(*//

标题:字符串加密;pascal字符表示

说明:应用于文件加密

设计:Zswang

日期:2002-02-19

支持:wjhu111@21cn.com

//*)

///////Begin Source

function StringToDisplay(mString: string): string;

var

 I: Integer;

 S: string;

begin

 Result := '';

 S := '';

 for I := 1 to Length(mString) do

   if mString[I] in [#32..#127] then

     S := S + mString[I]

   else begin

     if S <> '' then begin

       Result := Result + QuotedStr(S);

       S := '';

     end;

     Result := Result + Format('#$%x', [Ord(mString[I])]);

   end;

 if S <> '' then Result := Result + QuotedStr(S);

end; { StringToDisplay }

function DisplayToString(mDisplay: string): string;

var

 I: Integer;

 S: string;

 B: Boolean;

begin

 Result := '';

 B := False;

 mDisplay := mDisplay;

 for I := 1 to Length(mDisplay) do

   if B then case mDisplay[I] of

     '''': begin

       if S <> '' then Result := Result + StringReplace(S, '''''', '''', [rfReplaceAll]);

         if Copy(mDisplay, I + 1, 1) = '''' then Result := Result + '''';

         S := '';

         B := False;

       end;

     else S := S + mDisplay[I];

     end

   else case mDisplay[I] of

     '#', '''': begin

       if S <> '' then Result := Result + Chr(StrToIntDef(S, 0));

       S := '';

       B := mDisplay[I] = '''';

     end;

     '$', '0'..'9', 'a'..'f', 'A'..'F': S := S + mDisplay[I];

   end;

 if (not B) and (S <> '') then Result := Result + Chr(StrToIntDef(S, 0));

end; { DisplayToString }

function StringEncrypt(mStr: string; mKey: string): string;

var

 I, J: Integer;

begin

 J := 1;

 Result := '';

 for I := 1 to Length(mStr) do begin

   Result := Result + Char(Ord(mStr[I]) xor Ord(mKey[J]));

   if J + 1 <= Length(mKey) then

     Inc(J)

   else J := 1;

 end;

 { 自己加步骤 }

end; { StringEncrypt }

function StringDecrypt(mStr: string; mKey: string): string;

var

 I, J: Integer;

begin

 J := 1;

 Result := '';

 { 自己加步骤 }

 for I := 1 to Length(mStr) do begin

   Result := Result + Char(Ord(mStr[I]) xor Ord(mKey[J]));

   if J + 1 <= Length(mKey) then

     Inc(J)

   else J := 1;

 end;

end; { StringDecrypt }

///////End Source

///////Begin Demo

const

 cKey = '给你这一把钥匙,只能打开这一把锁';

procedure TForm1.Button1Click(Sender: TObject);

begin

 Memo2.Text := StringToDisplay(StringEncrypt(Memo1.Text, cKey));

end;

procedure TForm1.Button2Click(Sender: TObject);

begin

 Memo1.Text := StringDecrypt(DisplayToString(Memo2.Text), cKey);

end;

///////End Demo