textDecryption static method

String textDecryption(String cipherText)

Decryption cipherText and extract key from it .

Implementation

static String textDecryption(String cipherText) {
  // Setup letter to encryption and decryption
  LettersInit.instance.setupLetters();

  List<String> cipherList = cipherText.split("");

  String firstLetter = cipherList.first;
  String lastLetter = cipherList.last;

  int firstInt = LettersInit.instance.lettersWithStringKey[firstLetter] ?? 0;
  int secInt = LettersInit.instance.lettersWithStringKey[lastLetter] ?? 0;

  int length = firstInt + secInt;

  cipherList.removeAt(0);
  cipherList.removeLast();

  cipherText = cipherList.join();

  // extract key from Cipher Text
  String key = ExtractKey.extractKey(cipherText);

  // get cipher text without key
  cipherText = ExtractKey.extractCipherWithoutKey(cipherText);

  // convert Cipher Text ( String ) to Cipher Text ( List<int> )
  List<int> cipherTextAsInt = _convertCipherToInt(cipherText);

  // Decryption Cipher Text List<Int>
  List<int> plainInts = [];
  int i = 0;
  KeyModel keyModel = GenerateKey.getFullKey(key);
  while (i < (keyModel.key) + (keyModel.key % 263)) {
    plainInts = _convertCipherListIntToPlainListInt(
        i == 0 ? cipherTextAsInt : plainInts, key, length);
    ++i;
  }
  // Convert Plain List<int> to readable String
  String plainText = convertPlainIntToString(plainInts);
  return plainText;
}