// verified
private static ListOfDiffPairs UndoLastRound(ListOfDiffPairs diffPairs, UInt32 subKey)
{
var result = new ListOfDiffPairs();
for (var i = 0; i < numberOfPlain; ++i)
{
UInt32 firstCipherLeft = Feal4Helper.GetLeftHalf(diffPairs[i].Item1.Cipher);
UInt32 firstCipherRight = Feal4Helper.GetRightHalf(diffPairs[i].Item1.Cipher);
UInt32 secondCipherLeft = Feal4Helper.GetLeftHalf(diffPairs[i].Item2.Cipher);
UInt32 secondCipherRight = Feal4Helper.GetRightHalf(diffPairs[i].Item2.Cipher);
firstCipherLeft = firstCipherRight;
secondCipherLeft = secondCipherRight;
firstCipherRight = Feal4Helper.Fbox(firstCipherLeft ^ subKey) ^ (Feal4Helper.GetLeftHalf(diffPairs[i].Item1.Cipher));
secondCipherRight = Feal4Helper.Fbox(secondCipherLeft ^ subKey) ^ (Feal4Helper.GetLeftHalf(diffPairs[i].Item2.Cipher));
var firstObj = new PlainCipherPair <UInt64>(diffPairs[i].Item1.Plain,
Feal4Helper.Combine32BitHalfs(firstCipherLeft, firstCipherRight));
var secondObj = new PlainCipherPair <UInt64>(diffPairs[i].Item2.Plain,
Feal4Helper.Combine32BitHalfs(secondCipherLeft, secondCipherRight));
result.Add(Tuple.Create(firstObj, secondObj));
}
return(result);
}
public void TestCombine32BitHalfs()
{
const UInt32 leftHalf = 0b11010101111111110110101000001000;
const UInt32 rightHalf = 0b00010000010101101111111110101011;
const UInt64 expectedResult = 0b1101010111111111011010100000100000010000010101101111111110101011;
Feal4Helper.Combine32BitHalfs(leftHalf, rightHalf).Should().Be(expectedResult);
}
// verified
private ListOfDiffPairs UndoFinalOperation(ListOfDiffPairs data)
{
var result = new ListOfDiffPairs();
foreach (var item in data)
{
var firstLeftCipher = Feal4Helper.GetLeftHalf(item.Item1.Cipher);
var firstRightCipher = Feal4Helper.GetRightHalf(item.Item1.Cipher) ^ firstLeftCipher;
var secondLeftCipher = Feal4Helper.GetLeftHalf(item.Item2.Cipher);
var secondRightCipher = Feal4Helper.GetRightHalf(item.Item2.Cipher) ^ secondLeftCipher;
var firstRecombined = Feal4Helper.Combine32BitHalfs(firstLeftCipher, firstRightCipher);
var secondRecombined = Feal4Helper.Combine32BitHalfs(secondLeftCipher, secondRightCipher);
var firstObj = new PlainCipherPair64(item.Item1.Plain, firstRecombined);
var secondObj = new PlainCipherPair64(item.Item2.Plain, secondRecombined);
result.Add(Tuple.Create(firstObj, secondObj));
}
return(result);
}