The Qubes operating system is currently in the alpha stage, according to Rutkowska, who blogged about the release on her website. The system is based on the Xen hypervisor, X, and Linux, and can run most Linux applications, according to the project website. It uses a concept that she calls security by isolation, allowing users to separate security domains into lightweight virtual machines, which she calls AppVMs. Files and clipboard items can be shared between the virtual machines (VMs).
The system also virtualizes the graphical user interface, enabling applications in different AppVMs to share the same desktop, according to the project website. "We have designed the GUI virtualization subsystem with two primary goals: security and performance. Our GUI infrastructure introduces only about 2,500 lines of C code (LOC) into the privileged domain (Dom0), which is very little, and thus leaves not much space for bugs and potential attacks," noted the project website. "At the same time, due to smart use of Xen shared memory our GUI implementation is very efficient, so most virtualized applications really feel as if they were executed natively."
Networking code is contained in an unprivileged VM. Future developments include the sandboxing of storage drivers in an unprivileged VM, and secure system boot capabilities.
Officially, the system won't be at production quality until the end of this year, but Rutkowska says that the operating system is usable. "I use Qubes for pretty much all the other daily tasks, from work, shopping, banking, random browsing, to Qubes development itself," she wrote.