crypto/chacha20_generic.c - kernel/quantenna - Git at Google

 /*
  * ChaCha20 256-bit cipher algorithm, RFC7539
  *
  * Copyright (C) 2015 Martin Willi
  *
  * 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 <crypto/algapi.h>
 #include <linux/crypto.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <crypto/chacha20.h>

 static inline u32 rotl32(u32 v, u8 n)
 {
 	return (v << n) | (v >> (sizeof(v) * 8 - n));
 }

 static inline u32 le32_to_cpuvp(const void *p)
 {
 	return le32_to_cpup(p);
 }

 static void chacha20_block(u32 *state, void *stream)
 {
 	u32 x[16], *out = stream;
 	int i;

 	for (i = 0; i < ARRAY_SIZE(x); i++)
 		x[i] = state[i];

 	for (i = 0; i < 20; i += 2) {
 		x[0]  += x[4];    x[12] = rotl32(x[12] ^ x[0],  16);
 		x[1]  += x[5];    x[13] = rotl32(x[13] ^ x[1],  16);
 		x[2]  += x[6];    x[14] = rotl32(x[14] ^ x[2],  16);
 		x[3]  += x[7];    x[15] = rotl32(x[15] ^ x[3],  16);

 		x[8]  += x[12];   x[4]  = rotl32(x[4]  ^ x[8],  12);
 		x[9]  += x[13];   x[5]  = rotl32(x[5]  ^ x[9],  12);
 		x[10] += x[14];   x[6]  = rotl32(x[6]  ^ x[10], 12);
 		x[11] += x[15];   x[7]  = rotl32(x[7]  ^ x[11], 12);

 		x[0]  += x[4];    x[12] = rotl32(x[12] ^ x[0],   8);
 		x[1]  += x[5];    x[13] = rotl32(x[13] ^ x[1],   8);
 		x[2]  += x[6];    x[14] = rotl32(x[14] ^ x[2],   8);
 		x[3]  += x[7];    x[15] = rotl32(x[15] ^ x[3],   8);

 		x[8]  += x[12];   x[4]  = rotl32(x[4]  ^ x[8],   7);
 		x[9]  += x[13];   x[5]  = rotl32(x[5]  ^ x[9],   7);
 		x[10] += x[14];   x[6]  = rotl32(x[6]  ^ x[10],  7);
 		x[11] += x[15];   x[7]  = rotl32(x[7]  ^ x[11],  7);

 		x[0]  += x[5];    x[15] = rotl32(x[15] ^ x[0],  16);
 		x[1]  += x[6];    x[12] = rotl32(x[12] ^ x[1],  16);
 		x[2]  += x[7];    x[13] = rotl32(x[13] ^ x[2],  16);
 		x[3]  += x[4];    x[14] = rotl32(x[14] ^ x[3],  16);

 		x[10] += x[15];   x[5]  = rotl32(x[5]  ^ x[10], 12);
 		x[11] += x[12];   x[6]  = rotl32(x[6]  ^ x[11], 12);
 		x[8]  += x[13];   x[7]  = rotl32(x[7]  ^ x[8],  12);
 		x[9]  += x[14];   x[4]  = rotl32(x[4]  ^ x[9],  12);

 		x[0]  += x[5];    x[15] = rotl32(x[15] ^ x[0],   8);
 		x[1]  += x[6];    x[12] = rotl32(x[12] ^ x[1],   8);
 		x[2]  += x[7];    x[13] = rotl32(x[13] ^ x[2],   8);
 		x[3]  += x[4];    x[14] = rotl32(x[14] ^ x[3],   8);

 		x[10] += x[15];   x[5]  = rotl32(x[5]  ^ x[10],  7);
 		x[11] += x[12];   x[6]  = rotl32(x[6]  ^ x[11],  7);
 		x[8]  += x[13];   x[7]  = rotl32(x[7]  ^ x[8],   7);
 		x[9]  += x[14];   x[4]  = rotl32(x[4]  ^ x[9],   7);
 	}

 	for (i = 0; i < ARRAY_SIZE(x); i++)
 		out[i] = cpu_to_le32(x[i] + state[i]);

 	state[12]++;
 }

 static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
 			     unsigned int bytes)
 {
 	u8 stream[CHACHA20_BLOCK_SIZE];

