Stellar Security

Introducing Stellar Para: give 20%, get 20%

Mon, 28 Sep 2026 12:00:00 GMT

Today we're introducing Stellar Para, your credit in the Stellar eSIM app. Share your personal code, your friend saves on their first eSIM, and you earn credit that never expires.

Give 20%. Get 20%.

Open the Stellar eSIM app, go to Account and tap the first card, “Give 20%. Get 20%.” Create a free Stellar ID or sign in, and your personal code is there.
Send your code to a friend.
Your friend gets 20% off their first Stellar eSIM, up to €3.
When they complete that purchase, the same amount lands in your Stellar Para balance.

The two halves are always the same number: what your friend saves is what you earn. Say a friend uses your code and their first Stellar eSIM comes to €10.50. They pay €8.40, and €2.10 goes into your Stellar Para balance once their purchase is complete. The €3 cap sits on both sides, so as soon as 20% of the plan is worth more than €3, the discount stops at €3 and your credit stops there too. The exact amounts follow the eSIM your friend chooses, and the 20% applies to that first purchase only.

Where your balance goes

Stellar Para is spent in the Stellar eSIM app, on what you buy there anyway: your next eSIM, or a top-up for an eSIM you already have. At checkout the balance comes off the total and you pay what is left.

If your balance is bigger than the purchase, only what the purchase needs is taken, and the rest stays in your balance for the next one.

Spend it on eSIMs and top-ups

Your balance goes towards your next Stellar eSIM or a top-up.

Not cash

It can’t be withdrawn or exchanged for cash.

Credit that never expires

Your Stellar Para balance stays until you use it, however long that takes.

Credit with an expiry date quietly turns into a task: check when it runs out, find something to spend it on before it does. Stellar Para has no date to work against. Share your code this month, and if your next trip is a year away, the balance is still there and still worth the same.

Starting with Stellar eSIM

For now, Stellar Para lives in the Stellar eSIM app: the code you share and the balance you build are both there, and there is nothing to sign up for beyond a free Stellar ID. In the future, it will come to all Stellar products, including Stellar VPN and Stellar Antivirus.

Get your code

Download the Stellar eSIM app on the App Store or Google Play, find your code in Account and share it with a friend. Their first Stellar eSIM costs them less, and your balance starts with their purchase.

In this releaseStellar eSIMMobile data for travel, with a free Stellar VPN on every eSIM.

Get Stellar eSIM

Download on the App Store Get it on Google Play

Stellar eSIM is now available on iOS and Android

Mon, 31 Aug 2026 12:00:00 GMT

Staying connected abroad should be simple. It should also be private.

Today, we’re launching Stellar eSIM on both iOS and Android. With the Stellar eSIM app, you can choose a destination, buy a travel data plan and manage your eSIM directly from your phone — without swapping physical SIM cards or relying on expensive roaming packages.

And because connectivity is only part of the story, Stellar VPN is included free with every Stellar eSIM plan for the duration of the plan.

Travel data, now in your pocket

The new Stellar eSIM app is built to make mobile data abroad straightforward. Pick where you’re going, choose the plan that fits your trip and get your eSIM ready before you leave.

Explore destinations and regional coverage directly in Stellar eSIM.

Buy eSIM plans directly from your phone
Choose from local, regional and multi-country plans
Install your eSIM before travelling
See your remaining data and usage in the app
Top up supported eSIMs when you need more data
Keep your primary SIM and existing phone number alongside Stellar eSIM

No plastic SIM card. No airport kiosk. No waiting for a local mobile shop to open.

Stellar VPN included free

Travel often means using networks you do not control: airport Wi-Fi, hotel networks, cafés, trains and other public connections.

That is why every Stellar eSIM plan includes Stellar VPN at no additional cost for the full validity period of the eSIM plan.

Stellar VPN is included with every Stellar eSIM plan for the duration of the plan.

It is the same Stellar VPN experience designed to protect your internet connection and keep your browsing private. There is no separate VPN add-on to buy just because you are travelling.

Your eSIM gets you connected. Stellar VPN helps keep that connection private.

Ready before you land

You can buy and install your Stellar eSIM before your trip, so your mobile data is ready when you arrive. On supported plans, activation begins when the eSIM first connects to a supported network at the destination.

Install on the same phone in a tap, or use the QR code and manual activation details.

That means less time looking for Wi-Fi after landing and less dependence on traditional roaming.

