crypto/salsa20_generic.c - kernel/mindspeed - Git at Google

 /*
  * Salsa20: Salsa20 stream cipher algorithm
  *
  * Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
  *
  * Derived from:
  * - salsa20.c: Public domain C code by Daniel J. Bernstein <djb@cr.yp.to>
  *
  * Salsa20 is a stream cipher candidate in eSTREAM, the ECRYPT Stream
  * Cipher Project. It is designed by Daniel J. Bernstein <djb@cr.yp.to>.
  * More information about eSTREAM and Salsa20 can be found here:
  *   http://www.ecrypt.eu.org/stream/
  *   http://cr.yp.to/snuffle.html
  *
  * 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.
  *
  */

 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/crypto.h>
 #include <linux/types.h>
 #include <linux/bitops.h>
 #include <crypto/algapi.h>
 #include <asm/byteorder.h>

 #define SALSA20_IV_SIZE        8U
 #define SALSA20_MIN_KEY_SIZE  16U
 #define SALSA20_MAX_KEY_SIZE  32U

 /*
  * Start of code taken from D. J. Bernstein's reference implementation.
  * With some modifications and optimizations made to suit our needs.
  */

 /*
 salsa20-ref.c version 20051118
 D. J. Bernstein
 Public domain.
 */

 #define U32TO8_LITTLE(p, v) \
 	{ (p)[0] = (v >>  0) & 0xff; (p)[1] = (v >>  8) & 0xff; \
 	  (p)[2] = (v >> 16) & 0xff; (p)[3] = (v >> 24) & 0xff; }
 #define U8TO32_LITTLE(p)   \
 	(((u32)((p)[0])      ) | ((u32)((p)[1]) <<  8) | \
 	 ((u32)((p)[2]) << 16) | ((u32)((p)[3]) << 24)   )

 struct salsa20_ctx
 {
 	u32 input[16];
 };

 static void salsa20_wordtobyte(u8 output[64], const u32 input[16])
 {
 	u32 x[16];
 	int i;

 	memcpy(x, input, sizeof(x));
 	for (i = 20; i > 0; i -= 2) {
 		x[ 4] ^= rol32((x[ 0] + x[12]),  7);
 		x[ 8] ^= rol32((x[ 4] + x[ 0]),  9);
 		x[12] ^= rol32((x[ 8] + x[ 4]), 13);
 		x[ 0] ^= rol32((x[12] + x[ 8]), 18);
 		x[ 9] ^= rol32((x[ 5] + x[ 1]),  7);
 		x[13] ^= rol32((x[ 9] + x[ 5]),  9);
 		x[ 1] ^= rol32((x[13] + x[ 9]), 13);
 		x[ 5] ^= rol32((x[ 1] + x[13]), 18);
 		x[14] ^= rol32((x[10] + x[ 6]),  7);
 		x[ 2] ^= rol32((x[14] + x[10]),  9);
 		x[ 6] ^= rol32((x[ 2] + x[14]), 13);
 		x[10] ^= rol32((x[ 6] + x[ 2]), 18);
 		x[ 3] ^= rol32((x[15] + x[11]),  7);
 		x[ 7] ^= rol32((x[ 3] + x[15]),  9);
 		x[11] ^= rol32((x[ 7] + x[ 3]), 13);
 		x[15] ^= rol32((x[11] + x[ 7]), 18);
 		x[ 1] ^= rol32((x[ 0] + x[ 3]),  7);
 		x[ 2] ^= rol32((x[ 1] + x[ 0]),  9);
 		x[ 3] ^= rol32((x[ 2] + x[ 1]), 13);
 		x[ 0] ^= rol32((x[ 3] + x[ 2]), 18);
 		x[ 6] ^= rol32((x[ 5] + x[ 4]),  7);
 		x[ 7] ^= rol32((x[ 6] + x[ 5]),  9);
 		x[ 4] ^= rol32((x[ 7] + x[ 6]), 13);
 		x[ 5] ^= rol32((x[ 4] + x[ 7]), 18);
 		x[11] ^= rol32((x[10] + x[ 9]),  7);
 		x[ 8] ^= rol32((x[11] + x[10]),  9);
 		x[ 9] ^= rol32((x[ 8] + x[11]), 13);
 		x[10] ^= rol32((x[ 9] + x[ 8]), 18);
 		x[12] ^= rol32((x[15] + x[14]),  7);
 		x[13] ^= rol32((x[12] + x[15]),  9);
 		x[14] ^= rol32((x[13] + x[12]), 13);
 		x[15] ^= rol32((x[14] + x[13]), 18);
 	}
 	for (i = 0; i < 16; ++i)
 		x[i] += input[i];
 	for (i = 0; i < 16; ++i)
 		U32TO8_LITTLE(output + 4 * i,x[i]);
 }

