[deliverable/linux.git] / lib / chacha20.c

/*
 * 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 <linux/kernel.h>
#include <linux/export.h>
#include <linux/bitops.h>
#include <linux/cryptohash.h>
#include <asm/unaligned.h>
#include <crypto/chacha20.h>

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

extern 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]++;
}
EXPORT_SYMBOL(chacha20_block);
Commit	Line	Data
e192be9d TT	1	/*
	2	* ChaCha20 256-bit cipher algorithm, RFC7539
	3	*
	4	* Copyright (C) 2015 Martin Willi
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*/
	11
	12	#include <linux/kernel.h>
	13	#include <linux/export.h>
	14	#include <linux/bitops.h>
	15	#include <linux/cryptohash.h>
	16	#include <asm/unaligned.h>
	17	#include <crypto/chacha20.h>
	18
	19	static inline u32 rotl32(u32 v, u8 n)
	20	{
	21	return (v << n) \| (v >> (sizeof(v) * 8 - n));
	22	}
	23
	24	extern void chacha20_block(u32 state, void stream)
	25	{
	26	u32 x[16], *out = stream;
	27	int i;
	28
	29	for (i = 0; i < ARRAY_SIZE(x); i++)
	30	x[i] = state[i];
	31
	32	for (i = 0; i < 20; i += 2) {
	33	x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 16);
	34	x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 16);
	35	x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 16);
	36	x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 16);
	37
	38	x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 12);
	39	x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 12);
	40	x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 12);
	41	x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 12);
	42
	43	x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 8);
	44	x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 8);
	45	x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 8);
	46	x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 8);
	47
	48	x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 7);
	49	x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 7);
	50	x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 7);
	51	x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 7);
	52
	53	x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 16);
	54	x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 16);
	55	x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 16);
	56	x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 16);
	57
	58	x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 12);
	59	x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 12);
	60	x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 12);
	61	x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 12);
	62
	63	x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 8);
	64	x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 8);
65	x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 8);
66	x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 8);
67
68	x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 7);
69	x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 7);
70	x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 7);
71	x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 7);
72	}
73
74	for (i = 0; i < ARRAY_SIZE(x); i++)
75	out[i] = cpu_to_le32(x[i] + state[i]);
76
77	state[12]++;
78	}
79	EXPORT_SYMBOL(chacha20_block);