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/*

 * Cryptographic API.

 *

 * AES Cipher Algorithm.

 *

 * Based on Brian Gladman's code.

 *

 * Linux developers:

 *  Alexander Kjeldaas <astor@fast.no>

 *  Herbert Valerio Riedel <hvr@hvrlab.org>

 *  Kyle McMartin <kyle@debian.org>

 *  Adam J. Richter <adam@yggdrasil.com> (conversion to 2.5 API).

 *

 * 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.

 *

 * ---------------------------------------------------------------------------

 * Copyright (c) 2002, Dr Brian Gladman <brg@gladman.me.uk>, Worcester, UK.

 * All rights reserved.

 *

 * LICENSE TERMS

 *

 * The free distribution and use of this software in both source and binary

 * form is allowed (with or without changes) provided that:

 *

 *   1. distributions of this source code include the above copyright

 *      notice, this list of conditions and the following disclaimer;

 *

 *   2. distributions in binary form include the above copyright

 *      notice, this list of conditions and the following disclaimer

 *      in the documentation and/or other associated materials;

 *

 *   3. the copyright holder's name is not used to endorse products

 *      built using this software without specific written permission.

 *

 * ALTERNATIVELY, provided that this notice is retained in full, this product

 * may be distributed under the terms of the GNU General Public License (GPL),

 * in which case the provisions of the GPL apply INSTEAD OF those given above.

 *

 * DISCLAIMER

 *

 * This software is provided 'as is' with no explicit or implied warranties

 * in respect of its properties, including, but not limited to, correctness

 * and/or fitness for purpose.

 * ---------------------------------------------------------------------------

 */

/* Some changes from the Gladman version:

    s/RIJNDAEL(e_key)/E_KEY/g

    s/RIJNDAEL(d_key)/D_KEY/g

*/

#include <linux/module.h>

#include <linux/init.h>

#include <linux/types.h>

#include <linux/errno.h>

#include <linux/crypto.h>

#include <asm/byteorder.h>

#define AES_MIN_KEY_SIZE        16

#define AES_MAX_KEY_SIZE        32

#define AES_BLOCK_SIZE          16

static inline

u32 generic_rotr32 (const u32 x, const unsigned bits)

{

        const unsigned n = bits % 32;

        return (x >> n) | (x << (32 - n));

}

static inline

u32 generic_rotl32 (const u32 x, const unsigned bits)

{

        const unsigned n = bits % 32;

        return (x << n) | (x >> (32 - n));

}

#define rotl generic_rotl32

#define rotr generic_rotr32

/*

 * #define byte(x, nr) ((unsigned char)((x) >> (nr*8)))

 */

inline static u8

byte(const u32 x, const unsigned n)

{

        return x >> (n << 3);

}

#define u32_in(x) le32_to_cpu(*(const u32 *)(x))

#define u32_out(to, from) (*(u32 *)(to) = cpu_to_le32(from))

struct aes_ctx {

        int key_length;

        u32 E[60];

        u32 D[60];

};

#define E_KEY ctx->E

#define D_KEY ctx->D

static u8 pow_tab[256];

static u8 log_tab[256];

static u8 sbx_tab[256];

static u8 isb_tab[256];

static u32 rco_tab[10];

static u32 ft_tab[4][256];

static u32 it_tab[4][256];

static u32 fl_tab[4][256];

static u32 il_tab[4][256];

static inline u8

f_mult (u8 a, u8 b)

{

        u8 aa = log_tab[a], cc = aa + log_tab[b];

        return pow_tab[cc + (cc < aa ? 1 : 0)];

}

#define ff_mult(a,b)    (a && b ? f_mult(a, b) : 0)

#define f_rn(bo, bi, n, k)                                      \

    bo[n] =  ft_tab[0][byte(bi[n],0)] ^                           \

             ft_tab[1][byte(bi[(n + 1) & 3],1)] ^               \

             ft_tab[2][byte(bi[(n + 2) & 3],2)] ^               \

             ft_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)

#define i_rn(bo, bi, n, k)                                      \

    bo[n] =  it_tab[0][byte(bi[n],0)] ^                           \

             it_tab[1][byte(bi[(n + 3) & 3],1)] ^               \

             it_tab[2][byte(bi[(n + 2) & 3],2)] ^               \

             it_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)

