/*
 * Copyright (c) 2012-2020 MIRACL UK Ltd.
 *
 * This file is part of MIRACL Core
 * (see https://github.com/miracl/core).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


/*
 * Implementation of the NIST Advanced Ecryption Standard
 *
 * SU=m, SU is Stack Usage
 */

#include <stdlib.h>


#include "arch.h"
#include "core.h"

using namespace core;

/* this is fixed */
#define NB 4

/* Rotates 32-bit word left by 1, 2 or 3 byte  */

#define ROTL8(x) (((x)<<8)|((x)>>24))
#define ROTL16(x) (((x)<<16)|((x)>>16))
#define ROTL24(x) (((x)<<24)|((x)>>8))

static const uchar InCo[4] = {0xB, 0xD, 0x9, 0xE}; /* Inverse Coefficients */

static const uchar ptab[] =
{
    1, 3, 5, 15, 17, 51, 85, 255, 26, 46, 114, 150, 161, 248, 19, 53,
    95, 225, 56, 72, 216, 115, 149, 164, 247, 2, 6, 10, 30, 34, 102, 170,
    229, 52, 92, 228, 55, 89, 235, 38, 106, 190, 217, 112, 144, 171, 230, 49,
    83, 245, 4, 12, 20, 60, 68, 204, 79, 209, 104, 184, 211, 110, 178, 205,
    76, 212, 103, 169, 224, 59, 77, 215, 98, 166, 241, 8, 24, 40, 120, 136,
    131, 158, 185, 208, 107, 189, 220, 127, 129, 152, 179, 206, 73, 219, 118, 154,
    181, 196, 87, 249, 16, 48, 80, 240, 11, 29, 39, 105, 187, 214, 97, 163,
    254, 25, 43, 125, 135, 146, 173, 236, 47, 113, 147, 174, 233, 32, 96, 160,
    251, 22, 58, 78, 210, 109, 183, 194, 93, 231, 50, 86, 250, 21, 63, 65,
    195, 94, 226, 61, 71, 201, 64, 192, 91, 237, 44, 116, 156, 191, 218, 117,
    159, 186, 213, 100, 172, 239, 42, 126, 130, 157, 188, 223, 122, 142, 137, 128,
    155, 182, 193, 88, 232, 35, 101, 175, 234, 37, 111, 177, 200, 67, 197, 84,
    252, 31, 33, 99, 165, 244, 7, 9, 27, 45, 119, 153, 176, 203, 70, 202,
    69, 207, 74, 222, 121, 139, 134, 145, 168, 227, 62, 66, 198, 81, 243, 14,
    18, 54, 90, 238, 41, 123, 141, 140, 143, 138, 133, 148, 167, 242, 13, 23,
    57, 75, 221, 124, 132, 151, 162, 253, 28, 36, 108, 180, 199, 82, 246, 1
};

static const uchar ltab[] =
{
    0, 255, 25, 1, 50, 2, 26, 198, 75, 199, 27, 104, 51, 238, 223, 3,
    100, 4, 224, 14, 52, 141, 129, 239, 76, 113, 8, 200, 248, 105, 28, 193,
    125, 194, 29, 181, 249, 185, 39, 106, 77, 228, 166, 114, 154, 201, 9, 120,
    101, 47, 138, 5, 33, 15, 225, 36, 18, 240, 130, 69, 53, 147, 218, 142,
    150, 143, 219, 189, 54, 208, 206, 148, 19, 92, 210, 241, 64, 70, 131, 56,
    102, 221, 253, 48, 191, 6, 139, 98, 179, 37, 226, 152, 34, 136, 145, 16,
    126, 110, 72, 195, 163, 182, 30, 66, 58, 107, 40, 84, 250, 133, 61, 186,
    43, 121, 10, 21, 155, 159, 94, 202, 78, 212, 172, 229, 243, 115, 167, 87,
    175, 88, 168, 80, 244, 234, 214, 116, 79, 174, 233, 213, 231, 230, 173, 232,
    44, 215, 117, 122, 235, 22, 11, 245, 89, 203, 95, 176, 156, 169, 81, 160,
    127, 12, 246, 111, 23, 196, 73, 236, 216, 67, 31, 45, 164, 118, 123, 183,
    204, 187, 62, 90, 251, 96, 177, 134, 59, 82, 161, 108, 170, 85, 41, 157,
    151, 178, 135, 144, 97, 190, 220, 252, 188, 149, 207, 205, 55, 63, 91, 209,
    83, 57, 132, 60, 65, 162, 109, 71, 20, 42, 158, 93, 86, 242, 211, 171,
    68, 17, 146, 217, 35, 32, 46, 137, 180, 124, 184, 38, 119, 153, 227, 165,
    103, 74, 237, 222, 197, 49, 254, 24, 13, 99, 140, 128, 192, 247, 112, 7
};