Built for the Stellar ecosystem

Stellar eSIM brings private connectivity into the same ecosystem as Stellar VPN, StellarOS, Stellar Protect and our other privacy-focused products.

Our goal is not to make travel technology more complicated. It is to make secure connectivity feel invisible: choose a plan, connect and continue with your trip.

Travel connected. Travel private.

Available now on iOS and Android

Stellar eSIM is available now from the Apple App Store and Google Play. You can also browse and buy travel plans directly from Stellar Security.

Stellar eSIMFind the right data plan for your next trip.Browse destinations, regional plans and worldwide options.

Shop Stellar eSIM

Download on the App Store Get it on Google Play

Choose your destination, get your data plan and travel with Stellar VPN included.

Travel connected. Travel private.

Introducing the New Stellar Private Notes — End-to-End Encrypted Sync Across All Your Devices

Mon, 01 Dec 2025 12:00:00 GMT

Today, we’re proud to release one of the biggest updates to Stellar Private Notes since its first launch: a complete, zero-knowledge End-to-End Encryption (E2EE) engine with seamless sync across mobile and desktop.

This upgrade brings Stellar’s security philosophy directly into your daily note-taking workflow:
your notes, your keys, your privacy — always.

🔐 True Zero-Knowledge Encryption

With this update, every note you create is encrypted directly on your device using a unique
Master Key (MK) derived from your password.
Your encryption key never leaves your device.

Our servers only see encrypted blobs — unreadable to us and to anyone intercepting traffic.

No trackers.
No ads.
No analytics.

Just pure privacy.

🔄 Seamless Multi-Device Sync

We’ve rebuilt the sync engine around an offline-first design so your notes stay consistent across devices without compromising security:

Full E2EE across Android, iOS, and Desktop
Automatic background sync with conflict-aware merging
Live updates when editing on multiple devices
Offline queueing — changes sync automatically when you’re back online

Your private notes stay in sync, while your encryption keys never leave your devices.

🔒 Local App Lock

For additional privacy on shared or unlocked devices, you can enable a local
App Lock password. This is separate from your account login and stays fully local on your device.

Protects the app even if someone can unlock your phone
Keeps encryption keys locked in memory until the user unlocks
Works with and without server sync

Stellar respects your right to full control over when your data is accessible.

👨‍💻 Open Source, Transparent, Auditable

Our cryptographic engine is fully open source. Developers and security researchers can inspect, verify, and build on top of Stellar Private Notes.

Mobile app:
github.com/StellerSecurity/Steller.Phone.NotesApp
Backend API:
github.com/StellerSecurity/Stellar.Private.Notes.UI.APP.API

This is what privacy-first technology should look like: open, inspectable and independent of blind trust.

💻 Desktop Version

Our upcoming desktop version of Stellar Private Notes uses the same end-to-end encryption model as mobile.

That means one unified secure notes ecosystem — phone, tablet, and computer — all protected by your keys.

The desktop app will be released after final testing and polishing of the new E2EE & sync engine.

🚀 A Step Toward the Full Stellar Ecosystem

Stellar Private Notes is part of a larger privacy-focused ecosystem that includes StellarOS, Stellar VPN, Stellar Secret, Stellar Protect and more.

This release is a major milestone toward that mission: making strong privacy the default, not the exception.

🎉 Available Now

Update Stellar Private Notes from your preferred store or download it from our official channels. Your notes will automatically benefit from the new encryption and sync engine.

Your privacy matters. Your data is yours. And with this release — it stays that way.

Welcome to the new Stellar Private Notes.
Built in Switzerland. Protected by Stellar.

🚀 Say hello to StellarOS version 20250700

Mon, 04 Aug 2025 12:00:00 GMT

🚀 Say hello to StellarOS version 20250700

It’s here. A brand new version of StellarOS — built to give you even more privacy, more protection, and more peace of mind. 🔐✨

📦 Release version: 20250700

Over 300+ improvements across the system. Each one designed with one goal: keep you in control of your data. 🧠💾

Here’s a taste of what’s new:

