68 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
69 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
71 if ((err = crypto_cipher_setkey(child, key, keylen - bsize)))
73 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
77 gf128mul_free_64k(ctx->table);
79 /* initialize multiplication table for Key2 */
80 ctx->table = gf128mul_init_64k_bbe((be128 *)(key + keylen - bsize));
84 /* initialize optimization table */
85 for (i = 0; i < 128; i++) {
86 setbit128_bbe(&tmp, i);
88 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
96 struct crypto_tfm *tfm;
97 void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
100 static inline void inc(be128 *iv)
102 be64_add_cpu(&iv->b, 1);
104 be64_add_cpu(&iv->a, 1);
107 static inline void lrw_round(struct sinfo *s, void *dst, const void *src)
109 be128_xor(dst, &s->t, src); /* PP <- T xor P */
110 s->fn(s->tfm, dst, dst); /* CC <- E(Key2,PP) */
111 be128_xor(dst, dst, &s->t); /* C <- T xor CC */
114 /* this returns the number of consequative 1 bits starting
115 * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
116 static inline int get_index128(be128 *block)
119 __be32 *p = (__be32 *) block;
121 for (p += 3, x = 0; x < 128; p--, x += 32) {
122 u32 val = be32_to_cpup(p);
133 static int crypt(struct blkcipher_desc *d,
134 struct blkcipher_walk *w, struct priv *ctx,
135 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
139 const int bs = LRW_BLOCK_SIZE;
141 .tfm = crypto_cipher_tfm(ctx->child),
148 err = blkcipher_walk_virt(d, w);
149 if (!(avail = w->nbytes))
152 wsrc = w->src.virt.addr;
153 wdst = w->dst.virt.addr;
155 /* calculate first value of T */
160 gf128mul_64k_bbe(&s.t, ctx->table);
166 /* T <- I*Key2, using the optimization
167 * discussed in the specification */
168 be128_xor(&s.t, &s.t, &ctx->mulinc[get_index128(iv)]);
172 lrw_round(&s, wdst, wsrc);
176 } while ((avail -= bs) >= bs);
178 err = blkcipher_walk_done(d, w, avail);
179 if (!(avail = w->nbytes))
182 wsrc = w->src.virt.addr;
183 wdst = w->dst.virt.addr;
189 static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
190 struct scatterlist *src, unsigned int nbytes)
192 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
193 struct blkcipher_walk w;
195 blkcipher_walk_init(&w, dst, src, nbytes);
196 return crypt(desc, &w, ctx,
197 crypto_cipher_alg(ctx->child)->cia_encrypt);
200 static int decrypt(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_decrypt);
211 static int init_tfm(struct crypto_tfm *tfm)
213 struct crypto_cipher *cipher;
214 struct crypto_instance *inst = (void *)tfm->__crt_alg;
215 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
216 struct priv *ctx = crypto_tfm_ctx(tfm);
217 u32 *flags = &tfm->crt_flags;
219 cipher = crypto_spawn_cipher(spawn);
221 return PTR_ERR(cipher);
223 if (crypto_cipher_blocksize(cipher) != LRW_BLOCK_SIZE) {
224 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
225 crypto_free_cipher(cipher);
233 static void exit_tfm(struct crypto_tfm *tfm)
235 struct priv *ctx = crypto_tfm_ctx(tfm);
237 gf128mul_free_64k(ctx->table);
238 crypto_free_cipher(ctx->child);
241 static struct crypto_instance *alloc(struct rtattr **tb)
243 struct crypto_instance *inst;
244 struct crypto_alg *alg;
247 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
251 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
252 CRYPTO_ALG_TYPE_MASK);
254 return ERR_CAST(alg);
256 inst = crypto_alloc_instance("lrw", alg);
260 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
261 inst->alg.cra_priority = alg->cra_priority;
262 inst->alg.cra_blocksize = alg->cra_blocksize;
264 if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
265 else inst->alg.cra_alignmask = alg->cra_alignmask;
266 inst->alg.cra_type = &crypto_blkcipher_type;
268 if (!(alg->cra_blocksize % 4))
269 inst->alg.cra_alignmask |= 3;
270 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
271 inst->alg.cra_blkcipher.min_keysize =
272 alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
273 inst->alg.cra_blkcipher.max_keysize =
274 alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;
276 inst->alg.cra_ctxsize = sizeof(struct priv);
278 inst->alg.cra_init = init_tfm;
279 inst->alg.cra_exit = exit_tfm;
281 inst->alg.cra_blkcipher.setkey = setkey;
282 inst->alg.cra_blkcipher.encrypt = encrypt;
283 inst->alg.cra_blkcipher.decrypt = decrypt;
290 static void free(struct crypto_instance *inst)
292 crypto_drop_spawn(crypto_instance_ctx(inst));
296 static struct crypto_template crypto_tmpl = {
300 .module = THIS_MODULE,
303 static int __init crypto_module_init(void)
305 return crypto_register_template(&crypto_tmpl);
308 static void __exit crypto_module_exit(void)
310 crypto_unregister_template(&crypto_tmpl);
313 module_init(crypto_module_init);
314 module_exit(crypto_module_exit);
316 MODULE_LICENSE("GPL");
317 MODULE_DESCRIPTION("LRW block cipher mode");