Commit 64470f1b authored by Rik Snel's avatar Rik Snel Committed by David S. Miller

[CRYPTO] lrw: Liskov Rivest Wagner, a tweakable narrow block cipher mode

Main module, this implements the Liskov Rivest Wagner block cipher mode
in the new blockcipher API. The implementation is based on ecb.c.

The LRW-32-AES specification I used can be found at:
http://grouper.ieee.org/groups/1619/email/pdf00017.pdf

It implements the optimization specified as optional in the
specification, and in addition it uses optimized multiplication
routines from gf128mul.c.

Since gf128mul.[ch] is not tested on bigendian, this cipher mode
may currently fail badly on bigendian machines.
Signed-off-by: 's avatarRik Snel <rsnel@cube.dyndns.org>
Signed-off-by: 's avatarHerbert Xu <herbert@gondor.apana.org.au>
parent c494e070
......@@ -168,6 +168,19 @@ config CRYPTO_CBC
CBC: Cipher Block Chaining mode
This block cipher algorithm is required for IPSec.
config CRYPTO_LRW
tristate "LRW support (EXPERIMENTAL)"
depends on EXPERIMENTAL
select CRYPTO_BLKCIPHER
select CRYPTO_MANAGER
select CRYPTO_GF128MUL
help
LRW: Liskov Rivest Wagner, a tweakable, non malleable, non movable
narrow block cipher mode for dm-crypt. Use it with cipher
specification string aes-lrw-benbi, the key must be 256, 320 or 384.
The first 128, 192 or 256 bits in the key are used for AES and the
rest is used to tie each cipher block to its logical position.
config CRYPTO_DES
tristate "DES and Triple DES EDE cipher algorithms"
select CRYPTO_ALGAPI
......
......@@ -27,6 +27,7 @@ obj-$(CONFIG_CRYPTO_TGR192) += tgr192.o
obj-$(CONFIG_CRYPTO_GF128MUL) += gf128mul.o
obj-$(CONFIG_CRYPTO_ECB) += ecb.o
obj-$(CONFIG_CRYPTO_CBC) += cbc.o
obj-$(CONFIG_CRYPTO_LRW) += lrw.o
obj-$(CONFIG_CRYPTO_DES) += des.o
obj-$(CONFIG_CRYPTO_BLOWFISH) += blowfish.o
obj-$(CONFIG_CRYPTO_TWOFISH) += twofish.o
......
/* LRW: as defined by Cyril Guyot in
* http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
*
* Copyright (c) 2006 Rik Snel <rsnel@cube.dyndns.org>
*
* Based om ecb.c
* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*/
/* This implementation is checked against the test vectors in the above
* document and by a test vector provided by Ken Buchanan at
* http://www.mail-archive.com/stds-p1619@listserv.ieee.org/msg00173.html
*
* The test vectors are included in the testing module tcrypt.[ch] */
#include <crypto/algapi.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>
struct priv {
struct crypto_cipher *child;
/* optimizes multiplying a random (non incrementing, as at the
* start of a new sector) value with key2, we could also have
* used 4k optimization tables or no optimization at all. In the
* latter case we would have to store key2 here */
struct gf128mul_64k *table;
/* stores:
* key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
* key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
* key2*{ 0,0,...1,1,1,1,1 }, etc
* needed for optimized multiplication of incrementing values
* with key2 */
be128 mulinc[128];
};
static inline void setbit128_bbe(void *b, int bit)
{
__set_bit(bit ^ 0x78, b);
}
static int setkey(struct crypto_tfm *parent, const u8 *key,
unsigned int keylen)
{
struct priv *ctx = crypto_tfm_ctx(parent);
struct crypto_cipher *child = ctx->child;
int err, i;
be128 tmp = { 0 };
int bsize = crypto_cipher_blocksize(child);
crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
CRYPTO_TFM_REQ_MASK);
if ((err = crypto_cipher_setkey(child, key, keylen - bsize)))
return err;
crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
CRYPTO_TFM_RES_MASK);
if (ctx->table)
gf128mul_free_64k(ctx->table);
/* initialize multiplication table for Key2 */
ctx->table = gf128mul_init_64k_bbe((be128 *)(key + keylen - bsize));
if (!ctx->table)
return -ENOMEM;
/* initialize optimization table */
for (i = 0; i < 128; i++) {
setbit128_bbe(&tmp, i);
ctx->mulinc[i] = tmp;
gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
}
return 0;
}
struct sinfo {
be128 t;
struct crypto_tfm *tfm;
void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
};
static inline void inc(be128 *iv)
{
if (!(iv->b = cpu_to_be64(be64_to_cpu(iv->b) + 1)))
iv->a = cpu_to_be64(be64_to_cpu(iv->a) + 1);
}
static inline void round(struct sinfo *s, void *dst, const void *src)
{
be128_xor(dst, &s->t, src); /* PP <- T xor P */
