/* 
 * 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.
 * ---------------------------------------------------------------------------
 */

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

static inline u8 byte(const u32 x, const unsigned n)
{
        return x >> (n << 3);
}

static u8 pow_tab[256] __initdata;
static u8 log_tab[256] __initdata;
static u8 sbx_tab[256] __initdata;
static u8 isb_tab[256] __initdata;
static u32 rco_tab[10];

u32 crypto_ft_tab[4][256];
u32 crypto_fl_tab[4][256];
u32 crypto_it_tab[4][256];
u32 crypto_il_tab[4][256];

EXPORT_SYMBOL_GPL(crypto_ft_tab);
EXPORT_SYMBOL_GPL(crypto_fl_tab);
EXPORT_SYMBOL_GPL(crypto_it_tab);
EXPORT_SYMBOL_GPL(crypto_il_tab);

static inline u8 __init 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)

static void __init 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 primitive
         * 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;
                crypto_fl_tab[0][i] = t;
                crypto_fl_tab[1][i] = rol32(t, 8);
                crypto_fl_tab[2][i] = rol32(t, 16);
                crypto_fl_tab[3][i] = rol32(t, 24);

                t = ((u32) ff_mult(2, p)) |
                    ((u32) p << 8) |
                    ((u32) p << 16) | ((u32) ff_mult(3, p) << 24);

                crypto_ft_tab[0][i] = t;
                crypto_ft_tab[1][i] = rol32(t, 8);
                crypto_ft_tab[2][i] = rol32(t, 16);
                crypto_ft_tab[3][i] = rol32(t, 24);

                p = isb_tab[i];

                t = p;
                crypto_il_tab[0][i] = t;
                crypto_il_tab[1][i] = rol32(t, 8);
                crypto_il_tab[2][i] = rol32(t, 16);
                crypto_il_tab[3][i] = rol32(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);

                crypto_it_tab[0][i] = t;
                crypto_it_tab[1][i] = rol32(t, 8);
                crypto_it_tab[2][i] = rol32(t, 16);
                crypto_it_tab[3][i] = rol32(t, 24);
        }
}

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

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

#define imix_col(y,x)   do {            \
        u       = star_x(x);            \
        v       = star_x(u);            \
        w       = star_x(v);            \
        t       = w ^ (x);              \
        (y)     = u ^ v ^ w;            \
        (y)     ^= ror32(u ^ t, 8) ^    \
                ror32(v ^ t, 16) ^      \
                ror32(t, 24);           \
} while (0)

#define ls_box(x)               \
        crypto_fl_tab[0][byte(x, 0)] ^  \
        crypto_fl_tab[1][byte(x, 1)] ^  \
        crypto_fl_tab[2][byte(x, 2)] ^  \
        crypto_fl_tab[3][byte(x, 3)]

#define loop4(i)        do {            \
        t = ror32(t, 8);                \
        t = ls_box(t) ^ rco_tab[i];     \
        t ^= ctx->key_enc[4 * i];               \
        ctx->key_enc[4 * i + 4] = t;            \
        t ^= ctx->key_enc[4 * i + 1];           \
        ctx->key_enc[4 * i + 5] = t;            \
        t ^= ctx->key_enc[4 * i + 2];           \
        ctx->key_enc[4 * i + 6] = t;            \
        t ^= ctx->key_enc[4 * i + 3];           \
        ctx->key_enc[4 * i + 7] = t;            \
} while (0)

#define loop6(i)        do {            \
        t = ror32(t, 8);                \
        t = ls_box(t) ^ rco_tab[i];     \
        t ^= ctx->key_enc[6 * i];               \
        ctx->key_enc[6 * i + 6] = t;            \
        t ^= ctx->key_enc[6 * i + 1];           \
        ctx->key_enc[6 * i + 7] = t;            \
        t ^= ctx->key_enc[6 * i + 2];           \
        ctx->key_enc[6 * i + 8] = t;            \
        t ^= ctx->key_enc[6 * i + 3];           \
        ctx->key_enc[6 * i + 9] = t;            \
        t ^= ctx->key_enc[6 * i + 4];           \
        ctx->key_enc[6 * i + 10] = t;           \
        t ^= ctx->key_enc[6 * i + 5];           \
        ctx->key_enc[6 * i + 11] = t;           \
} while (0)

