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---
title: "GrapheneOS or CalyxOS?"
icon: 'material/cellphone-cog'
---
GrapheneOS and CalyxOS are often compared as similar options for people looking for an alternative Android OS for their Pixel devices. Below are some of the reasons why we recommend GrapheneOS over CalyxOS.
- [General Android Overview :material-arrow-right-drop-circle:](overview.md)
- [Android Recommendations :material-arrow-right-drop-circle:](../android.md)
## Update Frequency
CalyxOS has a track record of being slower to apply security and feature updates to its OS and core applications than other custom Android operating systems. Timely security updates are one of the most important factors to consider when determining whether an OS is secure enough for regular use, which is a requirement for privacy.
In contrast to that, GrapheneOS manages to stay close to upstream and in some cases even [deliver updates before the stock OS does](https://grapheneos.org/features#more-complete-patching).
As an example, [GrapheneOS's first Android 12 release](https://grapheneos.org/releases#2021102020) was in October 2021, whereas [CalyxOS moved to Android 12](https://calyxos.org/news/2022/01/19/android-12-changelog/) in January 2022.
## Sandboxed Google Play vs Privileged microG
When Google Play Services are used on GrapheneOS, they are confined using the highly restrictive, default [`untrusted_app`](https://source.android.com/security/selinux/concepts) [SELinux](https://en.wikipedia.org/wiki/Security-Enhanced_Linux) domain. As a result, you have full control as to what these apps can access via permissions, just like any other app you install. Additionally, you can selectively choose which profile(s) to install the Sandboxed Google Play in.
microG is a partially open-source re-implementation of Google Play Services.[^1] On CalyxOS, it runs in the highly privileged [`system_app`](https://source.android.com/security/selinux/concepts) SELinux domain like regular Google Play Services, and it uses [signature spoofing](https://github.com/microg/GmsCore/wiki/Signature-Spoofing) to masquerade as Google Play Services. This is less secure than Sandboxed Google Play's approach, which does not need access to sensitive system APIs.
When using Sandboxed Google Play, you have the option to reroute location requests to the Play Services API back to the OS location API, which uses satellite based location services. With microG, you have the option to choose between different backend location providers, including *shifting trust* to another location backend, like Mozilla; using [DejaVu](https://github.com/n76/DejaVu), a location backend that locally collects and saves RF-based location data to an offline database which can be used when GPS is not available; or to simply not use a network location backend at all.
Network location providers like Play Services or Mozilla rely the on the MAC addresses of surrounding WiFi access points and Bluetooth devices being submitted for location approximation. Choosing a network location like Mozilla to use with microG provides little to no privacy benefit over Google because you are still submitting the same data and trusting them to not profile you.
Local RF location backends like DejaVu require that the phone has a working GPS first for the local RF data collected to be useful. This makes them less effective as location providers, as the job of a location provider is to assist location approximation when satellite based services are not working.
If your [threat model](../basics/threat-modeling.md) requires protecting your location or the MAC addresses of nearby devices, rerouting location requests to the OS location API is probably the best option. The benefit brought by microG's custom location backend is minimal at best when compared to Sandboxed Google Play.
In terms of application compatibility, ==Sandboxed Google Play on GrapheneOS is always going to be more compatible== as it is the same code as what is released by Google. microG is a reimplementation of these services. As a result, it only supports the various parts that have been reimplemented, meaning some things such as [Google Play Games](https://play.google.com/googleplaygames) and [In-app Billing API](https://android-doc.github.io/google/play/billing/api.html) are not yet supported.
Larger apps, especially games, require [Play Asset Delivery](https://android-developers.googleblog.com/2020/06/introducing-google-play-asset-delivery.html) to be installed, which is currently not implemented in microG. Authentication using [FIDO](../basics/multi-factor-authentication.md#fido-fast-identity-online) with online services on Android also relies on Play Services, and does not currently work with microG.
