[C++] AES 128 ECB (electronic codebook) 구현

/* Serves as the initial round during encryption
* AddRoundKey is simply an XOR of a 128-bit block with the 128-bit key.
*/
void AES128::AddRoundKey(unsigned char * state, unsigned char * roundKey) {
    for (int i = 0; i < 16; i++) {
        state[i] ^= roundKey[i];
    }
}

/* Perform substitution to each of the 16 bytes
* Uses S-box as lookup table
*/
void AES128::E_SubBytes(unsigned char * state) {
    for (int i = 0; i < 16; i++) {
        state[i] = s[state[i]];
    }
}

// Shift left, adds diffusion
void AES128::E_ShiftRows(unsigned char * state) {
    unsigned char tmp[16];

    /* Column 1 */
    tmp[0] = state[0];
    tmp[1] = state[5];
    tmp[2] = state[10];
    tmp[3] = state[15];

    /* Column 2 */
    tmp[4] = state[4];
    tmp[5] = state[9];
    tmp[6] = state[14];
    tmp[7] = state[3];

    /* Column 3 */
    tmp[8] = state[8];
    tmp[9] = state[13];
    tmp[10] = state[2];
    tmp[11] = state[7];

    /* Column 4 */
    tmp[12] = state[12];
    tmp[13] = state[1];
    tmp[14] = state[6];
    tmp[15] = state[11];

    for (int i = 0; i < 16; i++) {
        state[i] = tmp[i];
    }
}

/* MixColumns uses mul2, mul3 look-up tables
* Source of diffusion
*/
void AES128::MixColumns(unsigned char * state) {
    unsigned char tmp[16];

    tmp[0] = (unsigned char)mul2[state[0]] ^ mul3[state[1]] ^ state[2] ^ state[3];
    tmp[1] = (unsigned char)state[0] ^ mul2[state[1]] ^ mul3[state[2]] ^ state[3];
    tmp[2] = (unsigned char)state[0] ^ state[1] ^ mul2[state[2]] ^ mul3[state[3]];
    tmp[3] = (unsigned char)mul3[state[0]] ^ state[1] ^ state[2] ^ mul2[state[3]];

    tmp[4] = (unsigned char)mul2[state[4]] ^ mul3[state[5]] ^ state[6] ^ state[7];
    tmp[5] = (unsigned char)state[4] ^ mul2[state[5]] ^ mul3[state[6]] ^ state[7];
    tmp[6] = (unsigned char)state[4] ^ state[5] ^ mul2[state[6]] ^ mul3[state[7]];
    tmp[7] = (unsigned char)mul3[state[4]] ^ state[5] ^ state[6] ^ mul2[state[7]];

    tmp[8] = (unsigned char)mul2[state[8]] ^ mul3[state[9]] ^ state[10] ^ state[11];
    tmp[9] = (unsigned char)state[8] ^ mul2[state[9]] ^ mul3[state[10]] ^ state[11];
    tmp[10] = (unsigned char)state[8] ^ state[9] ^ mul2[state[10]] ^ mul3[state[11]];
    tmp[11] = (unsigned char)mul3[state[8]] ^ state[9] ^ state[10] ^ mul2[state[11]];

    tmp[12] = (unsigned char)mul2[state[12]] ^ mul3[state[13]] ^ state[14] ^ state[15];
    tmp[13] = (unsigned char)state[12] ^ mul2[state[13]] ^ mul3[state[14]] ^ state[15];
    tmp[14] = (unsigned char)state[12] ^ state[13] ^ mul2[state[14]] ^ mul3[state[15]];
    tmp[15] = (unsigned char)mul3[state[12]] ^ state[13] ^ state[14] ^ mul2[state[15]];

    for (int i = 0; i < 16; i++) {
        state[i] = tmp[i];
    }
}

/* Each round operates on 128 bits at a time
* The number of rounds is defined in AESEncrypt()
*/
void AES128::E_Round(unsigned char * state, unsigned char * key) {
    E_SubBytes(state);
    E_ShiftRows(state);
    MixColumns(state);
    AddRoundKey(state, key);
}

// Same as Round() except it doesn't mix columns
void AES128::FinalRound(unsigned char * state, unsigned char * key) {
    E_SubBytes(state);
    E_ShiftRows(state);
    AddRoundKey(state, key);
}

