CipherGen constructor

CipherGen({ required int seed, })

Implementation

CipherGen({required int seed}){
  //Calculate p and q
  String password = seed.toString();
  if(password.length == 0 || password == null){
    throw CipherError.noPassword;
  }else if(password.length == 1){
    _pValue = int.parse(password);
    _pValue = _pValue!.isPrime()? _pValue : OptimusPrime.primeAfter(_pValue!);
    _qValue = (_pValue! + 1).isPrime()? (_pValue! + 1) : OptimusPrime.primeAfter(_pValue! + 1);
  }else{
    int midpoint = (password.length / 2).ceil();
    _pValue = int.parse(password.substring(0,midpoint));
    //Make it prime if it is not
    _pValue = _pValue!.isPrime() ? _pValue : OptimusPrime.primeAfter(_pValue!);
    //Parse q
    _qValue = int.parse(password.substring(midpoint,password.length));
    //Make it prime
    _qValue = _qValue!.isPrime() ? _qValue : OptimusPrime.primeAfter(_qValue!);
    //Make sure that p and q are never the same
    if(_pValue == _qValue){
      _qValue = OptimusPrime.primeAfter(_qValue!);
    }
  }
  //print('p = $p \nq = $q');
  //Find the largest value on the password
  int largestNumber = _pValue! < _qValue! ? _qValue! : _pValue!;
  int smallestNumber = _pValue! < _qValue! ? _pValue! : _qValue!;
  //Calculate N
  _N = _pValue! * _qValue!;
  //print('N = $N');
  //Calculate phi Φ
  _phi = (_pValue! - 1) * (_qValue! - 1);
  //print('phi = $phi');
  //Calculate e(Int between 1 and phi)
  //print('Largest int on the list is $largestNumber');
  //Make sure that e is coprime with N and phi
  List<int> possibleE = [];
  for(int i = 2; i < phi!; i++){
    if(i.coprimeWith(phi!) && i.coprimeWith(N!)){
      possibleE.add(i);
    }
  }
  //There are no numbers that can take the value of the variable e. None within range meet the criteria.
  if(possibleE.length == 0){
    throw CipherError.smallPassword;
  }
  int whichPosition = ((smallestNumber / largestNumber) * (possibleE.length - 1)).round();
  _e = possibleE[whichPosition];
  //print('e = $e');
  //Choose a d
    //Find the number n time where e * d (mod phi) == 1
  _d = e!.modInverse(phi!);
  //print('d = $d');
  //End of key variables generation
}