static void OpenMode(Mode mode)
{
using (StreamReader inReader = new StreamReader("in.txt"))
{
string openText = inReader.ReadLine();
using (StreamReader keyReader = new StreamReader(mode.ToString() + "\\" + "key.txt"))
{
IEncoder encoder;
try
{
switch (mode)
{
case Mode.Affine:
int a, b;
ReadAffineKeys(keyReader, out a, out b);
encoder = new AffineCipher(a, b);
break;
case Mode.Simple:
Dictionary <char, char> alphabet = ReadTable(keyReader);
encoder = new SimpleSubstitutionCipher(alphabet);
break;
default:
string keyWord = ReadKeyWord(keyReader);
encoder = new VigenereCipher(keyWord);
break;
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
return;
}
string cipher = encoder.EncryptText(openText);
using (StreamWriter cryptWriter = new StreamWriter(mode.ToString() + "\\" + "crypt.txt"))
{
cryptWriter.WriteLine(cipher);
}
string decryptText = encoder.DecryptText(cipher);
using (StreamWriter decryptWriter = new StreamWriter(mode.ToString() + "\\" + "decrypt.txt"))
{
decryptWriter.WriteLine(decryptText);
}
}
}
}
public string Analyze()
{
List <char> bestKey = FrequencySortedAlphabet(cipherText);
SimpleSubstitutionCipher cipher = new SimpleSubstitutionCipher(sortedAlphabet, bestKey);
string decryptedText = cipher.DecryptText(cipherText);
double score = NgramStatistics.CountTextScore(decryptedText);
for (int k = 0; k < 7; k++)
{
Random random = new Random();
parentKey = alphabet.Shuffle(random).ToList();
cipher = new SimpleSubstitutionCipher(alphabet, parentKey);
string text = cipher.DecryptText(cipherText);
rate = NgramStatistics.CountTextScore(text);
for (int t = 0; t < times; t++)
{
List <char> key = alphabet.Shuffle(random).ToList();
cipher = new SimpleSubstitutionCipher(alphabet, key);
string nextText = cipher.DecryptText(cipherText);
double currentRate = NgramStatistics.CountTextScore(nextText);
if (currentRate > rate)
{
parentKey = key;
text = nextText;
rate = currentRate;
for (int fail = 0; fail < 10000;)
{
int i = random.Next(alphabet.Count),
j = random.Next(alphabet.Count);
List <char> newKey = parentKey.Swap(i, j).ToList();
cipher = new SimpleSubstitutionCipher(alphabet, newKey);
string newText = cipher.DecryptText(cipherText);
double newRate = NgramStatistics.CountTextScore(newText);
if (newRate > rate)
{
parentKey = newKey;
text = newText;
rate = newRate;
fail = 0;
}
else
{
fail++;
}
}
}
}
if (rate > score)
{
score = rate;
decryptedText = text;
bestKey = parentKey;
}
}
return(decryptedText);
}
