在 Delphi 中生成随机密码

Question

我有一个生成随机密码的函数：

function GeneratePassword(ALength: Integer; Mode: TPasswordMode): string;
const
  cLower   = 'abcdefghijklmnopqrstuvwxyz';
  cUpper   = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
  cNumbers = '0123456789';
  cExtra   = '_.';
var
  i : Integer;
  S : string;
  iM: BYTE;
begin
  if Mode = [] then Exit;
  i := 0;
  Randomize;
  while (i < ALength)  do
  begin
    iM := RANDOM(4);
    case iM of
      0: if (pmLower in Mode) then begin
            S := S + cLower[1+RANDOM(Length(cLower))];
           Inc(i);
          end;
     1: if (pmUpper in Mode) then begin
           S := S + cUpper[1+RANDOM(Length(cUpper))];
          Inc(i);
         end;
      2: if (pmNumbers in Mode) then begin
           S := S + cNumbers[1+RANDOM(Length(cNumbers))];
           Inc(i);
          end;
      3: if (pmExtra in Mode) then begin
           S := S + cExtra[1+RANDOM(Length(cExtra))];
           Inc(i);
         end;
    end;
  end;
  Result := S;
end;

如何使这个函数使大写字母和特殊字符只出现一次，但总是出现？有时我生成密码时没有大写字母或特殊字符。

Answer 1

要确保有一个特殊字符和一个大写字母，您可以这样做：

function GeneratePassword(ALength: Integer; Mode: TPasswordModes): string;
const
  cLower   = 'abcdefghijklmnopqrstuvwxyz';
  cUpper   = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
  cNumbers = '0123456789';
  cExtra   = '_.';
var
  iM: Byte;
  i: integer;
begin
  if Mode = [] then Exit;

  Result := '';
  i := 0;

  if pmUpper in Mode then
    Inc(i);

  if pmExtra in Mode then
    Inc(i);

  // add lower case and/or number
  while Result.Length < (ALength - i)  do
  begin
    iM := Random(2);
    case iM of
      0: if (pmLower in Mode) then begin
           Result := Result + cLower[1 + Random(Length(cLower))];
         end;
      1: if (pmNumbers in Mode) then begin
           Result := Result + cNumbers[1 + Random(Length(cNumbers))];
         end;
    end;
  end;

  // add uppercase and/or extra
  if i > 0 then
  begin
    if pmUpper in Mode then
      Result := Result.Insert(1 + Random(Length(Result)), cUpper[1 + Random(Length(cUpper))]);

    if pmExtra in Mode then
      Result := Result.Insert(1 + Random(Length(Result)), cExtra[1 + Random(Length(cExtra))]);
  end;
end;

Answer 2

type
  TPasswordMode = (pmLower, pmUpper, pmNumbers, pmExtra);
  TPasswordModes = set of TPasswordMode;

implementation

function GeneratePassword(ALength: Integer; Mode: TPasswordModes): string;
const
  cLower   = 'abcdefghijklmnopqrstuvwxyz';
  cUpper   = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
  cNumbers = '0123456789';
  cExtra   = '_.';
var
  i : Integer;
  S : string;
  iM: BYTE;
begin
  if Mode = [] then Exit;
  i := 0;
  Randomize;
  while (i < ALength)  do
  begin
    iM := RANDOM(4);
    case iM of
      0: if (pmLower in Mode) then begin
           S := S + cLower[1+RANDOM(Length(cLower))];
           Inc(i);
         end;
      1: if (pmUpper in Mode) then begin
           S := S + cUpper[1+RANDOM(Length(cUpper))];
           Inc(i);
           Mode := Mode - [pmUpper]; // This I added
         end;
      2: if (pmNumbers in Mode) then begin
           S := S + cNumbers[1+RANDOM(Length(cNumbers))];
           Inc(i);
         end;
      3: if (pmExtra in Mode) then begin
           S := S + cExtra[1+RANDOM(Length(cExtra))];
           Inc(i);
           Mode := Mode - [pmExtra];  // This I added
         end;
    end;
  end;
  Result := S;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  ShowMessage(GeneratePassword(10,[pmLower,pmUpper,pmNumbers,pmExtra]));
end;

这不是一个完整的解决方案，但有了它，您至少会在使用 Upper 和 Extra 后立即从要求中删除它们。如果需要，您现在检查最后是否曾经添加过它们，然后在需要时添加它们。

---

编辑：

当我输入上述内容时，我很着急。您只需要最后检查生成的密码是否包含大写和额外字符。如果没有，您仍然需要添加它们，因为这是您的要求之一。

Answer 3

这是一个示例，首先确保所有额外的模式都被填充，其余的。它用空格预填充 Result，然后用随机字符替换，直到所有空格都被替换。

function GetRandomEmptyPos(const aStr: string): integer; inline;
begin
  // find random empty position
  repeat
    Result := Random(Length(aStr)) + 1;
  until aStr[Result] = ' ';
end;

function GeneratePassword2(aLength: Integer; aModes: TPasswordModes): string;
const
  cLower   = 'abcdefghijklmnopqrstuvwxyz';
  cUpper   = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
  cNumbers = '0123456789';
  cExtra   = '_.';
var
  i,vPos: integer;
  vMode: TPasswordMode;
begin
  if (aLength = 0) or (aModes = []) then Exit;
  Randomize;

  // Prefill Result with empty spaces
  Result := StringOfChar(' ', aLength);

  // Add extra characters at random places
  for vMode in aModes do
  begin
    vPos := GetRandomEmptyPos(Result);
    case vMode of
      pmLower:    Result[vPos] := cLower[Random(Length(cLower)) + 1];
      pmUpper:    Result[vPos] := cUpper[Random(Length(cUpper)) + 1];
      pmNumbers:  Result[vPos] := cNumbers[Random(Length(cNumbers)) + 1];
      pmExtra:    Result[vPos] := cExtra[Random(Length(cExtra)) + 1];
    end;
  end;

  // Add random char on emtpy spaces
  for i := 1 to Result.Length do
    if Result[i] = ' ' then
      Result[i] := String(cLower + cNumbers)[Random(Length(cLower) + Length(cNumbers)) + 1];
end;