#ifndef aes_h
#define aes_h

#define KEY_COUNT 1

#if KEY_COUNT > 0

#define BPOLY 0x1b //!< Lower 8 bits of (x^8+x^4+x^3+x+1), ie. (x^4+x^3+x+1).
#define BLOCKSIZE 16 //!< Block size in number of bytes.

#if KEY_COUNT == 1
#define KEYBITS 128 //!< Use AES128.
#elif KEY_COUNT == 2
#define KEYBITS 192 //!< Use AES196.
#elif KEY_COUNT == 3
#define KEYBITS 256 //!< Use AES256.
#else
#error Use 1, 2 or 3 keys!
#endif

#if KEYBITS == 128
#define ROUNDS 10 //!< Number of rounds.
#define KEYLENGTH 16 //!< Key length in number of bytes.
#elif KEYBITS == 192
#define ROUNDS 12 //!< Number of rounds.
#define KEYLENGTH 24 //!< // Key length in number of bytes.
#elif KEYBITS == 256
#define ROUNDS 14 //!< Number of rounds.
#define KEYLENGTH 32 //!< Key length in number of bytes.
#else
#error Key must be 128, 192 or 256 bits!
#endif

#define EXPANDED_KEY_SIZE (BLOCKSIZE * (ROUNDS+1)) //!< 176, 208 or 240 bytes.


const char kTable[KEYBITS/8] = {0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11
};


#define INITIALVECTOR_3 0x00112233
#define INITIALVECTOR_2 0x44556677
#define INITIALVECTOR_1 0x8899AABB
#define INITIALVECTOR_0 0xCCDDEEFF

unsigned char block1[ 256 ]; //!< Workspace 1.
unsigned char block2[ 256 ]; //!< Worksapce 2.
unsigned char tempbuff[ 256 ]; //


unsigned char *powTbl; //!< Final location of exponentiation lookup table.
unsigned char *logTbl; //!< Final location of logarithm lookup table.
unsigned char *sBox; //!< Final location of s-box.
unsigned char *sBoxInv; //!< Final location of inverse s-box.
unsigned char *expandedKey; //!< Final location of expanded key.

unsigned char chainCipherBlock[16];// Buffer for Cipher Block


#endif

#endif //aes_h

void CalcPowLog( unsigned char * powTbl, unsigned char * logTbl )
{
unsigned char i = 0;
unsigned char t = 1;

do {
// Use 0x03 as root for exponentiation and logarithms.
powTbl[i] = t;
logTbl[t] = i;
i++;

// Muliply t by 3 in GF(2^8).
t ^= (t << 1) ^ (t & 0x80 ? BPOLY : 0);
} while( t != 1 ); // Cyclic properties ensure that i < 255.

powTbl[255] = powTbl[0]; // 255 = '-0', 254 = -1, etc.
}



void CalcSBox( unsigned char * sBox )
{
unsigned char i, rot;
unsigned char temp;
unsigned char result;

// Fill all entries of sBox[].
i = 0;
do {
// Inverse in GF(2^8).
if( i > 0 ) {
temp = powTbl[ 255 - logTbl[i] ];
} else {
temp = 0;
}

// Affine transformation in GF(2).
result = temp ^ 0x63; // Start with adding a vector in GF(2).
for( rot = 0; rot < 4; rot++ ) {
// Rotate left.
temp = (temp<<1) | (temp>>7);

// Add rotated byte in GF(2).
result ^= temp;
}

// Put result in table.
sBox[i] = result;
} while( ++i != 0 );
}



void CalcSBoxInv( unsigned char * sBox, unsigned char * sBoxInv )
{
unsigned char i = 0;
unsigned char j = 0;