#define ls_box(x)                               \

    ( fl_tab[0][byte(x, 0)] ^                     \

      fl_tab[1][byte(x, 1)] ^                   \

      fl_tab[2][byte(x, 2)] ^                   \

      fl_tab[3][byte(x, 3)] )

#define f_rl(bo, bi, n, k)                                      \

    bo[n] =  fl_tab[0][byte(bi[n],0)] ^                           \

             fl_tab[1][byte(bi[(n + 1) & 3],1)] ^               \

             fl_tab[2][byte(bi[(n + 2) & 3],2)] ^               \

             fl_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)

#define i_rl(bo, bi, n, k)                                      \

    bo[n] =  il_tab[0][byte(bi[n],0)] ^                           \

             il_tab[1][byte(bi[(n + 3) & 3],1)] ^               \

             il_tab[2][byte(bi[(n + 2) & 3],2)] ^               \

             il_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)

static void

gen_tabs (void)

{

        u32 i, t;

        u8 p, q;

        /* log and power tables for GF(2**8) finite field with

           0x011b as modular polynomial - the simplest prmitive

           root is 0x03, used here to generate the tables */

        for (i = 0, p = 1; i < 256; ++i) {

                pow_tab[i] = (u8) p;

                log_tab[p] = (u8) i;

                p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0);

        }

        log_tab[1] = 0;

        for (i = 0, p = 1; i < 10; ++i) {

                rco_tab[i] = p;

                p = (p << 1) ^ (p & 0x80 ? 0x01b : 0);

        }

        for (i = 0; i < 256; ++i) {

                p = (i ? pow_tab[255 - log_tab[i]] : 0);

                q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2));

                p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2));

                sbx_tab[i] = p;

                isb_tab[p] = (u8) i;

        }

        for (i = 0; i < 256; ++i) {

                p = sbx_tab[i];

                t = p;

                fl_tab[0][i] = t;

                fl_tab[1][i] = rotl (t, 8);

                fl_tab[2][i] = rotl (t, 16);

                fl_tab[3][i] = rotl (t, 24);

                t = ((u32) ff_mult (2, p)) |

                    ((u32) p << 8) |

                    ((u32) p << 16) | ((u32) ff_mult (3, p) << 24);

                ft_tab[0][i] = t;

                ft_tab[1][i] = rotl (t, 8);

                ft_tab[2][i] = rotl (t, 16);

                ft_tab[3][i] = rotl (t, 24);

                p = isb_tab[i];

                t = p;

                il_tab[0][i] = t;

                il_tab[1][i] = rotl (t, 8);

                il_tab[2][i] = rotl (t, 16);

                il_tab[3][i] = rotl (t, 24);

                t = ((u32) ff_mult (14, p)) |

                    ((u32) ff_mult (9, p) << 8) |

                    ((u32) ff_mult (13, p) << 16) |

                    ((u32) ff_mult (11, p) << 24);

                it_tab[0][i] = t;

                it_tab[1][i] = rotl (t, 8);

                it_tab[2][i] = rotl (t, 16);

                it_tab[3][i] = rotl (t, 24);

        }

}

#define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)

#define imix_col(y,x)       \

    u   = star_x(x);        \

    v   = star_x(u);        \

    w   = star_x(v);        \

    t   = w ^ (x);          \

   (y)  = u ^ v ^ w;        \

   (y) ^= rotr(u ^ t,  8) ^ \

          rotr(v ^ t, 16) ^ \

          rotr(t,24)

