GrapheneOS feature overview

This is a newly created page (started 2020-12-05) and is in the process of being written. More details and links to more detailed documentation and relevant repositories will be added over time.

This is an overview of the current set of features differentiating GrapheneOS from the Android Open Source Project (AOSP). This page does not currently cover any of our historical features that are either not yet reimplemented or which became obsolete due to improvements in AOSP. Each major release of AOSP brings substantial privacy and security improvements, some of which have been based on our research and development work.

Partial list of GrapheneOS features:

• Hardened app runtime
• Stronger app sandbox
• Hardened libc providing defenses against the most common classes of vulnerabilities (memory corruption)
• Our own hardened malloc (memory allocator) leveraging modern hardware capabilities to provide substantial defenses against the most common classes of vulnerabilities (heap memory corruption) along with reducing the lifetime of sensitive data in memory
• Hardened kernel
• Prevention of dynamic native code execution in-memory or via the filesystem for the base OS without going via the package manager, etc.
• Filesystem access hardening
• Enhanced verified boot with better security properties and reduced attack surface
• Enhanced hardware-based attestation with more precise version information
• Eliminates remaining holes for apps to access hardware-based identifiers
• Greatly reduced remote, local and proximity-based attack surface by stripping out unnecessary code, making more features optional and disabling optional features by default or when the screen is locked
• Low-level improvements to the filesystem-based full disk encryption used on modern Android
• Support for logging out of user profiles without needing a device manager: makes them inactive so that they can't continue running code while using another profile, purges disk encryption keys (which are per-profile) from memory and hardware registers
• LTE-only mode to reduce cellular radio attack surface by disabling enormous amounts of legacy code
• Default enabled per-connection MAC randomization as an improvement over Android's default per-network MAC randomization reusing the same MAC address until the DHCP lease with that network expires
• Vanadium: hardened WebView and default browser
• Auditor: hardware-based attestation used to secure devices for users and organizations instead of using it as a form of DRM
• PDF Viewer: sandboxed, hardened PDF viewer using HiDPI rendering with pinch to zoom, text selection, etc.
• Secure application spawning system avoiding sharing address space layout and other secrets across applications
• Network permission toggle disallowing both direct and indirect network access, superior to a purely firewall-based implementation only disallowing direct access to the network without covering inter-process communication
• Sensors permission toggle
• Authenticated encryption for network time updates via a first party server to prevent attackers from changing the time and enabling attacks based on bypassing certificate / key expiry, etc.
• Proper support for disabling network time updates rather than just not using the results
• Connectivity checks via a first party server with the option to revert to the standard checks
• Hardened local build / signing infrastructure
• Seamless automatic OS update system that just works and stays out of the way in the background without disrupting device usage

Infrastructure features:

• Strict privacy and security practices for our infrastructure
• Services hosted on OVH without involving any additional parties for CDNs, mirrors or other services - we don't outsource to others
• Our services are built with open technology stacks to avoid being locked in to any particular hosting provider or vendor
• Open documentation on our infrastructure including listing out all of our services, guides on making similar setups, published configurations for each of our web services, etc.
• No proprietary services
• Authenticated encryption for all of our services
• Strong cipher configurations for all of our services (SSH, TLS, etc.)
• DNSSEC for all our domains
• SSHFP across all domains for pinning SSH keys
• DANE TLSA records for pinning keys for all our TLS services (unfortunately only used by a subset of other mail services in practice, and not yet web browsers)
• Static key pinning for our services in apps like Auditor
• No cookies or similar client-side state for anything other than login sessions, which are set up via SameSite=strict cookies and have server-side session tracking with the ability to log out of other sessions
• scrypt-based password hashing (likely Argon2 when the available implementations are more mature)

Beyond the technical features of the OS:

• Collaborative, open source project with a very active community and contributors
• Can make your own builds and make desired changes, so you aren't stuck with the decisions made by the upstream project
• Non-profit project avoiding conflicts of interest by keeping commercialization at a distance. Companies support the project rather than the project serving the needs of any particular company
• Strong privacy policies