/*********** First Letters Attack ************/
// TODO: ostatní jazyky nemají TopWords!!!
private List<string> FirstLettersAttack(string ciphertext, Storage.Languages language)
{
var keyLengths = GetKeyLengths(ciphertext);
int minWordLength = 3;
int testStringLength = 20;
double minSuccess = (double)20 / (double)1300;
foreach (int keyLength in keyLengths)
{
if (keyLength < 10)
continue;
string[] columns = GetDecryptColumns(ciphertext, keyLength);
string[] rows = GetRows(columns);
string[] sentence = rows.Take((int)Math.Ceiling((double)testStringLength / (double)keyLength)).ToArray();
var lang = Storage.GetLangChar(language);
DictionaryAttack firstAttack = new DictionaryAttack();
string[] topWords = lang.TopWords.Where(x => x.Length >= minWordLength).ToArray();
string[] topTopWords = topWords.Take(100).ToArray();
var keys = firstAttack.CrossFilter(sentence, topWords);
var opentexts = new string[keys.Length];
for (int i = 0; i < keys.Length; i++)
opentexts[i] = Decrypt(ciphertext, keys[i]);
Dictionary<string, int> probabilities = new Dictionary<string, int>();
for (int i = 0; i < keys.Length; i++)
probabilities[keys[i]] = Analyse.WordsContains(opentexts[i], topTopWords);
var resultKeys = probabilities.OrderByDescending(x => x.Value).ToDictionary(x => x.Key, x => x.Value);
var isthere = opentexts.Where(x => x.Contains("oznamenipodala")).Count() == 1;
if(resultKeys.Count > 0 && ((double)resultKeys.First().Value / (double)1300) > minSuccess)
return resultKeys.Take(10).Select(x => x.Key).ToList();
}
throw new Exceptions.MatchNotFound();
}
/*********************************************/
/*********** One big word attack *************/
/*********************************************/
private List<string> BigWordAttack(string ciphertext, Storage.Languages language)
{
ciphertext = Analyse.NormalizeText(ciphertext, Analyse.TextTypes.WithoutSpacesLower);
var keyLengths = GetKeyLengths(ciphertext);
LangCharacteristic lang = Storage.GetLangChar(language);
List<string> possKeys = new List<string>();
foreach (int keyLength in keyLengths)
{
string[] columns = GetDecryptColumns(ciphertext, keyLength);
string[] rows = GetRows(columns);
DictionaryAttack attack = new DictionaryAttack();
string[] keys = attack.GetKeys(rows, lang.TopWords);
string[] orderedKeys = OrderKeys(keys, ciphertext, lang);
if (orderedKeys.Length > 0)
possKeys.Add(orderedKeys[0]);
}
if (possKeys.Count > 0)
{
string[] finalKeys = OrderKeys(possKeys.ToArray(), ciphertext, lang);
return finalKeys.ToList();
}
throw new Exceptions.MatchNotFound();
}
/*********** test key length attack *******************/
private List<string> TestKeyLength(string ciphertext, Storage.Languages language)
{
int averageKeyLength = 10;
int minSentenceLength = 40;
var keyLengths = Maths.AllDivisors(ciphertext.Length);
var orderKeyLengths = keyLengths.OrderBy(x => Math.Abs(x - averageKeyLength)).ToArray();
foreach (int keyLength in orderKeyLengths)
{
string[] columns = GetDecryptColumns(ciphertext, keyLength);
string sentence = GetOpentext(columns).Take(minSentenceLength);
var lang = Storage.GetLangChar(language);
DictionaryAttack attack = new DictionaryAttack(lang.Dictionary, lang.SortedDictionary);
attack.Start(sentence, keyLength);
}
return new List<string>() { "abc" };
}
