public static CipherPredictionDictionary KnownWordPrediction(int[] data, string word)
{
const double PROBABILITY_PER_CHAR = 0.0625;
var pd = new CipherPredictionDictionary();
int wstart = FindWord(data, word);
if (wstart == -1)
{
return(pd);
}
for (int i = wstart; i - wstart < word.Length; i++)
{
pd.Add(data[i]).Add(word[i - wstart], PROBABILITY_PER_CHAR * word.Length);
}
return(pd);
}
public static CipherPredictionDictionary AggregateProbabilities(IEnumerable <CipherPredictionDictionary> dicts, IEnumerable <int> codelist)
{
CipherPredictionDictionary final = new CipherPredictionDictionary(codelist.Count());
foreach (int code in codelist) //for all possible codes
{
//initialize a new entry for this code
CipherPossibilities curP = final.Add(code);
foreach (CipherPredictionDictionary dict in dicts) //for all available dictionaries
{
CipherPossibilities p = dict.GetPossibilitiesForCode(code); //check if it contains possibilities for the code we're looking for
if (p != null)
{
curP.Assimilate(p); //if so, assimilate it
}
}
}
return(final);
}
public static CipherPredictionDictionary FirstLetterPrediction(int[] data, int spaceCode)
{
const double PROBABILITY_COEFFICIENT = 0.6;
const int PRED_DISTANCE = 3;
int[] freqs = CalcFirstFreqs(data, spaceCode);
var dict = new CipherPredictionDictionary(freqs.Length + 1);
for (int i = 0; i < freqs.Length; i++)
{
CipherPossibilities poss = dict.Add(freqs[i]);
//loop over indexes from (i - PRED_DISTANCE) to (i + PRED_DISTANCE), within the bounds of the array
for (int j = Math.Max(i - PRED_DISTANCE, 0); j < Math.Min(i + PRED_DISTANCE + 1, firstFreqOrder.Length); j++)
{
poss.Add(singleFreqOrder[j], (PRED_DISTANCE - Math.Abs(i - j)) / (double)PRED_DISTANCE * PROBABILITY_COEFFICIENT);
}
}
return(dict);
}
public static CipherPredictionDictionary SingleFrequencyPrediction(int[] data, CipherPair eof = null)
{
const double PROBABILITY_COEFFICIENT = 0.2;
const int PRED_DISTANCE = 4;
int[] freqs = CalcSingleFreqs(data, eof);
var dict = new CipherPredictionDictionary(freqs.Length + 1);
for (int i = 0; i < freqs.Length; i++)
{
CipherPossibilities poss = dict.Add(freqs[i]);
//loop over indexes from (i - PRED_DISTANCE) to (i + PRED_DISTANCE), within the bounds of the array
for (int j = Math.Max(i - PRED_DISTANCE, 0); j < Math.Min(i + PRED_DISTANCE + 1, singleFreqOrder.Length); j++)
{
poss.Add(singleFreqOrder[j], (PRED_DISTANCE - Math.Abs(i - j)) / (double)PRED_DISTANCE * PROBABILITY_COEFFICIENT);
}
}
dict.Insert(dict.Count, new CipherPossibilities(eof, 1.0));
return(dict);
}
public static CipherPredictionDictionary PairFrequencyPrediction(int[] data, IEnumerable <int> codelist, CipherPair eof = null)
{
const double PROBABILITY_COEFFICIENT = 0.3;
const int PRED_DISTANCE = 6;
ulong[] freqs = CalcPairFreqs(data, codelist.ToArray(), eof);
var dict = new CipherPredictionDictionary(freqs.Length + 1);
for (int i = 0; i < freqs.Length; i++)
{
CipherPossibilities poss1 = dict.Add((int)(freqs[i] >> 32)); //first char
CipherPossibilities poss2 = dict.Add((int)(freqs[i] & uint.MaxValue)); //second char
//loop over indexes from (i - PRED_DISTANCE) to (i + PRED_DISTANCE), within the bounds of the array
for (int j = Math.Max(i - PRED_DISTANCE, 0); j < Math.Min(i + PRED_DISTANCE + 1, pairFreqOrder.Length); j++)
{
double prob = (PRED_DISTANCE - Math.Abs(i - j)) / (double)PRED_DISTANCE * PROBABILITY_COEFFICIENT;
poss1.Assimilate(pairFreqOrder[j][0], prob);
poss2.Assimilate(pairFreqOrder[j][1], prob);
}
}
return(dict);
}
public void BestGuess()
{
CipherPair eof = null;
if (data[data.Length - 1] == data[data.Length - 2] && data[data.Length - 1] == data[data.Length - 3])
{
eof = new CipherPair(data[data.Length - 1], (char)26);
}
var codelist = data.Distinct();
var dicts = new List <CipherPredictionDictionary>();
dicts.Add(CipherPredictionDictionary.SingleFrequencyPrediction(data, eof));
int spaceCode = dicts[0].Find(p => p.MostLikely().Value == ' ').MostLikely().Code;
dicts.Add(CipherPredictionDictionary.PairFrequencyPrediction(data, codelist, eof));
dicts.Add(CipherPredictionDictionary.FirstLetterPrediction(data, spaceCode));
dicts.Add(CipherPredictionDictionary.KnownWordPrediction(data, "<untranslatable>"));
preDict = CipherPredictionDictionary.AggregateProbabilities(dicts, codelist);
dict = preDict.MostLikely();
dict.AddMissingValues(codelist);
charsetView.DataSource = dict.BindingList;
}
