Feds secretly subpoenaed the encrypted chat app Signal earlier this year

Earlier this year, Open Whisper Systems was served with a federal subpoena for records on its users, according to documents published today. Prosecutors were seeking data on two suspects who used Signal, an encrypted chat app produced by Open Whisper. Unfortunately for the government, Signal keeps only minimal logs on users, so the vast majority of the requested information was unavailable.
The American Civil Liberties Union, which represented Open Whisper Systems in the fight, has published a n