private int GuessKeySize(byte[] data)
{
var results = new List <KeySizeDistance>();
for (int keySizeGuess = MinKeySize; keySizeGuess <= MaxKeySize; keySizeGuess++)
{
var blocks = data.Chunks(keySizeGuess).ToArray();
var distances = new List <double>();
for (int block = 0; block < NumBlocksToAverage; block++)
{
var b1 = blocks[block].ToArray();
var b2 = blocks[block + 1].ToArray();
var distance = HammingCalculator.CalculateHammingDistance(b1, b2);
var normalized = (double)distance / keySizeGuess;
distances.Add(normalized);
}
if (distances.Count > 0)
{
var average = distances.Average();
results.Add(new KeySizeDistance(keySizeGuess, average));
}
}
var ordered = results.OrderBy(x => x.Distance).ToArray();
return(ordered.First().KeySize);
}
public void Test()
{
var a = "this is a test";
var b = "wokka wokka!!!";
var expectedDistance = 37;
var actualDistance = HammingCalculator.CalculateHammingDistance(a, b);
Assert.AreEqual(expectedDistance, actualDistance);
}
public void Test1()
{
var a = "a";
var b = "b";
var expectedDistance = 2;
var actualDistance = HammingCalculator.CalculateHammingDistance(a, b);
Assert.AreEqual(expectedDistance, actualDistance);
a = "c";
b = "d";
expectedDistance = 3;
actualDistance = HammingCalculator.CalculateHammingDistance(a, b);
Assert.AreEqual(expectedDistance, actualDistance);
}
public void Test2()
{
var a = "Ram";
var b = "Rom";
var expectedDistance = 3;
var actualDistance = HammingCalculator.CalculateHammingDistance(a, b);
Assert.AreEqual(expectedDistance, actualDistance);
a = "mam";
b = "man";
expectedDistance = 2;
actualDistance = HammingCalculator.CalculateHammingDistance(a, b);
Assert.AreEqual(expectedDistance, actualDistance);
}