#define loop8(i)        do {                    \
        t = ror32(t, 8);                        \
        t = ls_box(t) ^ rco_tab[i];             \
        t ^= ctx->key_enc[8 * i];                       \
        ctx->key_enc[8 * i + 8] = t;                    \
        t ^= ctx->key_enc[8 * i + 1];                   \
        ctx->key_enc[8 * i + 9] = t;                    \
        t ^= ctx->key_enc[8 * i + 2];                   \
        ctx->key_enc[8 * i + 10] = t;                   \
        t ^= ctx->key_enc[8 * i + 3];                   \
        ctx->key_enc[8 * i + 11] = t;                   \
        t  = ctx->key_enc[8 * i + 4] ^ ls_box(t);       \
        ctx->key_enc[8 * i + 12] = t;                   \
        t ^= ctx->key_enc[8 * i + 5];                   \
        ctx->key_enc[8 * i + 13] = t;                   \
        t ^= ctx->key_enc[8 * i + 6];                   \
        ctx->key_enc[8 * i + 14] = t;                   \
        t ^= ctx->key_enc[8 * i + 7];                   \
        ctx->key_enc[8 * i + 15] = t;                   \
} while (0)

/**
 * crypto_aes_expand_key - Expands the AES key as described in FIPS-197
 * @ctx:        The location where the computed key will be stored.
 * @in_key:     The supplied key.
 * @key_len:    The length of the supplied key.
 *
 * Returns 0 on success. The function fails only if an invalid key size (or
 * pointer) is supplied.
 * The expanded key size is 240 bytes (max of 14 rounds with a unique 16 bytes
 * key schedule plus a 16 bytes key which is used before the first round).
 * The decryption key is prepared for the "Equivalent Inverse Cipher" as
 * described in FIPS-197. The first slot (16 bytes) of each key (enc or dec) is
 * for the initial combination, the second slot for the first round and so on.
 */
int crypto_aes_expand_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
                unsigned int key_len)
{
        const __le32 *key = (const __le32 *)in_key;
        u32 i, t, u, v, w, j;

        if (key_len != AES_KEYSIZE_128 && key_len != AES_KEYSIZE_192 &&
                        key_len != AES_KEYSIZE_256)
                return -EINVAL;

        ctx->key_length = key_len;

        ctx->key_dec[key_len + 24] = ctx->key_enc[0] = le32_to_cpu(key[0]);
        ctx->key_dec[key_len + 25] = ctx->key_enc[1] = le32_to_cpu(key[1]);
        ctx->key_dec[key_len + 26] = ctx->key_enc[2] = le32_to_cpu(key[2]);
        ctx->key_dec[key_len + 27] = ctx->key_enc[3] = le32_to_cpu(key[3]);

        switch (key_len) {
        case AES_KEYSIZE_128:
                t = ctx->key_enc[3];
                for (i = 0; i < 10; ++i)
                        loop4(i);
                break;

        case AES_KEYSIZE_192:
                ctx->key_enc[4] = le32_to_cpu(key[4]);
                t = ctx->key_enc[5] = le32_to_cpu(key[5]);
                for (i = 0; i < 8; ++i)
                        loop6(i);
                break;

        case AES_KEYSIZE_256:
                ctx->key_enc[4] = le32_to_cpu(key[4]);
                ctx->key_enc[5] = le32_to_cpu(key[5]);
                ctx->key_enc[6] = le32_to_cpu(key[6]);
                t = ctx->key_enc[7] = le32_to_cpu(key[7]);
                for (i = 0; i < 7; ++i)
                        loop8(i);
                break;
        }

        ctx->key_dec[0] = ctx->key_enc[key_len + 24];
        ctx->key_dec[1] = ctx->key_enc[key_len + 25];
        ctx->key_dec[2] = ctx->key_enc[key_len + 26];
        ctx->key_dec[3] = ctx->key_enc[key_len + 27];

        for (i = 4; i < key_len + 24; ++i) {
                j = key_len + 24 - (i & ~3) + (i & 3);
                imix_col(ctx->key_dec[j], ctx->key_enc[i]);
        }
        return 0;
}
EXPORT_SYMBOL_GPL(crypto_aes_expand_key);

/**
 * crypto_aes_set_key - Set the AES key.
 * @tfm:        The %crypto_tfm that is used in the context.
 * @in_key:     The input key.
 * @key_len:    The size of the key.
 *
 * Returns 0 on success, on failure the %CRYPTO_TFM_RES_BAD_KEY_LEN flag in tfm
 * is set. The function uses crypto_aes_expand_key() to expand the key.
 * &crypto_aes_ctx _must_ be the private data embedded in @tfm which is
 * retrieved with crypto_tfm_ctx().
 */
int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
                unsigned int key_len)
{
        struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
        u32 *flags = &tfm->crt_flags;
        int ret;

        ret = crypto_aes_expand_key(ctx, in_key, key_len);
        if (!ret)
                return 0;

        *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
        return -EINVAL;
}
EXPORT_SYMBOL_GPL(crypto_aes_set_key);

