public static string brutalAffineDecrypt(string input)
{
string output = "";
int a;
var list = new List <int>();
for (int i = 1; i < CryptographyUtils.AlphabetLength; i++)
{
if (checkAffineKey(i, CryptographyUtils.AlphabetLength))
{
list.Add(i);
}
}
for (int i = 0; i < list.Count; i++)
{
a = list[i];
int aOpposite = CryptographyUtils.oppositeModulo(a, CryptographyUtils.AlphabetLength);
if (aOpposite == 0)
{
Console.WriteLine("Nie mogę znaleźć liczby przeciwnej w mod " + CryptographyUtils.AlphabetLength + " dla " + a + "!");
}
else
{
for (int b = 0; b < CryptographyUtils.AlphabetLength; b++)
{
output += affineDecrypt(aOpposite, b, input);
output += "\n";
}
}
}
return(output);
}
public static string affineEncrypt(int a, int b, string input)
{
//E(a,b,x)=a*x+b (mod 26)
if (CryptographyUtils.gcd(a, CryptographyUtils.AlphabetLength) != 1)
{
Console.WriteLine("Niepoprawny klucz do enkrypcji");
return(null);
}
return(CryptographyUtils.encrypt(a, b, input));
}
public static bool checkAffineKey(int a, int range)
{
if ((CryptographyUtils.gcd(a, range) == 1) && ((a * (CryptographyUtils.oppositeModulo(a, range)) % range) == 1))
{
return(true);
}
else
{
return(false);
}
}
public static string affineDecrypt(int a, int b, string input)
{
//D(a,b,y)=a'*(y-b) (mod 26)
int aOpposite = CryptographyUtils.oppositeModulo(a, CryptographyUtils.AlphabetLength);
if (aOpposite == 0)
{
Console.WriteLine("Nie mogę znaleźć liczby przeciwnej w mod " + CryptographyUtils.AlphabetLength + " dla " + a + "!");
return(null);
}
else
{
return(CryptographyUtils.decrypt(aOpposite, b, input));
}
}
public static string caesarEncrypt(int key, string input)
{
//E(k,x)=x+k (mod 26)
return(CryptographyUtils.encrypt(1, key, input));
}
public static string caesarDecrypt(int key, string input)
{
//D(k,y)=y-k (mod 26)
return(CryptographyUtils.decrypt(1, key, input));
}
public static string[] helpAffineDecrypt(string input, string inputHelper, int startingIndex)
{
//returns array of strings size 3, index 0 = decrypted cipher, index 1 = guessed a, index 2 = guessed b
//https://www.youtube.com/watch?v=ry3g0xN8QKU
if (inputHelper.Length < 2)
{
Console.WriteLine("Za mało danych aby odgadnac klucze!");
return(null);
}
string[] output = new string[3];
int[,] tab = new int[2, 2];
int firstPairIndex = 0;
int firstPairFound = 0;
int secondPairIndex = 0;
int secondPairFound = 0;
for (int i = startingIndex; i < inputHelper.Length; i++)
{
if (CryptographyUtils.checkCharAlphabeticLower(inputHelper[i]))
{
tab[0, 0] = Convert.ToInt32(inputHelper[i] - 97);
tab[0, 1] = Convert.ToInt32(input[i] - 97);
firstPairIndex = i;
firstPairFound = 1;
break;
}
if (CryptographyUtils.checkCharAlphabeticUpper(inputHelper[i]))
{
tab[0, 0] = Convert.ToInt32(inputHelper[i] - 'A');
tab[0, 1] = Convert.ToInt32(input[i] - 'A');
firstPairIndex = i;
firstPairFound = 1;
break;
}
}
if (firstPairFound == 1)
{
//Console.WriteLine("Znalazłem pierwsza pare");
firstPairIndex++;
if (firstPairIndex == inputHelper.Length - 1)
{
Console.WriteLine("Za mało danych w tekscie pomocniczym!");
return(null);
}
for (int i = firstPairIndex; i < inputHelper.Length; i++)
{
if (CryptographyUtils.checkCharAlphabeticLower(inputHelper[i]))
{
tab[1, 0] = Convert.ToInt32(inputHelper[i] - 'a');
tab[1, 1] = Convert.ToInt32(input[i] - 'a');
secondPairFound = 1;
secondPairIndex = i;
break;
}
if (CryptographyUtils.checkCharAlphabeticUpper(inputHelper[i]))
{
tab[1, 0] = Convert.ToInt32(inputHelper[i] - 'A');
tab[1, 1] = Convert.ToInt32(input[i] - 'A');
secondPairFound = 1;
secondPairIndex = i;
break;
}
}
if (secondPairFound == 1)
{
Console.WriteLine("Znalazłem dwie pary");
Console.WriteLine("extra: " + Convert.ToChar(tab[0, 0] + 97) + " " + Convert.ToChar(tab[1, 0] + 97));
Console.WriteLine("cipher: " + Convert.ToChar(tab[0, 1] + 97) + " " + Convert.ToChar(tab[1, 1] + 97));
Console.WriteLine("Sprawdzam...");
int a, b;
int x = Convert.ToInt32(tab[0, 0] - tab[1, 0]);
if (x < 0)
{
x += CryptographyUtils.AlphabetLength;
}
int y = Convert.ToInt32(tab[0, 1] - tab[1, 1]);
if (y < 0)
{
y += CryptographyUtils.AlphabetLength;
}
int xOpposite = CryptographyUtils.oppositeModulo(x, CryptographyUtils.AlphabetLength);
if (xOpposite != 0)
{
a = (y * xOpposite) % CryptographyUtils.AlphabetLength;
b = (tab[0, 1] - ((a * tab[0, 0]) % CryptographyUtils.AlphabetLength) + CryptographyUtils.AlphabetLength) % CryptographyUtils.AlphabetLength;
if (a != 0)
{
output[1] = a.ToString();
output[2] = b.ToString();
int aOpposite = CryptographyUtils.oppositeModulo(a, CryptographyUtils.AlphabetLength);
if (aOpposite == 0)
{
Console.WriteLine("Nie mogę znaleźć liczby przeciwnej w mod " + CryptographyUtils.AlphabetLength + " dla " + a + "!");
return(null);
}
else
{
Console.WriteLine("Udało się! Klucz to : " + a + ", " + b);
output[0] = affineDecrypt(a, b, input);
return(output);
}
}
else
{
Console.WriteLine("Niepoprawne a");
return(helpAffineDecrypt(input, inputHelper, secondPairIndex));
}
}
else
{
Console.WriteLine("Nie mogę znaleźć przeciwności dla " + x + " w mod " + CryptographyUtils.AlphabetLength);
if (secondPairIndex == inputHelper.Length - 1)
{
return(null);
}
return(helpAffineDecrypt(input, inputHelper, secondPairIndex));
}
}
else
{
Console.WriteLine("Za mało danych w tekscie pomocniczym!");
return(null);
}
}
else
{
Console.WriteLine("Za mało danych w tekscie pomocniczym!");
return(null);
}
return(null);
}