🎙️ Stellar Voice Changer is here!
Want to change how you sound? Just open the app, choose a voice, and you’re done. The change applies system-wide — every app, every time.
❌ No AI. ❌ No cloud. ✅ Just local algorithms doing the job right on your device.
📝 Stellar Private Notes — redesigned.
It’s simpler, cleaner, and faster to use. You can now share notes securely via Stellar Secret, built right into the notes app. 🔐📤
🛡️ Stellar Antivirus — upgraded.
⚡ Faster scans. 🔍 Smarter detection. 🚫 Stronger protection. Malware doesn’t stand a chance.
🌐 Stellar VPN — now invisible.
We improved speed and reliability. Just turn it on, and forget about it. It just works. 🟢
📁 Stellar Secret — now even more powerful.
Share files directly inside the app. Private sharing, simplified. 🔒📲
📵 New device-loss protections.
If your phone is lost, your data stays protected. We added better memory clearing and new safeguards while in AFU-mode. 🧠🧹
🧩 Security patches up to date.
The latest from Google — now live in StellarOS. 🛠️✅
🔐 Stellar Protect — two new options.
Explore them in Settings. You’ll see the difference immediately. 🧭
💡 And so much more.
Hundreds of under-the-hood changes. All with one focus: your privacy. 🛡️📱

🚀 Stellar Security Monthly Update – May 2025

Mon, 26 May 2025 12:00:00 GMT

Each month, we’ll be sharing the latest product updates, improvements, and new features across the Stellar ecosystem. Here’s what we’ve been working on in May:

🔒 Stellar Private Notes

Renamed: Stellar Notes is now Stellar Private Notes.
Open Source: We’re excited to announce that Stellar Private Notes is now open source!

🛡️ Stellar Antivirus

Google Play Update: Our app on the Google Play Store has received:
Critical bug fixes.
An updated scanning engine for improved threat detection and performance.
The update has been approved by Google and is live on the Play-store.

🔐 StellarSecret.io – Share a onetime secret message

Design Refresh: A fresh look with several UI improvements.
Encrypted File Sharing: You can now share encrypted files that are only viewable by the intended recipient.
Open Source: Stellar Secret is now open source too!

🌐 Stellar VPN

Performance Improvements: We’ve rolled out optimizations and important bug fixes for the android app.
Google Approval: The latest update has been approved by Google and is live.

💻 GitHub
All our open-source repositories can be found on our GitHub: https://github.com/StellerSecurity

For any questions please use our contact-form.

Stellar Notes Update: Search, Stability, and Open Source!

Fri, 25 Apr 2025 12:00:00 GMT

We’ve got some exciting news for all Stellar Notes users!

A fresh update has just been submitted to both Google Play and the Aurora Store. Here’s what’s new:

✨ Search Your Notes from the Home Page
Finding that important note just got way easier! You can now search directly from the home screen — no more endless scrolling.

🐞 Bug Fixes and Stability Improvements
We’ve squashed a few pesky bugs and made several under-the-hood improvements to make Stellar Notes faster, smoother, and more reliable.

This update should start rolling out over the next 2–3 days, so keep an eye out!

But that’s not all — we’re incredibly excited to announce that Stellar Notes is now open-source! 🚀

This means you can now review the entire codebase yourself. We want to be fully transparent: your data stays 100% on your device. Nothing is uploaded elsewhere, ever.

You can check out the code (and even contribute if you’d like!) over on GitHub:
🔗 https://github.com/StellerSecurity/Steller.Phone.NotesApp

Thank you for trusting Stellar Notes with your thoughts and ideas. We’re just getting started — and we can’t wait to keep building with you.

Stay tuned for even more updates soon! 🌟

Stellar Secret Just Got a Major Upgrade — Now With Encrypted File Sharing

Tue, 22 Apr 2025 12:00:00 GMT

We’re excited to announce a powerful new feature on Stellar Secret: you can now attach files to your secret messages — and just like your messages, these files are fully encrypted and viewable only once by the receiver.

🔒 One-Time, One-Viewer, Fully Encrypted

Here’s how it works:

When you send a message, you can now attach a file (up to 15 MB).
Both the message and the file are encrypted end-to-end.
The receiver can view the message and download the file once — after that, both are gone forever.
Even we can’t see what you share. No logs, no backups, no surveillance.

This is all made possible by the architecture behind Stellar Secret — which is, and always will be, open-source. Anyone can audit the code to verify that your data stays yours.

Today’s update supports files up to 15 MB in size. We know that’s just the beginning — and we’re already working on expanding this limit. This is the first step toward even richer, more secure forms of communication.

🌐 Check the Code

We believe in transparency. That’s why all of Stellar Secret’s code is available publicly:

Stellar Secret Website
Stellar Secret UI API
Stellar Secret API

Go ahead and poke around. Fork it, contribute, or just verify for yourself that everything is encrypted and private.

