Accessing private thumbnails provided by the Google Portable Contacts API

I'm currently using the Google Portable Contacts API to import my users' Google contacts to a web application.

When listing the thumbnail URLs for a given contact, the API returns one of the following two types of URLs:

• http://www.google.com/ig/c/photos/public/*
• http://www.google.com/ig/c/photos/private/*

Although I can access both of these types of URLs from th开发者_开发百科e authenticated user's web browser, trying to download the 'private' pictures to my server returns a 404 error (And a "malformed" error when I try to add OAuth credentials to my requests).

I need to download these 'private' pictures locally for image processing.

Is there any way I can do it?