[^1]: It should be noted that microG still uses proprietary Google binaries for some of its components such as DroidGuard. Push notifications, if enabled, still go through Google's servers just like with Play Services. Outside of default microG setups like on CalyxOS, it is possible to run microG in the unprivileged [`untrusted app`](https://source.android.com/security/selinux/concepts) SELinux domain and without the signature spoofing patch. However, microG's functionality and compatibility, which is already not nearly as broad as Sandboxed Google Play, will greatly diminish.
## Privileged eSIM Activation Application
Currently, eSIM activation is tied to a privileged proprietary application by Google. The app has the `READ_PRIVILEGED_PHONE_STATE` permission, giving Google access to your hardware identifiers such as the IMEI.
On GrapheneOS, the app comes disabled and you can *optionally* enable it after installing Sandboxed Google Play.
On CalyxOS, the app comes installed by default (regardless of whether you choose to have microG or not) and you cannot opt-out. This means that Google still has access to your hardware identifiers regardless of whether or not you need eSIM activation and they can be accessed persistently.
## Privileged App Extensions
Android 12 comes with special support for seamless app updates with [third-party app stores](https://android-developers.googleblog.com/2020/09/listening-to-developer-feedback-to.html). The popular Free and Open-Source Software (FOSS) repository [F-Droid](https://f-droid.org) doesn't implement this feature and requires a [privileged extension](https://f-droid.org/en/packages/org.fdroid.fdroid.privileged) to be included with the Android distribution in order to have unattended app updates.
CalyxOS includes the [privileged extension](https://f-droid.org/en/packages/org.fdroid.fdroid.privileged), which may lower device security.
On the other hand, GrapheneOS officially recommends [Sandboxed Google Play](https://grapheneos.org/usage#sandboxed-google-play) instead. Many FOSS Android apps are also in Google's Play Store but sometimes they are not (like [NewPipe](../frontends.md#newpipe-android)). In those cases, you can [keep up with updates using RSS](../android.md#manually-with-rss-notifications).
## Profiles
GrapheneOS significantly improves [user profiles](overview.md#user-profiles) in [multiple ways](https://grapheneos.org/features#improved-user-profiles), such as increasing the limit of how many profiles you can create (32 instead of the standard 4), allowing you to log out of user profiles, disabling app installation, and notification forwarding. All of these improvements make it so user profiles can be daily driven without sacrificing too much usability.
CalyxOS doesn't feature any improvements to user profiles over AOSP, and instead includes a device controller app so that the [work profile](overview.md#work-profile) can be used without needing to download a third party app such as [Shelter](../android.md#shelter). However, work profiles are not nearly as flexible (as you're limited to only one) and don't provide the same amount of isolation and security.
## Additional Hardening
GrapheneOS improves upon [AOSP](https://source.android.com/) security with:
- **Hardened WebView:** Vanadium WebView requires [64-bit](https://en.wikipedia.org/wiki/64-bit_computing) processes on the [WebView](https://developer.android.com/reference/android/webkit/WebView) process and disables legacy [32-bit](https://en.wikipedia.org/wiki/32-bit_computing) processes. It uses hardened compiler options such as [`-fwrapv`](https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html) and [`-fstack-protector-strong`](https://gcc.gnu.org/onlinedocs/gcc-4.9.3/gcc/Optimize-Options.html), which can help protect against [stack buffer overflows](https://en.wikipedia.org/wiki/Stack_buffer_overflow). [API](https://en.wikipedia.org/wiki/API)s such as the [battery status API](https://chromestatus.com/feature/4537134732017664) are disabled for privacy reasons. All system apps on GrapheneOS use the Vanadium WebView which means that apps which use WebView will also benefit from Vanadium's hardening. The [Vanadium patch set](https://github.com/GrapheneOS/Vanadium) is a lot more comprehensive than CalyxOS's [Chromium patch set](https://gitlab.com/CalyxOS/chromium-patches) which is derived from it.
- **Hardened Kernel:** GrapheneOS kernel includes some hardening from the [linux-hardened](https://github.com/GrapheneOS/linux-hardened) project and the [Kernel Self Protection Project (KSPP)](https://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project). CalyxOS uses the [same kernel](https://calyxos.org/docs/development/build/kernel/) as regular Android with some minor modifications.