We’re not stopping here. More updates are on the way — but in the meantime, go try the new feature and send a secret (or a file) today: stellarsecret.io

StellarOS: New Release 2025021500

Wed, 19 Feb 2025 12:00:00 GMT

Release version: 2025021500

Devices: Pixel 6a, Pixel 7a, Pixel 8a, Pixel 8, Pixel 9, Pro, XL.

A new version of stellarOS has been sent out, here is what we added:

– You can now in Stellar Protect disable, so it wont show StellarOS when the phone starts.

– Screen alive has been reduced from 20 minutes to 15 minutes. This means, if somebody takes your phone from you, while its unlocked, StellarOS will automaticlly close your phone with your password after 15 minutes, even if they keep touching the phones screen.

– Stellar Notes has been updated while we have fixed some bugs.

– Stellar Antivirus has been updated and detects viruses even faster.

– Stellar VPN has now been added to StellarOS, we will begin to move away from Mullvad VPN.

– The USB port is more secure and it is way more difficult now than ever to extract data.

– Latest security & firmware patches from Google has been added.

– If the phone is unlocked & somebody puts the phone in flight-mode the phone will lock itself.

– If the USB-extraction detector is not enabled, but the phone gets put inside into a computer, the phone will every 30-60 minutes restart itself, this delays brute-force attacks, and makes it more difficult to take data out.

– If somebody just touches the phone while its locked and the phone dont get opened, after 30 minutes the phone will restart and clear all data in the RAM.

– We increased the minimum of password length, from 7 till 8.

– The drop-detector & shake detector of the OS has been improved a lot.

– When users install eSim, normally it is required to scan a QR-code, but we have changed it. Now it is possible to do it without scanning any QR-code.

– When the phone is locked, it is no longer possible to see, which VPN-service a StellarOS is using.

– We changed auto-reboot timer from 3 hours to 2 hours. User can change it to 48 hours, but we recommend 8 hours.

For any questions, please use our contact-us page.

Thank you.

We’re going opensource – Github

Mon, 16 Dec 2024 12:00:00 GMT

Since the founding of Stellar Security, we’ve always been driven by a fundamental belief: privacy and security are essential for everyone. We’ve dedicated ourselves to developing a variety of products, all with the shared goal of safeguarding your privacy and security. Every product we create at Stellar Security is built with this mission in mind.

One core principle we’ve upheld from the beginning is transparency. We believe in making our software visible to the public. This is an important step in ensuring that you, our customer, can trust that our products do exactly what we promise.

Starting today, we’re gradually making our software code available on GitHub. You can explore it here: https://github.com/StellerSecurity.

Over time, we’ll continue to release more of our repositories to the public.

New version of StellarOS

Mon, 02 Dec 2024 12:00:00 GMT

A new version of StellarOS will soon be sent out, here is what we added and changed:

– If the phone is unlocked and somebody takes it, and somebody sets it to Airplane-mode, StellarOS will lock your phone with your password.

– We have made it possible to change the Boot-Animation, so when the phone starts up, you can change it, so it does not say “StellarOS” but something else. This is done by the Stellar Protect app.

– Until now, every StellarOS device had the same wallpaper, now we have changed it. Every StellarOS device will have a random wallpaper, so no StellarOS device looks the same anymore.

– Latest security patches from Google is applied.

– Stellar Notes app has been updated. We fixed some bugs with it.

– Stellar Protect app has been updated. It works even better now.

– Overall we improved the OS, to make sure, the phone is in the most secure mode, if somebody takes your phone from you.

We will let you know, once the update is out.

We’re working on iOS support

Mon, 25 Nov 2024 12:00:00 GMT

For the last months we have been working incredible hard on new apps and software for the Android-platform, while refining and improving everything over and over again.

There is no secret, that we often get requests about when our apps will support iOS. This is of course not an easy task, since Android and iOS are two completely different platforms. Luckily, from the beginning most of our apps are hybrid, which means, the software behind it, should work for the iOS platform as-well, but iOS brings some issues due it is more locked down than Android for apps such as Stellar Protect.

We have been testing our products and software for the last few months for iOS and some of our existing apps such as Stellar Notes works perfectly fine for iOS, without us needing to do any software changes.