s->fn(s->tfm, dst, dst); /* CC <- E(Key2,PP) */
be128_xor(dst, dst, &s->t); /* C <- T xor CC */
}
/* this returns the number of consequative 1 bits starting
* from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
static inline int get_index128(be128 *block)
{
int x;
__be32 *p = (__be32 *) block;
for (p += 3, x = 0; x < 128; p--, x += 32) {
u32 val = be32_to_cpup(p);
if (!~val)
continue;
return x + ffz(val);
}
return x;
}
static int crypt(struct blkcipher_desc *d,
struct blkcipher_walk *w, struct priv *ctx,
void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
{
int err;
unsigned int avail;
const int bs = crypto_cipher_blocksize(ctx->child);
struct sinfo s = {
.tfm = crypto_cipher_tfm(ctx->child),
.fn = fn
};
be128 *iv;
u8 *wsrc;
u8 *wdst;
err = blkcipher_walk_virt(d, w);
if (!(avail = w->nbytes))
return err;
wsrc = w->src.virt.addr;
wdst = w->dst.virt.addr;
/* calculate first value of T */
iv = (be128 *)w->iv;
s.t = *iv;
/* T <- I*Key2 */
gf128mul_64k_bbe(&s.t, ctx->table);
goto first;
for (;;) {
do {
/* T <- I*Key2, using the optimization
* discussed in the specification */
be128_xor(&s.t, &s.t, &ctx->mulinc[get_index128(iv)]);
inc(iv);
first:
round(&s, wdst, wsrc);
wsrc += bs;
wdst += bs;
} while ((avail -= bs) >= bs);
err = blkcipher_walk_done(d, w, avail);
if (!(avail = w->nbytes))
break;
wsrc = w->src.virt.addr;
wdst = w->dst.virt.addr;
}
return err;
}
static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
struct blkcipher_walk w;
blkcipher_walk_init(&w, dst, src, nbytes);
return crypt(desc, &w, ctx,
crypto_cipher_alg(ctx->child)->cia_encrypt);
}
static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
struct blkcipher_walk w;
blkcipher_walk_init(&w, dst, src, nbytes);
return crypt(desc, &w, ctx,
crypto_cipher_alg(ctx->child)->cia_decrypt);
}
static int init_tfm(struct crypto_tfm *tfm)
{
struct crypto_instance *inst = (void *)tfm->__crt_alg;
struct crypto_spawn *spawn = crypto_instance_ctx(inst);
struct priv *ctx = crypto_tfm_ctx(tfm);
u32 *flags = &tfm->crt_flags;
tfm = crypto_spawn_tfm(spawn);
if (IS_ERR(tfm))
return PTR_ERR(tfm);
if (crypto_tfm_alg_blocksize(tfm) != 16) {
*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
return -EINVAL;
}
ctx->child = crypto_cipher_cast(tfm);
return 0;
}
static void exit_tfm(struct crypto_tfm *tfm)
{
struct priv *ctx = crypto_tfm_ctx(tfm);
if (ctx->table)
gf128mul_free_64k(ctx->table);
crypto_free_cipher(ctx->child);
}
static struct crypto_instance *alloc(void *param, unsigned int len)
{
struct crypto_instance *inst;
struct crypto_alg *alg;
alg = crypto_get_attr_alg(param, len, CRYPTO_ALG_TYPE_CIPHER,
CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
if (IS_ERR(alg))
return ERR_PTR(PTR_ERR(alg));
inst = crypto_alloc_instance("lrw", alg);
if (IS_ERR(inst))
goto out_put_alg;
inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
inst->alg.cra_priority = alg->cra_priority;
inst->alg.cra_blocksize = alg->cra_blocksize;
if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
else inst->alg.cra_alignmask = alg->cra_alignmask;
inst->alg.cra_type = &crypto_blkcipher_type;
if (!(alg->cra_blocksize % 4))
inst->alg.cra_alignmask |= 3;
inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
inst->alg.cra_blkcipher.min_keysize =
alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
inst->alg.cra_blkcipher.max_keysize =
alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;
inst->alg.cra_ctxsize = sizeof(struct priv);
inst->alg.cra_init = init_tfm;
inst->alg.cra_exit = exit_tfm;
inst->alg.cra_blkcipher.setkey = setkey;
inst->alg.cra_blkcipher.encrypt = encrypt;
inst->alg.cra_blkcipher.decrypt = decrypt;
out_put_alg:
crypto_mod_put(alg);
return inst;
}
static void free(struct crypto_instance *inst)
{
crypto_drop_spawn(crypto_instance_ctx(inst));
kfree(inst);
}
static struct crypto_template crypto_tmpl = {
.name = "lrw",
.alloc = alloc,
.free = free,
.module = THIS_MODULE,
};
static int __init crypto_module_init(void)
{
return crypto_register_template(&crypto_tmpl);
}
static void __exit crypto_module_exit(void)
{
crypto_unregister_template(&crypto_tmpl);
}
module_init(crypto_module_init);
module_exit(crypto_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LRW block cipher mode");
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