static const uchar fbsub[] =
{
    99, 124, 119, 123, 242, 107, 111, 197, 48, 1, 103, 43, 254, 215, 171, 118,
    202, 130, 201, 125, 250, 89, 71, 240, 173, 212, 162, 175, 156, 164, 114, 192,
    183, 253, 147, 38, 54, 63, 247, 204, 52, 165, 229, 241, 113, 216, 49, 21,
    4, 199, 35, 195, 24, 150, 5, 154, 7, 18, 128, 226, 235, 39, 178, 117,
    9, 131, 44, 26, 27, 110, 90, 160, 82, 59, 214, 179, 41, 227, 47, 132,
    83, 209, 0, 237, 32, 252, 177, 91, 106, 203, 190, 57, 74, 76, 88, 207,
    208, 239, 170, 251, 67, 77, 51, 133, 69, 249, 2, 127, 80, 60, 159, 168,
    81, 163, 64, 143, 146, 157, 56, 245, 188, 182, 218, 33, 16, 255, 243, 210,
    205, 12, 19, 236, 95, 151, 68, 23, 196, 167, 126, 61, 100, 93, 25, 115,
    96, 129, 79, 220, 34, 42, 144, 136, 70, 238, 184, 20, 222, 94, 11, 219,
    224, 50, 58, 10, 73, 6, 36, 92, 194, 211, 172, 98, 145, 149, 228, 121,
    231, 200, 55, 109, 141, 213, 78, 169, 108, 86, 244, 234, 101, 122, 174, 8,
    186, 120, 37, 46, 28, 166, 180, 198, 232, 221, 116, 31, 75, 189, 139, 138,
    112, 62, 181, 102, 72, 3, 246, 14, 97, 53, 87, 185, 134, 193, 29, 158,
    225, 248, 152, 17, 105, 217, 142, 148, 155, 30, 135, 233, 206, 85, 40, 223,
    140, 161, 137, 13, 191, 230, 66, 104, 65, 153, 45, 15, 176, 84, 187, 22
};

static const uchar rbsub[] =
{
    82, 9, 106, 213, 48, 54, 165, 56, 191, 64, 163, 158, 129, 243, 215, 251,
    124, 227, 57, 130, 155, 47, 255, 135, 52, 142, 67, 68, 196, 222, 233, 203,
    84, 123, 148, 50, 166, 194, 35, 61, 238, 76, 149, 11, 66, 250, 195, 78,
    8, 46, 161, 102, 40, 217, 36, 178, 118, 91, 162, 73, 109, 139, 209, 37,
    114, 248, 246, 100, 134, 104, 152, 22, 212, 164, 92, 204, 93, 101, 182, 146,
    108, 112, 72, 80, 253, 237, 185, 218, 94, 21, 70, 87, 167, 141, 157, 132,
    144, 216, 171, 0, 140, 188, 211, 10, 247, 228, 88, 5, 184, 179, 69, 6,
    208, 44, 30, 143, 202, 63, 15, 2, 193, 175, 189, 3, 1, 19, 138, 107,
    58, 145, 17, 65, 79, 103, 220, 234, 151, 242, 207, 206, 240, 180, 230, 115,
    150, 172, 116, 34, 231, 173, 53, 133, 226, 249, 55, 232, 28, 117, 223, 110,
    71, 241, 26, 113, 29, 41, 197, 137, 111, 183, 98, 14, 170, 24, 190, 27,
    252, 86, 62, 75, 198, 210, 121, 32, 154, 219, 192, 254, 120, 205, 90, 244,
    31, 221, 168, 51, 136, 7, 199, 49, 177, 18, 16, 89, 39, 128, 236, 95,
    96, 81, 127, 169, 25, 181, 74, 13, 45, 229, 122, 159, 147, 201, 156, 239,
    160, 224, 59, 77, 174, 42, 245, 176, 200, 235, 187, 60, 131, 83, 153, 97,
    23, 43, 4, 126, 186, 119, 214, 38, 225, 105, 20, 99, 85, 33, 12, 125
};

static const unsign32 rco[] =
{1, 2, 4, 8, 16, 32, 64, 128, 27, 54, 108, 216, 171, 77, 154, 47};

