/// <summary>
/// Generates the round constants using GF(2^8) arithmetic.
/// </summary>
/// <returns> The round constants. </returns>
public static byte[] generateRoundConstants() //creates the round constants used in the key generation
{
byte[] constants = new byte[ROUNDS - 1]; //the first round uses the 128 bit key so no constant for that.
constants[0] = 1;
for (int ii = 1; ii < constants.Length; ii++)
{
constants[ii] = GF_TABLE.multiply(constants[ii - 1], 0x02);
}
return(constants);
}
/// <summary>
/// Conducts the mixColumns step of the AES algorithm. Now Deprecated
/// </summary>
public void mixColumns()
{
byte[] newBytes = new byte[SIZE];
for (int ii = 0; ii < newBytes.Length; ii++)
{ //2, 3, 1, 1 are hard-coded into the algorithm for the GF(2^8) multiplication here.
newBytes[ii] = (byte)(GFBox.multiply(2, bytes[startValue + ii]) ^
GFBox.multiply(3, bytes[startValue + WORD_LENGTH * (ii / WORD_LENGTH) + (ii + 1) % WORD_LENGTH]) ^
bytes[startValue + WORD_LENGTH * (ii / WORD_LENGTH) + (ii + 2) % WORD_LENGTH] ^
bytes[startValue + WORD_LENGTH * (ii / WORD_LENGTH) + (ii + 3) % WORD_LENGTH]);
}
Array.Copy(newBytes, 0, bytes, startValue, SIZE);
}