How users are going to take advantage of Qubes' application isolation capabilities is entirely up to them, Rutkowska said. "I realize this might be a tricky part for some users and some usage scenarios, yet, on the other hand, this seems to be the most flexible and powerful approach we could provide."
"People should realize that by mere fact of using Qubes OS they won't become automatically more secure -- it's how they are going to use it might make them significantly more secure," Rutkowska said.
Qubes is based on Linux, the X Window System and the Xen hypervisor -- a virtual machine manager. However, the developers have tried to limit the amount of code that could have critical security vulnerabilities.
"In Qubes OS we took a practical approach and we have tried to focus on all those sensitive parts of the OS, and to make them reasonably secure," Rutkowska said. "And, of course, in the first place, we tried to minimize the amount of those trusted parts, in which Qubes really stands out, I think."
That doesn't mean that Qubes is guaranteed to be free of security flaws. In fact, during the development stage, researchers working on the project found three critical vulnerabilities that could have impacted the operating system's security -- one in code they wrote themselves and two in hardware from Intel.
Rutkowska invited the security community to try to break Qubes and even pointed to a page that lists where the operating system's critical code is located.
Because it is based on Linux, Qubes can run most Linux applications. In the future, it might even support Windows applications running in Windows-based virtual machines through a commercial extension.
"We believe Qubes OS represents a reasonably secure OS," Rutkowska said. "In fact I'm not aware of any other solution currently on the market that would come close when it comes to secure desktop environment."