static const unsign32 ftable[] =
{
    0xa56363c6, 0x847c7cf8, 0x997777ee, 0x8d7b7bf6, 0xdf2f2ff, 0xbd6b6bd6,
    0xb16f6fde, 0x54c5c591, 0x50303060, 0x3010102, 0xa96767ce, 0x7d2b2b56,
    0x19fefee7, 0x62d7d7b5, 0xe6abab4d, 0x9a7676ec, 0x45caca8f, 0x9d82821f,
    0x40c9c989, 0x877d7dfa, 0x15fafaef, 0xeb5959b2, 0xc947478e, 0xbf0f0fb,
    0xecadad41, 0x67d4d4b3, 0xfda2a25f, 0xeaafaf45, 0xbf9c9c23, 0xf7a4a453,
    0x967272e4, 0x5bc0c09b, 0xc2b7b775, 0x1cfdfde1, 0xae93933d, 0x6a26264c,
    0x5a36366c, 0x413f3f7e, 0x2f7f7f5, 0x4fcccc83, 0x5c343468, 0xf4a5a551,
    0x34e5e5d1, 0x8f1f1f9, 0x937171e2, 0x73d8d8ab, 0x53313162, 0x3f15152a,
    0xc040408, 0x52c7c795, 0x65232346, 0x5ec3c39d, 0x28181830, 0xa1969637,
    0xf05050a, 0xb59a9a2f, 0x907070e, 0x36121224, 0x9b80801b, 0x3de2e2df,
    0x26ebebcd, 0x6927274e, 0xcdb2b27f, 0x9f7575ea, 0x1b090912, 0x9e83831d,
    0x742c2c58, 0x2e1a1a34, 0x2d1b1b36, 0xb26e6edc, 0xee5a5ab4, 0xfba0a05b,
    0xf65252a4, 0x4d3b3b76, 0x61d6d6b7, 0xceb3b37d, 0x7b292952, 0x3ee3e3dd,
    0x712f2f5e, 0x97848413, 0xf55353a6, 0x68d1d1b9, 0x0, 0x2cededc1,
    0x60202040, 0x1ffcfce3, 0xc8b1b179, 0xed5b5bb6, 0xbe6a6ad4, 0x46cbcb8d,
    0xd9bebe67, 0x4b393972, 0xde4a4a94, 0xd44c4c98, 0xe85858b0, 0x4acfcf85,
    0x6bd0d0bb, 0x2aefefc5, 0xe5aaaa4f, 0x16fbfbed, 0xc5434386, 0xd74d4d9a,
    0x55333366, 0x94858511, 0xcf45458a, 0x10f9f9e9, 0x6020204, 0x817f7ffe,
    0xf05050a0, 0x443c3c78, 0xba9f9f25, 0xe3a8a84b, 0xf35151a2, 0xfea3a35d,
    0xc0404080, 0x8a8f8f05, 0xad92923f, 0xbc9d9d21, 0x48383870, 0x4f5f5f1,
    0xdfbcbc63, 0xc1b6b677, 0x75dadaaf, 0x63212142, 0x30101020, 0x1affffe5,
    0xef3f3fd, 0x6dd2d2bf, 0x4ccdcd81, 0x140c0c18, 0x35131326, 0x2fececc3,
    0xe15f5fbe, 0xa2979735, 0xcc444488, 0x3917172e, 0x57c4c493, 0xf2a7a755,
    0x827e7efc, 0x473d3d7a, 0xac6464c8, 0xe75d5dba, 0x2b191932, 0x957373e6,
    0xa06060c0, 0x98818119, 0xd14f4f9e, 0x7fdcdca3, 0x66222244, 0x7e2a2a54,
    0xab90903b, 0x8388880b, 0xca46468c, 0x29eeeec7, 0xd3b8b86b, 0x3c141428,
    0x79dedea7, 0xe25e5ebc, 0x1d0b0b16, 0x76dbdbad, 0x3be0e0db, 0x56323264,
    0x4e3a3a74, 0x1e0a0a14, 0xdb494992, 0xa06060c, 0x6c242448, 0xe45c5cb8,
    0x5dc2c29f, 0x6ed3d3bd, 0xefacac43, 0xa66262c4, 0xa8919139, 0xa4959531,
    0x37e4e4d3, 0x8b7979f2, 0x32e7e7d5, 0x43c8c88b, 0x5937376e, 0xb76d6dda,
    0x8c8d8d01, 0x64d5d5b1, 0xd24e4e9c, 0xe0a9a949, 0xb46c6cd8, 0xfa5656ac,
    0x7f4f4f3, 0x25eaeacf, 0xaf6565ca, 0x8e7a7af4, 0xe9aeae47, 0x18080810,
    0xd5baba6f, 0x887878f0, 0x6f25254a, 0x722e2e5c, 0x241c1c38, 0xf1a6a657,
    0xc7b4b473, 0x51c6c697, 0x23e8e8cb, 0x7cdddda1, 0x9c7474e8, 0x211f1f3e,
    0xdd4b4b96, 0xdcbdbd61, 0x868b8b0d, 0x858a8a0f, 0x907070e0, 0x423e3e7c,
    0xc4b5b571, 0xaa6666cc, 0xd8484890, 0x5030306, 0x1f6f6f7, 0x120e0e1c,
    0xa36161c2, 0x5f35356a, 0xf95757ae, 0xd0b9b969, 0x91868617, 0x58c1c199,
    0x271d1d3a, 0xb99e9e27, 0x38e1e1d9, 0x13f8f8eb, 0xb398982b, 0x33111122,
    0xbb6969d2, 0x70d9d9a9, 0x898e8e07, 0xa7949433, 0xb69b9b2d, 0x221e1e3c,
    0x92878715, 0x20e9e9c9, 0x49cece87, 0xff5555aa, 0x78282850, 0x7adfdfa5,
    0x8f8c8c03, 0xf8a1a159, 0x80898909, 0x170d0d1a, 0xdabfbf65, 0x31e6e6d7,
    0xc6424284, 0xb86868d0, 0xc3414182, 0xb0999929, 0x772d2d5a, 0x110f0f1e,
    0xcbb0b07b, 0xfc5454a8, 0xd6bbbb6d, 0x3a16162c
};