// Iterate through all elements in sBoxInv using i.
do {
// Search through sBox using j.
do {
// Check if current j is the inverse of current i.
if( sBox[ j ] == i ) {
// If so, set sBoxInc and indicate search finished.
sBoxInv[ i ] = j;
j = 255;
}
} while( ++j != 0 );
} while( ++i != 0 );
}



void CycleLeft( unsigned char * row )
{
// Cycle 4 bytes in an array left once.
unsigned char temp = row[0];
row[0] = row[1];
row[1] = row[2];
row[2] = row[3];
row[3] = temp;
}



void InvMixColumn( unsigned char * column )
{
unsigned char r0, r1, r2, r3;

r0 = column[1] ^ column[2] ^ column[3];
r1 = column[0] ^ column[2] ^ column[3];
r2 = column[0] ^ column[1] ^ column[3];
r3 = column[0] ^ column[1] ^ column[2];

column[0] = (column[0] << 1) ^ (column[0] & 0x80 ? BPOLY : 0);
column[1] = (column[1] << 1) ^ (column[1] & 0x80 ? BPOLY : 0);
column[2] = (column[2] << 1) ^ (column[2] & 0x80 ? BPOLY : 0);
column[3] = (column[3] << 1) ^ (column[3] & 0x80 ? BPOLY : 0);

r0 ^= column[0] ^ column[1];
r1 ^= column[1] ^ column[2];
r2 ^= column[2] ^ column[3];
r3 ^= column[0] ^ column[3];

column[0] = (column[0] << 1) ^ (column[0] & 0x80 ? BPOLY : 0);
column[1] = (column[1] << 1) ^ (column[1] & 0x80 ? BPOLY : 0);
column[2] = (column[2] << 1) ^ (column[2] & 0x80 ? BPOLY : 0);
column[3] = (column[3] << 1) ^ (column[3] & 0x80 ? BPOLY : 0);

r0 ^= column[0] ^ column[2];
r1 ^= column[1] ^ column[3];
r2 ^= column[0] ^ column[2];
r3 ^= column[1] ^ column[3];

column[0] = (column[0] << 1) ^ (column[0] & 0x80 ? BPOLY : 0);
column[1] = (column[1] << 1) ^ (column[1] & 0x80 ? BPOLY : 0);
column[2] = (column[2] << 1) ^ (column[2] & 0x80 ? BPOLY : 0);
column[3] = (column[3] << 1) ^ (column[3] & 0x80 ? BPOLY : 0);

column[0] ^= column[1] ^ column[2] ^ column[3];
r0 ^= column[0];
r1 ^= column[0];
r2 ^= column[0];
r3 ^= column[0];

column[0] = r0;
column[1] = r1;
column[2] = r2;
column[3] = r3;
}



void SubBytes( unsigned char * bytes, unsigned char count )
{
do {
*bytes = sBox[ *bytes ]; // Substitute every byte in state.
bytes++;
} while( --count );
}



void InvSubBytesAndXOR( unsigned char * bytes, unsigned char * key, unsigned char count )
{
do {
// *bytes = sBoxInv[ *bytes ] ^ *key; // Inverse substitute every byte in state and add key.
*bytes = block2[ *bytes ] ^ *key; // Use block2 directly. Increases speed.
bytes++;
key++;
} while( --count );
}



void InvShiftRows( unsigned char * state )
{
unsigned char temp;

// Note: State is arranged column by column.

// Cycle second row right one time.
temp = state[ 1 + 3*4 ];
state[ 1 + 3*4 ] = state[ 1 + 2*4 ];
state[ 1 + 2*4 ] = state[ 1 + 1*4 ];
state[ 1 + 1*4 ] = state[ 1 + 0*4 ];
state[ 1 + 0*4 ] = temp;

// Cycle third row right two times.
temp = state[ 2 + 0*4 ];
state[ 2 + 0*4 ] = state[ 2 + 2*4 ];
state[ 2 + 2*4 ] = temp;
temp = state[ 2 + 1*4 ];
state[ 2 + 1*4 ] = state[ 2 + 3*4 ];
state[ 2 + 3*4 ] = temp;

