public string AuthCalcWebUrl(AuthLevel authLevel)
{
if( _sharedSecret == null ) throw new FlickrException(0, "AuthGetToken requires signing. Please supply api key and secret.");
string hash = _sharedSecret + "api_key" + _apiKey + "perms" + authLevel.ToString().ToLower();
hash = Md5Hash(hash);
string url = AuthUrl + "?api_key=" + _apiKey + "&perms=" + authLevel.ToString().ToLower();
url += "&api_sig=" + hash;
return url;
}