// verified
private ListOfDiffPairs GetChosenPlaintexts(UInt64 diff)
{
var result = new ListOfDiffPairs();
var plains = new UInt64[]
{
8293413307042899260,
2417420169597379724,
7391341682234711011,
1294612218368839102,
3427586664725945798,
8120399254031000395,
4954062227563315182,
7287792347285229213,
6369026791565508293,
3497943451105456066,
635651540614717595,
466693664381143020
};
for (var i = 0; i < numberOfPlain; ++i)
{
var firstPlain = randomNumberGenerator.GetNextUInt64();
var secondPlain = firstPlain ^ diff;
var firstCipher = feal4Encryptor.Encrypt(firstPlain, subKeys);
var secondCipher = feal4Encryptor.Encrypt(secondPlain, subKeys);
var first = new PlainCipherPair64(firstPlain, firstCipher);
var second = new PlainCipherPair64(secondPlain, secondCipher);
result.Add(Tuple.Create(first, second));
}
return(result);
}
// 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);
}
// verified
private UInt32 CrackLastRound(UInt32 outDiff, ListOfDiffPairs chosenPlaintexts)
{
Console.WriteLine("CRACK LAST ROUND");
for (UInt32 fakeK = 0; ; ++fakeK)
{
var score = GetScore(outDiff, chosenPlaintexts, fakeK);
if (score == numberOfPlain)
{
return(fakeK);
}
if (fakeK == UInt32.MaxValue)
{
break;
}
}
throw new ArgumentException();
}
// verified
private static int GetScore(UInt32 outDiff, ListOfDiffPairs chosenPlaintexts,
UInt32 fakeK32)
{
var score = 0;
for (var i = 0; i < numberOfPlain; ++i)
{
var cipherLeft = Feal4Helper.GetLeftHalf(chosenPlaintexts[i].Item1.Cipher) ^
Feal4Helper.GetLeftHalf(chosenPlaintexts[i].Item2.Cipher);
var cipherRight = Feal4Helper.GetRightHalf(chosenPlaintexts[i].Item1.Cipher) ^
Feal4Helper.GetRightHalf(chosenPlaintexts[i].Item2.Cipher);
var y = cipherRight;
var z = cipherLeft ^ outDiff;
var firstFakeLeft =
Feal4Helper.GetLeftHalf(chosenPlaintexts[i].Item1.Cipher);
var firstFakeRight =
Feal4Helper.GetRightHalf(chosenPlaintexts[i].Item1.Cipher);
var secondFakeLeft =
Feal4Helper.GetLeftHalf(chosenPlaintexts[i].Item2.Cipher);
var secondFakeRight =
Feal4Helper.GetRightHalf(chosenPlaintexts[i].Item2.Cipher);
var y0 = firstFakeRight;
var y1 = secondFakeRight;
var fakeInput0 = y0 ^ fakeK32;
var fakeInput1 = y1 ^ fakeK32;
var fakeOut0 = Feal4Helper.Fbox(fakeInput0);
var fakeOut1 = Feal4Helper.Fbox(fakeInput1);
var fakeDiff = fakeOut0 ^ fakeOut1;
if (fakeDiff == z)
{
++score;
}
else
{
break;
}
}
return(score);
}
// 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);
}