 static const char sigma[16] = "expand 32-byte k";
 static const char tau[16] = "expand 16-byte k";

 static void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k, u32 kbytes)
 {
 	const char *constants;

 	ctx->input[1] = U8TO32_LITTLE(k + 0);
 	ctx->input[2] = U8TO32_LITTLE(k + 4);
 	ctx->input[3] = U8TO32_LITTLE(k + 8);
 	ctx->input[4] = U8TO32_LITTLE(k + 12);
 	if (kbytes == 32) { /* recommended */
 		k += 16;
 		constants = sigma;
 	} else { /* kbytes == 16 */
 		constants = tau;
 	}
 	ctx->input[11] = U8TO32_LITTLE(k + 0);
 	ctx->input[12] = U8TO32_LITTLE(k + 4);
 	ctx->input[13] = U8TO32_LITTLE(k + 8);
 	ctx->input[14] = U8TO32_LITTLE(k + 12);
 	ctx->input[0] = U8TO32_LITTLE(constants + 0);
 	ctx->input[5] = U8TO32_LITTLE(constants + 4);
 	ctx->input[10] = U8TO32_LITTLE(constants + 8);
 	ctx->input[15] = U8TO32_LITTLE(constants + 12);
 }

 static void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv)
 {
 	ctx->input[6] = U8TO32_LITTLE(iv + 0);
 	ctx->input[7] = U8TO32_LITTLE(iv + 4);
 	ctx->input[8] = 0;
 	ctx->input[9] = 0;
 }

 static void salsa20_encrypt_bytes(struct salsa20_ctx *ctx, u8 *dst,
 				  const u8 *src, unsigned int bytes)
 {
 	u8 buf[64];

 	if (dst != src)
 		memcpy(dst, src, bytes);

 	while (bytes) {
 		salsa20_wordtobyte(buf, ctx->input);

 		ctx->input[8]++;
 		if (!ctx->input[8])
 			ctx->input[9]++;

 		if (bytes <= 64) {
 			crypto_xor(dst, buf, bytes);
 			return;
 		}

 		crypto_xor(dst, buf, 64);
 		bytes -= 64;
 		dst += 64;
 	}
 }

 /*
  * End of code taken from D. J. Bernstein's reference implementation.
  */

 static int setkey(struct crypto_tfm *tfm, const u8 *key,
 		  unsigned int keysize)
 {
 	struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
 	salsa20_keysetup(ctx, key, keysize);
 	return 0;
 }

 static int encrypt(struct blkcipher_desc *desc,
 		   struct scatterlist *dst, struct scatterlist *src,
 		   unsigned int nbytes)
 {
 	struct blkcipher_walk walk;
 	struct crypto_blkcipher *tfm = desc->tfm;
 	struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
 	int err;

 	blkcipher_walk_init(&walk, dst, src, nbytes);
 	err = blkcipher_walk_virt_block(desc, &walk, 64);

 	salsa20_ivsetup(ctx, walk.iv);

 	if (likely(walk.nbytes == nbytes))
 	{
 		salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
 				      walk.src.virt.addr, nbytes);
 		return blkcipher_walk_done(desc, &walk, 0);
 	}

 	while (walk.nbytes >= 64) {
 		salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
 				      walk.src.virt.addr,
 				      walk.nbytes - (walk.nbytes % 64));
 		err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64);
 	}

 	if (walk.nbytes) {
 		salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
 				      walk.src.virt.addr, walk.nbytes);
 		err = blkcipher_walk_done(desc, &walk, 0);
 	}

 	return err;
 }

 static struct crypto_alg alg = {
 	.cra_name           =   "salsa20",
 	.cra_driver_name    =   "salsa20-generic",
 	.cra_priority       =   100,
 	.cra_flags          =   CRYPTO_ALG_TYPE_BLKCIPHER,
 	.cra_type           =   &crypto_blkcipher_type,
 	.cra_blocksize      =   1,
 	.cra_ctxsize        =   sizeof(struct salsa20_ctx),
 	.cra_alignmask      =	3,
 	.cra_module         =   THIS_MODULE,
 	.cra_list           =   LIST_HEAD_INIT(alg.cra_list),
 	.cra_u              =   {
 		.blkcipher = {
 			.setkey         =   setkey,
 			.encrypt        =   encrypt,
 			.decrypt        =   encrypt,
 			.min_keysize    =   SALSA20_MIN_KEY_SIZE,
 			.max_keysize    =   SALSA20_MAX_KEY_SIZE,
 			.ivsize         =   SALSA20_IV_SIZE,
 		}
 	}
 };

 static int __init salsa20_generic_mod_init(void)
 {
 	return crypto_register_alg(&alg);
 }