Our goal is to focus a lot on the iOS-platform in the beginning of 2025, where it will be possible to get our apps on the App-Store if everything goes to plan.

For any questions, we can be contacted on our contact-us page: https://stellarsecurity.com/contact-us

Stellar VPN for Android has been released

Wed, 20 Nov 2024 12:00:00 GMT

We can announce that Stellar VPN for Android has been approved by Google.

This means, Stellar VPN is now available at Google PlayStore, Aurora Store and Aptoide.

Stellar VPN offers a global-network with servers covering most of the world. Any connection to our servers is zero-logging, this means, we don’t store any info on the websites and apps you use. We don’t store your ip-address or any private info you have.

Everything is private, as it should be.

“Be private. Be encrypted. Be Anonymous. This is Stellar VPN.”

As a VPN-provider, we don’t even need your email address, you can use a generated account number to sign in with. This means, we even don’t know you exist.

We truly deeply believe in giving our users a choice. You can provide an email or you can use something random. It is up to you. We do not want to interfere with your privacy.

Stellar VPN allows for up to 5 devices per subscription.
No Logging
Use a email or a random account number to sign in with.
Buy with Crypto, Credit-card or Bank transfer
Offline purchases in stores (coming in 2025).

Our goal is in the future to make it possible to buy Stellar VPN in offline purchases, so you can buy it with cash. Our design and engineering team is working on this and we expect it to be ready in 2025.

Stellar VPN is the beginning of a new era of VPN. In the future, we will do things in a way that has not been seen before.

For Stellar Phones, Stellar VPN is already included.

You can read more about Stellar VPN here: https://stellarsecurity.com/stellar-vpn

For any questions, you can use our contact-form: https://stellarsecurity.com/contact-us

Global VPN Protection with StellarOS

Tue, 29 Oct 2024 12:00:00 GMT

We’re excited to introduce a new VPN protection feature for StellarOS!

Many users have multiple profiles on their devices and want to use VPN across all of them. Previously, this required installing a VPN app for each profile, meaning that if one profile had the app installed, any other profiles would not be protected by a VPN.

This setup created several challenges:

Each profile required its own VPN app installation.
New VPN licenses had to be purchased for each profile.
Users had to remember the VPN status for each individual profile.

To address these issues, we’ve developed Global VPN Protection. With this feature, if you have a VPN set up on one profile and Stellar Protect installed, you can enable “Global VPN Protection” from Stellar Protect. Once activated, all profiles will automatically use the same VPN settings.

Now, managing VPN for all your profiles is easier than ever!

StellarOS: New Release 20241710

Sun, 20 Oct 2024 12:00:00 GMT

Release version: 20241710

Devices: Pixel 6a, Pixel 7a, Pixel 8a, Pixel 8, Pixel 9, Pro, XL.

A new version of stellarOS has been sent out, here is what we added:

– It is now possible to disable Control Center, when the phone is locked. (So you cant swipe from the top and down to see notifications, change settings and so on, when the phone is locked). It can be disabled through Stellar Protect.

– Global VPN Protection. When enabled in Stellar Protect, every connection is required to go through the VPN provider, this means any DNS-leaks is removed. It applies for all users you have.

– Security patches from Google has been applied.

– We fixed several bugs across the OS, which extends the battery-life with atleast 1 hour.

– We added security enhancements for Stellar Protect, to ensure, any settings cannot be changed remotely by an attacker.

– We added more protection to the USB-port that protects any attempts for data-extraction.

More updates coming soon.

Introducing Stellar Shield

Thu, 03 Oct 2024 12:00:00 GMT

Over the last months we have been working incredible hard on a new type of privacy screen for mobile-devices. We call it Stellar Shield.

Our durable glass protects against scratches and cracks while ensuring your conversations stay private. With advanced technology, Stellar Shield blocks prying eyes from viewing your screen at an angle. Easy to install and compatible with all cases, it seamlessly blends into your device, offering both style and security.

Inside the package, you find everything you need for adding Stellar Shield to your device. We also included two free gift-cards for Stellar VPN and Stellar Antivirus inside the package.

For more info watch the video or learn more here.

Enabling Stellar Protect as device-owner

Thu, 12 Sep 2024 12:00:00 GMT

Since Android SDK 34 came out it is required that Stellar Protect is device-owner of the device this allows the wiping-mechanism to work properly. This is because Google changed the permissions of the wipe API since the SDK 34 came out.