static const unsign32 rtable[] =
{
    0x50a7f451, 0x5365417e, 0xc3a4171a, 0x965e273a, 0xcb6bab3b, 0xf1459d1f,
    0xab58faac, 0x9303e34b, 0x55fa3020, 0xf66d76ad, 0x9176cc88, 0x254c02f5,
    0xfcd7e54f, 0xd7cb2ac5, 0x80443526, 0x8fa362b5, 0x495ab1de, 0x671bba25,
    0x980eea45, 0xe1c0fe5d, 0x2752fc3, 0x12f04c81, 0xa397468d, 0xc6f9d36b,
    0xe75f8f03, 0x959c9215, 0xeb7a6dbf, 0xda595295, 0x2d83bed4, 0xd3217458,
    0x2969e049, 0x44c8c98e, 0x6a89c275, 0x78798ef4, 0x6b3e5899, 0xdd71b927,
    0xb64fe1be, 0x17ad88f0, 0x66ac20c9, 0xb43ace7d, 0x184adf63, 0x82311ae5,
    0x60335197, 0x457f5362, 0xe07764b1, 0x84ae6bbb, 0x1ca081fe, 0x942b08f9,
    0x58684870, 0x19fd458f, 0x876cde94, 0xb7f87b52, 0x23d373ab, 0xe2024b72,
    0x578f1fe3, 0x2aab5566, 0x728ebb2, 0x3c2b52f, 0x9a7bc586, 0xa50837d3,
    0xf2872830, 0xb2a5bf23, 0xba6a0302, 0x5c8216ed, 0x2b1ccf8a, 0x92b479a7,
    0xf0f207f3, 0xa1e2694e, 0xcdf4da65, 0xd5be0506, 0x1f6234d1, 0x8afea6c4,
    0x9d532e34, 0xa055f3a2, 0x32e18a05, 0x75ebf6a4, 0x39ec830b, 0xaaef6040,
    0x69f715e, 0x51106ebd, 0xf98a213e, 0x3d06dd96, 0xae053edd, 0x46bde64d,
    0xb58d5491, 0x55dc471, 0x6fd40604, 0xff155060, 0x24fb9819, 0x97e9bdd6,
    0xcc434089, 0x779ed967, 0xbd42e8b0, 0x888b8907, 0x385b19e7, 0xdbeec879,
    0x470a7ca1, 0xe90f427c, 0xc91e84f8, 0x0, 0x83868009, 0x48ed2b32,
    0xac70111e, 0x4e725a6c, 0xfbff0efd, 0x5638850f, 0x1ed5ae3d, 0x27392d36,
    0x64d90f0a, 0x21a65c68, 0xd1545b9b, 0x3a2e3624, 0xb1670a0c, 0xfe75793,
    0xd296eeb4, 0x9e919b1b, 0x4fc5c080, 0xa220dc61, 0x694b775a, 0x161a121c,
    0xaba93e2, 0xe52aa0c0, 0x43e0223c, 0x1d171b12, 0xb0d090e, 0xadc78bf2,
    0xb9a8b62d, 0xc8a91e14, 0x8519f157, 0x4c0775af, 0xbbdd99ee, 0xfd607fa3,
    0x9f2601f7, 0xbcf5725c, 0xc53b6644, 0x347efb5b, 0x7629438b, 0xdcc623cb,
    0x68fcedb6, 0x63f1e4b8, 0xcadc31d7, 0x10856342, 0x40229713, 0x2011c684,
    0x7d244a85, 0xf83dbbd2, 0x1132f9ae, 0x6da129c7, 0x4b2f9e1d, 0xf330b2dc,
    0xec52860d, 0xd0e3c177, 0x6c16b32b, 0x99b970a9, 0xfa489411, 0x2264e947,
    0xc48cfca8, 0x1a3ff0a0, 0xd82c7d56, 0xef903322, 0xc74e4987, 0xc1d138d9,
    0xfea2ca8c, 0x360bd498, 0xcf81f5a6, 0x28de7aa5, 0x268eb7da, 0xa4bfad3f,
    0xe49d3a2c, 0xd927850, 0x9bcc5f6a, 0x62467e54, 0xc2138df6, 0xe8b8d890,
    0x5ef7392e, 0xf5afc382, 0xbe805d9f, 0x7c93d069, 0xa92dd56f, 0xb31225cf,
    0x3b99acc8, 0xa77d1810, 0x6e639ce8, 0x7bbb3bdb, 0x97826cd, 0xf418596e,
    0x1b79aec, 0xa89a4f83, 0x656e95e6, 0x7ee6ffaa, 0x8cfbc21, 0xe6e815ef,
    0xd99be7ba, 0xce366f4a, 0xd4099fea, 0xd67cb029, 0xafb2a431, 0x31233f2a,
    0x3094a5c6, 0xc066a235, 0x37bc4e74, 0xa6ca82fc, 0xb0d090e0, 0x15d8a733,
    0x4a9804f1, 0xf7daec41, 0xe50cd7f, 0x2ff69117, 0x8dd64d76, 0x4db0ef43,
    0x544daacc, 0xdf0496e4, 0xe3b5d19e, 0x1b886a4c, 0xb81f2cc1, 0x7f516546,
    0x4ea5e9d, 0x5d358c01, 0x737487fa, 0x2e410bfb, 0x5a1d67b3, 0x52d2db92,
    0x335610e9, 0x1347d66d, 0x8c61d79a, 0x7a0ca137, 0x8e14f859, 0x893c13eb,
    0xee27a9ce, 0x35c961b7, 0xede51ce1, 0x3cb1477a, 0x59dfd29c, 0x3f73f255,
    0x79ce1418, 0xbf37c773, 0xeacdf753, 0x5baafd5f, 0x146f3ddf, 0x86db4478,
    0x81f3afca, 0x3ec468b9, 0x2c342438, 0x5f40a3c2, 0x72c31d16, 0xc25e2bc,
    0x8b493c28, 0x41950dff, 0x7101a839, 0xdeb30c08, 0x9ce4b4d8, 0x90c15664,
    0x6184cb7b, 0x70b632d5, 0x745c6c48, 0x4257b8d0
};

