private byte[] InverseSecondRound(byte[] cipherText, byte[] roundKey)
{
var inversedRoundKey = Aes16Helper.AddRoundKey(cipherText, roundKey);
var inversedShiftRow = Aes16Helper.ShiftRow(inversedRoundKey);
var inversedNibbleSubstitution = Aes16Helper.InverseNibbleSubstitution(inversedShiftRow);
return(inversedNibbleSubstitution);
}
private byte[] InverseFirstRound(byte[] firstRoundCipherText, byte[] roundKey)
{
var inversedRoundKey = Aes16Helper.AddRoundKey(firstRoundCipherText, roundKey);
var inversedMixColumns = Aes16Helper.InverseMixColumns(inversedRoundKey);
var inversedShiftRow = Aes16Helper.ShiftRow(inversedMixColumns);
var inversedNibbleSubstitution = Aes16Helper.InverseNibbleSubstitution(inversedShiftRow);
return(inversedNibbleSubstitution);
}
private byte[] GetFirstRoundResult(byte[] zeroRoundResult, byte[] roundKey)
{
// Nibble substitution
var nibbled = Aes16Helper.NibbleSubstitution(zeroRoundResult);
// Shift row
var shiftedRowBytes = Aes16Helper.ShiftRow(nibbled);
var mixedBytes = Aes16Helper.MixColumns(shiftedRowBytes);
return(Aes16Helper.AddRoundKey(new[] { mixedBytes[0], mixedBytes[1] }, roundKey));
}
