在Delphi中生成随机密码

Question

生成随机密码的函数如下:

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;

如何使这个函数使一个大写字母和一个特殊字符只出现一次，但总是出现?当我生成密码时，有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，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，但有了这个，你至少可以在要求中删除Upper和Extra。现在，您可以在最后检查它们是否曾经在需要时添加过，然后在需要时添加它们。

编辑:

---

我打上面的东西时很匆忙。您只需要在最后检查生成的密码是否包含Upper和Extra字符。如果没有，您仍然需要添加它们，因为这是您的需求之一。

Answer 3

下面是一个例子，首先确保所有额外的模式都被填充，其余的。它以空格作为Result的前缀，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;

Answer 4

未细化的代码，但也许它可以是有用的…

function RandomPassword(PLen: Integer): string;
var
strBase: string;
strUpper: string;
strSpecial: string;
strRecombine: string;
begin
strRecombine:='';
Result := '';
Randomize;
//string with all possible chars
strBase   := 'abcdefghijklmnopqrstuvwxyz1234567890';
strUpper:='ABCDEFGHIJKLMNOPQRSTUVWXYZ';
strSpecial:='@!_';
// Start Random
strRecombine:= strUpper[Random(Length(strUpper)) + 1];
Result:=strRecombine;
strRecombine:= strSpecial[Random(Length(strSpecial))+1];
repeat
Result := Result +  strBase[Random(Length(strBase)) + 1];
until (Length(Result) = PLen);
RandomRange(2, Length(strBase)); 
Result[RandomRange(2, PLen)]:=strRecombine[1];
//result:=Result+strRecombine;
end;