 static void __exit salsa20_generic_mod_fini(void)
 {
 	crypto_unregister_alg(&alg);
 }

 module_init(salsa20_generic_mod_init);
 module_exit(salsa20_generic_mod_fini);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm");
 MODULE_ALIAS("salsa20");
	/*
	* Salsa20: Salsa20 stream cipher algorithm
	*
	* Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
	*
	* Derived from:
	* - salsa20.c: Public domain C code by Daniel J. Bernstein <djb@cr.yp.to>
	*
	* Salsa20 is a stream cipher candidate in eSTREAM, the ECRYPT Stream
	* Cipher Project. It is designed by Daniel J. Bernstein <djb@cr.yp.to>.
	* More information about eSTREAM and Salsa20 can be found here:
	* http://www.ecrypt.eu.org/stream/
	* http://cr.yp.to/snuffle.html
	*
	* 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.
	*
	*/

	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/errno.h>
	#include <linux/crypto.h>
	#include <linux/types.h>
	#include <linux/bitops.h>
	#include <crypto/algapi.h>
	#include <asm/byteorder.h>

	#define SALSA20_IV_SIZE 8U
	#define SALSA20_MIN_KEY_SIZE 16U
	#define SALSA20_MAX_KEY_SIZE 32U

	/*
	* Start of code taken from D. J. Bernstein's reference implementation.
	* With some modifications and optimizations made to suit our needs.
	*/

	/*
	salsa20-ref.c version 20051118
	D. J. Bernstein
	Public domain.
	*/

	#define U32TO8_LITTLE(p, v) \
	{ (p)[0] = (v >> 0) & 0xff; (p)[1] = (v >> 8) & 0xff; \
	(p)[2] = (v >> 16) & 0xff; (p)[3] = (v >> 24) & 0xff; }
	#define U8TO32_LITTLE(p) \
	(((u32)((p)[0]) ) \| ((u32)((p)[1]) << 8) \| \
	((u32)((p)[2]) << 16) \| ((u32)((p)[3]) << 24) )

	struct salsa20_ctx
	{
	u32 input[16];
	};

	static void salsa20_wordtobyte(u8 output[64], const u32 input[16])
	{
	u32 x[16];
	int i;

	memcpy(x, input, sizeof(x));
	for (i = 20; i > 0; i -= 2) {
	x[ 4] ^= rol32((x[ 0] + x[12]), 7);
	x[ 8] ^= rol32((x[ 4] + x[ 0]), 9);
	x[12] ^= rol32((x[ 8] + x[ 4]), 13);
	x[ 0] ^= rol32((x[12] + x[ 8]), 18);
	x[ 9] ^= rol32((x[ 5] + x[ 1]), 7);
	x[13] ^= rol32((x[ 9] + x[ 5]), 9);
	x[ 1] ^= rol32((x[13] + x[ 9]), 13);
	x[ 5] ^= rol32((x[ 1] + x[13]), 18);
	x[14] ^= rol32((x[10] + x[ 6]), 7);
	x[ 2] ^= rol32((x[14] + x[10]), 9);
	x[ 6] ^= rol32((x[ 2] + x[14]), 13);
	x[10] ^= rol32((x[ 6] + x[ 2]), 18);
	x[ 3] ^= rol32((x[15] + x[11]), 7);
	x[ 7] ^= rol32((x[ 3] + x[15]), 9);
	x[11] ^= rol32((x[ 7] + x[ 3]), 13);
	x[15] ^= rol32((x[11] + x[ 7]), 18);
	x[ 1] ^= rol32((x[ 0] + x[ 3]), 7);
	x[ 2] ^= rol32((x[ 1] + x[ 0]), 9);
	x[ 3] ^= rol32((x[ 2] + x[ 1]), 13);
	x[ 0] ^= rol32((x[ 3] + x[ 2]), 18);
	x[ 6] ^= rol32((x[ 5] + x[ 4]), 7);
	x[ 7] ^= rol32((x[ 6] + x[ 5]), 9);
	x[ 4] ^= rol32((x[ 7] + x[ 6]), 13);
	x[ 5] ^= rol32((x[ 4] + x[ 7]), 18);
	x[11] ^= rol32((x[10] + x[ 9]), 7);
	x[ 8] ^= rol32((x[11] + x[10]), 9);
	x[ 9] ^= rol32((x[ 8] + x[11]), 13);
	x[10] ^= rol32((x[ 9] + x[ 8]), 18);
	x[12] ^= rol32((x[15] + x[14]), 7);
	x[13] ^= rol32((x[12] + x[15]), 9);
	x[14] ^= rol32((x[13] + x[12]), 13);
	x[15] ^= rol32((x[14] + x[13]), 18);
	}
	for (i = 0; i < 16; ++i)
	x[i] += input[i];
	for (i = 0; i < 16; ++i)
	U32TO8_LITTLE(output + 4 * i,x[i]);
	}