/* Used in Round() and serves as the final round during decryption
* SubRoundKey is simply an XOR of a 128-bit block with the 128-bit key.
* So basically does the same as AddRoundKey in the encryption
*/
void AES128::SubRoundKey(unsigned char * state, unsigned char * roundKey) {
    for (int i = 0; i < 16; i++) {
        state[i] ^= roundKey[i];
    }
}

/* InverseMixColumns uses mul9, mul11, mul13, mul14 look-up tables
* Unmixes the columns by reversing the effect of MixColumns in encryption
*/
void AES128::InverseMixColumns(unsigned char * state) {
    unsigned char tmp[16];

    tmp[0] = (unsigned char)mul14[state[0]] ^ mul11[state[1]] ^ mul13[state[2]] ^ mul9[state[3]];
    tmp[1] = (unsigned char)mul9[state[0]] ^ mul14[state[1]] ^ mul11[state[2]] ^ mul13[state[3]];
    tmp[2] = (unsigned char)mul13[state[0]] ^ mul9[state[1]] ^ mul14[state[2]] ^ mul11[state[3]];
    tmp[3] = (unsigned char)mul11[state[0]] ^ mul13[state[1]] ^ mul9[state[2]] ^ mul14[state[3]];

    tmp[4] = (unsigned char)mul14[state[4]] ^ mul11[state[5]] ^ mul13[state[6]] ^ mul9[state[7]];
    tmp[5] = (unsigned char)mul9[state[4]] ^ mul14[state[5]] ^ mul11[state[6]] ^ mul13[state[7]];
    tmp[6] = (unsigned char)mul13[state[4]] ^ mul9[state[5]] ^ mul14[state[6]] ^ mul11[state[7]];
    tmp[7] = (unsigned char)mul11[state[4]] ^ mul13[state[5]] ^ mul9[state[6]] ^ mul14[state[7]];

    tmp[8] = (unsigned char)mul14[state[8]] ^ mul11[state[9]] ^ mul13[state[10]] ^ mul9[state[11]];
    tmp[9] = (unsigned char)mul9[state[8]] ^ mul14[state[9]] ^ mul11[state[10]] ^ mul13[state[11]];
    tmp[10] = (unsigned char)mul13[state[8]] ^ mul9[state[9]] ^ mul14[state[10]] ^ mul11[state[11]];
    tmp[11] = (unsigned char)mul11[state[8]] ^ mul13[state[9]] ^ mul9[state[10]] ^ mul14[state[11]];

    tmp[12] = (unsigned char)mul14[state[12]] ^ mul11[state[13]] ^ mul13[state[14]] ^ mul9[state[15]];
    tmp[13] = (unsigned char)mul9[state[12]] ^ mul14[state[13]] ^ mul11[state[14]] ^ mul13[state[15]];
    tmp[14] = (unsigned char)mul13[state[12]] ^ mul9[state[13]] ^ mul14[state[14]] ^ mul11[state[15]];
    tmp[15] = (unsigned char)mul11[state[12]] ^ mul13[state[13]] ^ mul9[state[14]] ^ mul14[state[15]];

    for (int i = 0; i < 16; i++) {
        state[i] = tmp[i];
    }
}

// Shifts rows right (rather than left) for decryption
void AES128::D_ShiftRows(unsigned char * state) {
    unsigned char tmp[16];

    /* Column 1 */
    tmp[0] = state[0];
    tmp[1] = state[13];
    tmp[2] = state[10];
    tmp[3] = state[7];

    /* Column 2 */
    tmp[4] = state[4];
    tmp[5] = state[1];
    tmp[6] = state[14];
    tmp[7] = state[11];

    /* Column 3 */
    tmp[8] = state[8];
    tmp[9] = state[5];
    tmp[10] = state[2];
    tmp[11] = state[15];

    /* Column 4 */
    tmp[12] = state[12];
    tmp[13] = state[9];
    tmp[14] = state[6];
    tmp[15] = state[3];

    for (int i = 0; i < 16; i++) {
        state[i] = tmp[i];
    }
}

/* Perform substitution to each of the 16 bytes
* Uses inverse S-box as lookup table
*/
void AES128::D_SubBytes(unsigned char * state) {
    for (int i = 0; i < 16; i++) { // Perform substitution to each of the 16 bytes
        state[i] = inv_s[state[i]];
    }
}

/* Each round operates on 128 bits at a time
* The number of rounds is defined in AESDecrypt()
* Not surprisingly, the steps are the encryption steps but reversed
*/
void AES128::D_Round(unsigned char * state, unsigned char * key) {
    SubRoundKey(state, key);
    InverseMixColumns(state);
    D_ShiftRows(state);
    D_SubBytes(state);
}

