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Code Block

language	delphi

const CK_SINGATURE = '!CK!';
const CK_MAX_MSG_LEN = 1024*8;

function CKReadPassword(sFileName:string):string;
var
  sFilelenPWD: TFileStreamWORD;
  lenPWD, lenPWD_oldbuff: WORDPAnsiChar;
  sEncryptedPWDsFile: AnsiStringTFileStream;
  buffsEncryptedPWD: PAnsiCharAnsiString;
begin
  GetMem( buff, CK_MAX_MSG_LEN);
  ZeroMemory( buff, CK_MAX_MSG_LEN);

  if FileExists(sFileName) then begin
    lenPWD_old := 0;
    sFile := TFileStream.Create( sFileName, fmOpenRead);
    if sFile.Handle<>THandle(nil) then begin
      sFile.Seek( -4, soFromEnd);
      sFile.Read( PAnsiChar(buff)^, 4);
      if buff=CK_SINGATURE then
      begin
        // has master key, so need to erase it
        sFile.Seek( -6, soFromEnd);
        sFile.Read( lenPwd, 2);
        sFile.Seek( -(lenPWD + 6), soFromEnd);
        sFile.Read( PAnsIChar(buff)^, lenPWD);
        Result := trim(string(buff));
      end;
      sFile.Destroy;
    end;
  end;

  FreeMem(buff);
end;

function CKUpdatePassword(sFileName, sPWD:String):Boolean;
var
  sFile: TFileStream;
  lenPWD, lenPWD_old: WORD;
  sEncryptedPWD: AnsiString;
  buff: PAnsiChar;
begin
  GetMem( buff, CK_MAX_MSG_LEN);
  ZeroMemory( buff, CK_MAX_MSG_LEN);

  if not FileExists(sFileName) then begin
    Result := False;
  end else begin
    lenPWD_old := 0;
    sFile := TFileStream.Create( sFileName, fmOpenReadWrite);
    if sFile.Handle<>THandle(nil) then begin
      sFile.Seek( -4, soFromEnd);
      sFile.Read( PAnsiChar(buff)^, 4);
      if buff=CK_SINGATURE then
      begin
        // has master key, so need to erase it
        sFile.Seek( -6, soFromEnd);
        sFile.Read( lenPwd, 2);
        sFile.Seek( -(lenPWD + 6), soFromEnd);
        lenPWD_old := lenPWD;
      end else sFile.Seek( 0, soFromEnd);

      while Length(sPWD)<lenPWD_old do sPWD := sPWD + ' ';

      sEncryptedPWD := AnsiString(sPWD);
      lenPWD := Length(sEncryptedPWD);
      sFile.Write(if PAnsiChar(sEncryptedPWD)^, lenPWD);
 (lenPWD>CK_MAX_MSG_LEN) then begin
      sFile.Write( lenPWD, 2);
      sFile.Write( PAnsiChar(CK_SINGATURE)^, 4);
 // Too long encrypted password
        Result  sFile.Destroy;
:= False
      Resultend :=else True;begin
    end else Result := False  sFile.Write( PAnsiChar(sEncryptedPWD)^, lenPWD);
  end;

  FreeMem(buff);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  if not FileExists(eMasterFile.Text) then begin      sFile.Write( lenPWD, 2);
        sFile.Write( PAnsiChar(CK_SINGATURE)^, 4);
    ShowMessage( 'Please select program fileResult you want'):= True;
    end else beginend;

    if (CKUpdatePassword( eMasterFile.Text, ePWD.Text)=True) then begin
      ShowMessage('Successfully Changed !!');
      Close;
    end;
  end;
end;

sFile.Destroy;

    end else Result := False;
  end;

  FreeMem(buff);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  if not FileExists(eMasterFile.Text) then begin
    ShowMessage( 'Please select program file you want');
  end else begin
    if (CKUpdatePassword( eMasterFile.Text, ePWD.Text)=True) then begin
      ShowMessage('Successfully Changed !!');
      Close;
    end;
  end;
end;

Below code provides Below code provides better secure way to store secret key

Code Block

language	delphi

uses IdCoder, IdCoderMIME, IdGlobal;

.
.
.