- **Hardened Memory Allocator:** GrapheneOS uses the [hardened malloc](https://github.com/GrapheneOS/hardened_malloc) subproject as its memory allocator. This focuses on hardening against [memory heap corruption](https://en.wikipedia.org/wiki/Memory_corruption). CalyxOS uses the default AOSP [Scudo Malloc](https://source.android.com/devices/tech/debug/scudo), which is generally [less effective](https://twitter.com/danielmicay/status/1033671709197398016). Hardened Malloc has uncovered vulnerabilities in AOSP which have been [fixed](https://github.com/GrapheneOS/platform_system_core/commit/be11b59725aa6118b0e1f0712572e835c3d50746) by GrapheneOS such as [CVE-2021-0703](https://nvd.nist.gov/vuln/detail/CVE-2021-0703).
- **Secure Exec Spawning:** GrapheneOS [spawns](https://en.wikipedia.org/wiki/Spawn_(computing)) fresh processes as opposed to using the [Zygote model](https://ayusch.com/android-internals-the-android-os-boot-process) used by AOSP and CalyxOS. The Zygote model weakens [Address Space Layout Randomization](https://en.wikipedia.org/wiki/Address_space_layout_randomization) (ASLR) and is considered [less secure](https://wenke.gtisc.gatech.edu/papers/morula.pdf). Creating [fresh processes](https://grapheneos.org/usage#exec-spawning) is safer but will have some performance penalty when launching a new application. These penalties are not really noticeable unless you have an [old device](https://support.google.com/nexus/answer/4457705) with slow storage such as the Pixel 3a/3a XL as it has [eMMC](https://en.wikipedia.org/wiki/MultiMediaCard#eMMC).
**Please note that these are just a few examples and are not an extensive list of GrapheneOS's hardening**. For a more complete list, please read GrapheneOS' [official documentation](https://grapheneos.org/features).

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---
title: Android Overview
icon: material/cellphone-check
---
Android is a secure operating system that has strong [app sandboxing](https://source.android.com/security/app-sandbox), [Verified Boot](https://source.android.com/security/verifiedboot) (AVB), and a robust [permission](https://developer.android.com/guide/topics/permissions/overview) control system.
## Choosing an Android Distribution
When you buy an Android phone, the device's default operating system often comes with invasive integration with apps and services that are not part of the [Android Open-Source Project](https://source.android.com/). An example of such is Google Play Services, which has irrevocable privileges to access your files, contacts storage, call logs, SMS messages, location, camera, microphone, hardware identifiers, and so on. These apps and services increase the attack surface of your device and are the source of various privacy concerns with Android.
This problem could be solved by using a custom Android distribution that does not come with such invasive integration. Unfortunately, many custom Android distributions often violate the Android security model by not supporting critical security features such as AVB, rollback protection, firmware updates, and so on. Some distributions also ship [`userdebug`](https://source.android.com/setup/build/building#choose-a-target) builds which expose root via [ADB](https://developer.android.com/studio/command-line/adb) and require [more permissive](https://github.com/LineageOS/android_system_sepolicy/search?q=userdebug&type=code) SELinux policies to accommodate debugging features, resulting in a further increased attack surface and weakened security model.
Ideally, when choosing a custom Android distribution, you should make sure that it upholds the Android security model. At the very least, the distribution should have production builds, support for AVB, rollback protection, timely firmware and operating system updates, and SELinux in [enforcing mode](https://source.android.com/security/selinux/concepts#enforcement_levels). All of our recommended Android distributions satisfy these criteria.
[Our Android System Recommendations :material-arrow-right-drop-circle:](../android.md){ .md-button }
## Avoid Rooting
[Rooting](https://en.wikipedia.org/wiki/Rooting_(Android)) Android phones can decrease security significantly as it weakens the complete [Android security model](https://en.wikipedia.org/wiki/Android_(operating_system)#Security_and_privacy). This can decrease privacy should there be an exploit that is assisted by the decreased security. Common rooting methods involve directly tampering with the boot partition, making it impossible to perform successful Verified Boot. Apps that require root will also modify the system partition meaning that Verified Boot would have to remain disabled. Having root exposed directly in the user interface also increases the [attack surface](https://en.wikipedia.org/wiki/Attack_surface) of your device and may assist in [privilege escalation](https://en.wikipedia.org/wiki/Privilege_escalation) vulnerabilities and SELinux policy bypasses.
