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355 lines
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<li><a href="/"><img src="/mask-icon.svg" alt=""/>GrapheneOS</a></li>
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<li aria-current="page"><a href="/features">Features</a></li>
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<li><a href="/install/">Install</a></li>
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<li><a href="/build">Build</a></li>
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<li><a href="/usage">Usage</a></li>
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<li><a href="/faq">FAQ</a></li>
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<li><a href="/releases">Releases</a></li>
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<li><a href="/history/">History</a></li>
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<li><a href="/articles/">Articles</a></li>
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<li><a href="/contact">Contact</a></li>
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<main id="features">
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<h1><a href="#features">Features overview</a></h1>
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<p>GrapheneOS is a private and secure mobile operating system with great functionality
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and usability. It starts from the strong baseline of the
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<a href="https://source.android.com/">Android Open Source Project (AOSP)</a> and
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takes great care to avoid increasing attack surface or hurting the strong security
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model. GrapheneOS makes substantial improvements to both privacy and security through
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many carefully designed features built to function against real adversaries. The
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project cares a lot about usability and app compatibility so those are taken into
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account for all of our features.</p>
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<p>GrapheneOS is focused on substance rather than branding and marketing. It doesn't
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take the typical approach of piling on a bunch of insecure features depending on the
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adversaries not knowing about them and regressing actual privacy/security. It's a very
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technical project building privacy and security into the OS rather than including
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assorted unhelpful frills or bundling subjective third party apps choices.</p>
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<p>GrapheneOS is also hard at work on filling in gaps from not bundling Google apps
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and services into the OS. We aren't against users using Google services but it doesn't
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belong integrated into the OS in an invasive way. GrapheneOS won't take the shortcut
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of simply bundling a very incomplete and poorly secured third party reimplementation
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of Google services into the OS. That wouldn't ever be something users could rely upon.
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It will also always be chasing a moving target while offering poorer security than the
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real thing if the focus is on simply getting things working without great care for
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doing it robustly and securely.</p>
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<p>This page provides an overview of currently implemented features differentiating
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GrapheneOS from AOSP. It doesn't document our many historical features that are not no
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longer included for one reason or another. Many of our features were implemented in
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AOSP, Linux, <a href="https://llvm.org/">LLVM</a> and other projects GrapheneOS is
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based on and those aren't listed here. In many cases, we've been involved in getting
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those features implemented in core infrastructure projects.</p>
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<nav id="table-of-contents">
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<h2><a href="#table-of-contents">Table of contents</a></h2>
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<ul>
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<li><a href="#grapheneos">GrapheneOS</a></li>
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<li><a href="#services">Services</a></li>
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<li><a href="#project">Project</a></li>
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</ul>
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</nav>
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<section id="grapheneos">
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<h2><a href="#grapheneos">GrapheneOS</a></h2>
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<p>Partial list of GrapheneOS features beyond what AOSP 11 provides:</p>
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<ul>
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<li>Hardened app runtime</li>
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<li>Stronger app sandbox</li>
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<li><a href="https://github.com/GrapheneOS/platform_bionic">Hardened libc</a>
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providing defenses against the most common classes of vulnerabilities (memory
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corruption)</li>
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<li>
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Our own <a href="https://github.com/GrapheneOS/hardened_malloc">hardened
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malloc (memory allocator)</a> leveraging modern hardware capabilities
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to provide substantial defenses against the most common classes of
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vulnerabilities (heap memory corruption) along with reducing the lifetime
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of sensitive data in memory. The <a
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href="https://github.com/GrapheneOS/hardened_malloc/blob/main/README.md">hardened_malloc
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README</a> has extensive documentation on it. The hardened_malloc
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project is portable to other Linux-based operating systems and is being
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adopted by other security-focused operating systems like Whonix. Our
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allocator also heavily influenced the design of the <a
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href="https://www.openwall.com/lists/musl/2020/05/13/1">next-generation
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musl malloc implementation</a> which offers substantially better security than
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musl's previous malloc while still having minimal memory usage and code size.
