GrapheneOS
GrapheneOS is an open source privacy and security focused mobile OS with Android app compatibility.
Official releases are available on the releases page and installation instructions are on the install page.
See the GitHub organization for sources of the OS and various standalone sub-projects including the cutting edge new hardened memory allocator and other projects.
The official GrapheneOS releases are supported by the Auditor app and attestation service for hardware-based attestation. For more details, see the about page and tutorial. You can also extend these with support for your own builds.
Early stage of development
GrapheneOS is a privacy / security research and engineering project that has been under way for over 5 years. It recently became rebranded as GrapheneOS and is taking a different direction based on obtaining funding for the research and development work as a non-profit open source project rather than being a company. The reborn project is still in a very early stage and lots of the past work on privacy and security has not yet been restored for the new incarnation of the OS.
The grapheneos.org site is very new and is currently being put together. It will have lots of additional documentation and tutorials in the future along with coverage of various software, firmware and hardware privacy/security topics.
GrapheneOS is being supported with funding and developers from various companies and other organizations interested in contributing to this shared base for a feature rich private and secure mobile operating system able to run many existing applications. It will take more time to organize and deploy these resources in order for the project to have a strong development team with proper infrastructure behind it.
Roadmap
Details on the roadmap of the project will be posted on the site in the near future. In the long term, it aims to move beyond a hardened fork of the Android Open Source Project. Achieving the goals requires moving away from relying the Linux kernel as the core of the OS and foundation of the security model. It needs to move towards a microkernel-based model with a Linux compatibility layer, with many stepping stones leading towards that goal including adopting virtualization-based isolation.
The initial phase for the long-term roadmap of moving away from the current foundation will be to deploy and integrate a hypervisor like Xen to leverage it for reinforcing existing security boundaries. Linux would be running inside the virtual machines at this point, inside and outside of the sandboxes being reinforced. In the longer term, Linux inside the sandboxes can be replaced with a compatibility layer like gVisor, which would need to be ported to arm64 and given a new backend alongside the existing KVM backend. Over the longer term, i.e. many years from now, Linux can fade away completely and so can the usage of virtualization. The anticipation is that many other projects are going to be interested in this kind of migration, so it's not going to be solely a GrapheneOS project, as demonstrated by the current existence of the gVisor project and various other projects working on virtualization deployments for mobile. Having a hypervisor with verified boot still intact will also provide a way to achieve some of the goals based on extensions to Trusted Execution Environment (TEE) functionality even without having GrapheneOS hardware.
Hardware and firmware security are core parts of the project, but it's currently limited to research and submitting suggestions and bug reports upstream. In the long term, the project will need to move into the hardware space.