“Open Whisper Systems, the makers of Signal, revealed Tuesday that the company had received a federal subpoena earlier this year for records and other details on two of its users as part of a federal grand jury investigation in Virginia.
But unfortunately for the government, Signal keeps as little data as possible on its users, and therefore Open Whisper Systems was unable to hand over anything useful to the FBI agents that could help them in their investigation.”
Source: Signal is Most Secure Messenger, ‘Useless Data’ Obtained by FBI Proves It All