public int FindBlockSize()
{
var aggregated = new Dictionary <int, float>();
int start = 10;
int end = 32;
int blocks = 4;
for (int i = start; i < end * 3; i++)
{
Base64 encrypted = eo.EncryptConsistentKey(new String('A', i), unknownString);
var keys = HammingDistance.FindDistancePerKeySize(start, end, encrypted.Decode(), blocks);
foreach (var kvp in keys)
{
if (aggregated.ContainsKey(kvp.Key))
{
aggregated[kvp.Key] += kvp.Value;
}
else
{
aggregated.Add(kvp.Key, kvp.Value);
}
}
}
var possibleKey = aggregated.OrderBy(x => x.Value).Take(1);
return(possibleKey.Select(x => x.Key).Single());
}
public void FindDistancePerKeySize()
{
string source = "abcdefghabcdefgh";
int correctKeySize = 8;
int hammingDistance = 0;
var result = HammingDistance.FindDistancePerKeySize(2, 10, source);
Assert.AreEqual(result[correctKeySize], hammingDistance);
}
public void FindDistancePerKeySizeWithInvalidBlockNumber()
{
try
{
string source = "abcdef";
var result = HammingDistance.FindDistancePerKeySize(2, 10, source, 3);
Assert.Fail();
}
catch (ArgumentException)
{
return;
}
}
public string[] BreakXorFile(Base64 data, int startKeySize = 2, int endKeySize = 60, int numberOfBlocks = 2)
{
int take = 10;
Hex source = data;
var possibleKeySizes = HammingDistance.FindDistancePerKeySize(startKeySize, endKeySize, source.ToString(), numberOfBlocks).OrderBy(x => x.Value).Select(x => x.Key).Take(take);
foreach (var possibleKeySize in possibleKeySizes)
{
StringBuilder sb = new StringBuilder();
var transposedBlocks = source.CreateAndTransposeBlocks(possibleKeySize);
var decryptedBlocks = new List <string>();
bool foundOne = false;
foreach (var block in transposedBlocks)
{
var decrypted = this.TryDecrypt(block);
var c = CharacterCounter.FindKey(decrypted);
if (c == '\0')
{
if (foundOne)
{
sb.Append('?');
decryptedBlocks.Add(decrypted['A']);
}
else
{
break;
}
}
else
{
foundOne = true;
sb.Append(c);
decryptedBlocks.Add(decrypted[c]);
}
}
string key = sb.ToString();
if (key.Length > 0)
{
StringBuilder decrypted = new StringBuilder();
for (int i = 0; i < decryptedBlocks[0].Length; i++)
{
foreach (string block in decryptedBlocks)
{
if (i < block.Length)
{
decrypted.Append(block[i]);
}
}
}
return(new string[] { key, decrypted.ToString() });
}
}
return(new string[] { "", "" });
}