const CK_SINGATURE = '!CK!';
const CK_SINGATURE_KEY = 'ChunKang';
const CK_MAX_MSG_LEN = 1024 * 8;
const CK_ENC_VAR_RANGE=10;

function CKEncrypt(const Source:string; Salt:string): string;
var
  i, lenSalt, key, keyWeight: Word;
  InString: string;
begin
  Result := '';
  if (Salt = '') then begin
    Result := Source;
  end InString:else string;
begin
    ResultInString := ''; TIdEncoderMIME.EncodeString(Source, IndyTextEncoding_UTF8);

  if  (SaltlenSalt := '') then beginLength(Salt);

    ResultkeyWeight := Source0;
    for endi else:= begin
1 to lenSalt do InStringkeyWeight := TIdEncoderMIME.EncodeString(Source, IndyTextEncoding_UTF8 keyWeight + ord(Salt[i]);

    lenSaltkeyWeight := Length(Salt) keyWeight mod CK_ENC_VAR_RANGE;

    for keyWeighti := 0; 1 to Length(InString) do
    for i := 1 to lenSalt do keyWeightbegin
      key := keyWeight( + ord(Salt[(i]);
 mod lenSalt)  keyWeight := keyWeight+ 1]) mod CK_ENC_VAR_RANGE);

      Result := Result  for i := 1 to Length(InString) do+ CHAR(Byte(InString[i]) + key - keyWeight);
    beginend;
  end;
end;

function CKDecrypt(const InString:string;  key := ( ord(Salt[(i mod lenSalt) + 1]) mod CK_ENC_VAR_RANGE)Salt:string): string;
var
  i, lenSalt, key, keyWeight: Word;
  Target: string;
begin
  if Result(Salt := Result + CHAR(Byte(InString[i]) + key - keyWeight) '') then begin
    Target := InString;
  end else end;begin
     endlenSalt := Length(Salt);
end;

function CKDecrypt(const InString:string; Salt:string): string;
var
  i, lenSalt, key, keyWeight: Word;
  Target: string;
begin
  if (Salt = '') then begin
    Target := InString;
  end else begin
    lenSalt := Length(Salt);

    keyWeight := 0;
    for i := 1 to lenSalt do keyWeight := keyWeight + ord(Salt[i]);
    keyWeight := keyWeight mod CK_ENC_VAR_RANGE;

    Target := '';
    for i := 1 to Length(InString) do
    begin
      key := ( ord(Salt[(i mod lenSalt) + 1]) mod CK_ENC_VAR_RANGE);
      Target := Target + CHAR(Byte(InString[i]) - key + keyWeight);
    end;
    Result := TIdDecoderMIME.DecodeString(Target, IndyTextEncoding_UTF8);
  end;
end;

function CKReadPassword(sFileName:string):string;
var
  sFile: TFileStream;
  lenPWD, lenPWD_old: WORD;
  sEncryptedPWD: AnsiString;
  buff: PAnsiChar;
  tmp: AnsiString;
begin
  GetMem( buff, CK_MAX_MSG_LEN);
  ZeroMemory( buff, CK_MAX_MSG_LEN);

  if FileExists(sFileName) then begin
    lenPWD_old := 0;
    sFile := TFileStream.Create( sFileName, fmOpenRead);
    if sFile.Handle<>THandle(nil) then begin
    keyWeight := 0;
    for i := 1 to lenSalt do keyWeight := keyWeight + ord(Salt[i]);
    keyWeight := keyWeight mod CK_ENC_VAR_RANGE;

    Target := '';
    for i := 1 to Length(InString) do
    begin
      key := ( ord(Salt[(i mod lenSalt) + 1]) mod CK_ENC_VAR_RANGE);
      Target := Target + CHAR(Byte(InString[i]) - key + keyWeight);
    end;
    Result := TIdDecoderMIME.DecodeString(Target, IndyTextEncoding_UTF8);
  end;
end;

function CKReadPassword(sFileName:string):string;
var
  lenPWD: WORD;
  buff: PAnsiChar;
  tmp: AnsiString;
  sFile: TFileStream;
  sEncryptedPWD: AnsiString;
begin
  GetMem( buff, CK_MAX_MSG_LEN);
  ZeroMemory( buff, CK_MAX_MSG_LEN);