#define MR_TOBYTE(x) ((uchar)((x)))

static unsign32 pack(const uchar *b)
{
    /* pack bytes into a 32-bit Word */
    return ((unsign32)b[3] << 24) | ((unsign32)b[2] << 16) | ((unsign32)b[1] << 8) | (unsign32)b[0];
}

static void unpack(unsign32 a, uchar *b)
{
    /* unpack bytes from a word */
    b[0] = MR_TOBYTE(a);
    b[1] = MR_TOBYTE(a >> 8);
    b[2] = MR_TOBYTE(a >> 16);
    b[3] = MR_TOBYTE(a >> 24);
}

/* SU= 8 */
static uchar bmul(uchar x, uchar y)
{
    /* x.y= AntiLog(Log(x) + Log(y)) */
    if (x && y) return ptab[(ltab[x] + ltab[y]) % 255];
    else return 0;
}

static unsign32 SubByte(unsign32 a)
{
    uchar b[4];
    unpack(a, b);
    b[0] = fbsub[b[0]];
    b[1] = fbsub[b[1]];
    b[2] = fbsub[b[2]];
    b[3] = fbsub[b[3]];
    return pack(b);
}

/* SU= 16 */
static uchar product(unsign32 x, unsign32 y)
{
    /* dot product of two 4-byte arrays */
    uchar xb[4], yb[4];
    unpack(x, xb);
    unpack(y, yb);
    return bmul(xb[0], yb[0])^bmul(xb[1], yb[1])^bmul(xb[2], yb[2])^bmul(xb[3], yb[3]);
}

static unsign32 InvMixCol(unsign32 x)
{
    /* matrix Multiplication */
    unsign32 y, m;
    uchar b[4];

    m = pack(InCo);
    b[3] = product(m, x);
    m = ROTL24(m);
    b[2] = product(m, x);
    m = ROTL24(m);
    b[1] = product(m, x);
    m = ROTL24(m);
    b[0] = product(m, x);
    y = pack(b);
    return y;
}

/* SU= 8 */
/* reset cipher */
void core::AES_reset(core::aes *a, int mode, char *iv)
{
    /* reset mode, or reset iv */
    int i;
    a->mode = mode;
    for (i = 0; i < 4 * NB; i++)
        a->f[i] = 0;
    if (mode != ECB && iv != NULL)
    {
        for (i = 0; i < 4 * NB; i++)
            a->f[i] = iv[i];
    }
}

void core::AES_getreg(core::aes *a, char *ir)
{
    int i;
    for (i = 0; i < 4 * NB; i++) ir[i] = a->f[i];
}

/* SU= 72 */
/* Initialise cipher */
int core::AES_init(core::aes* a, int mode, int nk, char *key, char *iv)
{
    /* Key length Nk=16, 24 or 32 bytes */
    /* Key Scheduler. Create expanded encryption key */
    int i, j, k, N, nr;
    unsign32 CipherKey[8];

    nk /= 4;

    if (nk != 4 && nk != 6 && nk != 8) return 0;

    nr = 6 + nk;

    a->Nk = nk;
    a->Nr = nr;

    AES_reset(a, mode, iv);

    N = NB * (nr + 1);

    for (i = j = 0; i < nk; i++, j += 4)
    {
        CipherKey[i] = pack((uchar *)&key[j]);
    }
    for (i = 0; i < nk; i++) a->fkey[i] = CipherKey[i];
    for (j = nk, k = 0; j < N; j += nk, k++)
    {
        a->fkey[j] = a->fkey[j - nk] ^ SubByte(ROTL24(a->fkey[j - 1]))^rco[k];
        if (nk <= 6)
        {
            for (i = 1; i < nk && (i + j) < N; i++)
                a->fkey[i + j] = a->fkey[i + j - nk] ^ a->fkey[i + j - 1];
        }
        else
        {
            for (i = 1; i < 4 && (i + j) < N; i++)
                a->fkey[i + j] = a->fkey[i + j - nk] ^ a->fkey[i + j - 1];
            if ((j + 4) < N) a->fkey[j + 4] = a->fkey[j + 4 - nk] ^ SubByte(a->fkey[j + 3]);
            for (i = 5; i < nk && (i + j) < N; i++)
                a->fkey[i + j] = a->fkey[i + j - nk] ^ a->fkey[i + j - 1];
        }

    }
    /* now for the expanded decrypt key in reverse order */

    for (j = 0; j < NB; j++) a->rkey[j + N - NB] = a->fkey[j];
    for (i = NB; i < N - NB; i += NB)
    {
        k = N - NB - i;
        for (j = 0; j < NB; j++) a->rkey[k + j] = InvMixCol(a->fkey[i + j]);
    }
    for (j = N - NB; j < N; j++) a->rkey[j - N + NB] = a->fkey[j];
    return 1;
}

