private string CheckThat(string key, string cipher)
{
string _result = SomeInstruments.DelSym(key);
if (cipher == "Rail_Fence_ENG" || cipher == "Rail_Fence_ALL")
{
_result = SomeInstruments.DelAlp(_result);
try
{
int.Parse(_result);
}
catch (FormatException)
{
_result = "";
}
}
else if (cipher == "Playfair_ENG" || cipher == "Vigenere_ENG")
{
_result = SomeInstruments.ForText(_result);
}
else
{
_result = SomeInstruments.ForTextRUS(_result);
}
return(_result.ToLower());
}
static public string DeCipherRUS(string FileText, string key)
{
string text = SomeInstruments.ForTextRUS(FileText.ToLower());
string result = "";
text.ToLower();
// create a key
int _priLenKey = key.Length;
while (key.Length < text.Length)
{
key += alphabetRUS[(alphabetRUS.IndexOf(key[key.Length - _priLenKey]) + 1) % 26];
}
// create chiphertext
int _index;
for (int i = 0; i < text.Length; i++)
{
_index = (alphabetRUS.IndexOf(text[i]) + 33 - alphabetRUS.IndexOf(key[i])) % 33;
result += alphabetRUS[_index];
}
return(SomeInstruments.CreateTextRUS(FileText, result));
}