A private computer in your pocket.
An operating system that forgets.
Boot any PC from a tiny USB dongle. BTDOS™ runs entirely in memory, and when you shut down, the whole session disappears.
- 0 bytes written to the PC
- ~20 s to a desktop
- Signed, checked at every start
How it works
Four steps, and the dongle tells you where you are.
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Plug it in
Put the dongle in any PC and choose it in the boot menu.
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It checks itself
Every file is compared with its signature before anything runs.
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Work as usual
Desktop, Firefox, files and Wi-Fi, all in memory. The PC's drives stay untouched.
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Pull it out
Hold the button and pull the stick. Memory is wiped and the PC powers off.
BTDOSec
Security isn't an app you launch. It's six layers, each checking the next before it hands over, from the chip in the dongle to the moment you pull it out.
Scroll to build the shield, one layer at a time.
The dongle's chip
The dongle has its own processor between the PC and the memory card. Its firmware decides which parts of the card may be written at all, and the key that checks your PIN is burned into its one-time eFuses.
Stops a PC, or malware on it, quietly changing the system on the stick.
Boot verification
Every file of the system is listed in a manifest signed with Ed25519. Before anything starts, BTDOS checks the signature and every file against it.
Stops a changed system. One wrong file and BTDOS refuses to start, and says which one.
Write-protected system
The boot and system parts of the card stay locked by the dongle. An update only goes through while you hold its button for six seconds, and it locks again by itself.
Stops anything changing the system without your hand on the dongle.
RAM-only runtime
BTDOS copies itself into memory and runs from there. The PC's drives stay untouched, the browser keeps nothing, and Firefox is walled off in its own restricted user.
Stops traces on the PC, and a hacked website reaching your Vault or the dongle.
Encrypted Vault
Files, passwords, notes and Wi-Fi keys live in a Vault on the dongle, encrypted with AES-256-GCM. It opens into memory only and locks again when you're done.
Stops someone who has the dongle from reading what you saved.
Emergency shutdown
Hold the button and pull the dongle out, or press Ctrl+Alt+Backspace: every program stops, memory is wiped and the PC powers off.
Stops someone getting into a session you left running.
How BTDOSec worksBTDOSec
Security isn't an app you launch. It's six layers that hand over to each other, from the chip in the dongle to the moment you pull it out.
6 of 6 layersEmergency shutdown
The dongle's chip
Decides which parts of the card may be written at all. Your PIN's key lives in its one-time eFuses.
Boot verification
Every file is checked against a signed list before anything runs. One changed file and BTDOS refuses to start.
Write-protected system
The PC can't change the system on the stick. Updates only go through while you hold the button.
RAM-only runtime
Everything runs in memory, the PC's drives stay untouched, and Firefox is walled off in its own user.
Encrypted Vault
Passwords, notes and Wi-Fi keys, encrypted on the dongle and opened into memory only.
Emergency shutdown
Hold the button and pull the stick, or press the panic key: memory is wiped, the PC powers off.
Why not just a normal live USB?
Fair question. The idea isn't new, and Tails does it well. What BTDOS adds is the hardware: a dongle with its own chip, screen and button that takes part in keeping you safe.
| Live USB | Tails | BTDOS | |
|---|---|---|---|
| Runs in memory, forgets at shutdown | Often | Yes | Yes |
| Encrypted storage for what you keep | Sometimes | Yes | Yes, the Vault |
| Tor built in | No | Yes, always | Yes, when you want it |
| Pull the stick to wipe memory | No | Yes | Yes, hold the button |
| The stick refuses writes from the PC | No | No | Yes, in its firmware |
| Whole system checked at every start | No | No | Yes, signed |
| Screen lock PIN kept in hardware | No | No | Yes |
| Tells you if someone else started it | No | No | Yes, start counter |
| Its own screen and button | No | No | Yes |
| Years of independent review | Varies | Yes | Not yet |
Tails has years of public review that BTDOS doesn't have yet. If you need proven today, use Tails.
We're working on it.
BTDOS runs on our own hardware and test machines. It isn't ready for a public release yet, and we'd rather get it right than get it out early.
- Desktop, files, terminal and Firefox, all in memory
- Wi-Fi, Bluetooth, sound, Tor and a VPN
- BTDOSec: signed system, write-protected dongle, PIN lock
- Vault with passwords and notes
- Testing on many more PCs
- A download and an easy installer
Why the name?
It's short for B's T-Dongle OS. It started as one person's operating system for one USB dongle, and the name was never meant to be clever. It stayed.
B's T-Dongle OS
Why these colours?
Cobalt blue that turns teal: calm and trustworthy, which is what BTDOS is for. The corner of the logo dissolves into pixels, because BTDOS forgets.
What is it built from?
Everything is compiled from its original source code, from the Linux kernel to the desktop, which we wrote ourselves. The one exception is Mozilla's Firefox.