Guided tour of the app
Fifteen screens, real captures from the app. Click through using the list of steps, or simply tap the screen to move on.
1 First launch
One screen, not a wizard: at the top the choice between a new account and linking to an existing TalX device, below it picture and name. “New account” generates a key pair locally – that is the entire sign-up.
2 Name & picture
The display name is required, the profile picture optional. Both can be changed at any time later; changes go out automatically, encrypted, to all connected contacts.
3 Permissions
Only after setup does TalX ask for rights – before that you would not know what for. “Nearby devices” is the Bluetooth discovery used for delivery without internet. Camera, microphone and NFC are only requested once you actually use them.
4 Empty chat list
There is no directory in which you could look somebody up. A contact only comes into existence when two devices deliberately exchange their public keys once. The practical side effect: strangers cannot message you.
5 Connect a contact
At the top sits your own key as a QR code – the other person scans it and that is that. One direction is enough: the scanner announces itself back, authenticated, and the contact then exists on both devices. Below: scan yourself, NFC, or a short code from a distance.
6 By code, remotely
For the case where you cannot see each other. One side shows a short code, the other enters it together with a shared handle.
7 The code
Behind it sits J-PAKE: the short code turns into a strong, mutually authenticated key. An eavesdropper gets exactly one guess per attempt – brute-forcing a recording later is impossible by construction. That is why a code you can read out over the phone is enough.
8 The chat list
“Online” here concretely means: within short range, or connected through the brokering. For this the app sends a tiny sign of life every 45 seconds – but only if a connection exists at all.
9 The chat
The received message shows the path actually used – here “Internet”, because both devices were connected directly. Your own messages show a clock: sent, but not yet confirmed. The tick only arrives with the recipient’s confirmation, and in groups only once everyone has confirmed.
10 Attachments & “once”
At the very top the “view once” switch: the recipient can open the medium exactly once and save it while doing so, after which it is deleted – your own copy too. Below that: gallery, camera and arbitrary files.
11 Safety number
The step almost nobody takes: compare the numbers over a second channel and mark them as verified. Only then is it ruled out that somebody was in between when you connected. The same dialogue holds “reset encrypted session” and “block contact” – the latter works only on your device, and the contact is not notified.
12 Create a group
The group name passes through the same filter against far-right content as display names. Whoever creates the group gets the “creator” role.
13 Group info
Every member with their role, plus a switch for moderator rights and a button to remove them. There is no server checking rights – on receipt, every device checks for itself whether the sender holds the role for this change. A tampered app can send claims; the other devices do not believe them.
14 Settings
“Stay active in the background” keeps reception and delivery running even when the app is closed. “Offline connections” decides whether TalX may reach nearby devices directly. Above it sits Sidelink – honestly marked “not available”, because Android gives apps no access to it.
15 Backup
The chat history is encrypted locally with AES-256 and only then uploaded to the private app folder of your Google account. You decide per type what goes in; the automatic backup runs daily, weekly or monthly. Restoring needs the passphrase and a second factor.
Real captures from TalX 0.85.4, taken with the screenshot protection switched off for the purpose.
Setting up, for real
Section titled “Setting up, for real”-
First launch. Everything on one screen: at the top the toggle between “new account” and “link device”, below it the profile picture and name. “New account” generates a key pair locally – that is the entire sign-up.
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Name and picture. The display name is required, the profile picture optional. Both can be changed at any time later; changes go out automatically, encrypted, to all connected contacts. For the picture there is a cropping editor with zoom, free rotation and panning.
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Permissions. Only afterwards does TalX ask for rights – before that you would not know what for. It needs “nearby devices” (Bluetooth discovery) and access to the local network; notifications are optional. Camera, microphone and NFC are only requested once you actually use them.
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Connect your first contact. Without a contact the chat list is empty – there is no directory in which you could search for anyone. That is exactly the point.
What does not explain itself
Section titled “What does not explain itself”The tick does not mean “sent”
Section titled “The tick does not mean “sent””In many messengers a tick appears as soon as the message reaches the server. TalX has no server that could confirm this. The tick therefore appears only once the other device has reported receipt – in groups only once everyone has reported. Until then it says “waiting for delivery”.
The small symbol on every message
Section titled “The small symbol on every message”Every delivered message shows which path it actually took: Bluetooth, Wi-Fi, internet, relay or Sidelink. On messages you sent it appears with the confirmation – before that the path is simply not yet known.
“Post-quantum protection active” in the chat header
Section titled ““Post-quantum protection active” in the chat header”After connecting, both sides negotiate an additional post-quantum secret in the background. While that runs it says “being set up…”. If the app on the other side is too old for it, TalX says so as well instead of keeping quiet.
“Online” here means: reachable right now
Section titled ““Online” here means: reachable right now”Every 45 seconds the app sends a tiny sign of life to its contacts – but only if a connection exists at all. If none does, there is naturally no presence information either. So “online” means: within short range, or connected through the relay.
“View once” applies to both sides
Section titled ““View once” applies to both sides”A medium sent this way appears to the recipient only as a placeholder. Tapping opens it exactly once, full screen – and it can still be saved to the gallery at that moment. After that the file is deleted. The same applies to your own sent copy.
The safety number is the step almost nobody takes
Section titled “The safety number is the step almost nobody takes”Tap the shield symbol in the chat, compare the numbers with the other person over a second channel – in person or by phone, not in the same chat – and mark them as verified if they match. Only then is it ruled out that somebody was in between when you connected. If the number later changes unexpectedly, TalX warns you.
Blocking is not deleting
Section titled “Blocking is not deleting”Tap the shield symbol in the chat → “Block contact” stops accepting anything from that person – no messages, attachments, calls or profile details, not even in shared groups. The chat history is kept; to remove it, long-press in the chat list as before.
Delivery confirmations and the presence heartbeat deliberately keep running: if both stopped at once, the other side would know immediately. And a block survives a re-pairing – even with a fresh key.
The “offline connections” switch
Section titled “The “offline connections” switch”On by default. Switched off, TalX immediately stops Bluetooth, LAN and Sidelink discovery and communicates only over the online paths. Useful if the device should not be visible on unfamiliar networks – the price is that delivery then depends on an internet connection.
The background service and its limit
Section titled “The background service and its limit”“Stay active in the background” keeps receiving and delivery running even when the app is closed – with a permanent notification that Android requires in this case. Honestly: some manufacturers’ aggressive battery optimisation can still kill the service. That is why the profile screen has a button that leads straight to the system battery list.
Connecting contacts – which route, when
Section titled “Connecting contacts – which route, when”| Route | What it is for |
|---|---|
| QR code | You are in the same place. Scanning in one direction is enough – the contact then exists on both devices. |
| NFC | Hold the phones together. The other person only needs their screen unlocked. |
| Encrypted link | Send a one-time link over any channel you like. |
| Code (remotely) | You are not in the same place. One side shows a short code, the other enters it – eavesdropping-proof, ideal over the phone. |
More on this: connecting contacts.