/*

 * copyright (c) 2007 Michael Niedermayer <michaelni@gmx.at>

 *

 * some optimization ideas from aes128.c by Reimar Doeffinger

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include <string.h>

#include "config.h"

#include "aes.h"

#include "aes_internal.h"

#include "attributes.h"

#include "error.h"

#include "intreadwrite.h"

#include "macros.h"

#include "mem.h"

#include "thread.h"

const int av_aes_size= sizeof(AVAES);

struct AVAES *av_aes_alloc(void)

{

    return av_mallocz(sizeof(struct AVAES));

}

static const uint8_t rcon[10] = {

    0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36

};

static uint8_t     sbox[256];

static uint8_t inv_sbox[256];

#if CONFIG_SMALL

static uint32_t enc_multbl[1][256];

static uint32_t dec_multbl[1][256];

#else

static uint32_t enc_multbl[4][256];

static uint32_t dec_multbl[4][256];

#endif

#if HAVE_BIGENDIAN

#   define ROT(x, s) (((x) >> (s)) | ((x) << (32-(s))))

#else

#   define ROT(x, s) (((x) << (s)) | ((x) >> (32-(s))))

#endif

static inline void addkey(av_aes_block *dst, const av_aes_block *src,

                          const av_aes_block *round_key)

{

    dst->u64[0] = src->u64[0] ^ round_key->u64[0];

    dst->u64[1] = src->u64[1] ^ round_key->u64[1];

}

static inline void addkey_s(av_aes_block *dst, const uint8_t *src,

                            const av_aes_block *round_key)

{

    dst->u64[0] = AV_RN64(src)     ^ round_key->u64[0];

    dst->u64[1] = AV_RN64(src + 8) ^ round_key->u64[1];

}

static inline void addkey_d(uint8_t *dst, const av_aes_block *src,

                            const av_aes_block *round_key)

{

    AV_WN64(dst,     src->u64[0] ^ round_key->u64[0]);

    AV_WN64(dst + 8, src->u64[1] ^ round_key->u64[1]);

}

static void subshift(av_aes_block s0[2], int s, const uint8_t *box)

{

    unsigned char *s1_dst = (unsigned char*)s0[0].u8 + 3 - s;

    const unsigned char *s1_src = s1_dst + sizeof(*s0);

    unsigned char *s3_dst = (unsigned char*)s0[0].u8 + s + 1;

    const unsigned char *s3_src = s3_dst + sizeof(*s0);

    s0[0].u8[ 0] = box[s0[1].u8[ 0]];

    s0[0].u8[ 4] = box[s0[1].u8[ 4]];

    s0[0].u8[ 8] = box[s0[1].u8[ 8]];

    s0[0].u8[12] = box[s0[1].u8[12]];

    s1_dst[ 0] = box[s1_src[ 4]];

    s1_dst[ 4] = box[s1_src[ 8]];

    s1_dst[ 8] = box[s1_src[12]];

    s1_dst[12] = box[s1_src[ 0]];

    s0[0].u8[ 2] = box[s0[1].u8[10]];

    s0[0].u8[10] = box[s0[1].u8[ 2]];

    s0[0].u8[ 6] = box[s0[1].u8[14]];

    s0[0].u8[14] = box[s0[1].u8[ 6]];

    s3_dst[ 0] = box[s3_src[12]];

    s3_dst[12] = box[s3_src[ 8]];

    s3_dst[ 8] = box[s3_src[ 4]];

    s3_dst[ 4] = box[s3_src[ 0]];

}

static inline int mix_core(uint32_t multbl[][256], int a, int b, int c, int d)

{

#if CONFIG_SMALL

    return multbl[0][a] ^ ROT(multbl[0][b], 8) ^ ROT(multbl[0][c], 16) ^ ROT(multbl[0][d], 24);

#else

    return multbl[0][a] ^ multbl[1][b] ^ multbl[2][c] ^ multbl[3][d];

#endif

}

static inline void mix(av_aes_block state[2], uint32_t multbl[][256], int s1, int s3)

{

    uint8_t (*src)[4] = state[1].u8x4;

    state[0].u32[0] = mix_core(multbl, src[0][0], src[s1    ][1], src[2][2], src[s3    ][3]);

    state[0].u32[1] = mix_core(multbl, src[1][0], src[s3 - 1][1], src[3][2], src[s1 - 1][3]);

    state[0].u32[2] = mix_core(multbl, src[2][0], src[s3    ][1], src[0][2], src[s1    ][3]);

    state[0].u32[3] = mix_core(multbl, src[3][0], src[s1 - 1][1], src[1][2], src[s3 - 1][3]);

}

static inline void aes_crypt(AVAES *a, int s, const uint8_t *sbox_arg,

                         uint32_t multbl[][256])

{

    int r;

    for (r = a->rounds - 1; r > 0; r--) {

        mix(a->state, multbl, 3 - s, 1 + s);

        addkey(&a->state[1], &a->state[0], &a->round_key[r]);

    }

    subshift(&a->state[0], s, sbox_arg);

}

static void aes_encrypt(AVAES *a, uint8_t *dst, const uint8_t *src,

                        int count, uint8_t *iv, int rounds)

