Secure chat app Signal received its first federal grand jury subpoena this year.
The summons, from the US Department of Justice, required developer Open Whisper Systems to provide information on two Signal users for a federal investigation. But since the app is designed to minimize the collection of user data, OWS can produce only the date and time a user registered with Signal, and their last date of connectivity to the service. The company specifically does not store details about a user's contacts and groups, or with whom they have been communicating.
"All message contents are end-to-end encrypted, so we don't have that information, either," OWS said in a blog post.
Signal, often referred to as Edward Snowden's favorite encrypted messaging app, arrived on Android late last year, before hitting the desktop in April with Android sync support; iOS desktop support arrived last week.
Open Whisper Systems's first subpoena, issued in the first half of 2016, originally included a broad gag order preventing the firm from publicly acknowledging the court order. But with a little help from the American Civil Liberties Union (ACLU), the firm was able to publish the transcripts online for the world to see.
"The fact that the government didn't put up much of a fight suggests that secrecy—and not transparency—has become a governmental default when it comes to demands for our electronic information," ACLU Center for Democracy staff attorney Brett Max Kaufman wrote in a blog post.
Open Whisper Systems, meanwhile, said it remains committed to "treating any further requests the same way": working with organizations like the ACLU and publishing transcripts of its responses to government requests.
OWS is also the force behind the Signal Protocol, which powers the encryption built into WhatsApp, Facebook Messenger, and Google's Allo.