public static void Do()
{
Console.WriteLine($"SPN: rounds {SubstitutionPermutationNetwork.RoundsCount}, blocksize {SubstitutionPermutationNetwork.BlockSizeBytes * 8 } bits");
var expectedKey = SubstitutionPermutationNetwork.GenerateRandomKey();
Console.WriteLine($"key: {expectedKey.ToHexUpperCase()}");
var spn = new SubstitutionPermutationNetwork(expectedKey);
var plainTextString = new string('X', SubstitutionPermutationNetwork.BlockSizeBytes);
var plainText = Encoding.ASCII.GetBytes(plainTextString);
var encryptedBytes = spn.EncryptBlock(plainText);
var decryptedBytes = spn.DecryptBlock(encryptedBytes);
var decryptedString = Encoding.ASCII.GetString(decryptedBytes);
Console.WriteLine($"{plainTextString} -> {encryptedBytes.ToHexUpperCase()} -> {decryptedString}");
HackCipher(spn, expectedKey, 6000);
}
static void Main(string[] args)
{
// ProofOfConecpt.Do();
// return;
if (args.Length < 1)
{
Console.WriteLine("Usage: sploit.exe <fileToDecrypt> [expectedKey]");
Environment.Exit(1);
}
var expectedKey = args.Length >= 2 ? File.ReadAllBytes(args[1]) : new byte[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
byte[] imageBytes;
try
{
imageBytes = File.ReadAllBytes(args[0]);
}
catch (Exception e)
{
Console.WriteLine($"Can't read data from file {args[0]}", e);
Environment.Exit(1);
return;
}
var spn = new SubstitutionPermutationNetwork(SubstitutionPermutationNetwork.GenerateRandomKey());
var pairs = GeneratePlainEncryptedPairs(imageBytes);
var plains = pairs.Select(tuple => tuple.Item1).ToArray();
var encs = pairs.Select(tuple => tuple.Item2).ToArray();
var linearCryptoanalysis = new LinearCryptoanalysis(spn);
var bestLayerApproximations = linearCryptoanalysis.ChooseBestPathsStartingFromSingleSBoxInRound0(Exploit.maxSBoxesInLastRound, Exploit.maxSBoxesInRound, Exploit.thresholdBias).ToList();
Console.WriteLine($"Total approximations: {bestLayerApproximations.Count}");
var solutions = new List <Solution>();
foreach (var approximationsGroup in bestLayerApproximations
.Where(layer => layer.round0sboxNum % 8 == 3 || (layer.round0sboxNum % 8 == 4 && ((layer.round0x & 0x01) == 0)))
.GroupBy(layer => layer.ActivatedSboxesNums.Aggregate("", (s, num) => s + num))
.OrderBy(group => group.Key))
{
foreach (var approximation in approximationsGroup.Distinct().OrderByDescending(layer => layer.inputProbability.Bias()).Take(6))
{
solutions.AddRange(Exploit.HackApproximation(plains, encs, approximation, expectedKey));
}
}
var solutionsDict = Exploit.OrderSolutions(solutions, expectedKey);
var imageLength = imageBytes.Length - SubstitutionPermutationNetwork.GenerateRandomIV().Length;
if (imageLength >= 65536)
{
throw new Exception("Unexpected image ciphertext length");
}
Console.WriteLine("\nBruting left bits..");
var plaintextPrefixFrom4 = new byte[] { 0, 0, 0, 0, 0, 0, 0x36, 0, 0, 0 };
var hackedKey = GetFinalSolution(solutionsDict, imageBytes.Take(24).ToArray(), plaintextPrefixFrom4);
if (hackedKey != null)
{
Console.WriteLine($"\nHACKED KEY: {hackedKey.ToHexUpperCase()}");
}
else
{
Console.WriteLine("BAD LUCK. Key not hacked");
}
}
public static List <Solution> HackApproximation(byte[][] plains, byte[][] encs, Layer bestLayerApproximation, byte[] expectedKey)
{
int iterationsCount = plains.Length;
Console.WriteLine($"\nBEST OPTION: round0sboxNum {bestLayerApproximation.round0sboxNum}\tround0x {bestLayerApproximation.round0x}\tround0y {bestLayerApproximation.round0y}\tbias {bestLayerApproximation.inputProbability.Bias()}\toutSBoxes {string.Join(",", bestLayerApproximation.ActivatedSboxesNums)}\tLastRoundInputBits {SubstitutionPermutationNetwork.GetBitString(bestLayerApproximation.inputBits)}");
var targetPartialSubkeys = GenerateTargetPartialSubkeys(bestLayerApproximation.ActivatedSboxesNums)
.Select(targetPartialSubkey => (targetPartialSubkey, SubstitutionPermutationNetwork.GetBytesBigEndian(targetPartialSubkey)))
.ToList();
var keyProbabilities = targetPartialSubkeys
.ToDictionary(u => u.Item1, u => 0);
var hackingSubstitutionPermutationNetwork = new SubstitutionPermutationNetwork(SubstitutionPermutationNetwork.GenerateRandomKey());
for (int i = 0; i < plains.Length; i++)
{
if (i > 0 && i % (plains.Length / 4) == 0)
{
Console.WriteLine($" done {i} iterations of {iterationsCount}");
}
var plain = plains[i];
var enc = encs[i];
HackIteration(plain, enc, bestLayerApproximation.round0sboxNum, bestLayerApproximation.round0x, bestLayerApproximation.inputBits, targetPartialSubkeys, hackingSubstitutionPermutationNetwork, keyProbabilities);
}
return(GetSolutions(bestLayerApproximation, keyProbabilities, expectedKey, iterationsCount));
}