/* initialise the key schedule from the user supplied key */

#define loop4(i)                                    \

{   t = rotr(t,  8); t = ls_box(t) ^ rco_tab[i];    \

    t ^= E_KEY[4 * i];     E_KEY[4 * i + 4] = t;    \

    t ^= E_KEY[4 * i + 1]; E_KEY[4 * i + 5] = t;    \

    t ^= E_KEY[4 * i + 2]; E_KEY[4 * i + 6] = t;    \

    t ^= E_KEY[4 * i + 3]; E_KEY[4 * i + 7] = t;    \

}

#define loop6(i)                                    \

{   t = rotr(t,  8); t = ls_box(t) ^ rco_tab[i];    \

    t ^= E_KEY[6 * i];     E_KEY[6 * i + 6] = t;    \

    t ^= E_KEY[6 * i + 1]; E_KEY[6 * i + 7] = t;    \

    t ^= E_KEY[6 * i + 2]; E_KEY[6 * i + 8] = t;    \

    t ^= E_KEY[6 * i + 3]; E_KEY[6 * i + 9] = t;    \

    t ^= E_KEY[6 * i + 4]; E_KEY[6 * i + 10] = t;   \

    t ^= E_KEY[6 * i + 5]; E_KEY[6 * i + 11] = t;   \

}

#define loop8(i)                                    \

{   t = rotr(t,  8); ; t = ls_box(t) ^ rco_tab[i];  \

    t ^= E_KEY[8 * i];     E_KEY[8 * i + 8] = t;    \

    t ^= E_KEY[8 * i + 1]; E_KEY[8 * i + 9] = t;    \

    t ^= E_KEY[8 * i + 2]; E_KEY[8 * i + 10] = t;   \

    t ^= E_KEY[8 * i + 3]; E_KEY[8 * i + 11] = t;   \

    t  = E_KEY[8 * i + 4] ^ ls_box(t);    \

    E_KEY[8 * i + 12] = t;                \

    t ^= E_KEY[8 * i + 5]; E_KEY[8 * i + 13] = t;   \

    t ^= E_KEY[8 * i + 6]; E_KEY[8 * i + 14] = t;   \

    t ^= E_KEY[8 * i + 7]; E_KEY[8 * i + 15] = t;   \

}

static int

aes_set_key(void *ctx_arg, const u8 *in_key, unsigned int key_len, u32 *flags)

{

        struct aes_ctx *ctx = ctx_arg;

        u32 i, t, u, v, w;

        if (key_len != 16 && key_len != 24 && key_len != 32) {

                *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;

                return -EINVAL;

        }

        ctx->key_length = key_len;

        E_KEY[0] = u32_in (in_key);

        E_KEY[1] = u32_in (in_key + 4);

        E_KEY[2] = u32_in (in_key + 8);

        E_KEY[3] = u32_in (in_key + 12);

        switch (key_len) {

        case 16:

                t = E_KEY[3];

                for (i = 0; i < 10; ++i)

                        loop4 (i);

                break;

        case 24:

                E_KEY[4] = u32_in (in_key + 16);

                t = E_KEY[5] = u32_in (in_key + 20);

                for (i = 0; i < 8; ++i)

                        loop6 (i);

                break;

        case 32:

                E_KEY[4] = u32_in (in_key + 16);

                E_KEY[5] = u32_in (in_key + 20);

                E_KEY[6] = u32_in (in_key + 24);

                t = E_KEY[7] = u32_in (in_key + 28);

                for (i = 0; i < 7; ++i)

                        loop8 (i);

                break;

        }

        D_KEY[0] = E_KEY[0];

        D_KEY[1] = E_KEY[1];

        D_KEY[2] = E_KEY[2];

        D_KEY[3] = E_KEY[3];

        for (i = 4; i < key_len + 24; ++i) {

                imix_col (D_KEY[i], E_KEY[i]);

        }

        return 0;

}

/* encrypt a block of text */

#define f_nround(bo, bi, k) \

    f_rn(bo, bi, 0, k);     \

    f_rn(bo, bi, 1, k);     \

    f_rn(bo, bi, 2, k);     \

    f_rn(bo, bi, 3, k);     \

    k += 4

#define f_lround(bo, bi, k) \

    f_rl(bo, bi, 0, k);     \

    f_rl(bo, bi, 1, k);     \

    f_rl(bo, bi, 2, k);     \

    f_rl(bo, bi, 3, k)

static void aes_encrypt(void *ctx_arg, u8 *out, const u8 *in)

