Facebook encryption case: US judge keeps documents secret

A US judge on Monday rejected a bid by two civil rights groups that had sought to force the release of documents describing a secret US government effort to compel Facebook Inc to decrypt voice conversations between users on its Messenger app.

The issue arose in a joint federal and state investigation into activities of the MS-13 gang in Fresno, California, revolving around the end-to-end encryption Facebook uses to protect calls on its Messenger service from interception.