  if FileExists(sFileName) then begin
    sFile := TFileStream.Create( sFileName, fmOpenRead);
    if sFile.Handle<>THandle(nil) then begin
      sFile.Seek( -4, soFromEnd);
      sFile.Read( PAnsiChar(buff)^, 4);
      if buff=CK_SINGATURE then
      begin
        // has master key, so need to erase it
        sFile.Seek( -6, soFromEnd);
        sFile.Read( lenPwd, 2);
        sFile.Seek( -( -4lenPWD + 6), soFromEnd);
        sFile.Read( PAnsiCharPAnsIChar(buff)^, 4lenPWD);
      if buff=CK_SINGATURE then
      begin
        // has master key, so need to erase it
 tmp := ansiString(string(buff));
        tmp := sFile.SeekCKDecrypt( -6tmp, soFromEndCK_SINGATURE_KEY);
        sFile.Read( lenPwd, 2Result := Trim(tmp);
      end;
  sFile.Seek( -(lenPWD + 6), soFromEnd) sFile.Destroy;
    end;
  end;

  sFile.Read( PAnsIChar(buff)^, lenPWD);
        tmp := ansiString(string(buff));
        tmp := CKDecrypt( tmp, CK_SINGATURE_KEYFreeMem(buff);
end;

function CKUpdatePassword(sFileName, sPWD:String):Boolean;
var
  buff: PAnsiChar;
  sFile: TFileStream;
  lenPWD, lenPWD_old: WORD;
  sEncryptedPWD: AnsiString;
begin
  GetMem( buff, CK_MAX_MSG_LEN);
  ZeroMemory(      Result := Trim(tmp);
      end;buff, CK_MAX_MSG_LEN);

  if not FileExists(sFileName) then sFile.Destroy;begin
    end;
Result := endFalse;

  FreeMem(buff);
end;

function CKUpdatePassword(sFileName, sPWD:String):Boolean;
var
  sFile: TFileStream; else begin
  lenPWD,  lenPWD_old := WORD0;
  sEncryptedPWD: AnsiString;
 sFile buff: PAnsiChar;
begin
  GetMem= TFileStream.Create( buffsFileName, CK_MAX_MSG_LENfmOpenReadWrite);
  ZeroMemory( buff, CK_MAX_MSG_LEN);

  if not FileExists(sFileNamesFile.Handle<>THandle(nil) then begin
    Result := False  sFile.Seek( -4, soFromEnd);
  end else begin
  sFile.Read(  lenPWD_old := 0;
PAnsiChar(buff)^, 4);
      sFileif := TFileStream.Create( sFileName, fmOpenReadWrite);
 buff=CK_SINGATURE then
   if sFile.Handle<>THandle(nil) then begin
        // has sFile.Seek( -4, soFromEnd);
master key, so need to erase it
        sFile.ReadSeek( PAnsiChar(buff)^-6, 4soFromEnd);
        if buff=CK_SINGATURE thensFile.Read( lenPwd, 2);
      begin
  sFile.Seek( -(lenPWD + 6), soFromEnd);
  // has master key, so need to erase itlenPWD_old := lenPWD;
      end else sFile.Seek( -60, soFromEnd);

      while Length(sPWD)<lenPWD_old do sPWD := sPWD sFile.Read( lenPwd, 2)+ ' ';

      sEncryptedPWD := sFile.Seek( -(lenPWD + 6), soFromEndCKEncrypt(sPWD, CK_SINGATURE_KEY);
        lenPWD_old := lenPWDLength(sEncryptedPWD);
      endif else sFile.Seek( 0, soFromEnd);
(lenPWD>CK_MAX_MSG_LEN) then begin
      while Length(sPWD)<lenPWD_old do sPWD := sPWD + ' ';

 // too long message length
        sEncryptedPWDResult := CKEncrypt(sPWD, CK_SINGATURE_KEY)False;
      lenPWDend := Length(sEncryptedPWD);
else begin
        sFile.Write( PAnsiChar(sEncryptedPWD)^, lenPWD);
        sFile.Write( lenPWD, 2);
        sFile.Write( PAnsiChar(CK_SINGATURE)^, 4);
        Result := sFile.DestroyTrue;

      end;
    Result := TruesFile.Destroy;
    end else Result := False;
  end;

  FreeMem(buff);
end;

procedure Test;
begin
  CKUpdatePassword( "c:\foo.exe", "hello kitty");
  ShowMessage( CKReadPassword( "c:\foo.exe"));
end;

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