{

        const struct aes_ctx *ctx = ctx_arg;

        u32 b0[4], b1[4];

        const u32 *kp = E_KEY + 4;

        b0[0] = u32_in (in) ^ E_KEY[0];

        b0[1] = u32_in (in + 4) ^ E_KEY[1];

        b0[2] = u32_in (in + 8) ^ E_KEY[2];

        b0[3] = u32_in (in + 12) ^ E_KEY[3];

        if (ctx->key_length > 24) {

                f_nround (b1, b0, kp);

                f_nround (b0, b1, kp);

        }

        if (ctx->key_length > 16) {

                f_nround (b1, b0, kp);

                f_nround (b0, b1, kp);

        }

        f_nround (b1, b0, kp);

        f_nround (b0, b1, kp);

        f_nround (b1, b0, kp);

        f_nround (b0, b1, kp);

        f_nround (b1, b0, kp);

        f_nround (b0, b1, kp);

        f_nround (b1, b0, kp);

        f_nround (b0, b1, kp);

        f_nround (b1, b0, kp);

        f_lround (b0, b1, kp);

        u32_out (out, b0[0]);

        u32_out (out + 4, b0[1]);

        u32_out (out + 8, b0[2]);

        u32_out (out + 12, b0[3]);

}

/* decrypt a block of text */

#define i_nround(bo, bi, k) \

    i_rn(bo, bi, 0, k);     \

    i_rn(bo, bi, 1, k);     \

    i_rn(bo, bi, 2, k);     \

    i_rn(bo, bi, 3, k);     \

    k -= 4

#define i_lround(bo, bi, k) \

    i_rl(bo, bi, 0, k);     \

    i_rl(bo, bi, 1, k);     \

    i_rl(bo, bi, 2, k);     \

    i_rl(bo, bi, 3, k)

static void aes_decrypt(void *ctx_arg, u8 *out, const u8 *in)

{

        const struct aes_ctx *ctx = ctx_arg;

        u32 b0[4], b1[4];

        const int key_len = ctx->key_length;

        const u32 *kp = D_KEY + key_len + 20;

        b0[0] = u32_in (in) ^ E_KEY[key_len + 24];

        b0[1] = u32_in (in + 4) ^ E_KEY[key_len + 25];

        b0[2] = u32_in (in + 8) ^ E_KEY[key_len + 26];

        b0[3] = u32_in (in + 12) ^ E_KEY[key_len + 27];

        if (key_len > 24) {

                i_nround (b1, b0, kp);

                i_nround (b0, b1, kp);

        }

        if (key_len > 16) {

                i_nround (b1, b0, kp);

                i_nround (b0, b1, kp);

        }

        i_nround (b1, b0, kp);

        i_nround (b0, b1, kp);

        i_nround (b1, b0, kp);

        i_nround (b0, b1, kp);

        i_nround (b1, b0, kp);

        i_nround (b0, b1, kp);

        i_nround (b1, b0, kp);

        i_nround (b0, b1, kp);

        i_nround (b1, b0, kp);

        i_lround (b0, b1, kp);

        u32_out (out, b0[0]);

        u32_out (out + 4, b0[1]);

        u32_out (out + 8, b0[2]);

        u32_out (out + 12, b0[3]);

}

static struct crypto_alg aes_alg = {

        .cra_name               =       "aes",

        .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,

        .cra_blocksize          =       AES_BLOCK_SIZE,

        .cra_ctxsize            =       sizeof(struct aes_ctx),

        .cra_module             =       THIS_MODULE,

        .cra_list               =       LIST_HEAD_INIT(aes_alg.cra_list),

        .cra_u                  =       {

                .cipher = {

                        .cia_min_keysize        =       AES_MIN_KEY_SIZE,

                        .cia_max_keysize        =       AES_MAX_KEY_SIZE,

                        .cia_setkey             =       aes_set_key,

                        .cia_encrypt            =       aes_encrypt,

                        .cia_decrypt            =       aes_decrypt

                }

        }

};

static int __init aes_init(void)

{

        gen_tabs();

        return crypto_register_alg(&aes_alg);

}

static void __exit aes_fini(void)

{

        crypto_unregister_alg(&aes_alg);

}

module_init(aes_init);

module_exit(aes_fini);

MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm");

MODULE_LICENSE("Dual BSD/GPL");