Adblockers, which modify the [hosts file](https://en.wikipedia.org/wiki/Hosts_(file)) (AdAway) and firewalls (AFWall+) which require root access persistently are dangerous and should not be used. They are also not the correct way to solve their intended purposes. For Adblocking we suggest encrypted [DNS](../dns.md) or [VPN](../vpn.md) server blocking solutions instead. RethinkDNS, TrackerControl and AdAway in non-root mode will take up the VPN slot (by using a local loopback VPN) preventing you from using privacy enhancing services such as Orbot or a real VPN server.
AFWall+ works based on the [packet filtering](https://en.wikipedia.org/wiki/Firewall_(computing)#Packet_filter) approach and may be bypassable in some situations.
We do not believe that the security sacrifices made by rooting a phone are worth the questionable privacy benefits of those apps.
## Verified Boot
[Verified Boot](https://source.android.com/security/verifiedboot) is an important part of the Android security model. It provides protection against [evil maid](https://en.wikipedia.org/wiki/Evil_maid_attack) attacks, malware persistence, and ensures security updates cannot be downgraded with [rollback protection](https://source.android.com/security/verifiedboot/verified-boot#rollback-protection).
Android 10 and above has moved away from full-disk encryption to more flexible [file-based encryption](https://source.android.com/security/encryption/file-based). Your data is encrypted using unique encryption keys, and the operating system files are left unencrypted.
Verified Boot ensures the integrity of the operating system files, thereby preventing an adversary with physical access from tampering or installing malware on the device. In the unlikely case that malware is able to exploit other parts of the system and gain higher privileged access, Verified Boot will prevent and revert changes to the system partition upon rebooting the device.
Unfortunately, OEMs are only obliged to support Verified Boot on their stock Android distribution. Only a few OEMs such as Google support custom AVB key enrollment on their devices. Additionally, some AOSP derivatives such as LineageOS or /e/ OS do not support Verified Boot even on hardware with Verified Boot support for third-party operating systems. We recommend that you check for support **before** purchasing a new device. AOSP derivatives which do not support Verified Boot are **not** recommended.
Many OEMs also have broken implementation of Verified Boot that you have to be aware of beyond their marketing. For example, the Fairphone 3 and 4 are not secure by default, as the [stock bootloader trusts the public AVB signing key](https://forum.fairphone.com/t/bootloader-avb-keys-used-in-roms-for-fairphone-3-4/83448/11). This breaks verified boot on a stock Fairphone device, as the system will boot alternative Android operating systems such (such as /e/) [without any warning](https://source.android.com/security/verifiedboot/boot-flow#locked-devices-with-custom-root-of-trust) about custom operating system usage.
## Firmware Updates
Firmware updates are critical for maintaining security and without them your device cannot be secure. OEMs have support agreements with their partners to provide the closed-source components for a limited support period. These are detailed in the monthly [Android Security Bulletins](https://source.android.com/security/bulletin).
As the components of the phone, such as the processor and radio technologies rely on closed-source components, the updates must be provided by the respective manufacturers. Therefore, it is important that you purchase a device within an active support cycle. [Qualcomm](https://www.qualcomm.com/news/releases/2020/12/16/qualcomm-and-google-announce-collaboration-extend-android-os-support-and) and [Samsung](https://news.samsung.com/us/samsung-galaxy-security-extending-updates-knox/) support their devices for 4 years, while cheaper products often have shorter support cycles. With the introduction of the [Pixel 6](https://support.google.com/pixelphone/answer/4457705), Google now makes their own SoC and they will provide a minimum of 5 years of support.
EOL devices which are no longer supported by the SoC manufacturer cannot receive firmware updates from OEM vendors or after market Android distributors. This means that security issues with those devices will remain unfixed.
