GrapheneOS is a private and secure mobile operating system with great functionality and usability. It starts from the strong baseline of the Android Open Source Project (AOSP) and takes great care to avoid increasing attack surface or hurting the strong security model. GrapheneOS makes substantial improvements to both privacy and security through many carefully designed features built to function against real adversaries. The project cares a lot about usability and app compatibility so those are taken into account for all of our features.
GrapheneOS is focused on substance rather than branding and marketing. It doesn't take the typical approach of piling on a bunch of insecure features depending on the adversaries not knowing about them and regressing actual privacy/security. It's a very technical project building privacy and security into the OS rather than including assorted unhelpful frills or bundling subjective third party apps choices.
GrapheneOS is also hard at work on filling in gaps from not bundling Google apps and services into the OS. We aren't against users using Google services but it doesn't belong integrated into the OS in an invasive way. GrapheneOS won't take the shortcut of simply bundling a very incomplete and poorly secured third party reimplementation of Google services into the OS. That wouldn't ever be something users could rely upon. It will also always be chasing a moving target while offering poorer security than the real thing if the focus is on simply getting things working without great care for doing it robustly and securely.
This page provides an overview of currently implemented features differentiating GrapheneOS from AOSP. It doesn't document our many historical features that are not no longer included for one reason or another. Many of our features were implemented in AOSP, Linux, LLVM and other projects GrapheneOS is based on and those aren't listed here. In many cases, we've been involved in getting those features implemented in core infrastructure projects.
Partial list of GrapheneOS features beyond what AOSP 11 provides:
- 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. The hardened_malloc README has extensive documentation on it. The hardened_malloc project is portable to other Linux-based operating systems and is being adopted by other security-focused operating systems like Whonix. Our allocator also heavily influenced the design of the next-generation musl malloc implementation which offers substantially better security than musl's previous malloc while still having minimal memory usage and code size.
- Hardened compiler toolchain
- 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 (NFC, Bluetooth, etc.), when the screen is locked (connecting new USB peripherals, camera access) and optionally after a timeout (Bluetooth)
- 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 and purges the disk encryption keys (which are per-profile) from memory and hardware registers
- Indicators for active camera and microphone usage are enabled by default alongside the traditional location indicator
- Support longer passwords by default (64 characters) without a device manager
- Stricter implementation of the optional fingerprint unlock feature permitting only 5 attempts rather than 20 before permanent lockout (our recommendation is still keeping sensitive data in user profiles without fingerprint unlock)
- PIN scrambling option
- 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 (can still use the standard implementation or fully disable it)
- Vanadium: hardened WebView and default browser — the WebView is what most other apps use to handle web content, so you benefit from Vanadium in many apps even if you choose another browser
- Hardware-based security verification and monitoring: the Auditor app app and attestation service provide strong hardware-based verification of the authenticity and integrity of the firmware/software on the device. A strong pairing-based approach is used which also provides verification of the device's identity based on the hardware backed key generated for each pairing. Software-based checks are layered on top with trust securely chained from the hardware. For more details, see the about page and tutorial.
- PDF Viewer: sandboxed, hardened PDF viewer using HiDPI rendering with pinch to zoom, text selection, etc.
- Encrypted backups via integration of the Seedvault app with support for local backups and any cloud storage provider with a storage provider app
- 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 (enabled by default for compatibility)
- Sensors permission toggle: disallow access to all other sensors not covered by existing Android permissions (enabled by default for compatibility)
- 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, with full support for the standard automatic rollback if the first boot of the updated OS fails
- Require unlocking to access sensitive function via quick tiles
- Minor changes to default settings to prefer privacy over small conveniences: personalized keyboard suggestions based on gathering input history are disabled by default, sensitive notifications are hidden on the lockscreen by default and passwords are hidden during entry by default
- Minimal bundled apps and services. Only essential apps are integrated into the OS. We don't make partnerships with apps and services to bundle them into the OS. An app may be the best choice today and poor choice in the future. Our approach will be recommending certain apps during the initial setup, not hard-wiring them into the OS.
- No Google apps and services. These can be used on GrapheneOS but only if they avoid requiring invasive OS integration. Building privileged support for Google services into the OS isn't something we're going to be doing, even if that's partially open source like microG.
Service infrastructure features:
- Strict privacy and security practices for our infrastructure
- Unnecessary logging is avoided and logs are automatically purged after 10 days
- Services are hosted entirely via our own dedicated servers and virtual machines from OVH without involving any additional parties for CDNs, SaaS platforms, mirrors or other services
- 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.) with only modern AEAD ciphers providing forward secrecy
- Our web sites do not include any third party content and entirely forbid it via strict Content Security Policy rules
- Our web sites disable referrer headers to maximize privacy
- Our web sites fully enable cross origin isolation and disable embedding in other content
- DNSSEC implemented for all of our domains to provide a root of trust for encryption and authentication for domain/server configuration
- DNS Certification Authority Authorization (CAA) records for all of our domains permitting only Let's Encrypt to issue certificates with fully integrated support for the experimental
validationmethodspinning our Let's Encrypt accounts as the only ones allowed to issue certificates
- DANE TLSA records for pinning keys for all our TLS services
- Our mail server enforces DNSSEC/DANE to provide authenticated encryption when sending mail including alert messages from the attestation service
- SSHFP across all domains for pinning SSH keys
- Static key pinning for our services in apps like Auditor
- Our web services use robust OCSP stapling with Must-Staple
- No persistent 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
- Proven record of the team standing up against attempts to compromise the integrity of the project and placing it above personal gain