Paranoia: real and hypothetical

Real:

Apple deletes WikiLeaks ap.

Wikileaks App was an unofficial paid-for download that gave people access to the free Wikileaks Twitter feed and documents held on its website.

It was taken down after three days and 4,000 downloads.

Wikileaks apps are still available for other phones, such as those running Google Android.

All of the material offered by the Wikileaks iPhone app can be accessed for free via the phone's browser and other non-Wikileaks apps.

Hypothetical:
How do you know that all the WikiLeaks material is authentic? Is there any way to be sure that no WikiLeaker improved them a bit?

In addition to people with agendas, I think that mass of cables would offer an irresistible temptation to practical jokers.

Would like to get in touch with Ben Newman

Thanks in advance.