If Stellar Protect does not give you alert about this, then you do not need to follow this guide. This means, Stellar Protect has the required permissions. So nothing is required from your part.

For StellarOS or Stellar Phone users, you DO not need to follow this guide.

This can be done in a few steps, and takes around 10 minutes.

Setup

You need a computer and a USB-cable before you can follow the steps below.
You can also watch this video: YouTube video player

Turn your phone on.
Connect your phone with a USB to your computer.
Enable developer mode:
Navigate to the Settings → About phone section.
Tap the Build Number option seven times until you see the “You are now a developer!” message

On some devices, these sections might be located or named differently. For more details, please refer to the Android documentation.

A alert on your computer might show up: Please allow the USB-connection.
Install the Stellar Security for Android app on the device via the app installation package from Stellar Center or using other suitable methods of installation (for example .apk).

For this scenario to work correctly, do not launch the app before running the ADB command described in step 7.

Install ADB on your computer.
Connect the device to the computer using a USB cable.
The system will show a dialog asking whether to allow the device debugging on the computer. Click OK.
Start ADB and run the following command:

adb shell dpm set-device-owner stellar.phone.protect/com.stellar.phone.protect.AdminReceiver

How Antivirus works and why you need Stellar Antivirus

Sun, 01 Sep 2024 12:00:00 GMT

Antivirus software is like a security guard for your device. It helps protect it from harmful programs (viruses, malware) that can mess up your files, slow down your device, or even steal your personal information. Antivirus software has several features to keep your device safe:

Real-time scanning: Constantly checks files and websites for threats as you use your device.
Automatic updates: Keeps the antivirus up to date with the latest protections against new threats.
Firewall protection: Blocks unauthorized access to your device.
Safe browsing: Warns you about dangerous websites and links.
Virus removal: Finds and deletes harmful programs if your device gets infected.

You need antivirus to keep your device safe, so you can browse the internet, download files, and use apps without worrying about getting infected by something dangerous. It’s an essential tool to help keep your digital life secure.

The above reasons, is why we developed Stellar Antivirus. Our antivirus app works for newer android devices, mac and window-devices. It protects them against harmful viruses and will automatically block any known viruses, so they wont harm your device. For all Stellar Phones, Stellar Antivirus is already included directly to the heart of the system.

Why StellarOS have removed USB-data completely and only allows charging

Mon, 26 Aug 2024 12:00:00 GMT

On StellarOS, we’ve disabled the ability to connect to the phone via USB, allowing it only for charging. This decision was made for several reasons. First, the USB port poses a significant security risk, as it could enable third parties to extract data from your phone or install malware on the OS without your knowledge.

Secondly, technology is evolving. We believe that most users primarily use the USB connection for charging, while data is increasingly stored in the cloud. This makes the USB port unnecessary for data transfer or backup purposes.

In short, there’s no longer a need for the USB port to serve any function beyond charging.

How we have done it

On StellarOS, enabling USB data is impossible. The USB functionality is completely disabled, preventing any connections to computers or other external devices. The OS permits only charging through the USB port, and all USB-related software has been removed.

We’ve integrated a feature called “USB-C Control” directly into the kernel, which disables every aspect of USB functionality—not just at the software level but also at the hardware level. This significantly enhances the USB-C port’s resistance to potential attacks.

A key priority for us is ensuring that our OS is consistently updated with the latest firmware and software from Android (AOSP). In April 2024 and June 2024, Google released two critical updates that patched vulnerabilities in the bootloader. Previously, it was possible to restart a Pixel phone in AFU mode, access the bootloader, and dump the phone’s RAM, which could lead to data extraction. However, these exploits have now been fixed.

For more protection, it is also possible to enable “wipe if USB-extraction is detected“. If StellarOS detects any USB-data extraction, the OS will wipe the entire phone immediately, this is done by Stellar Protect which is deeply integrated to StellarOS.

How StellarOS handles AFU- and BFU mode

Wed, 21 Aug 2024 12:00:00 GMT

A phone can have two modes: Before-First-Unlock mode and After-First-Unlock mode.

When the phone is not in your hand, the best mode a phone can be in, is in the Before-First Unlock mode. In this state, the device’s data is highly encrypted, and most of it is inaccessible, even to the operating system.

What is Before-First-Unlock (BFU) and After-First-Unlock (AFU)?