{

    while (count--) {

        addkey_s(&a->state[1], src, &a->round_key[rounds]);

        if (iv)

            addkey_s(&a->state[1], iv, &a->state[1]);

        aes_crypt(a, 2, sbox, enc_multbl);

        addkey_d(dst, &a->state[0], &a->round_key[0]);

        if (iv)

            memcpy(iv, dst, 16);

        src += 16;

        dst += 16;

    }

}

static void aes_decrypt(AVAES *a, uint8_t *dst, const uint8_t *src,

                        int count, uint8_t *iv, int rounds)

{

    while (count--) {

        addkey_s(&a->state[1], src, &a->round_key[rounds]);

        aes_crypt(a, 0, inv_sbox, dec_multbl);

        if (iv) {

            addkey_s(&a->state[0], iv, &a->state[0]);

            memcpy(iv, src, 16);

        }

        addkey_d(dst, &a->state[0], &a->round_key[0]);

        src += 16;

        dst += 16;

    }

}

void av_aes_crypt(AVAES *a, uint8_t *dst, const uint8_t *src,

                  int count, uint8_t *iv, int decrypt)

{

    a->crypt(a, dst, src, count, iv, a->rounds);

}

static void init_multbl2(uint32_t tbl[][256], const int c[4],

                         const uint8_t *log8, const uint8_t *alog8,

                         const uint8_t *sbox_arg)

{

    int i;

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

        int x = sbox_arg[i];

        if (x) {

            int k, l, m, n;

            x = log8[x];

            k = alog8[x + log8[c[0]]];

            l = alog8[x + log8[c[1]]];

            m = alog8[x + log8[c[2]]];

            n = alog8[x + log8[c[3]]];

            tbl[0][i] = AV_NE(MKBETAG(k, l, m, n), MKTAG(k, l, m, n));

#if !CONFIG_SMALL

            tbl[1][i] = ROT(tbl[0][i], 8);

            tbl[2][i] = ROT(tbl[0][i], 16);

            tbl[3][i] = ROT(tbl[0][i], 24);

#endif

        }

    }

}

static AVOnce aes_static_init = AV_ONCE_INIT;

static av_cold void aes_init_static(void)

{

    uint8_t log8[256];

    uint8_t alog8[512];

    int i, j = 1;

    for (i = 0; i < 255; i++) {

        alog8[i] = alog8[i + 255] = j;

        log8[j] = i;

        j ^= j + j;

        if (j > 255)

            j ^= 0x11B;

    }

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

        j = i ? alog8[255 - log8[i]] : 0;

        j ^= (j << 1) ^ (j << 2) ^ (j << 3) ^ (j << 4);

        j = (j ^ (j >> 8) ^ 99) & 255;

        inv_sbox[j] = i;

        sbox[i]     = j;

    }

    init_multbl2(dec_multbl, (const int[4]) { 0xe, 0x9, 0xd, 0xb },

                 log8, alog8, inv_sbox);

    init_multbl2(enc_multbl, (const int[4]) { 0x2, 0x1, 0x1, 0x3 },

                 log8, alog8, sbox);

}

// this is based on the reference AES code by Paulo Barreto and Vincent Rijmen

int av_aes_init(AVAES *a, const uint8_t *key, int key_bits, int decrypt)

{

    int i, j, t, rconpointer = 0;

    uint8_t tk[8][4];

    int KC = key_bits >> 5;

    int rounds = KC + 6;

    a->rounds = rounds;

    a->crypt = decrypt ? aes_decrypt : aes_encrypt;

#if ARCH_X86 && HAVE_X86ASM && HAVE_AESNI_EXTERNAL

    ff_init_aes_x86(a, decrypt);

#elif ARCH_AARCH64 && HAVE_ARM_AES

    ff_init_aes_aarch64(a, decrypt);

#endif

    ff_thread_once(&aes_static_init, aes_init_static);

    if (key_bits != 128 && key_bits != 192 && key_bits != 256)

        return AVERROR(EINVAL);

    memcpy(tk, key, KC * 4);

    memcpy(a->round_key[0].u8, key, KC * 4);

    for (t = KC * 4; t < (rounds + 1) * 16; t += KC * 4) {

        for (i = 0; i < 4; i++)

            tk[0][i] ^= sbox[tk[KC - 1][(i + 1) & 3]];

        tk[0][0] ^= rcon[rconpointer++];

        for (j = 1; j < KC; j++) {

            if (KC != 8 || j != KC >> 1)

                for (i = 0; i < 4; i++)

                    tk[j][i] ^= tk[j - 1][i];

            else

                for (i = 0; i < 4; i++)

                    tk[j][i] ^= sbox[tk[j - 1][i]];

        }

        memcpy((unsigned char*)a->round_key + t, tk, KC * 4);

    }

    if (decrypt) {

        for (i = 1; i < rounds; i++) {

            av_aes_block tmp[3];

            tmp[2] = a->round_key[i];

            subshift(&tmp[1], 0, sbox);

            mix(tmp, dec_multbl, 1, 3);

            a->round_key[i] = tmp[0];

        }

    } else {

        for (i = 0; i < (rounds + 1) >> 1; i++)

            FFSWAP(av_aes_block, a->round_key[i], a->round_key[rounds - i]);

    }

    return 0;

}