Check if app is liked on Facebook without requesting permission

public boolean isLikedOnFacebook( String signedRequest ) throws IOException, JsonException
   {
      String payload = signedRequest.split( "\\." )[ 1 ];
      String replaced1 = payload.replaceAll( "-", "+" );
      String replaced2 = replaced1.replaceAll( "_", "/" );
      BASE64Decoder decoder = new BASE64Decoder();
      byte[] decodedBytes = null;
      decodedBytes = decoder.decodeBuffer( replaced2 );
      String decodedString = new String( decodedBytes );
      JsonObject jsonObject = new JsonObject( decodedString );
      if( jsonObject.getJsonObject( "page" ).get( "liked" ).equals( "true" ) )
      {
         return true;
      }
      else
      {
         return false;
      }
   }