Before First Unlock (BFU) refers to the state of a device, particularly smartphones, before the user has unlocked it for the first time after a restart. In this state, the device’s data is highly encrypted, and most of it is inaccessible, even to the operating system. This is because the encryption keys needed to decrypt the data are not available until the user enters their passcode or uses biometric authentication.

After First Unlock (AFU) refers to the state of the device after it has been unlocked at least once following a restart. In this state, some encryption keys remain in memory, allowing easier access to certain data without requiring the user’s credentials again. While the device is still secure, more data is accessible in AFU mode compared to BFU mode, making AFU a more vulnerable state in terms of potential forensic analysis or unauthorized access.

With these descriptions, it is now clear why the phone should be in BFU-mode when your phone is not in your hands. When the phone is in BFU-mode, the phone is way more secure, than when the phone is in AFU-mode.

How StellarOS makes sure your phone goes to BFU-mode

In our operating system, StellarOS we have added multiple protections that will set your phone into BFU-mode; those protections run in the background, without the user notifying it. This also makes the user-experience seamless. Those protections only run when the phone is in AFU-mode.

We call this Reboot-Emergency:

When the phone hasn’t been unlocked for x-time (default 4 hours), the phone will restart on its own.
If the phone gets dropped to the ground or shaken hard a internal timer will start, that after 1 hour of the event occured will restart the phone and set it into BFU-mode, unless the phone gets unlocked. (phone gets locked with your password as-well in this case).
If the phone gets set into Flight-mode or loses all signals to Wi-Fi / cellular connection the phone will restart after 1 hour and be set into BFU-mode.
If the user writes their login password wrong the phone will restart after 1 hour and be set into BFU-mode.
StellarOS will on every 3rd failed login-attempt restart the phone (this delays brute-force attacks, but also makes sure the phone is being set into BFU-mode).
If a USB-connection is being doing the phone will restart after 1 hour and be set into BFU-mode. (Notice: this only runs, if the user has not enabled the delete phone if USB-connection is detected).

There are more security mechanisms into the OS, which we will discuss later. But, as you can see, StellarOS has a lot of different mechanisms to be sure that your phone is in BFU-state, when it is not in your hand.

Most operating-systems only have “auto-reboot after x-time”, but the auto-rebooting itself is not enough to make sure that the phone becomes BFU-state before an attacker exploits the data. This is why we have added more helpers for this.

Notice: the internal timers will only run, if the phone is in AFU-state. When the phone gets unlocked, all timers will be cleared, this prevents the phone from suddenly restarting for no reason.

We’re always working on new mechanisms to the Reboot-Emergency that make sure the phone gets into the BFU-mode without you having the device in your hand. Read more about our encrypted phone here.

For any questions contact us here: https://stellarsecurity.com/contact-us

Stellar Security

Introducing Stellar Para: give 20%, get 20%

Give 20%. Get 20%.

Where your balance goes

Credit that never expires

Starting with Stellar eSIM

Get your code

Stellar eSIM is now available on iOS and Android

Travel data, now in your pocket

Stellar VPN included free

Ready before you land

Built for the Stellar ecosystem

Available now on iOS and Android

Introducing the New Stellar Private Notes — End-to-End Encrypted Sync Across All Your Devices

🔐 True Zero-Knowledge Encryption

🔄 Seamless Multi-Device Sync

🔒 Local App Lock

👨‍💻 Open Source, Transparent, Auditable

💻 Desktop Version

🚀 A Step Toward the Full Stellar Ecosystem

🎉 Available Now

🚀 Say hello to StellarOS version 20250700

🚀 Stellar Security Monthly Update – May 2025

Stellar Notes Update: Search, Stability, and Open Source!

Stellar Secret Just Got a Major Upgrade — Now With Encrypted File Sharing

🔒 One-Time, One-Viewer, Fully Encrypted

📁 File Sharing Starts Now

🌐 Check the Code

StellarOS: New Release 2025021500

We’re going opensource – Github

New version of StellarOS

We’re working on iOS support

Stellar VPN for Android has been released

Global VPN Protection with StellarOS

StellarOS: New Release 20241710

Introducing Stellar Shield

Enabling Stellar Protect as device-owner

Setup

How Antivirus works and why you need Stellar Antivirus

Why StellarOS have removed USB-data completely and only allows charging

How we have done it

How StellarOS handles AFU- and BFU mode

What is Before-First-Unlock (BFU) and After-First-Unlock (AFU)?

How StellarOS makes sure your phone goes to BFU-mode