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

 	while (bytes >= CHACHA20_BLOCK_SIZE) {
 		chacha20_block(state, stream);
 		crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);
 		bytes -= CHACHA20_BLOCK_SIZE;
 		dst += CHACHA20_BLOCK_SIZE;
 	}
 	if (bytes) {
 		chacha20_block(state, stream);
 		crypto_xor(dst, stream, bytes);
 	}
 }

 void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv)
 {
 	static const char constant[16] = "expand 32-byte k";

 	state[0]  = le32_to_cpuvp(constant +  0);
 	state[1]  = le32_to_cpuvp(constant +  4);
 	state[2]  = le32_to_cpuvp(constant +  8);
 	state[3]  = le32_to_cpuvp(constant + 12);
 	state[4]  = ctx->key[0];
 	state[5]  = ctx->key[1];
 	state[6]  = ctx->key[2];
 	state[7]  = ctx->key[3];
 	state[8]  = ctx->key[4];
 	state[9]  = ctx->key[5];
 	state[10] = ctx->key[6];
 	state[11] = ctx->key[7];
 	state[12] = le32_to_cpuvp(iv +  0);
 	state[13] = le32_to_cpuvp(iv +  4);
 	state[14] = le32_to_cpuvp(iv +  8);
 	state[15] = le32_to_cpuvp(iv + 12);
 }
 EXPORT_SYMBOL_GPL(crypto_chacha20_init);

 int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key,
 			   unsigned int keysize)
 {
 	struct chacha20_ctx *ctx = crypto_tfm_ctx(tfm);
 	int i;

 	if (keysize != CHACHA20_KEY_SIZE)
 		return -EINVAL;

 	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
 		ctx->key[i] = le32_to_cpuvp(key + i * sizeof(u32));

 	return 0;
 }
 EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);

 int crypto_chacha20_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
 			  struct scatterlist *src, unsigned int nbytes)
 {
 	struct blkcipher_walk walk;
 	u32 state[16];
 	int err;

 	blkcipher_walk_init(&walk, dst, src, nbytes);
 	err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);

 	crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);

 	while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
 		chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
 				 rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
 		err = blkcipher_walk_done(desc, &walk,
 					  walk.nbytes % CHACHA20_BLOCK_SIZE);
 	}

 	if (walk.nbytes) {
 		chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
 				 walk.nbytes);
 		err = blkcipher_walk_done(desc, &walk, 0);
 	}

 	return err;
 }
 EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);

 static struct crypto_alg alg = {
 	.cra_name		= "chacha20",
 	.cra_driver_name	= "chacha20-generic",
 	.cra_priority		= 100,
 	.cra_flags		= CRYPTO_ALG_TYPE_BLKCIPHER,
 	.cra_blocksize		= 1,
 	.cra_type		= &crypto_blkcipher_type,
 	.cra_ctxsize		= sizeof(struct chacha20_ctx),
 	.cra_alignmask		= sizeof(u32) - 1,
 	.cra_module		= THIS_MODULE,
 	.cra_u			= {
 		.blkcipher = {
 			.min_keysize	= CHACHA20_KEY_SIZE,
 			.max_keysize	= CHACHA20_KEY_SIZE,
 			.ivsize		= CHACHA20_IV_SIZE,
 			.geniv		= "seqiv",
 			.setkey		= crypto_chacha20_setkey,
 			.encrypt	= crypto_chacha20_crypt,
 			.decrypt	= crypto_chacha20_crypt,
 		},
 	},
 };

 static int __init chacha20_generic_mod_init(void)
 {
 	return crypto_register_alg(&alg);
 }

 static void __exit chacha20_generic_mod_fini(void)
 {
 	crypto_unregister_alg(&alg);
 }

 module_init(chacha20_generic_mod_init);
 module_exit(chacha20_generic_mod_fini);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
 MODULE_DESCRIPTION("chacha20 cipher algorithm");
 MODULE_ALIAS_CRYPTO("chacha20");
 MODULE_ALIAS_CRYPTO("chacha20-generic");
	/*
	* ChaCha20 256-bit cipher algorithm, RFC7539
	*
	* Copyright (C) 2015 Martin Willi
	*
	* 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 <crypto/algapi.h>
	#include <linux/crypto.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <crypto/chacha20.h>

	static inline u32 rotl32(u32 v, u8 n)
	{
	return (v << n) \| (v >> (sizeof(v) * 8 - n));
	}

	static inline u32 le32_to_cpuvp(const void *p)
	{
	return le32_to_cpup(p);
	}

	static void chacha20_block(u32 state, void stream)
	{
	u32 x[16], *out = stream;
	int i;

	for (i = 0; i < ARRAY_SIZE(x); i++)
	x[i] = state[i];

	for (i = 0; i < 20; i += 2) {
	x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 16);
	x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 16);
	x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 16);
	x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 16);

	x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 12);
	x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 12);
	x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 12);
	x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 12);