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<ul>
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<li>Fully out-of-line metadata with protection from corruption, ruling
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out traditional allocator exploitation</li>
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<li>Separate memory regions for metadata, large allocations and each
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slab allocation size class with high entropy random bases and no
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address space reuse between the different regions</li>
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<li>Deterministic detection of any invalid free</li>
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<li>Zero-on-free with detection of write-after-free via checking that
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memory is still zeroed before handing it out again</li>
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<li>Delayed reuse of address space and memory allocations through the
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combination of deterministic and randomized quarantines to mitigate
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use-after-free vulnerabilities</li>
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<li>Fine-grained randomization</li>
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<li>Aggressive consistency checks</li>
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<li>Memory protected guard regions around allocations larger than 16k
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with randomization of guard region sizes for 128k and above</li>
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<li>Allocations smaller than 16k have guard regions around each of the
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slabs containing allocations (for example, 16 byte allocations are in
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4096 byte slabs with 4096 byte guard regions before and after)</li>
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<li>Random canaries with a leading zero are added to these smaller
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allocations to block C string overflows, absorb small overflows
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and detect linear overflows or other heap corruption when the
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canary value is checked (primarily on free)</li>
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</ul>
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</li>
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<li>Hardened compiler toolchain</li>
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<li>
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Hardened kernel
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<ul>
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<li>Support for dynamically loaded kernel modules is disabled and
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the minimal set of modules for the device model are built into the
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kernel to substantially improve the granularity of Control Flow
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Integrity (CFI) and reduce attack surface.</li>
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<li>4-level page tables are enabled on arm64 to provide a much larger
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address space (48-bit instead of 39-bit) with significantly higher
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entropy Address Space Layout Randomization (33-bit instead of
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24-bit).</li>
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<li>Random canaries with a leading zero are added to the kernel heap
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(slub) to block C string overflows, absorb small overflows and detect
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linear overflows or other heap corruption when the canary value is
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checked (on free, copies to/from userspace, etc.).</li>
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<li>Memory is wiped (zeroed) as soon as it's released in both the
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low-level kernel page allocator and higher level kernel heap allocator
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(slub). This substantially reduces the lifetime of sensitive data in
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memory, mitigates use-after-free vulnerabilities and makes most
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uninitialized data usage vulnerabilities harmless. Without our
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changes, memory that's released retains data indefinitely until the
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memory is handed out for other uses and gets partially or fully
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overwritten by new data.</li>
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<li>Kernel stack allocations are zeroed to make most uninitialized
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data usage vulnerabilities harmless.</li>
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<li>Assorted attack surface reduction through disabling features or
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setting up infrastructure to dynamically enable/disable them only as
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needed (perf, ptrace).</li>
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<li>Assorted upstream hardening features are enabled, including many
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which we played a part in developing and landing upstream as part of
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our linux-hardened project (which we intend to revive as a more active
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project again).</li>
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</ul>
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</li>
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<li>Prevention of dynamic native code execution in-memory or via the filesystem
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for the base OS without going via the package manager, etc.</li>
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<li>Filesystem access hardening</li>
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<li>Enhanced <a href="https://source.android.com/security/verifiedboot">verified boot</a>
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with better security properties and reduced attack surface</li>
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<li>Enhanced hardware-based attestation with more precise version information</li>
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<li>Eliminates remaining holes for apps to access hardware-based identifiers</li>
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<li>Greatly reduced remote, local and proximity-based attack surface by
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stripping out unnecessary code, making more features optional and disabling
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optional features by default (NFC, Bluetooth, etc.), when the screen is
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locked (connecting new USB peripherals, camera access) and optionally after a
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timeout (Bluetooth)</li>
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<li>Option to disable native debugging (ptrace) to reduce local attack surface
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(still enabled by default for compatibility)</li>
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<li>Low-level improvements to the <a href="/faq#encryption">filesystem-based
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full disk encryption</a> used on modern Android</li>
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<li>Support for logging out of user profiles without needing a device manager:
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makes them inactive so that they can't continue running code while using
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another profile and purges the disk encryption keys (which are per-profile)
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from memory and hardware registers</li>
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<li>Indicators for active camera and microphone usage are enabled by default
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alongside the traditional location indicator</li>
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<li>Support longer passwords by default (64 characters) without a device manager</li>
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<li>Stricter implementation of the optional fingerprint unlock feature permitting
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only 5 attempts rather than 20 before permanent lockout (our recommendation is
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still keeping sensitive data in user profiles without fingerprint unlock)</li>
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<li>PIN scrambling option</li>
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<li><a href="/usage#lte-only-mode">LTE-only mode</a> to reduce cellular radio
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attack surface by disabling enormous amounts of legacy code</li>
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<li><a href="/usage#wifi-privacy-associated">Default enabled per-connection MAC randomization</a>
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as an improvement over Android's default per-network MAC randomization reusing
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the same MAC address until the DHCP lease with that network expires (can still
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use the standard implementation or fully disable it)</li>
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<li>Vanadium: hardened WebView and default browser — the WebView is what most
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other apps use to handle web content, so you benefit from Vanadium in many apps
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even if you choose another browser</li>
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<li>Hardware-based security verification and monitoring: the
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<a href="https://github.com/GrapheneOS/Auditor/releases">Auditor app</a> app and
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<a href="https://attestation.app/">attestation service</a> provide strong
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hardware-based verification of the authenticity and integrity of the
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firmware/software on the device. A strong pairing-based approach is used which
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also provides verification of the device's identity based on the hardware backed
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key generated for each pairing. Software-based checks are layered on top with
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trust securely chained from the hardware. For more details, see the
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<a href="https://attestation.app/about">about page</a>
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and <a href="https://attestation.app/tutorial">tutorial</a>.</li>
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<li><a href="https://github.com/GrapheneOS/PdfViewer">PDF Viewer</a>: sandboxed,
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hardened PDF viewer using HiDPI rendering with pinch to zoom, text selection,
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etc.</li>
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<li>Encrypted backups via integration of the
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<a href="https://github.com/seedvault-app/seedvault">Seedvault app</a> with
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support for local backups and any cloud storage provider with a storage provider
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app</li>
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<li><a href="/usage#exec-spawning">Secure application spawning system</a> avoiding
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sharing address space layout and other secrets across applications</li>
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<li>Network permission toggle for disallowing both direct and indirect access
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to any of the available networks. The device-local network (localhost) is also
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guarded by this permission, which is important for preventing apps from using
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it to communicate between profiles. Unlike a firewall-based implementation,
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the Network permission toggle prevents apps from using the network via APIs
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provided by the OS or other apps in the same profile as long as they're marked
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appropriately.</li>
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<li>The standard INTERNET permission used as the basis for the Network
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permission toggle is enhanced with a second layer of enforcement and proper
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support for granting/revoking it on a per-profile basis.</li>
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<li>Sensors permission toggle: disallow access to all other sensors not covered by
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existing Android permissions (enabled by default for compatibility)</li>
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<li>Authenticated encryption for network time updates via a first party server to
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prevent attackers from changing the time and enabling attacks based on bypassing
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certificate / key expiry, etc.</li>
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<li>Proper support for disabling network time updates rather than just not using
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the results</li>
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<li>Connectivity checks via a first party server with the option to revert to the
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standard checks</li>
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<li>Hardened local build / signing infrastructure</li>
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<li><a href="/usage#updates">Seamless automatic OS update system</a> that just
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works and stays out of the way in the background without disrupting device
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usage, with full support for the standard automatic rollback if the first boot
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of the updated OS fails</li>
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<li>Require unlocking to access sensitive functionality via quick tiles</li>
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<li>Minor changes to default settings to prefer privacy over small conveniences:
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personalized keyboard suggestions based on gathering input history are disabled by
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default, sensitive notifications are hidden on the lockscreen by default and
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passwords are hidden during entry by default</li>
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<li><a href="/faq#bundled-apps">Minimal bundled apps and services</a>. Only
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essential apps are integrated into the OS. We don't make partnerships with
