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<main id="features">
<h1><a href="#features">Features overview</a></h1>
<p>GrapheneOS is a private and secure mobile operating system with great functionality
and usability. It starts from the strong baseline of the
<a href="https://source.android.com/">Android Open Source Project (AOSP)</a> 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.</p>
<p>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.</p>
<p>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.</p>
<p>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, <a href="https://llvm.org/">LLVM</a> 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.</p>
<nav id="table-of-contents">
<h2><a href="#table-of-contents">Table of contents</a></h2>
<ul>
<li><a href="#grapheneos">GrapheneOS</a></li>
<li><a href="#services">Services</a></li>
<li><a href="#project">Project</a></li>
</ul>
</nav>
<section id="grapheneos">
<h2><a href="#grapheneos">GrapheneOS</a></h2>
<p>Partial list of GrapheneOS features beyond what AOSP 11 provides:</p>
<ul>
<li>Hardened app runtime</li>
<li>Stronger app sandbox</li>
<li>Hardened libc providing defenses against the most common classes of
vulnerabilities (memory corruption)</li>
<li>Our own <a href="https://github.com/GrapheneOS/hardened_malloc">hardened malloc (memory allocator)</a>
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
<a href="https://github.com/GrapheneOS/hardened_malloc/blob/master/README.md">hardened_malloc
README</a> 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 <a href="https://www.openwall.com/lists/musl/2020/05/13/1">next-generation
musl malloc implementation</a> which offers substantially better security than musl's
previous malloc while still having minimal memory usage and code size.</li>
<li>Hardened compiler toolchain</li>
<li>Hardened kernel</li>
<li>Prevention of dynamic native code execution in-memory or via the filesystem
for the base OS without going via the package manager, etc.</li>
<li>Filesystem access hardening</li>
<li>Enhanced <a href="https://source.android.com/security/verifiedboot">verified boot</a> with better security properties and reduced attack surface</li>
<li>Enhanced hardware-based attestation with more precise version information</li>
<li>Eliminates remaining holes for apps to access hardware-based identifiers</li>
<li>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)</li>
<li>Low-level improvements to the filesystem-based full disk encryption used on
modern Android</li>
<li>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</li>
<li>Indicators for active camera and microphone usage are enabled by default
alongside the traditional location indicator</li>
<li>Support longer passwords by default without a device manager</li>
<li>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)</li>
<li>PIN scrambling option</li>
<li><a href="/usage#lte-only-mode">LTE-only mode</a> to reduce cellular radio
attack surface by disabling enormous amounts of legacy code</li>
<li><a href="/usage#wifi-privacy-associated">Default enabled per-connection MAC randomization</a>
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)</li>
<li>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</li>
<li>Hardware-based security verification and monitoring: the
<a href="https://github.com/GrapheneOS/Auditor/releases">Auditor app</a> app and
<a href="https://attestation.app/">attestation service</a> 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
<a href="https://attestation.app/about">about page</a>
and <a href="https://attestation.app/tutorial">tutorial</a>.</li>
<li><a href="https://github.com/GrapheneOS/PdfViewer">PDF Viewer</a>: sandboxed,
hardened PDF viewer using HiDPI rendering with pinch to zoom, text selection,
etc.</li>
<li>Encrypted backups via integration of the
<a href="https://github.com/seedvault-app/seedvault">Seedvault app</a> with
support for local backups and any cloud storage provider with a storage provider
app</li>
<li><a href="/usage#exec-spawning">Secure application spawning system</a> avoiding
sharing address space layout and other secrets across applications</li>
<li>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)</li>
<li>Sensors permission toggle: disallow access to all other sensors not covered by
existing Android permissions (enabled by default for compatibility)</li>
<li>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.</li>
<li>Proper support for disabling network time updates rather than just not using
the results</li>
<li>Connectivity checks via a first party server with the option to revert to the
standard checks</li>
<li>Hardened local build / signing infrastructure</li>
<li><a href="/usage#updates">Seamless automatic OS update system</a> 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</li>
<li>Require unlocking to access sensitive function via quick tiles</li>
<li>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</li>
</ul>
</section>
<section id="services">
<h2><a href="#services">Services</a></h2>
<p>Service infrastructure features:</p>
<ul>
<li>Strict privacy and security practices for our infrastructure</li>
<li>Unnecessary logging is avoided and logs are automatically purged after 10 days</li>
<li>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</li>
<li>Our services are built with open technology stacks to avoid being locked in to
any particular hosting provider or vendor</li>
<li>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.</li>
<li>No proprietary services</li>
<li>Authenticated encryption for all of our services</li>
<li>Strong cipher configurations for all of our services (SSH, TLS, etc.) with
only modern AEAD ciphers providing forward secrecy</li>
<li>Our web services use robust OCSP stapling with Must-Staple</li>
<li>Our web sites do not include any third party content and entirely forbid
it via strict Content Security Policy rules</li>
<li>Our web sites disable referrer headers to maximize privacy</li>
<li>Our web sites fully enable cross origin isolation and disable embedding in
other content</li>
<li>DNSSEC implemented for all of our domains</li>
<li>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 <code>accounturi</code> and
<code>validationmethods</code> pinning our Let's Encrypt accounts as the only ones
allowed to issue certificates</li>
<li>DANE TLSA records for pinning keys for all our TLS services</li>
<li>Our mail server enforces DNSSEC/DANE to provide authenticated encryption
when sending mail including alert messages from the attestation service</li>
<li>SSHFP across all domains for pinning SSH keys</li>
<li>Static key pinning for our services in apps like Auditor</li>
<li>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</li>
<li>scrypt-based password hashing (likely Argon2 when the available implementations
are more mature)</li>
</ul>
</section>
<section id="project">
<h2><a href="#project">Project</a></h2>
<p>Beyond the technical features of the OS:</p>
<ul>
<li>Collaborative, open source project with a very active community and contributors</li>
<li>Can make your own builds and make desired changes, so you aren't stuck with
the decisions made by the upstream project</li>
<li>Non-profit project avoiding conflicts of interest by keeping commercialization
at a distance. Companies support the project
<a href="/faq#company">rather than the project serving the needs of any
particular company</a></li>
<li><a href="/faq#privacy-policy">Strong privacy policies</a></li>
</ul>
</section>
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