/* SU= 80 */
/* Encrypt a single block */
void core::AES_ecb_encrypt(core::aes *a, uchar *buff)
{
    int i, j, k;
    unsign32 p[4], q[4], *x, *y, *t;

    for (i = j = 0; i < NB; i++, j += 4)
    {
        p[i] = pack((uchar *)&buff[j]);
        p[i] ^= a->fkey[i];
    }

    k = NB;
    x = p;
    y = q;

    /* State alternates between x and y */
    for (i = 1; i < a->Nr; i++)
    {

        y[0] = a->fkey[k] ^ ftable[MR_TOBYTE(x[0])] ^
               ROTL8(ftable[MR_TOBYTE(x[1] >> 8)])^
               ROTL16(ftable[MR_TOBYTE(x[2] >> 16)])^
               ROTL24(ftable[x[3] >> 24]);
        y[1] = a->fkey[k + 1] ^ ftable[MR_TOBYTE(x[1])] ^
               ROTL8(ftable[MR_TOBYTE(x[2] >> 8)])^
               ROTL16(ftable[MR_TOBYTE(x[3] >> 16)])^
               ROTL24(ftable[x[0] >> 24]);
        y[2] = a->fkey[k + 2] ^ ftable[MR_TOBYTE(x[2])] ^
               ROTL8(ftable[MR_TOBYTE(x[3] >> 8)])^
               ROTL16(ftable[MR_TOBYTE(x[0] >> 16)])^
               ROTL24(ftable[x[1] >> 24]);
        y[3] = a->fkey[k + 3] ^ ftable[MR_TOBYTE(x[3])] ^
               ROTL8(ftable[MR_TOBYTE(x[0] >> 8)])^
               ROTL16(ftable[MR_TOBYTE(x[1] >> 16)])^
               ROTL24(ftable[x[2] >> 24]);

        k += 4;
        t = x;
        x = y;
        y = t;    /* swap pointers */
    }

    /* Last Round */

    y[0] = a->fkey[k] ^ (unsign32)fbsub[MR_TOBYTE(x[0])] ^
           ROTL8((unsign32)fbsub[MR_TOBYTE(x[1] >> 8)])^
           ROTL16((unsign32)fbsub[MR_TOBYTE(x[2] >> 16)])^
           ROTL24((unsign32)fbsub[x[3] >> 24]);
    y[1] = a->fkey[k + 1] ^ (unsign32)fbsub[MR_TOBYTE(x[1])] ^
           ROTL8((unsign32)fbsub[MR_TOBYTE(x[2] >> 8)])^
           ROTL16((unsign32)fbsub[MR_TOBYTE(x[3] >> 16)])^
           ROTL24((unsign32)fbsub[x[0] >> 24]);
    y[2] = a->fkey[k + 2] ^ (unsign32)fbsub[MR_TOBYTE(x[2])] ^
           ROTL8((unsign32)fbsub[MR_TOBYTE(x[3] >> 8)])^
           ROTL16((unsign32)fbsub[MR_TOBYTE(x[0] >> 16)])^
           ROTL24((unsign32)fbsub[x[1] >> 24]);
    y[3] = a->fkey[k + 3] ^ (unsign32)fbsub[MR_TOBYTE(x[3])] ^
           ROTL8((unsign32)fbsub[MR_TOBYTE(x[0] >> 8)])^
           ROTL16((unsign32)fbsub[MR_TOBYTE(x[1] >> 16)])^
           ROTL24((unsign32)fbsub[x[2] >> 24]);

    for (i = j = 0; i < NB; i++, j += 4)
    {
        unpack(y[i], (uchar *)&buff[j]);
        x[i] = y[i] = 0; /* clean up stack */
    }
}

/* SU= 80 */
/* Decrypt a single block */
void core::AES_ecb_decrypt(core::aes *a, uchar *buff)
{
    int i, j, k;
    unsign32 p[4], q[4], *x, *y, *t;

    for (i = j = 0; i < NB; i++, j += 4)
    {
        p[i] = pack((uchar *)&buff[j]);
        p[i] ^= a->rkey[i];
    }

    k = NB;
    x = p;
    y = q;

    /* State alternates between x and y */
    for (i = 1; i < a->Nr; i++)
    {
        /* Nr is number of rounds. May be odd. */

        y[0] = a->rkey[k] ^ rtable[MR_TOBYTE(x[0])] ^
               ROTL8(rtable[MR_TOBYTE(x[3] >> 8)])^
               ROTL16(rtable[MR_TOBYTE(x[2] >> 16)])^
               ROTL24(rtable[x[1] >> 24]);
        y[1] = a->rkey[k + 1] ^ rtable[MR_TOBYTE(x[1])] ^
               ROTL8(rtable[MR_TOBYTE(x[0] >> 8)])^
               ROTL16(rtable[MR_TOBYTE(x[3] >> 16)])^
               ROTL24(rtable[x[2] >> 24]);
        y[2] = a->rkey[k + 2] ^ rtable[MR_TOBYTE(x[2])] ^
               ROTL8(rtable[MR_TOBYTE(x[1] >> 8)])^
               ROTL16(rtable[MR_TOBYTE(x[0] >> 16)])^
               ROTL24(rtable[x[3] >> 24]);
        y[3] = a->rkey[k + 3] ^ rtable[MR_TOBYTE(x[3])] ^
               ROTL8(rtable[MR_TOBYTE(x[2] >> 8)])^
               ROTL16(rtable[MR_TOBYTE(x[1] >> 16)])^
               ROTL24(rtable[x[0] >> 24]);

        k += 4;
        t = x;
        x = y;
        y = t;    /* swap pointers */
    }