Fairphone, for example, markets their devices as receiving 6 years of support. However, the SoC (Qualcomm Snapdragon 750G on the Fairphone 4) has a considerably shorter EOL date. This means that firmware security updates from Qualcomm for the Fairphone 4 will end in September 2023, regardless of whether Fairphone continues to release software security updates.
## Android Versions
It's important to not use an [end-of-life](https://endoflife.date/android) version of Android. Newer versions of Android not only receive security updates for the operating system but also important privacy enhancing updates too. For example, [prior to Android 10](https://developer.android.com/about/versions/10/privacy/changes), any apps with the [`READ_PHONE_STATE`](https://developer.android.com/reference/android/Manifest.permission#READ_PHONE_STATE) permission could access sensitive and unique serial numbers of your phone such as [IMEI](https://en.wikipedia.org/wiki/International_Mobile_Equipment_Identity), [MEID](https://en.wikipedia.org/wiki/Mobile_equipment_identifier), your SIM card's [IMSI](https://en.wikipedia.org/wiki/International_mobile_subscriber_identity), whereas now they must be system apps to do so. System apps are only provided by the OEM or Android distribution.
## Android Permissions
[Permissions on Android](https://developer.android.com/guide/topics/permissions/overview) grant you control over what apps are allowed to access. Google regularly makes [improvements](https://developer.android.com/about/versions/11/privacy/permissions) on the permission system in each successive version. All apps you install are strictly [sandboxed](https://source.android.com/security/app-sandbox), therefore, there is no need to install any antivirus apps. A smartphone with the latest version of Android will always be more secure than an old smartphone with an antivirus that you have paid for. It's better not to pay for antivirus software and to save money to buy a new smartphone such as a Google Pixel.
Should you want to run an app that you're unsure about, consider using a user or work profile.
## Media Access
Quite a few applications allows you to "share" a file with them for media upload. If you want to, for example, tweet a picture to Twitter, do not grant Twitter access to your "media and photos", because it will have access to all of your pictures then. Instead, go to your file manager (documentsUI), hold onto the picture, then share it with Twitter.
## User Profiles
Multiple user profiles can be found in **Settings** → **System** → **Multiple users** and are the simplest way to isolate in Android.
With user profiles, you can impose restrictions on a specific profile, such as: making calls, using SMS, or installing apps on the device. Each profile is encrypted using its own encryption key and cannot access the data of any other profiles. Even the device owner cannot view the data of other profiles without knowing their password. Multiple user profiles are a more secure method of isolation.
## Work Profile
[Work Profiles](https://support.google.com/work/android/answer/6191949) are another way to isolate individual apps and may be more convenient than separate user profiles.
A **device controller** app such as [Shelter](#recommended-apps) is required to create a Work Profile without an enterprise MDM, unless you're using a custom Android OS which includes one.
The work profile is dependent on a device controller to function. Features such as *File Shuttle* and *contact search blocking* or any kind of isolation features must be implemented by the controller. You must also fully trust the device controller app, as it has full access to your data inside of the work profile.
This method is generally less secure than a secondary user profile; however, it does allow you the convenience of running apps in both the work and personal profiles simultaneously.
## VPN Killswitch
Android 7 and above supports a VPN killswitch and it is available without the need to install third-party apps. This feature can prevent leaks if the VPN is disconnected. It can be found in :gear: **Settings** → **Network & internet** → **VPN** → :gear: → **Block connections without VPN**.
## Global Toggles
Modern Android devices have global toggles for disabling Bluetooth and location services. Android 12 introduced toggles for the camera and microphone. When not in use, we recommend disabling these features. Apps cannot use disabled features (even if granted individual permission) until re-enabled.
## Google
If you are using a device with Google services, either your stock operating system or an operating system that safely sandboxes Google Play Services like GrapheneOS, there are a number of additional changes you can make to improve your privacy. We still recommend avoiding Google services entirely, or limiting Google Play services to a specific user/work profile by combining a device controller like *Shelter* with GrapheneOS's Sandboxed Google Play.
