public void Challenge06_BreakRepeatingXOR()
{
//Console.WriteLine(Utils.GetHammingDistance(Encoding.UTF8.GetBytes("this is a test"),
// Encoding.UTF8.GetBytes("wokka wokka!!!")));
var base64 = File.ReadAllText("6.txt").Replace("\n", "");
var cipher = Convert.FromBase64String(base64);
var len = Xor.GuessRepeatingKeyLength(cipher, 40);
var key = Xor.BreakRepeating(cipher, len);
Assert.Equal("Terminator X: Bring the noise", Encoding.UTF8.GetString(key));
//Console.WriteLine($"Password:\"{Encoding.UTF8.GetString(key)}\"");
//Console.WriteLine(Set1.XORDecrypt(cipher, key));
}
public void Challenge20_Fixed_Nonce_CTR_Statistically()
{
var(encryptedLines, plainTextLines) = ReadAndEncryptWithCTR("20.txt", 0);
var minLength = encryptedLines.Min(x => x.Length);
var maxLength = encryptedLines.Max(x => x.Length);
var expectedChars = "0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM-'\".,:;!? /";
var keystream = new List <byte>(maxLength);
for (int i = minLength; i <= maxLength; ++i)
{
var cipher = encryptedLines.Where(x => x.Length >= i)
.Select(x => x.Take(i))
.SelectMany(x => x)
.ToArray();
var key = Xor.BreakRepeating(cipher, i, expectedChars);
if (i == minLength)
{
keystream.AddRange(key);
}
else
{
keystream.Add(key[i - 1]);
}
}
for (int j = 0; j < encryptedLines.Count; j++)
{
byte[] encryptedLine = encryptedLines[j];
var line = new char[encryptedLine.Length];
for (int i = 0; i < line.Length; ++i)
{
line[i] = Convert.ToChar((byte)(encryptedLine[i] ^ keystream[i]));
}
var decryptedLowerCase = new string(line).ToLowerInvariant();
var originalLowerCase = plainTextLines[j].ToLowerInvariant();
switch (j)
{
case 21:
// shake 'till your clear, make it disappear, make the next / after the ceremony, let the rhyme rest in peace
Assert.Equal("shake 'till your clear, make it disappear, make the next / after the ceremony, let the rhyme rest iy peace", decryptedLowerCase);
break;
case 26:
Assert.Equal(new string(originalLowerCase.Replace("observe", "observr").SkipLast(12).ToArray()), new string(decryptedLowerCase.SkipLast(12).ToArray()));
break;
case 29:
// program into the speed of the rhyme, prepare to start / rhythm's out of the radius, insane as the craziest
Assert.Equal("program into the speed of the rhyme, prepare to start / rhythm's out of the radius, insane as the ceaziest", decryptedLowerCase);
break;
case 41:
// i wanna hear some of them def rhymes, you know what i'm sayin'? / and together, we can get paid in full
Assert.Equal("i wanna hear some of them def rhymes, you know what i'm sayin'? / and together, we can get paid in qull", decryptedLowerCase);
break;
case 46:
Assert.Equal(new string(originalLowerCase.Replace("move", "mxve").SkipLast(10).ToArray()), new string(decryptedLowerCase.SkipLast(10).ToArray()));
break;
default:
Assert.Equal(originalLowerCase, decryptedLowerCase);
break;
}
}
}