    /* Last Round */
    y[0] = a->rkey[k] ^ (unsign32)rbsub[MR_TOBYTE(x[0])] ^
           ROTL8((unsign32)rbsub[MR_TOBYTE(x[3] >> 8)])^
           ROTL16((unsign32)rbsub[MR_TOBYTE(x[2] >> 16)])^
           ROTL24((unsign32)rbsub[x[1] >> 24]);
    y[1] = a->rkey[k + 1] ^ (unsign32)rbsub[MR_TOBYTE(x[1])] ^
           ROTL8((unsign32)rbsub[MR_TOBYTE(x[0] >> 8)])^
           ROTL16((unsign32)rbsub[MR_TOBYTE(x[3] >> 16)])^
           ROTL24((unsign32)rbsub[x[2] >> 24]);
    y[2] = a->rkey[k + 2] ^ (unsign32)rbsub[MR_TOBYTE(x[2])] ^
           ROTL8((unsign32)rbsub[MR_TOBYTE(x[1] >> 8)])^
           ROTL16((unsign32)rbsub[MR_TOBYTE(x[0] >> 16)])^
           ROTL24((unsign32)rbsub[x[3] >> 24]);
    y[3] = a->rkey[k + 3] ^ (unsign32)rbsub[MR_TOBYTE(x[3])] ^
           ROTL8((unsign32)rbsub[MR_TOBYTE(x[2] >> 8)])^
           ROTL16((unsign32)rbsub[MR_TOBYTE(x[1] >> 16)])^
           ROTL24((unsign32)rbsub[x[0] >> 24]);

    for (i = j = 0; i < NB; i++, j += 4)
    {
        unpack(y[i], (uchar *)&buff[j]);
        x[i] = y[i] = 0; /* clean up stack */
    }

}

/* simple default increment function */
static void increment(char *f)
{
    int i;
    for (i = 0; i < 16; i++)
    {
        f[i]++;
        if (f[i] != 0) break;
    }
}

/* SU= 40 */
/* Encrypt using selected mode of operation */
unsign32 core::AES_encrypt(core::aes* a, char *buff)
{
    int j, bytes;
    char st[16];
    unsign32 fell_off;

    /* Supported Modes of Operation */

    fell_off = 0;
    switch (a->mode)
    {
    case ECB:
        AES_ecb_encrypt(a, (uchar *)buff);
        return 0;
    case CBC:
        for (j = 0; j < 4 * NB; j++) buff[j] ^= a->f[j];
        AES_ecb_encrypt(a, (uchar *)buff);
        for (j = 0; j < 4 * NB; j++) a->f[j] = buff[j];
        return 0;

    case CFB1:
    case CFB2:
    case CFB4:
        bytes = a->mode - CFB1 + 1;
        for (j = 0; j < bytes; j++) fell_off = (fell_off << 8) | a->f[j];
        for (j = 0; j < 4 * NB; j++) st[j] = a->f[j];
        for (j = bytes; j < 4 * NB; j++) a->f[j - bytes] = a->f[j];
        AES_ecb_encrypt(a, (uchar *)st);
        for (j = 0; j < bytes; j++)
        {
            buff[j] ^= st[j];
            a->f[16 - bytes + j] = buff[j];
        }
        return fell_off;

    case OFB1:
    case OFB2:
    case OFB4:
    case OFB8:
    case OFB16:

        bytes = a->mode - OFB1 + 1;
        AES_ecb_encrypt(a, (uchar *)(a->f));
        for (j = 0; j < bytes; j++) buff[j] ^= a->f[j];
        return 0;

    case CTR1:
    case CTR2:
    case CTR4:
    case CTR8:
    case CTR16:

        bytes = a->mode - CTR1 + 1;
        for (j = 0; j < 4 * NB; j++) st[j] = a->f[j];
        AES_ecb_encrypt(a, (uchar *)st);
        for (j = 0; j < bytes; j++) buff[j] ^= st[j];
        increment(a->f);
        return 0;

    default:
        return 0;
    }
}

/* SU= 40 */
/* Decrypt using selected mode of operation */
unsign32 core::AES_decrypt(core::aes *a, char *buff)
{
    int j, bytes;
    char st[16];
    unsign32 fell_off;

