以前用Delphi写的CSDN免积分下载器

用了AlphaControl皮肤组件，原理很简单，就是CSDN的一个漏洞。我主要是使用WinInet来获取相关信息，然后从里面分析出真实的下载URL，同时我也是用了AES加密。
function GetWebPage(const Url: string):string;
var
  Session,
  Httpfile:HINTERNET;
  szSizeBuffer:Pointer;
  dwLengthSizeBuffer:DWord;
  dwReserved:DWord;
  dwFileSize:DWord;
  dwBytesRead:DWord;
  Contents:PChar;
begin
  Session:=InternetOpen('',0,niL,niL,0);
  Httpfile:=InternetOpenUrl(Session,PChar(Url),niL,0,0,0);
  dwLengthSizeBuffer:=1024;
  HttpQueryInfo(HttpFile,5,szSizeBuffer,dwLengthSizeBuffer,dwReserved);
  GetMem(Contents,dwFileSize);
  InternetReadFile(HttpFile,Contents,dwFileSize,dwBytesRead);
  InternetCloseHandle(HttpFile);
  InternetCloseHandle(Session);
  Result:=StrPas(Contents);
  FreeMem(Contents);
end;

function GetStr(StrSource, StrBegin, StrEnd: string): string;
var
  stStart,stEnd:integer;
begin
  stStart:=AnsiPos(strbegin,strsource)+length(strbegin);
  stEnd:=AnsiPos(strend,strsource);
  result:=copy(strsource,stStart,stEnd-stStart);
end;

procedure TForm1.Button1Click(Sender: TObject);
const
  AdWord = '3E000000B51B13E4074D1118B04E7693AA69E83500D5BED19BE728446313287450D8D279FDDBD96622EB0F9827AE165B7596037A36C815C3AD86AD5D1D6B7B6116ACD237';
  AdDes = 'www.51dev.net';
var
  Csdn: string;
  CsdnId: string;
  Html: string;
  IE: Variant;
begin
  if Edit1.Text = '' then
  begin
    ShowMessage('ＩＤ不能为空！');
    Exit;
    Edit1.SetFocus;
  end;
  Csdn := GY.DeEncrypt_text(AdWord, AdDes);
  CsdnId := Csdn + Trim(Edit1.Text);
  Html := GetWebPage(CsdnId);
  Html := StringReplace(Html, '\', '', [rfReplaceAll]);
  Html := StringReplace(Html, '"', '', [rfReplaceAll]);
  Html := GetStr(Html, 'url:', '}');
  //ShowMessage(Html);
  IE := CreateOleObject('InternetExplorer.Application');
  IE.Visible := True;
  IE.left := 0;
  IE.top := 0;
  IE.width := 260;
  IE.Height := 200;
  IE.Navigate(Html);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Web.Navigate('http://www.lsworks.net/Ad');
end;

procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
  if not(Key in ['0'..'9']) then
  begin
    ShowMessage('您输入的不是数字，请输入数字！');
    Key := #0;
    Edit1.SetFocus;
  end;
end;

http://www.lsworks.net/article/10.html