	static const char sigma[16] = "expand 32-byte k";
	static const char tau[16] = "expand 16-byte k";

	static void salsa20_keysetup(struct salsa20_ctx ctx, const u8 k, u32 kbytes)
	{
	const char *constants;

	ctx->input[1] = U8TO32_LITTLE(k + 0);
	ctx->input[2] = U8TO32_LITTLE(k + 4);
	ctx->input[3] = U8TO32_LITTLE(k + 8);
	ctx->input[4] = U8TO32_LITTLE(k + 12);
	if (kbytes == 32) { /* recommended */
	k += 16;
	constants = sigma;
	} else { /* kbytes == 16 */
	constants = tau;
	}
	ctx->input[11] = U8TO32_LITTLE(k + 0);
	ctx->input[12] = U8TO32_LITTLE(k + 4);
	ctx->input[13] = U8TO32_LITTLE(k + 8);
	ctx->input[14] = U8TO32_LITTLE(k + 12);
	ctx->input[0] = U8TO32_LITTLE(constants + 0);
	ctx->input[5] = U8TO32_LITTLE(constants + 4);
	ctx->input[10] = U8TO32_LITTLE(constants + 8);
	ctx->input[15] = U8TO32_LITTLE(constants + 12);
	}

	static void salsa20_ivsetup(struct salsa20_ctx ctx, const u8 iv)
	{
	ctx->input[6] = U8TO32_LITTLE(iv + 0);
	ctx->input[7] = U8TO32_LITTLE(iv + 4);
	ctx->input[8] = 0;
	ctx->input[9] = 0;
	}

	static void salsa20_encrypt_bytes(struct salsa20_ctx ctx, u8 dst,
	const u8 *src, unsigned int bytes)
	{
	u8 buf[64];

	if (dst != src)
	memcpy(dst, src, bytes);

	while (bytes) {
	salsa20_wordtobyte(buf, ctx->input);

	ctx->input[8]++;
	if (!ctx->input[8])
	ctx->input[9]++;

	if (bytes <= 64) {
	crypto_xor(dst, buf, bytes);
	return;
	}

	crypto_xor(dst, buf, 64);
	bytes -= 64;
	dst += 64;
	}
	}

	/*
	* End of code taken from D. J. Bernstein's reference implementation.
	*/

	static int setkey(struct crypto_tfm tfm, const u8 key,
	unsigned int keysize)
	{
	struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
	salsa20_keysetup(ctx, key, keysize);
	return 0;
	}

	static int encrypt(struct blkcipher_desc *desc,
	struct scatterlist dst, struct scatterlist src,
	unsigned int nbytes)
	{
	struct blkcipher_walk walk;
	struct crypto_blkcipher *tfm = desc->tfm;
	struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
	int err;

	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt_block(desc, &walk, 64);

	salsa20_ivsetup(ctx, walk.iv);

	if (likely(walk.nbytes == nbytes))
	{
	salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
	walk.src.virt.addr, nbytes);
	return blkcipher_walk_done(desc, &walk, 0);
	}

	while (walk.nbytes >= 64) {
	salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
	walk.src.virt.addr,
	walk.nbytes - (walk.nbytes % 64));
	err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64);
	}

	if (walk.nbytes) {
	salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
	walk.src.virt.addr, walk.nbytes);
	err = blkcipher_walk_done(desc, &walk, 0);
	}

	return err;
	}

	static struct crypto_alg alg = {
	.cra_name = "salsa20",
	.cra_driver_name = "salsa20-generic",
	.cra_priority = 100,
	.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
	.cra_type = &crypto_blkcipher_type,
	.cra_blocksize = 1,
	.cra_ctxsize = sizeof(struct salsa20_ctx),
	.cra_alignmask = 3,
	.cra_module = THIS_MODULE,
	.cra_list = LIST_HEAD_INIT(alg.cra_list),
	.cra_u = {
	.blkcipher = {
	.setkey = setkey,
	.encrypt = encrypt,
	.decrypt = encrypt,
	.min_keysize = SALSA20_MIN_KEY_SIZE,
	.max_keysize = SALSA20_MAX_KEY_SIZE,
	.ivsize = SALSA20_IV_SIZE,
	}
	}
	};

	static int __init salsa20_generic_mod_init(void)
	{
	return crypto_register_alg(&alg);
	}

	static void __exit salsa20_generic_mod_fini(void)
	{
	crypto_unregister_alg(&alg);
	}

	module_init(salsa20_generic_mod_init);
	module_exit(salsa20_generic_mod_fini);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm");
	MODULE_ALIAS("salsa20");