Passwortsicherheit II (Delphi 2009)

[xZise]

negaHs ( ) Passwortsicherheit arbeitet noch mit Ansistrings. Für Unicode muss das ganze verbreitert werden. Außerdem kann es da Bereichsüberprüfungsfehler geben, weshalb ich das jetzt mit Delphi 2009 bzw. Unicodestring kompatibel gemacht habe:

Delphi-Quellcode:

function PassphraseQuality(const Password : string): Extended;
// returns computed Quality in range 0.0 to 1.0
// source extracted from Delphi Encryption Compendium, DEC
// Convert to Delphi 2009 by Fabian (Nickname: xZise)

  function Diff(const AWord1, AWord2 : Word) : Word; overload;
  begin
    if AWord1 > AWord2 then
      Result := AWord1 - AWord2
    else
      Result := AWord2 - AWord1;
  end;

  function Diff(const AByte1, AByte2 : Byte) : Byte; overload;
  begin
    if AByte1 > AByte2 then
      Result := AByte1 - AByte2
    else
      Result := AByte2 - AByte1;
  end;

  {$IFDEF Unicode}
  function Entropy(P: PWordArray; L: Integer): Extended;
  {$ELSE}
  function Entropy(P: PByteArray; L: Integer): Extended;
  {$ENDIF}
  var
    Freq: Extended;
    I: Integer;
    {$IFDEF Unicode}
    Accu: array [Word] of LongWord;
    {$ELSE}
    Accu: array [Byte] of LongWord;
    {$ENDIF}
  begin
    Result := 0.0;
    if L <= 0 then Exit;
    FillChar(Accu, SizeOf(Accu), 0);
    for I := 0 to L-1 do Inc(Accu[P[I]]);
    for I := 0 to High(Accu) do
      if Accu[I] <> 0 then
      begin
        Freq := Accu[I] / L;
        Result := Result - Freq * (Ln(Freq) / Ln(2));
      end;
  end;

  function Differency: Extended;
  var
    S: string;
    L,I: Integer;
  begin
    Result := 0.0;
    L := Length(Password);
    if L <= 1 then Exit;
    SetLength(S, L-1);
    for I := 2 to L do
    begin
      {$IFDEF Unicode}
      Word(S[I-1]) := Diff(Word(Password[I-1]), Word(Password[I]));
      {$ELSE}
      Byte(S[I-1]) := Diff(Byte(Password[I-1]), Byte(Password[I]));
      {$ENDIF}
    end;

    Result := Entropy(Pointer(S), Length(S));
  end;

  function KeyDiff: Extended;
  const
    TableDE = '^1234567890ß´qwertzuiopü+asdfghjklöä#<yxcvbnm,.-°!"§$%&/()=?`QWERTZUIOPÜ*ASDFGHJKLÖÄ''>YXCVBNM;:_';
  var
    S: string;
    L,I,J: Integer;
  begin
    Result := 0.0;
    L := Length(Password);
    if L <= 1 then Exit;
    S := Password;
    UniqueString(S);
    for I := 1 to L do
    begin
      J := Pos(S[I], TableDE);
      if J > 0 then S[I] := Char(J);
    end;
    for I := 2 to L do
    begin
      {$IFDEF Unicode}
      Word(S[I-1]) := Diff(Word(S[I-1]), Word(S[I]));
      {$ELSE}
      Byte(S[I-1]) := Diff(Byte(S[I-1]), Byte(S[I]));
      {$ENDIF}
    end;
    Result := Entropy(Pointer(S), L-1);
  end;

const
  GoodLength = 10.0; // good length of Passphrases
var
  L: Extended;
begin
  Result := Entropy(Pointer(Password), Length(Password));
  if Result <> 0 then
  begin
    Result := Result * (Ln(Length(Password)) / Ln(GoodLength));
    L := KeyDiff + Differency;
    if L <> 0 then L := L / 64;
    Result := Result * L;
    if Result < 0 then Result := -Result;
    if Result > 1 then Result := 1;
  end;
end;

Ansonsten sollte sie genauso arbeiten wie die von negaH. Und vielleicht sollte man statt einen Compilerschalter das überladen lassen?

MfG
xZise