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apps and services to bundle them into the OS. An app may be the best choice
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today and poor choice in the future. Our approach will be recommending certain
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apps during the initial setup, not hard-wiring them into the OS.</li>
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<li>No Google apps and services. These can be used on GrapheneOS but only if
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they avoid requiring invasive OS integration. Building privileged support for
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Google services into the OS isn't something we're going to be doing, even if
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that's partially open source like microG.</li>
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</ul>
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</section>
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<section id="services">
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<h2><a href="#services">Services</a></h2>
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<p>Service infrastructure features:</p>
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<ul>
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<li>Strict privacy and security practices for our infrastructure</li>
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<li>Unnecessary logging is avoided and logs are automatically purged after 10 days</li>
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<li>Services are hosted entirely via our own dedicated servers and virtual
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machines from OVH without involving any additional parties for CDNs, SaaS
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platforms, mirrors or other services</li>
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<li>Our services are built with open technology stacks to avoid being locked in to
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any particular hosting provider or vendor</li>
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<li>Open documentation on our infrastructure including listing out all of our
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services, guides on making similar setups, published configurations for each
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of our web services, etc.</li>
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<li>No proprietary services</li>
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<li>Authenticated encryption for all of our services</li>
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<li>Strong cipher configurations for all of our services (SSH, TLS, etc.) with
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only modern AEAD ciphers providing forward secrecy</li>
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<li>Our web sites do not include any third party content and entirely forbid
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it via strict Content Security Policy rules</li>
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<li>Our web sites disable referrer headers to maximize privacy</li>
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<li>Our web sites fully enable cross origin isolation and disable embedding in
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other content</li>
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<li><a href="https://internet.nl/faqs/dnssec/">DNSSEC</a> implemented for all
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of our domains to provide a root of trust for encryption and authentication
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for domain/server configuration</li>
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<li>DNS Certification Authority Authorization (CAA) records for all of our
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domains permitting only Let's Encrypt to issue certificates with fully
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integrated support for the experimental <code>accounturi</code> and
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<code>validationmethods</code> pinning our Let's Encrypt accounts as the only ones
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allowed to issue certificates</li>
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<li>DANE TLSA records for pinning keys for all our TLS services</li>
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<li>Our mail server enforces DNSSEC/DANE to provide authenticated encryption
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when sending mail including alert messages from the attestation service</li>
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<li>SSHFP across all domains for pinning SSH keys</li>
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<li>Static key pinning for our services in apps like Auditor</li>
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<li>Our web services use robust OCSP stapling with Must-Staple</li>
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<li>No persistent cookies or similar client-side state for anything other than
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login sessions, which are set up via SameSite=strict cookies and have
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server-side session tracking with the ability to log out of other
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sessions</li>
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<li>scrypt-based password hashing (likely Argon2 when the available implementations
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are more mature)</li>
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</ul>
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</section>
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<section id="project">
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<h2><a href="#project">Project</a></h2>
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<p>Beyond the technical features of the OS:</p>
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<ul>
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<li>Collaborative, <a href="/source">open source project</a> with a
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<a href="/contact#community">very active community</a> and contributors</li>
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<li>Can make your own builds and make desired changes, so you aren't stuck with
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the decisions made by the upstream project</li>
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<li>Non-profit project avoiding conflicts of interest by keeping commercialization
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at a distance. Companies support the project
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<a href="/faq#company">rather than the project serving the needs of any
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particular company</a></li>
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<li><a href="/faq#privacy-policy">Strong privacy policies</a> across all our
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software and services</li>
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<li><a href="/history/">Proven record</a> of the team standing up against
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attempts to compromise the integrity of the project and placing it above
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personal gain</li>
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</ul>
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</section>
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<a href="/"><img src="/mask-icon.svg" width="512" height="512" alt=""/>GrapheneOS</a>
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<li><a href="https://github.com/GrapheneOS">GitHub</a></li>
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<li><a href="https://reddit.com/r/GrapheneOS">Reddit</a></li>
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<li><a href="https://www.linkedin.com/company/grapheneos/">LinkedIn</a></li>
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