// Same as Round() but no InverseMixColumns
void AES128::InitialRound(unsigned char * state, unsigned char * key) {
    SubRoundKey(state, key);
    D_ShiftRows(state);
    D_SubBytes(state);
}

/* The AES encryption function
* Organizes the confusion and diffusion steps into one function
*/
void AES128::AESEncrypt(unsigned char * message, unsigned char * expandedKey, unsigned char * encryptedMessage) {
    unsigned char state[16]; // Stores the first 16 bytes of original message

    for (int i = 0; i < 16; i++) {
        state[i] = message[i];
    }

    int numberOfRounds = 9;

    AddRoundKey(state, expandedKey); // Initial round

    for (int i = 0; i < numberOfRounds; i++) {
        E_Round(state, expandedKey + (16 * (i + 1)));
    }

    FinalRound(state, expandedKey + 160);

    // Copy encrypted state to buffer
    for (int i = 0; i < 16; i++) {
        encryptedMessage[i] = state[i];
    }
}
std::string AES128::CustomEncrypter(std::string Decrypted_Data, std::string Crypt_Key) {
    int originalLen = strlen((const char *)Decrypted_Data.c_str());

    int paddedMessageLen = originalLen;

    if ((paddedMessageLen % 16) != 0) {
        paddedMessageLen = (paddedMessageLen / 16 + 1) * 16;
    }

    unsigned char * paddedMessage = new unsigned char[paddedMessageLen];
    for (int i = 0; i < paddedMessageLen; i++) {
        if (i >= originalLen) {
            paddedMessage[i] = 0;
        } else {
            paddedMessage[i] = Decrypted_Data[i];
        }
    }

    unsigned char * encryptedMessage = new unsigned char[paddedMessageLen];

    int Crypt_Key_Size = Crypt_Key.size();
    if (Crypt_Key_Size < 16) {
        for (int i = 0; i < 16 - Crypt_Key_Size; i++) {//aes PKCS7 패딩
            Crypt_Key = Crypt_Key + (char)(16 - Crypt_Key_Size);
        }
    }

    unsigned char key[16];

    for (int i = 0; i < 16; i++) {
        key[i] = (unsigned int)Crypt_Key[i];
    }

    unsigned char expandedKey[176];
    KeyExpansion(key, expandedKey);

    for (int i = 0; i < paddedMessageLen; i += 16) {
        AESEncrypt(paddedMessage + i, expandedKey, encryptedMessage + i);
    }
    std::string result;
    result.assign((char *)encryptedMessage, paddedMessageLen);

    delete[] paddedMessage;
    delete[] encryptedMessage;

    Base64 base64;
    return base64.base64e(result);
}

/* The AES decryption function
* Organizes all the decryption steps into one function
*/
void AES128::AESDecrypt(unsigned char * encryptedMessage, unsigned char * expandedKey, unsigned char * decryptedMessage) {
    unsigned char state[16]; // Stores the first 16 bytes of encrypted message

    for (int i = 0; i < 16; i++) {
        state[i] = encryptedMessage[i];
    }

    InitialRound(state, expandedKey + 160);

    int numberOfRounds = 9;

    for (int i = 8; i >= 0; i--) {
        D_Round(state, expandedKey + (16 * (i + 1)));
    }

    SubRoundKey(state, expandedKey); // Final round

                                     // Copy decrypted state to buffer
    for (int i = 0; i < 16; i++) {
        decryptedMessage[i] = state[i];
    }
}

std::string AES128::CustomDecrypter(std::string Encrypted_Data, std::string Crypt_Key) {
    Base64 base64;
    std::string UnBase64_Encrypted_Data = base64.base64d(Encrypted_Data);
    char* msg = new char[UnBase64_Encrypted_Data.size() + 1];
    strcpy(msg, UnBase64_Encrypted_Data.c_str());

    int n = strlen((const char*)msg);

    unsigned char * encryptedMessage = new unsigned char[n];
    for (int i = 0; i < n; i++) {
        encryptedMessage[i] = (unsigned char)msg[i];
    }
    delete[] msg;

    int Crypt_Key_Size = Crypt_Key.size();
    if (Crypt_Key_Size < 16) {
        for (int i = 0; i < 16 - Crypt_Key_Size; i++) {//aes PKCS7 패딩
            Crypt_Key = Crypt_Key + (char)(16 - Crypt_Key_Size);
        }
    }

    unsigned char key[16];

    for (int i = 0; i < 16; i++) {
        key[i] = (unsigned int)Crypt_Key[i];
    }

    unsigned char expandedKey[176];
    KeyExpansion(key, expandedKey);

    int messageLen = strlen((const char *)encryptedMessage);

    unsigned char * decryptedMessage = new unsigned char[messageLen];

    for (int i = 0; i < messageLen; i += 16) {
        AESDecrypt(encryptedMessage + i, expandedKey, decryptedMessage + i);
    }

    std::string Output;

