// ---- Отправка картинки на стену ----
procedure TidVKClient.PostWallPicture(const to_id, AFile: string);
var
 Multi : TIdMultiPartFormDataStream;
 Signature : string;
 URL : string;
begin
 Multi := TIdMultiPartFormDataStream.Create;

 Signature := StrTobase64(file_get_contents(AFile), 0);
 Signature := Copy(Signature, 0, 1024);
 ShowMessage(IntToStr(Length(Signature)));
 Signature := GetMD5(Signature);

 url := 'http://vkontakte.ru/graffiti.php?to_id=' + to_id + '&group_id=0';


 Multi.AddFormField('Signature', Signature);
 Multi.AddFile('Filedata', AFile, 'image/png');
 HTTP.Post(url, multi);
end;