text: /**************************************************************
                          AES128 
  Author:   Uli Kretzschmar
               MSP430 Systems
               Freising
  AES software support for encryption and decryption
  ECCN 5D002 TSU - Technology / Software Unrestricted
  **************************************************************/
  
  // foreward sbox
  static const unsigned char sbox[256] = {
  //0     1    2      3     4    5     6     7      8    9     A      B    C     D     E     F
    0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,       //0
    0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,       //1
    0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,       //2
    0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,       //3
    0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,       //4
    0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,       //5
    0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,       //6
    0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,       //7
    0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,       //8
    0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,       //9
    0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,       //A
    0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,       //B
    0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,       //C
    0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,       //D
    0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,       //E
    0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f,
      0xb0, 0x54, 0xbb, 0x16
  };                              //F   
  // inverse sbox
  static const unsigned char rsbox[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
  };
  // round constant
  static const unsigned char Rcon[11] = {
    0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
  };
  
  
  // expand the key
  static void
  expandKey(unsigned char *expandedKey, const unsigned char *key)
  {
    unsigned short ii, buf1;
  
    for(ii = 0; ii < 16; ii++) {
      expandedKey[ii] = key[ii];
    }
    
    for(ii = 1; ii < 11; ii++) {
      buf1 = expandedKey[ii * 16 - 4];
      expandedKey[ii * 16 + 0] =
        sbox[expandedKey[ii * 16 - 3]] ^ expandedKey[(ii - 1) * 16 +
                                                     0] ^ Rcon[ii];
      expandedKey[ii * 16 + 1] =
        sbox[expandedKey[ii * 16 - 2]] ^ expandedKey[(ii - 1) * 16 + 1];
      expandedKey[ii * 16 + 2] =
        sbox[expandedKey[ii * 16 - 1]] ^ expandedKey[(ii - 1) * 16 + 2];
      expandedKey[ii * 16 + 3] = sbox[buf1] ^ expandedKey[(ii - 1) * 16 + 3];
      expandedKey[ii * 16 + 4] =
        expandedKey[(ii - 1) * 16 + 4] ^ expandedKey[ii * 16 + 0];
      expandedKey[ii * 16 + 5] =
        expandedKey[(ii - 1) * 16 + 5] ^ expandedKey[ii * 16 + 1];
      expandedKey[ii * 16 + 6] =
        expandedKey[(ii - 1) * 16 + 6] ^ expandedKey[ii * 16 + 2];
      expandedKey[ii * 16 + 7] =
        expandedKey[(ii - 1) * 16 + 7] ^ expandedKey[ii * 16 + 3];
      expandedKey[ii * 16 + 8] =
        expandedKey[(ii - 1) * 16 + 8] ^ expandedKey[ii * 16 + 4];
      expandedKey[ii * 16 + 9] =
        expandedKey[(ii - 1) * 16 + 9] ^ expandedKey[ii * 16 + 5];
      expandedKey[ii * 16 + 10] =
        expandedKey[(ii - 1) * 16 + 10] ^ expandedKey[ii * 16 + 6];
      expandedKey[ii * 16 + 11] =
        expandedKey[(ii - 1) * 16 + 11] ^ expandedKey[ii * 16 + 7];
      expandedKey[ii * 16 + 12] =
        expandedKey[(ii - 1) * 16 + 12] ^ expandedKey[ii * 16 + 8];
      expandedKey[ii * 16 + 13] =
        expandedKey[(ii - 1) * 16 + 13] ^ expandedKey[ii * 16 + 9];
      expandedKey[ii * 16 + 14] =
        expandedKey[(ii - 1) * 16 + 14] ^ expandedKey[ii * 16 + 10];
      expandedKey[ii * 16 + 15] =
        expandedKey[(ii - 1) * 16 + 15] ^ expandedKey[ii * 16 + 11];
    }
  
  
  }
  
  // multiply by 2 in the galois field
  static unsigned char
  galois_mul2(unsigned char value)
  {
    if(value >> 7) {
      value = value << 1;
      return (value ^ 0x1b);
    } else {
      return value << 1;
    }
  }
  