/* encrypt a block of text */

#define f_rn(bo, bi, n, k)      do {                            \
        bo[n] = crypto_ft_tab[0][byte(bi[n], 0)] ^                      \
                crypto_ft_tab[1][byte(bi[(n + 1) & 3], 1)] ^            \
                crypto_ft_tab[2][byte(bi[(n + 2) & 3], 2)] ^            \
                crypto_ft_tab[3][byte(bi[(n + 3) & 3], 3)] ^ *(k + n);  \
} while (0)

#define f_nround(bo, bi, k)     do {\
        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;                 \
} while (0)

#define f_rl(bo, bi, n, k)      do {                            \
        bo[n] = crypto_fl_tab[0][byte(bi[n], 0)] ^                      \
                crypto_fl_tab[1][byte(bi[(n + 1) & 3], 1)] ^            \
                crypto_fl_tab[2][byte(bi[(n + 2) & 3], 2)] ^            \
                crypto_fl_tab[3][byte(bi[(n + 3) & 3], 3)] ^ *(k + n);  \
} while (0)

#define f_lround(bo, bi, k)     do {\
        f_rl(bo, bi, 0, k);     \
        f_rl(bo, bi, 1, k);     \
        f_rl(bo, bi, 2, k);     \
        f_rl(bo, bi, 3, k);     \
} while (0)

static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
        const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
        const __le32 *src = (const __le32 *)in;
        __le32 *dst = (__le32 *)out;
        u32 b0[4], b1[4];
        const u32 *kp = ctx->key_enc + 4;
        const int key_len = ctx->key_length;

        b0[0] = le32_to_cpu(src[0]) ^ ctx->key_enc[0];
        b0[1] = le32_to_cpu(src[1]) ^ ctx->key_enc[1];
        b0[2] = le32_to_cpu(src[2]) ^ ctx->key_enc[2];
        b0[3] = le32_to_cpu(src[3]) ^ ctx->key_enc[3];

        if (key_len > 24) {
                f_nround(b1, b0, kp);
                f_nround(b0, b1, kp);
        }

        if (key_len > 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);

        dst[0] = cpu_to_le32(b0[0]);
        dst[1] = cpu_to_le32(b0[1]);
        dst[2] = cpu_to_le32(b0[2]);
        dst[3] = cpu_to_le32(b0[3]);
}

/* decrypt a block of text */

#define i_rn(bo, bi, n, k)      do {                            \
        bo[n] = crypto_it_tab[0][byte(bi[n], 0)] ^                      \
                crypto_it_tab[1][byte(bi[(n + 3) & 3], 1)] ^            \
                crypto_it_tab[2][byte(bi[(n + 2) & 3], 2)] ^            \
                crypto_it_tab[3][byte(bi[(n + 1) & 3], 3)] ^ *(k + n);  \
} while (0)

#define i_nround(bo, bi, k)     do {\
        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;                 \
} while (0)

#define i_rl(bo, bi, n, k)      do {                    \
        bo[n] = crypto_il_tab[0][byte(bi[n], 0)] ^              \
        crypto_il_tab[1][byte(bi[(n + 3) & 3], 1)] ^            \
        crypto_il_tab[2][byte(bi[(n + 2) & 3], 2)] ^            \
        crypto_il_tab[3][byte(bi[(n + 1) & 3], 3)] ^ *(k + n);  \
} while (0)

#define i_lround(bo, bi, k)     do {\
        i_rl(bo, bi, 0, k);     \
        i_rl(bo, bi, 1, k);     \
        i_rl(bo, bi, 2, k);     \
        i_rl(bo, bi, 3, k);     \
} while (0)

static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
        const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
        const __le32 *src = (const __le32 *)in;
        __le32 *dst = (__le32 *)out;
        u32 b0[4], b1[4];
        const int key_len = ctx->key_length;
        const u32 *kp = ctx->key_dec + 4;

        b0[0] = le32_to_cpu(src[0]) ^  ctx->key_dec[0];
        b0[1] = le32_to_cpu(src[1]) ^  ctx->key_dec[1];
        b0[2] = le32_to_cpu(src[2]) ^  ctx->key_dec[2];
        b0[3] = le32_to_cpu(src[3]) ^  ctx->key_dec[3];

        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);

        dst[0] = cpu_to_le32(b0[0]);
        dst[1] = cpu_to_le32(b0[1]);
        dst[2] = cpu_to_le32(b0[2]);
        dst[3] = cpu_to_le32(b0[3]);
}

static struct crypto_alg aes_alg = {
        .cra_name               =       "aes",
        .cra_driver_name        =       "aes-generic",
        .cra_priority           =       100,
        .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
        .cra_blocksize          =       AES_BLOCK_SIZE,
        .cra_ctxsize            =       sizeof(struct crypto_aes_ctx),
        .cra_alignmask          =       3,
        .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             =       crypto_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");
MODULE_ALIAS("aes");