// Cycle fourth row right three times, ie. left once.
temp = state[ 3 + 0*4 ];
state[ 3 + 0*4 ] = state[ 3 + 1*4 ];
state[ 3 + 1*4 ] = state[ 3 + 2*4 ];
state[ 3 + 2*4 ] = state[ 3 + 3*4 ];
state[ 3 + 3*4 ] = temp;
}



void InvMixColumns( unsigned char * state )
{
InvMixColumn( state + 0*4 );
InvMixColumn( state + 1*4 );
InvMixColumn( state + 2*4 );
InvMixColumn( state + 3*4 );
}



void XORBytes( unsigned char * bytes1, unsigned char * bytes2, unsigned char count )
{
do {
*bytes1 ^= *bytes2; // Add in GF(2), ie. XOR.
bytes1++;
bytes2++;
} while( --count );
}



void CopyBytes( unsigned char * to, unsigned char * from, unsigned char count )
{
do {
*to = *from;
to++;
from++;
} while( --count );
}



void KeyExpansion( unsigned char * expandedKey )
{
unsigned char temp[4];
unsigned char i;
unsigned char Rcon[4] = { 0x01, 0x00, 0x00, 0x00 }; // Round constant.

const char * key = kTable;

// Copy key to start of expanded key.
i = KEYLENGTH;
do {
*expandedKey = *key;
expandedKey++;
key++;
} while( --i );

// Prepare last 4 bytes of key in temp.
expandedKey -= 4;
temp[0] = *(expandedKey++);
temp[1] = *(expandedKey++);
temp[2] = *(expandedKey++);
temp[3] = *(expandedKey++);

// Expand key.
i = KEYLENGTH;
while( i < BLOCKSIZE*(ROUNDS+1) ) {
// Are we at the start of a multiple of the key size?
if( (i % KEYLENGTH) == 0 ) {
CycleLeft( temp ); // Cycle left once.
SubBytes( temp, 4 ); // Substitute each byte.
XORBytes( temp, Rcon, 4 ); // Add constant in GF(2).
*Rcon = (*Rcon << 1) ^ (*Rcon & 0x80 ? BPOLY : 0);
}

// Keysize larger than 24 bytes, ie. larger that 192 bits?
#if KEYLENGTH > 24
// Are we right past a block size?
else if( (i % KEYLENGTH) == BLOCKSIZE ) {
SubBytes( temp, 4 ); // Substitute each byte.
}
#endif

// Add bytes in GF(2) one KEYLENGTH away.
XORBytes( temp, expandedKey - KEYLENGTH, 4 );

// Copy result to current 4 bytes.
*(expandedKey++) = temp[ 0 ];
*(expandedKey++) = temp[ 1 ];
*(expandedKey++) = temp[ 2 ];
*(expandedKey++) = temp[ 3 ];

i += 4; // Next 4 bytes.
}
}



void InvCipher( unsigned char * block, unsigned char * expandedKey )
{
unsigned char round = ROUNDS-1;
expandedKey += BLOCKSIZE * ROUNDS;

XORBytes( block, expandedKey, 16 );
expandedKey -= BLOCKSIZE;

do {
InvShiftRows( block );
InvSubBytesAndXOR( block, expandedKey, 16 );
expandedKey -= BLOCKSIZE;
InvMixColumns( block );
} while( --round );

InvShiftRows( block );
InvSubBytesAndXOR( block, expandedKey, 16 );
}



void aesInit( unsigned char * tempbuf )
{
powTbl = block1;
logTbl = block2;
CalcPowLog( powTbl, logTbl );

sBox = tempbuf;
CalcSBox( sBox );

expandedKey = block1;
KeyExpansion( expandedKey );

sBoxInv = block2; // Must be block2.
CalcSBoxInv( sBox, sBoxInv );
}



void aesDecrypt( unsigned char * buffer, unsigned char * chainBlock )
{
unsigned char temp[ BLOCKSIZE ];

CopyBytes( temp, buffer, BLOCKSIZE );
InvCipher( buffer, expandedKey );
XORBytes( buffer, chainBlock, BLOCKSIZE );
CopyBytes( chainBlock, temp, BLOCKSIZE );
}