Your iPhone holds some of your most private information – messages, photos and personal data secured by encryption, that even Apple itself cannot access. But a legal battle between the tech giant and the UK government is now testing the limits of that security.

U.K. rights groups have asked a British court to open a hearing Friday on Apple’s bid to avoid building spy capability into its encrypted cloud storage.

A London court hearing, reported to be Apple's appeal against a British government order to create a "back door" to its encrypted cloud storage systems, was held in secret on Friday, with media not allowed to attend despite a formal request.

The BBC - along with civil liberties groups and some US politicians - argue the case should be heard in public.