  // straight foreward aes encryption implementation
  //   first the group of operations
  //     - addroundkey
  //     - subbytes
  //     - shiftrows
  //     - mixcolums
  //   is executed 9 times, after this addroundkey to finish the 9th round, 
  //   after that the 10th round without mixcolums
  //   no further subfunctions to save cycles for function calls
  //   no structuring with "for (....)" to save cycles
  static void
  aes_encr(unsigned char *state, unsigned char *expandedKey)
  {
    unsigned char buf1, buf2, buf3, round;
  
    for(round = 0; round < 9; round++) {
      // addroundkey, sbox and shiftrows
      // row 0
      state[0] = sbox[(state[0] ^ expandedKey[(round * 16)])];
      state[4] = sbox[(state[4] ^ expandedKey[(round * 16) + 4])];
      state[8] = sbox[(state[8] ^ expandedKey[(round * 16) + 8])];
      state[12] = sbox[(state[12] ^ expandedKey[(round * 16) + 12])];
      // row 1
      buf1 = state[1] ^ expandedKey[(round * 16) + 1];
      state[1] = sbox[(state[5] ^ expandedKey[(round * 16) + 5])];
      state[5] = sbox[(state[9] ^ expandedKey[(round * 16) + 9])];
      state[9] = sbox[(state[13] ^ expandedKey[(round * 16) + 13])];
      state[13] = sbox[buf1];
      // row 2
      buf1 = state[2] ^ expandedKey[(round * 16) + 2];
      buf2 = state[6] ^ expandedKey[(round * 16) + 6];
      state[2] = sbox[(state[10] ^ expandedKey[(round * 16) + 10])];
      state[6] = sbox[(state[14] ^ expandedKey[(round * 16) + 14])];
      state[10] = sbox[buf1];
      state[14] = sbox[buf2];
      // row 3
      buf1 = state[15] ^ expandedKey[(round * 16) + 15];
      state[15] = sbox[(state[11] ^ expandedKey[(round * 16) + 11])];
      state[11] = sbox[(state[7] ^ expandedKey[(round * 16) + 7])];
      state[7] = sbox[(state[3] ^ expandedKey[(round * 16) + 3])];
      state[3] = sbox[buf1];
  
      // mixcolums //////////
      // col1
      buf1 = state[0] ^ state[1] ^ state[2] ^ state[3];
      buf2 = state[0];
      buf3 = state[0] ^ state[1];
      buf3 = galois_mul2(buf3);
      state[0] = state[0] ^ buf3 ^ buf1;
      buf3 = state[1] ^ state[2];
      buf3 = galois_mul2(buf3);
      state[1] = state[1] ^ buf3 ^ buf1;
      buf3 = state[2] ^ state[3];
      buf3 = galois_mul2(buf3);
      state[2] = state[2] ^ buf3 ^ buf1;
      buf3 = state[3] ^ buf2;
      buf3 = galois_mul2(buf3);
      state[3] = state[3] ^ buf3 ^ buf1;
      // col2
      buf1 = state[4] ^ state[5] ^ state[6] ^ state[7];
      buf2 = state[4];
      buf3 = state[4] ^ state[5];
      buf3 = galois_mul2(buf3);
      state[4] = state[4] ^ buf3 ^ buf1;
      buf3 = state[5] ^ state[6];
      buf3 = galois_mul2(buf3);
      state[5] = state[5] ^ buf3 ^ buf1;
      buf3 = state[6] ^ state[7];
      buf3 = galois_mul2(buf3);
      state[6] = state[6] ^ buf3 ^ buf1;
      buf3 = state[7] ^ buf2;
      buf3 = galois_mul2(buf3);
      state[7] = state[7] ^ buf3 ^ buf1;
      // col3
      buf1 = state[8] ^ state[9] ^ state[10] ^ state[11];
      buf2 = state[8];
      buf3 = state[8] ^ state[9];
      buf3 = galois_mul2(buf3);
      state[8] = state[8] ^ buf3 ^ buf1;
      buf3 = state[9] ^ state[10];
      buf3 = galois_mul2(buf3);
      state[9] = state[9] ^ buf3 ^ buf1;
      buf3 = state[10] ^ state[11];
      buf3 = galois_mul2(buf3);
      state[10] = state[10] ^ buf3 ^ buf1;
      buf3 = state[11] ^ buf2;
      buf3 = galois_mul2(buf3);
      state[11] = state[11] ^ buf3 ^ buf1;
      // col4
      buf1 = state[12] ^ state[13] ^ state[14] ^ state[15];
      buf2 = state[12];
      buf3 = state[12] ^ state[13];
      buf3 = galois_mul2(buf3);
      state[12] = state[12] ^ buf3 ^ buf1;
      buf3 = state[13] ^ state[14];
      buf3 = galois_mul2(buf3);
      state[13] = state[13] ^ buf3 ^ buf1;
      buf3 = state[14] ^ state[15];
      buf3 = galois_mul2(buf3);
      state[14] = state[14] ^ buf3 ^ buf1;
      buf3 = state[15] ^ buf2;
      buf3 = galois_mul2(buf3);
      state[15] = state[15] ^ buf3 ^ buf1;
  