    Output.assign((char*)decryptedMessage, messageLen);

    delete[] decryptedMessage;
    delete[] encryptedMessage;

    return Output;
}

#pragma once
/* "AES.h" defines the look-up tables and KeyExpansion function
* used in encrypt and decrypt
*/
#ifndef AES_H
#define AES_H

// Encryption: Forward Rijndael S-box 
unsigned char s[256] =
{
    0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
    0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
    0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
    0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
    0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
    0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
    0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
    0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
    0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
    0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
    0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
    0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
    0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
    0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
    0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
    0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16
};

// Encryption: Multiply by 2 for MixColumns
unsigned char mul2[] =
{
    0x00,0x02,0x04,0x06,0x08,0x0a,0x0c,0x0e,0x10,0x12,0x14,0x16,0x18,0x1a,0x1c,0x1e,
    0x20,0x22,0x24,0x26,0x28,0x2a,0x2c,0x2e,0x30,0x32,0x34,0x36,0x38,0x3a,0x3c,0x3e,
    0x40,0x42,0x44,0x46,0x48,0x4a,0x4c,0x4e,0x50,0x52,0x54,0x56,0x58,0x5a,0x5c,0x5e,
    0x60,0x62,0x64,0x66,0x68,0x6a,0x6c,0x6e,0x70,0x72,0x74,0x76,0x78,0x7a,0x7c,0x7e,
    0x80,0x82,0x84,0x86,0x88,0x8a,0x8c,0x8e,0x90,0x92,0x94,0x96,0x98,0x9a,0x9c,0x9e,
    0xa0,0xa2,0xa4,0xa6,0xa8,0xaa,0xac,0xae,0xb0,0xb2,0xb4,0xb6,0xb8,0xba,0xbc,0xbe,
    0xc0,0xc2,0xc4,0xc6,0xc8,0xca,0xcc,0xce,0xd0,0xd2,0xd4,0xd6,0xd8,0xda,0xdc,0xde,
    0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xee,0xf0,0xf2,0xf4,0xf6,0xf8,0xfa,0xfc,0xfe,
    0x1b,0x19,0x1f,0x1d,0x13,0x11,0x17,0x15,0x0b,0x09,0x0f,0x0d,0x03,0x01,0x07,0x05,
    0x3b,0x39,0x3f,0x3d,0x33,0x31,0x37,0x35,0x2b,0x29,0x2f,0x2d,0x23,0x21,0x27,0x25,
    0x5b,0x59,0x5f,0x5d,0x53,0x51,0x57,0x55,0x4b,0x49,0x4f,0x4d,0x43,0x41,0x47,0x45,
    0x7b,0x79,0x7f,0x7d,0x73,0x71,0x77,0x75,0x6b,0x69,0x6f,0x6d,0x63,0x61,0x67,0x65,
    0x9b,0x99,0x9f,0x9d,0x93,0x91,0x97,0x95,0x8b,0x89,0x8f,0x8d,0x83,0x81,0x87,0x85,
    0xbb,0xb9,0xbf,0xbd,0xb3,0xb1,0xb7,0xb5,0xab,0xa9,0xaf,0xad,0xa3,0xa1,0xa7,0xa5,
    0xdb,0xd9,0xdf,0xdd,0xd3,0xd1,0xd7,0xd5,0xcb,0xc9,0xcf,0xcd,0xc3,0xc1,0xc7,0xc5,
    0xfb,0xf9,0xff,0xfd,0xf3,0xf1,0xf7,0xf5,0xeb,0xe9,0xef,0xed,0xe3,0xe1,0xe7,0xe5
};