    /* Supported modes of operation */
    fell_off = 0;
    switch (a->mode)
    {
    case ECB:
        AES_ecb_decrypt(a, (uchar *)buff);
        return 0;
    case CBC:
        for (j = 0; j < 4 * NB; j++)
        {
            st[j] = a->f[j];
            a->f[j] = buff[j];
        }
        AES_ecb_decrypt(a, (uchar *)buff);
        for (j = 0; j < 4 * NB; j++)
        {
            buff[j] ^= st[j];
            st[j] = 0;
        }
        return 0;
    case CFB1:
    case CFB2:
    case CFB4:
        bytes = a->mode - CFB1 + 1;
        for (j = 0; j < bytes; j++) fell_off = (fell_off << 8) | a->f[j];
        for (j = 0; j < 4 * NB; j++) st[j] = a->f[j];
        for (j = bytes; j < 4 * NB; j++) a->f[j - bytes] = a->f[j];
        AES_ecb_encrypt(a, (uchar *)st);
        for (j = 0; j < bytes; j++)
        {
            a->f[16 - bytes + j] = buff[j];
            buff[j] ^= st[j];
        }
        return fell_off;
    case OFB1:
    case OFB2:
    case OFB4:
    case OFB8:
    case OFB16:
        bytes = a->mode - OFB1 + 1;
        AES_ecb_encrypt(a, (uchar *)(a->f));
        for (j = 0; j < bytes; j++) buff[j] ^= a->f[j];
        return 0;

    case CTR1:
    case CTR2:
    case CTR4:
    case CTR8:
    case CTR16:

        bytes = a->mode - CTR1 + 1;
        for (j = 0; j < 4 * NB; j++) st[j] = a->f[j];
        AES_ecb_encrypt(a, (uchar *)st);
        for (j = 0; j < bytes; j++) buff[j] ^= st[j];
        increment(a->f);
        return 0;

    default:
        return 0;
    }
}

/* Clean up and delete left-overs */
void core::AES_end(core::aes *a)
{
    /* clean up */
    int i;
    for (i = 0; i < NB * (a->Nr + 1); i++)
        a->fkey[i] = a->rkey[i] = 0;
    for (i = 0; i < 4 * NB; i++)
        a->f[i] = 0;
}

/* AES encryption/decryption. Encrypt byte array M using key K and returns ciphertext */
void core::AES_CBC_IV0_ENCRYPT(octet *k, octet *m, octet *c)
{
    /* AES CBC encryption, with Null IV and key k */
    /* Input is from an octet string m, output is to an octet string c */
    /* Input is padded as necessary to make up a full final block */
    aes a;
    int fin;
    int i, j, ipt, opt;
    char buff[16];
    int padlen;

    OCT_clear(c);
    if (m->len == 0) return;
    AES_init(&a, CBC, k->len, k->val, NULL);

    ipt = opt = 0;
    fin = 0;
    for (;;)
    {
        for (i = 0; i < 16; i++)
        {
            if (ipt < m->len) buff[i] = m->val[ipt++];
            else
            {
                fin = 1;
                break;
            }
        }
        if (fin) break;
        AES_encrypt(&a, buff);
        for (i = 0; i < 16; i++)
            if (opt < c->max) c->val[opt++] = buff[i];
    }

    /* last block, filled up to i-th index */

    padlen = 16 - i;
    for (j = i; j < 16; j++) buff[j] = padlen;
    AES_encrypt(&a, buff);
    for (i = 0; i < 16; i++)
        if (opt < c->max) c->val[opt++] = buff[i];
    AES_end(&a);
    c->len = opt;
}

/* decrypts and returns TRUE if all consistent, else returns FALSE */
int core::AES_CBC_IV0_DECRYPT(octet *k, octet *c, octet *m)
{
    /* padding is removed */
    aes a;
    int i, ipt, opt, ch;
    char buff[16];
    int fin, bad;
    int padlen;
    ipt = opt = 0;

    OCT_clear(m);
    if (c->len == 0) return 1;
    ch = c->val[ipt++];

    AES_init(&a, CBC, k->len, k->val, NULL);
    fin = 0;

    for (;;)
    {
        for (i = 0; i < 16; i++)
        {
            buff[i] = ch;
            if (ipt >= c->len)
            {
                fin = 1;
                break;
            }
            else ch = c->val[ipt++];
        }
        AES_decrypt(&a, buff);
        if (fin) break;
        for (i = 0; i < 16; i++)
            if (opt < m->max) m->val[opt++] = buff[i];
    }
    AES_end(&a);
    bad = 0;
    padlen = buff[15];
    if (i != 15 || padlen < 1 || padlen > 16) bad = 1;
    if (padlen >= 2 && padlen <= 16)
        for (i = 16 - padlen; i < 16; i++) if (buff[i] != padlen) bad = 1;

    if (!bad) for (i = 0; i < 16 - padlen; i++)
            if (opt < m->max) m->val[opt++] = buff[i];

    m->len = opt;
    if (bad) return 0;
    return 1;
}

/*
#include <stdio.h>

#define KK 32

int main()
{
    int i;
    aes a;
    unsign32 t;
    uchar x,y;

    char key[KK];
    char block[16];
    char iv[16];
    for (i=0;i<KK;i++) key[i]=5;
    key[0]=1;
    for (i=0;i<16;i++) iv[i]=i;
    for (i=0;i<16;i++) block[i]=i;

    AES_init(&a,CTR16,KK,key,iv);

    printf("Plain=   ");
    for (i=0;i<16;i++) printf("%02x",block[i]);
    printf("\n");
    AES_encrypt(&a,block);
    printf("Encrypt= ");
    for (i=0;i<16;i++) printf("%02x",(uchar)block[i]);
    printf("\n");
    AES_reset(&a,CTR16,iv);
    AES_decrypt(&a,block);
    printf("Decrypt= ");
    for (i=0;i<16;i++) printf("%02x",(uchar)block[i]);
    printf("\n");

    AES_end(&a);

    return 0;
}

*/