https://www.cnbc.com/2018/06/07/encrypted-messaging-why-it-matters-in-muellers-russia-probe.html

Encrypted messaging services are an increasingly common way for users to keep their text messages private. Now, they could play a role in special counsel Robert Mueller's Russia probe.

CNBC reported on Wednesday that Mueller's team is requesting that witnesses turn in their personal phones to inspect their encrypted messagingprograms and potentially view conversations between associates linked to President Donald Trump. The conversations occurred on the messaging services WhatsApp, Confide, Signal and Dust, sources said.