// Encryption: Multiply by 3 for MixColumns
unsigned char mul3[] =
{
    0x00,0x03,0x06,0x05,0x0c,0x0f,0x0a,0x09,0x18,0x1b,0x1e,0x1d,0x14,0x17,0x12,0x11,
    0x30,0x33,0x36,0x35,0x3c,0x3f,0x3a,0x39,0x28,0x2b,0x2e,0x2d,0x24,0x27,0x22,0x21,
    0x60,0x63,0x66,0x65,0x6c,0x6f,0x6a,0x69,0x78,0x7b,0x7e,0x7d,0x74,0x77,0x72,0x71,
    0x50,0x53,0x56,0x55,0x5c,0x5f,0x5a,0x59,0x48,0x4b,0x4e,0x4d,0x44,0x47,0x42,0x41,
    0xc0,0xc3,0xc6,0xc5,0xcc,0xcf,0xca,0xc9,0xd8,0xdb,0xde,0xdd,0xd4,0xd7,0xd2,0xd1,
    0xf0,0xf3,0xf6,0xf5,0xfc,0xff,0xfa,0xf9,0xe8,0xeb,0xee,0xed,0xe4,0xe7,0xe2,0xe1,
    0xa0,0xa3,0xa6,0xa5,0xac,0xaf,0xaa,0xa9,0xb8,0xbb,0xbe,0xbd,0xb4,0xb7,0xb2,0xb1,
    0x90,0x93,0x96,0x95,0x9c,0x9f,0x9a,0x99,0x88,0x8b,0x8e,0x8d,0x84,0x87,0x82,0x81,
    0x9b,0x98,0x9d,0x9e,0x97,0x94,0x91,0x92,0x83,0x80,0x85,0x86,0x8f,0x8c,0x89,0x8a,
    0xab,0xa8,0xad,0xae,0xa7,0xa4,0xa1,0xa2,0xb3,0xb0,0xb5,0xb6,0xbf,0xbc,0xb9,0xba,
    0xfb,0xf8,0xfd,0xfe,0xf7,0xf4,0xf1,0xf2,0xe3,0xe0,0xe5,0xe6,0xef,0xec,0xe9,0xea,
    0xcb,0xc8,0xcd,0xce,0xc7,0xc4,0xc1,0xc2,0xd3,0xd0,0xd5,0xd6,0xdf,0xdc,0xd9,0xda,
    0x5b,0x58,0x5d,0x5e,0x57,0x54,0x51,0x52,0x43,0x40,0x45,0x46,0x4f,0x4c,0x49,0x4a,
    0x6b,0x68,0x6d,0x6e,0x67,0x64,0x61,0x62,0x73,0x70,0x75,0x76,0x7f,0x7c,0x79,0x7a,
    0x3b,0x38,0x3d,0x3e,0x37,0x34,0x31,0x32,0x23,0x20,0x25,0x26,0x2f,0x2c,0x29,0x2a,
    0x0b,0x08,0x0d,0x0e,0x07,0x04,0x01,0x02,0x13,0x10,0x15,0x16,0x1f,0x1c,0x19,0x1a
};

// Used in KeyExpansion
unsigned char rcon[256] = {
    0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,
    0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39,
    0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a,
    0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8,
    0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef,
    0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc,
    0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b,
    0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3,
    0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94,
    0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20,
    0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35,
    0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f,
    0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04,
    0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63,
    0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd,
    0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d
};

// Decryption: Inverse Rijndael S-box
unsigned char inv_s[256] =
{
    0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
    0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
    0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
    0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
    0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
    0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
    0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
    0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
    0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
    0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
    0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
    0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
    0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
    0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
    0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
    0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D
};

