Maybe March 30, 2016:

The Strange Origins of TrueCrypt, ISIS’s Favored Encryption Tool

By Evan Ratliff for The New Yorker (paywall)

In isis’s training and operational planning, Callimachi reported, the group appeared to routinely use a piece of software called TrueCrypt. When one would-be bomber was dispatched from Syria to France, Callimachi writes, “an Islamic State computer specialist handed him a USB key. It contained CCleaner, a program used to erase a user’s online history on a given computer, as well as TrueCrypt, an encryption program that was widely available at the time and that experts say has not yet been cracked.”