Tails, which leaves no trace of Internet activity on computers, was reportedly used by the NSA whistle-blower in discussions with journalists.
The operating system reportedly favored by former NSA contractor Edward Snowden to keep his conversations with journalists secret has graduated to 1.0 status.
The OS known as The Amnesiac Incognito Live System, or Tails, reached the milestone on Tuesday after nearly five years in development, according to the new version's release notes. Created by anonymous developers, the free software is intended to allow private, anonymous use of the Internet.
"Version 1.0 is often an important milestone that denotes the maturity of a free software project," the official announcement reads. "The first public version of what would become Tails was released on June 23, 2009, when it was called Amnesia. That was almost five years ago. Tails 1.0 marks the 36th stable release since then."
The software is credited as being instrumental to Snowden, journalist Glenn Greenwald, and documentary film maker Laura Poitras. The trio used the software to protect communications about the National Security Agency's controversial surveillance programs, according to a Wired report in mid-April.
After booting up with the Linux-based software from a DVD, SD card, or USB drive, a computer can travel around the Internet without leaving a trace of its activity on the device unless explicitly told to do so. Tails incorporates privacy and encryption tools like Tor, which allows the software to create a private network pathway that distributes traffic over several locations on the Internet.
Originally designed and developed as a routing project by the US Naval Research Laboratory, Tor has been used to hide various Internet activities, including illegal online drug transactions and the sidestepping of state-imposed Internet bans. Tor is listed in Tails' financial disclosure as a major backer.
The operating system features a complete collection of built-in apps, including a Web browser, instant-messaging client, email client, office suite, and image and sound editor. The post said the new release features a number of security fixes and it urged users to upgrade as soon as possible.