// Decryption: Multiply by 9 for InverseMixColumns
unsigned char mul9[256] =
{
    0x00,0x09,0x12,0x1b,0x24,0x2d,0x36,0x3f,0x48,0x41,0x5a,0x53,0x6c,0x65,0x7e,0x77,
    0x90,0x99,0x82,0x8b,0xb4,0xbd,0xa6,0xaf,0xd8,0xd1,0xca,0xc3,0xfc,0xf5,0xee,0xe7,
    0x3b,0x32,0x29,0x20,0x1f,0x16,0x0d,0x04,0x73,0x7a,0x61,0x68,0x57,0x5e,0x45,0x4c,
    0xab,0xa2,0xb9,0xb0,0x8f,0x86,0x9d,0x94,0xe3,0xea,0xf1,0xf8,0xc7,0xce,0xd5,0xdc,
    0x76,0x7f,0x64,0x6d,0x52,0x5b,0x40,0x49,0x3e,0x37,0x2c,0x25,0x1a,0x13,0x08,0x01,
    0xe6,0xef,0xf4,0xfd,0xc2,0xcb,0xd0,0xd9,0xae,0xa7,0xbc,0xb5,0x8a,0x83,0x98,0x91,
    0x4d,0x44,0x5f,0x56,0x69,0x60,0x7b,0x72,0x05,0x0c,0x17,0x1e,0x21,0x28,0x33,0x3a,
    0xdd,0xd4,0xcf,0xc6,0xf9,0xf0,0xeb,0xe2,0x95,0x9c,0x87,0x8e,0xb1,0xb8,0xa3,0xaa,
    0xec,0xe5,0xfe,0xf7,0xc8,0xc1,0xda,0xd3,0xa4,0xad,0xb6,0xbf,0x80,0x89,0x92,0x9b,
    0x7c,0x75,0x6e,0x67,0x58,0x51,0x4a,0x43,0x34,0x3d,0x26,0x2f,0x10,0x19,0x02,0x0b,
    0xd7,0xde,0xc5,0xcc,0xf3,0xfa,0xe1,0xe8,0x9f,0x96,0x8d,0x84,0xbb,0xb2,0xa9,0xa0,
    0x47,0x4e,0x55,0x5c,0x63,0x6a,0x71,0x78,0x0f,0x06,0x1d,0x14,0x2b,0x22,0x39,0x30,
    0x9a,0x93,0x88,0x81,0xbe,0xb7,0xac,0xa5,0xd2,0xdb,0xc0,0xc9,0xf6,0xff,0xe4,0xed,
    0x0a,0x03,0x18,0x11,0x2e,0x27,0x3c,0x35,0x42,0x4b,0x50,0x59,0x66,0x6f,0x74,0x7d,
    0xa1,0xa8,0xb3,0xba,0x85,0x8c,0x97,0x9e,0xe9,0xe0,0xfb,0xf2,0xcd,0xc4,0xdf,0xd6,
    0x31,0x38,0x23,0x2a,0x15,0x1c,0x07,0x0e,0x79,0x70,0x6b,0x62,0x5d,0x54,0x4f,0x46
};

// Decryption: Multiply by 11 for InverseMixColumns
unsigned char mul11[256] =
{
    0x00,0x0b,0x16,0x1d,0x2c,0x27,0x3a,0x31,0x58,0x53,0x4e,0x45,0x74,0x7f,0x62,0x69,
    0xb0,0xbb,0xa6,0xad,0x9c,0x97,0x8a,0x81,0xe8,0xe3,0xfe,0xf5,0xc4,0xcf,0xd2,0xd9,
    0x7b,0x70,0x6d,0x66,0x57,0x5c,0x41,0x4a,0x23,0x28,0x35,0x3e,0x0f,0x04,0x19,0x12,
    0xcb,0xc0,0xdd,0xd6,0xe7,0xec,0xf1,0xfa,0x93,0x98,0x85,0x8e,0xbf,0xb4,0xa9,0xa2,
    0xf6,0xfd,0xe0,0xeb,0xda,0xd1,0xcc,0xc7,0xae,0xa5,0xb8,0xb3,0x82,0x89,0x94,0x9f,
    0x46,0x4d,0x50,0x5b,0x6a,0x61,0x7c,0x77,0x1e,0x15,0x08,0x03,0x32,0x39,0x24,0x2f,
    0x8d,0x86,0x9b,0x90,0xa1,0xaa,0xb7,0xbc,0xd5,0xde,0xc3,0xc8,0xf9,0xf2,0xef,0xe4,
    0x3d,0x36,0x2b,0x20,0x11,0x1a,0x07,0x0c,0x65,0x6e,0x73,0x78,0x49,0x42,0x5f,0x54,
    0xf7,0xfc,0xe1,0xea,0xdb,0xd0,0xcd,0xc6,0xaf,0xa4,0xb9,0xb2,0x83,0x88,0x95,0x9e,
    0x47,0x4c,0x51,0x5a,0x6b,0x60,0x7d,0x76,0x1f,0x14,0x09,0x02,0x33,0x38,0x25,0x2e,
    0x8c,0x87,0x9a,0x91,0xa0,0xab,0xb6,0xbd,0xd4,0xdf,0xc2,0xc9,0xf8,0xf3,0xee,0xe5,
    0x3c,0x37,0x2a,0x21,0x10,0x1b,0x06,0x0d,0x64,0x6f,0x72,0x79,0x48,0x43,0x5e,0x55,
    0x01,0x0a,0x17,0x1c,0x2d,0x26,0x3b,0x30,0x59,0x52,0x4f,0x44,0x75,0x7e,0x63,0x68,
    0xb1,0xba,0xa7,0xac,0x9d,0x96,0x8b,0x80,0xe9,0xe2,0xff,0xf4,0xc5,0xce,0xd3,0xd8,
    0x7a,0x71,0x6c,0x67,0x56,0x5d,0x40,0x4b,0x22,0x29,0x34,0x3f,0x0e,0x05,0x18,0x13,
    0xca,0xc1,0xdc,0xd7,0xe6,0xed,0xf0,0xfb,0x92,0x99,0x84,0x8f,0xbe,0xb5,0xa8,0xa3
};