    }
    // 10th round without mixcols
    state[0] = sbox[(state[0] ^ expandedKey[(round * 16)])];
    state[4] = sbox[(state[4] ^ expandedKey[(round * 16) + 4])];
    state[8] = sbox[(state[8] ^ expandedKey[(round * 16) + 8])];
    state[12] = sbox[(state[12] ^ expandedKey[(round * 16) + 12])];
    // row 1
    buf1 = state[1] ^ expandedKey[(round * 16) + 1];
    state[1] = sbox[(state[5] ^ expandedKey[(round * 16) + 5])];
    state[5] = sbox[(state[9] ^ expandedKey[(round * 16) + 9])];
    state[9] = sbox[(state[13] ^ expandedKey[(round * 16) + 13])];
    state[13] = sbox[buf1];
    // row 2
    buf1 = state[2] ^ expandedKey[(round * 16) + 2];
    buf2 = state[6] ^ expandedKey[(round * 16) + 6];
    state[2] = sbox[(state[10] ^ expandedKey[(round * 16) + 10])];
    state[6] = sbox[(state[14] ^ expandedKey[(round * 16) + 14])];
    state[10] = sbox[buf1];
    state[14] = sbox[buf2];
    // row 3
    buf1 = state[15] ^ expandedKey[(round * 16) + 15];
    state[15] = sbox[(state[11] ^ expandedKey[(round * 16) + 11])];
    state[11] = sbox[(state[7] ^ expandedKey[(round * 16) + 7])];
    state[7] = sbox[(state[3] ^ expandedKey[(round * 16) + 3])];
    state[3] = sbox[buf1];
    // last addroundkey
    state[0] ^= expandedKey[160];
    state[1] ^= expandedKey[161];
    state[2] ^= expandedKey[162];
    state[3] ^= expandedKey[163];
    state[4] ^= expandedKey[164];
    state[5] ^= expandedKey[165];
    state[6] ^= expandedKey[166];
    state[7] ^= expandedKey[167];
    state[8] ^= expandedKey[168];
    state[9] ^= expandedKey[169];
    state[10] ^= expandedKey[170];
    state[11] ^= expandedKey[171];
    state[12] ^= expandedKey[172];
    state[13] ^= expandedKey[173];
    state[14] ^= expandedKey[174];
    state[15] ^= expandedKey[175];
  }
  
  // straight foreward aes decryption implementation
  //   the order of substeps is the exact reverse of decryption
  //   inverse functions:
  //       - addRoundKey is its own inverse
  //       - rsbox is inverse of sbox
  //       - rightshift instead of leftshift
  //       - invMixColumns = barreto + mixColumns
  //   no further subfunctions to save cycles for function calls
  //   no structuring with "for (....)" to save cycles
  static void
  aes_decr(unsigned char *state, unsigned char *expandedKey)
  {
    unsigned char buf1, buf2, buf3;
    signed char round;
  
    round = 9;
  
    // initial addroundkey
    state[0] ^= expandedKey[160];
    state[1] ^= expandedKey[161];
    state[2] ^= expandedKey[162];
    state[3] ^= expandedKey[163];
    state[4] ^= expandedKey[164];
    state[5] ^= expandedKey[165];
    state[6] ^= expandedKey[166];
    state[7] ^= expandedKey[167];
    state[8] ^= expandedKey[168];
    state[9] ^= expandedKey[169];
    state[10] ^= expandedKey[170];
    state[11] ^= expandedKey[171];
    state[12] ^= expandedKey[172];
    state[13] ^= expandedKey[173];
    state[14] ^= expandedKey[174];
    state[15] ^= expandedKey[175];
  