	x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 8);
	x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 8);
	x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 8);
	x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 8);

	x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 7);
	x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 7);
	x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 7);
	x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 7);

	x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 16);
	x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 16);
	x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 16);
	x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 16);

	x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 12);
	x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 12);
	x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 12);
	x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 12);

	x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 8);
	x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 8);
	x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 8);
	x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 8);

	x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 7);
	x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 7);
	x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 7);
	x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 7);
	}

	for (i = 0; i < ARRAY_SIZE(x); i++)
	out[i] = cpu_to_le32(x[i] + state[i]);

	state[12]++;
	}

	static void chacha20_docrypt(u32 state, u8 dst, const u8 *src,
	unsigned int bytes)
	{
	u8 stream[CHACHA20_BLOCK_SIZE];

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

	while (bytes >= CHACHA20_BLOCK_SIZE) {
	chacha20_block(state, stream);
	crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);
	bytes -= CHACHA20_BLOCK_SIZE;
	dst += CHACHA20_BLOCK_SIZE;
	}
	if (bytes) {
	chacha20_block(state, stream);
	crypto_xor(dst, stream, bytes);
	}
	}

	void crypto_chacha20_init(u32 state, struct chacha20_ctx ctx, u8 *iv)
	{
	static const char constant[16] = "expand 32-byte k";

	state[0] = le32_to_cpuvp(constant + 0);
	state[1] = le32_to_cpuvp(constant + 4);
	state[2] = le32_to_cpuvp(constant + 8);
	state[3] = le32_to_cpuvp(constant + 12);
	state[4] = ctx->key[0];
	state[5] = ctx->key[1];
	state[6] = ctx->key[2];
	state[7] = ctx->key[3];
	state[8] = ctx->key[4];
	state[9] = ctx->key[5];
	state[10] = ctx->key[6];
	state[11] = ctx->key[7];
	state[12] = le32_to_cpuvp(iv + 0);
	state[13] = le32_to_cpuvp(iv + 4);
	state[14] = le32_to_cpuvp(iv + 8);
	state[15] = le32_to_cpuvp(iv + 12);
	}
	EXPORT_SYMBOL_GPL(crypto_chacha20_init);

	int crypto_chacha20_setkey(struct crypto_tfm tfm, const u8 key,
	unsigned int keysize)
	{
	struct chacha20_ctx *ctx = crypto_tfm_ctx(tfm);
	int i;

	if (keysize != CHACHA20_KEY_SIZE)
	return -EINVAL;

	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
	ctx->key[i] = le32_to_cpuvp(key + i * sizeof(u32));

	return 0;
	}
	EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);

	int crypto_chacha20_crypt(struct blkcipher_desc desc, struct scatterlist dst,
	struct scatterlist *src, unsigned int nbytes)
	{
	struct blkcipher_walk walk;
	u32 state[16];
	int err;

	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);

	crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);

	while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
	chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
	rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
	err = blkcipher_walk_done(desc, &walk,
	walk.nbytes % CHACHA20_BLOCK_SIZE);
	}

	if (walk.nbytes) {
	chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
	walk.nbytes);
	err = blkcipher_walk_done(desc, &walk, 0);
	}

	return err;
	}
	EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);

	static struct crypto_alg alg = {
	.cra_name = "chacha20",
	.cra_driver_name = "chacha20-generic",
	.cra_priority = 100,
	.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
	.cra_blocksize = 1,
	.cra_type = &crypto_blkcipher_type,
	.cra_ctxsize = sizeof(struct chacha20_ctx),
	.cra_alignmask = sizeof(u32) - 1,
	.cra_module = THIS_MODULE,
	.cra_u = {
	.blkcipher = {
	.min_keysize = CHACHA20_KEY_SIZE,
	.max_keysize = CHACHA20_KEY_SIZE,
	.ivsize = CHACHA20_IV_SIZE,
	.geniv = "seqiv",
	.setkey = crypto_chacha20_setkey,
	.encrypt = crypto_chacha20_crypt,
	.decrypt = crypto_chacha20_crypt,
	},
	},
	};

	static int __init chacha20_generic_mod_init(void)
	{
	return crypto_register_alg(&alg);
	}

	static void __exit chacha20_generic_mod_fini(void)
	{
	crypto_unregister_alg(&alg);
	}

	module_init(chacha20_generic_mod_init);
	module_exit(chacha20_generic_mod_fini);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
	MODULE_DESCRIPTION("chacha20 cipher algorithm");
	MODULE_ALIAS_CRYPTO("chacha20");
	MODULE_ALIAS_CRYPTO("chacha20-generic");