// Decryption: Multiply by 13 for InverseMixColumns
unsigned char mul13[256] =
{
    0x00,0x0d,0x1a,0x17,0x34,0x39,0x2e,0x23,0x68,0x65,0x72,0x7f,0x5c,0x51,0x46,0x4b,
    0xd0,0xdd,0xca,0xc7,0xe4,0xe9,0xfe,0xf3,0xb8,0xb5,0xa2,0xaf,0x8c,0x81,0x96,0x9b,
    0xbb,0xb6,0xa1,0xac,0x8f,0x82,0x95,0x98,0xd3,0xde,0xc9,0xc4,0xe7,0xea,0xfd,0xf0,
    0x6b,0x66,0x71,0x7c,0x5f,0x52,0x45,0x48,0x03,0x0e,0x19,0x14,0x37,0x3a,0x2d,0x20,
    0x6d,0x60,0x77,0x7a,0x59,0x54,0x43,0x4e,0x05,0x08,0x1f,0x12,0x31,0x3c,0x2b,0x26,
    0xbd,0xb0,0xa7,0xaa,0x89,0x84,0x93,0x9e,0xd5,0xd8,0xcf,0xc2,0xe1,0xec,0xfb,0xf6,
    0xd6,0xdb,0xcc,0xc1,0xe2,0xef,0xf8,0xf5,0xbe,0xb3,0xa4,0xa9,0x8a,0x87,0x90,0x9d,
    0x06,0x0b,0x1c,0x11,0x32,0x3f,0x28,0x25,0x6e,0x63,0x74,0x79,0x5a,0x57,0x40,0x4d,
    0xda,0xd7,0xc0,0xcd,0xee,0xe3,0xf4,0xf9,0xb2,0xbf,0xa8,0xa5,0x86,0x8b,0x9c,0x91,
    0x0a,0x07,0x10,0x1d,0x3e,0x33,0x24,0x29,0x62,0x6f,0x78,0x75,0x56,0x5b,0x4c,0x41,
    0x61,0x6c,0x7b,0x76,0x55,0x58,0x4f,0x42,0x09,0x04,0x13,0x1e,0x3d,0x30,0x27,0x2a,
    0xb1,0xbc,0xab,0xa6,0x85,0x88,0x9f,0x92,0xd9,0xd4,0xc3,0xce,0xed,0xe0,0xf7,0xfa,
    0xb7,0xba,0xad,0xa0,0x83,0x8e,0x99,0x94,0xdf,0xd2,0xc5,0xc8,0xeb,0xe6,0xf1,0xfc,
    0x67,0x6a,0x7d,0x70,0x53,0x5e,0x49,0x44,0x0f,0x02,0x15,0x18,0x3b,0x36,0x21,0x2c,
    0x0c,0x01,0x16,0x1b,0x38,0x35,0x22,0x2f,0x64,0x69,0x7e,0x73,0x50,0x5d,0x4a,0x47,
    0xdc,0xd1,0xc6,0xcb,0xe8,0xe5,0xf2,0xff,0xb4,0xb9,0xae,0xa3,0x80,0x8d,0x9a,0x97
};