    // 10th round without mixcols
    state[0] = rsbox[state[0]] ^ expandedKey[(round * 16)];
    state[4] = rsbox[state[4]] ^ expandedKey[(round * 16) + 4];
    state[8] = rsbox[state[8]] ^ expandedKey[(round * 16) + 8];
    state[12] = rsbox[state[12]] ^ expandedKey[(round * 16) + 12];
    // row 1
    buf1 = rsbox[state[13]] ^ expandedKey[(round * 16) + 1];
    state[13] = rsbox[state[9]] ^ expandedKey[(round * 16) + 13];
    state[9] = rsbox[state[5]] ^ expandedKey[(round * 16) + 9];
    state[5] = rsbox[state[1]] ^ expandedKey[(round * 16) + 5];
    state[1] = buf1;
    // row 2
    buf1 = rsbox[state[2]] ^ expandedKey[(round * 16) + 10];
    buf2 = rsbox[state[6]] ^ expandedKey[(round * 16) + 14];
    state[2] = rsbox[state[10]] ^ expandedKey[(round * 16) + 2];
    state[6] = rsbox[state[14]] ^ expandedKey[(round * 16) + 6];
    state[10] = buf1;
    state[14] = buf2;
    // row 3
    buf1 = rsbox[state[3]] ^ expandedKey[(round * 16) + 15];
    state[3] = rsbox[state[7]] ^ expandedKey[(round * 16) + 3];
    state[7] = rsbox[state[11]] ^ expandedKey[(round * 16) + 7];
    state[11] = rsbox[state[15]] ^ expandedKey[(round * 16) + 11];
    state[15] = buf1;
  
    for(round = 8; round >= 0; round--) {
      // barreto
      //col1
      buf1 = galois_mul2(galois_mul2(state[0] ^ state[2]));
      buf2 = galois_mul2(galois_mul2(state[1] ^ state[3]));
      state[0] ^= buf1;
      state[1] ^= buf2;
      state[2] ^= buf1;
      state[3] ^= buf2;
      //col2
      buf1 = galois_mul2(galois_mul2(state[4] ^ state[6]));
      buf2 = galois_mul2(galois_mul2(state[5] ^ state[7]));
      state[4] ^= buf1;
      state[5] ^= buf2;
      state[6] ^= buf1;
      state[7] ^= buf2;
      //col3
      buf1 = galois_mul2(galois_mul2(state[8] ^ state[10]));
      buf2 = galois_mul2(galois_mul2(state[9] ^ state[11]));
      state[8] ^= buf1;
      state[9] ^= buf2;
      state[10] ^= buf1;
      state[11] ^= buf2;
      //col4
      buf1 = galois_mul2(galois_mul2(state[12] ^ state[14]));
      buf2 = galois_mul2(galois_mul2(state[13] ^ state[15]));
      state[12] ^= buf1;
      state[13] ^= buf2;
      state[14] ^= buf1;
      state[15] ^= buf2;
      // mixcolums //////////
      // col1
      buf1 = state[0] ^ state[1] ^ state[2] ^ state[3];
      buf2 = state[0];
      buf3 = state[0] ^ state[1];
      buf3 = galois_mul2(buf3);
      state[0] = state[0] ^ buf3 ^ buf1;
      buf3 = state[1] ^ state[2];
      buf3 = galois_mul2(buf3);
      state[1] = state[1] ^ buf3 ^ buf1;
      buf3 = state[2] ^ state[3];
      buf3 = galois_mul2(buf3);
      state[2] = state[2] ^ buf3 ^ buf1;
      buf3 = state[3] ^ buf2;
      buf3 = galois_mul2(buf3);
      state[3] = state[3] ^ buf3 ^ buf1;
      // col2
      buf1 = state[4] ^ state[5] ^ state[6] ^ state[7];
      buf2 = state[4];
      buf3 = state[4] ^ state[5];
      buf3 = galois_mul2(buf3);
      state[4] = state[4] ^ buf3 ^ buf1;
      buf3 = state[5] ^ state[6];
      buf3 = galois_mul2(buf3);
      state[5] = state[5] ^ buf3 ^ buf1;
      buf3 = state[6] ^ state[7];
      buf3 = galois_mul2(buf3);
      state[6] = state[6] ^ buf3 ^ buf1;
      buf3 = state[7] ^ buf2;
      buf3 = galois_mul2(buf3);
      state[7] = state[7] ^ buf3 ^ buf1;
      // col3
      buf1 = state[8] ^ state[9] ^ state[10] ^ state[11];
      buf2 = state[8];
      buf3 = state[8] ^ state[9];
      buf3 = galois_mul2(buf3);
      state[8] = state[8] ^ buf3 ^ buf1;
      buf3 = state[9] ^ state[10];
      buf3 = galois_mul2(buf3);
      state[9] = state[9] ^ buf3 ^ buf1;
      buf3 = state[10] ^ state[11];
      buf3 = galois_mul2(buf3);
      state[10] = state[10] ^ buf3 ^ buf1;
      buf3 = state[11] ^ buf2;
      buf3 = galois_mul2(buf3);
      state[11] = state[11] ^ buf3 ^ buf1;
      // col4
      buf1 = state[12] ^ state[13] ^ state[14] ^ state[15];
      buf2 = state[12];
      buf3 = state[12] ^ state[13];
      buf3 = galois_mul2(buf3);
      state[12] = state[12] ^ buf3 ^ buf1;
      buf3 = state[13] ^ state[14];
      buf3 = galois_mul2(buf3);
      state[13] = state[13] ^ buf3 ^ buf1;
      buf3 = state[14] ^ state[15];
      buf3 = galois_mul2(buf3);
      state[14] = state[14] ^ buf3 ^ buf1;
      buf3 = state[15] ^ buf2;
      buf3 = galois_mul2(buf3);
      state[15] = state[15] ^ buf3 ^ buf1;
  
