linux-imx

/*

 * 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 <asm/unaligned.h>

#include <crypto/internal/skcipher.h>

#include <linux/module.h>

​

#define SALSA20_IV_SIZE        8

#define SALSA20_MIN_KEY_SIZE  16

#define SALSA20_MAX_KEY_SIZE  32

#define SALSA20_BLOCK_SIZE    64

​

struct salsa20_ctx {

    u32 initial_state[16];

};

​

static void salsa20_block(u32 *state, __le32 *stream)

{

    u32 x[16];

    int i;

​

    memcpy(x, state, sizeof(x));

​

    for (i = 0; i < 20; 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++)

        stream[i] = cpu_to_le32(x[i] + state[i]);

​

    if (++state[8] == 0)

        state[9]++;

}

​

static void salsa20_docrypt(u32 *state, u8 *dst, const u8 *src,

                unsigned int bytes)

{

    __le32 stream[SALSA20_BLOCK_SIZE / sizeof(__le32)];

​

    if (dst != src)

        memcpy(dst, src, bytes);

​

    while (bytes >= SALSA20_BLOCK_SIZE) {