// Decryption: Multiply by 14 for InverseMixColumns
unsigned char mul14[256] =
{
    0x00,0x0e,0x1c,0x12,0x38,0x36,0x24,0x2a,0x70,0x7e,0x6c,0x62,0x48,0x46,0x54,0x5a,
    0xe0,0xee,0xfc,0xf2,0xd8,0xd6,0xc4,0xca,0x90,0x9e,0x8c,0x82,0xa8,0xa6,0xb4,0xba,
    0xdb,0xd5,0xc7,0xc9,0xe3,0xed,0xff,0xf1,0xab,0xa5,0xb7,0xb9,0x93,0x9d,0x8f,0x81,
    0x3b,0x35,0x27,0x29,0x03,0x0d,0x1f,0x11,0x4b,0x45,0x57,0x59,0x73,0x7d,0x6f,0x61,
    0xad,0xa3,0xb1,0xbf,0x95,0x9b,0x89,0x87,0xdd,0xd3,0xc1,0xcf,0xe5,0xeb,0xf9,0xf7,
    0x4d,0x43,0x51,0x5f,0x75,0x7b,0x69,0x67,0x3d,0x33,0x21,0x2f,0x05,0x0b,0x19,0x17,
    0x76,0x78,0x6a,0x64,0x4e,0x40,0x52,0x5c,0x06,0x08,0x1a,0x14,0x3e,0x30,0x22,0x2c,
    0x96,0x98,0x8a,0x84,0xae,0xa0,0xb2,0xbc,0xe6,0xe8,0xfa,0xf4,0xde,0xd0,0xc2,0xcc,
    0x41,0x4f,0x5d,0x53,0x79,0x77,0x65,0x6b,0x31,0x3f,0x2d,0x23,0x09,0x07,0x15,0x1b,
    0xa1,0xaf,0xbd,0xb3,0x99,0x97,0x85,0x8b,0xd1,0xdf,0xcd,0xc3,0xe9,0xe7,0xf5,0xfb,
    0x9a,0x94,0x86,0x88,0xa2,0xac,0xbe,0xb0,0xea,0xe4,0xf6,0xf8,0xd2,0xdc,0xce,0xc0,
    0x7a,0x74,0x66,0x68,0x42,0x4c,0x5e,0x50,0x0a,0x04,0x16,0x18,0x32,0x3c,0x2e,0x20,
    0xec,0xe2,0xf0,0xfe,0xd4,0xda,0xc8,0xc6,0x9c,0x92,0x80,0x8e,0xa4,0xaa,0xb8,0xb6,
    0x0c,0x02,0x10,0x1e,0x34,0x3a,0x28,0x26,0x7c,0x72,0x60,0x6e,0x44,0x4a,0x58,0x56,
    0x37,0x39,0x2b,0x25,0x0f,0x01,0x13,0x1d,0x47,0x49,0x5b,0x55,0x7f,0x71,0x63,0x6d,
    0xd7,0xd9,0xcb,0xc5,0xef,0xe1,0xf3,0xfd,0xa7,0xa9,0xbb,0xb5,0x9f,0x91,0x83,0x8d
};

// Auxiliary function for KeyExpansion
void KeyExpansionCore(unsigned char * in, unsigned char i) {
    // Rotate left by one byte: shift left 
    unsigned char t = in[0];
    in[0] = in[1];
    in[1] = in[2];
    in[2] = in[3];
    in[3] = t;

    // S-box 4 bytes 
    in[0] = s[in[0]];
    in[1] = s[in[1]];
    in[2] = s[in[2]];
    in[3] = s[in[3]];

    // RCon
    in[0] ^= rcon[i];
}

/* The main KeyExpansion function
* Generates additional keys using the original key
* Total of 11 128-bit keys generated, including the original
* Keys are stored one after the other in expandedKeys
*/
void KeyExpansion(unsigned char inputKey[16], unsigned char expandedKeys[176]) {
    // The first 128 bits are the original key
    for (int i = 0; i < 16; i++) {
        expandedKeys[i] = inputKey[i];
    }

    int bytesGenerated = 16; // Bytes we've generated so far
    int rconIteration = 1; // Keeps track of rcon value
    unsigned char tmpCore[4]; // Temp storage for core

    while (bytesGenerated < 176) {
        /* Read 4 bytes for the core
        * They are the previously generated 4 bytes
        * Initially, these will be the final 4 bytes of the original key
        */
        for (int i = 0; i < 4; i++) {
            tmpCore[i] = expandedKeys[i + bytesGenerated - 4];
        }

        // Perform the core once for each 16 byte key
        if (bytesGenerated % 16 == 0) {
            KeyExpansionCore(tmpCore, rconIteration++);
        }

        for (unsigned char a = 0; a < 4; a++) {
            expandedKeys[bytesGenerated] = expandedKeys[bytesGenerated - 16] ^ tmpCore[a];
            bytesGenerated++;
        }

    }
}

#endif