crypto/lrw.c - linux - Git at Google

 /* 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");
	/* 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 <- IKey2 /
	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");