### Advanced Protection Program
If you have a Google account we suggest enrolling in the [Advanced Protection Program](https://landing.google.com/advancedprotection/). It is available at no cost to anyone with two or more hardware security keys with [FIDO](../basics/multi-factor-authentication.md#fido-fast-identity-online) support.
The Advanced Protection Program provides enhanced threat monitoring and enables:
- Stricter two factor authentication; e.g. that [FIDO](../basics/multi-factor-authentication.md#fido-fast-identity-online) **must** be used and disallows the use of [SMS OTPs](../basics/multi-factor-authentication.md#sms-or-email-mfa), [TOTP](../basics/multi-factor-authentication.md#time-based-one-time-password-totp) and [OAuth](https://en.wikipedia.org/wiki/OAuth)
- Only Google and verified third-party apps can access account data
- Scanning of incoming emails on Gmail accounts for [phishing](https://en.wikipedia.org/wiki/Phishing#Email_phishing) attempts
- Stricter [safe browser scanning](https://www.google.com/chrome/privacy/whitepaper.html#malware) with Google Chrome
- Stricter recovery process for accounts with lost credentials
If you use non-sandboxed Google Play Services (common on stock operating systems), the Advanced Protection Program also comes with [additional benefits](https://support.google.com/accounts/answer/9764949?hl=en) such as:
- Not allowing app installation outside of the Google Play Store, the OS vendor's app store, or via [`adb`](https://en.wikipedia.org/wiki/Android_Debug_Bridge)
- Mandatory automatic device scanning with [Play Protect](https://support.google.com/googleplay/answer/2812853?hl=en#zippy=%2Chow-malware-protection-works%2Chow-privacy-alerts-work)
- Warning you about unverified applications
### Google Play System Updates
In the past, Android security updates had to be shipped by the operating system vendor. Android has become more modular beginning with Android 10, and Google can push security updates for **some** system components via the privileged Play Services.
If you have an EOL device shipped with Android 10 or above and are unable to run any of our recommended operating systems on your device, you are likely going to be better off sticking with your OEM Android installation (as opposed to an operating system not listed here such as LineageOS or /e/ OS). This will allow you to receive **some** security fixes from Google, while not violating the Android security model by using an insecure Android derivative and increasing your attack surface. We would still recommend upgrading to a supported device as soon as possible.
### Advertising ID
All devices with Google Play Services installed automatically generate an [advertising ID](https://support.google.com/googleplay/android-developer/answer/6048248?hl=en) used for targeted advertising. Disable this feature to limit the data collected about you.
On Android distributions with [Sandboxed Google Play](https://grapheneos.org/usage#sandboxed-google-play), go to :gear: **Settings** → **Apps** → **Sandboxed Google Play** → **Google Settings** → **Ads**, and select *Delete advertising ID*.
On Android distributions with privileged Google Play Services (such as stock OSes), the setting may be in one of several locations. Check
- :gear: **Settings** → **Google** → **Ads**
- :gear: **Settings** → **Privacy** → **Ads**
You will either be given the option to delete your advertising ID or to *Opt out of interest-based ads*, this varies between OEM distributions of Android. If presented with the option to delete the advertising ID that is preferred. If not, then make sure to opt out and reset your advertising ID.
### SafetyNet and Play Integrity API
[SafetyNet](https://developer.android.com/training/safetynet/attestation) and the [Play Integrity APIs](https://developer.android.com/google/play/integrity) are generally used for [banking apps](https://grapheneos.org/usage#banking-apps). Many banking apps will work fine in GrapheneOS with sandboxed Play services, however some non-financial apps have their own crude anti-tampering mechanisms which might fail. GrapheneOS passes the `basicIntegrity` check, but not the certification check `ctsProfileMatch`. Devices with Android 8 or later have hardware attestation support which cannot be bypassed without leaked keys or serious vulnerabilities.
As for Google Wallet, we don't recommend this due to their [privacy policy](https://payments.google.com/payments/apis-secure/get_legal_document?ldo=0&ldt=privacynotice&ldl=en), which states you must opt-out if you don't want your credit rating and personal information shared with affiliate marketing services.