      // addroundkey, rsbox and shiftrows
      // row 0
      state[0] = rsbox[state[0]] ^ expandedKey[(round * 16)];
      state[4] = rsbox[state[4]] ^ expandedKey[(round * 16) + 4];
      state[8] = rsbox[state[8]] ^ expandedKey[(round * 16) + 8];
      state[12] = rsbox[state[12]] ^ expandedKey[(round * 16) + 12];
      // row 1
      buf1 = rsbox[state[13]] ^ expandedKey[(round * 16) + 1];
      state[13] = rsbox[state[9]] ^ expandedKey[(round * 16) + 13];
      state[9] = rsbox[state[5]] ^ expandedKey[(round * 16) + 9];
      state[5] = rsbox[state[1]] ^ expandedKey[(round * 16) + 5];
      state[1] = buf1;
      // row 2
      buf1 = rsbox[state[2]] ^ expandedKey[(round * 16) + 10];
      buf2 = rsbox[state[6]] ^ expandedKey[(round * 16) + 14];
      state[2] = rsbox[state[10]] ^ expandedKey[(round * 16) + 2];
      state[6] = rsbox[state[14]] ^ expandedKey[(round * 16) + 6];
      state[10] = buf1;
      state[14] = buf2;
      // row 3
      buf1 = rsbox[state[3]] ^ expandedKey[(round * 16) + 15];
      state[3] = rsbox[state[7]] ^ expandedKey[(round * 16) + 3];
      state[7] = rsbox[state[11]] ^ expandedKey[(round * 16) + 7];
      state[11] = rsbox[state[15]] ^ expandedKey[(round * 16) + 11];
      state[15] = buf1;
    }
  
  
  }
  
  // encrypt
  void
  aes_encrypt(unsigned char *state, const unsigned char *key)
  {
    unsigned char expandedKey[176];
  
    expandKey(expandedKey, key);  // expand the key into 176 bytes
    aes_encr(state, expandedKey);
  }
  // decrypt
  void
  aes_decrypt(unsigned char *state, const unsigned char *key)
  {
    unsigned char expandedKey[176];
  
    expandKey(expandedKey, key);  // expand the key into 176 bytes
    aes_decr(state, expandedKey);
  }
  