JaenanTok 재난톡 v1.0.2
No tower. No server. Just the phones near you.
An emergency messenger that reaches the people around you over Bluetooth alone. No internet, no cellular, no server, no account. Messages relay device to device, up to seven hops out.
iOS 15+ · Android 8.0+ · 한국어 · English · 日本語 · 中文
Hop 0 of 7 1 of 17 reached Relaying
One phone sends an SOS; the mesh carries it outward until the hop budget runs out. Illustration, not live traffic.
01 — The channel
The whole network is the room you are standing in
JaenanTok forms a Bluetooth Low Energy mesh out of whoever is nearby. That is the entire infrastructure. When an earthquake takes the base stations down, or you are three floors underground, the mesh is unaffected — because it never depended on any of it.
Bluetooth, and nothing else
No internet, no cellular, no Wi-Fi. Each phone both advertises and scans, so any two within Bluetooth range find each other on their own — no pairing, no code to read out.
Nothing to sign up for
There is no server to hold an account, so there is no account. Install it, pick a nickname, and you are on the mesh. Messages live in a database on your own phone and nowhere else.
Range grows with people
How far a message travels depends on the phones and what is between them. Every extra person carrying the app is another possible relay, so the mesh widens as a crowd gathers.
02 — Relay
Out of range is not out of reach
A phone you cannot hear directly can still hear you, if someone standing between you agrees to pass it on. Each relay spends one of the packet’s seven hops. Relaying is a setting, and it starts switched off — the app will not spend your battery on someone else’s message without being asked.
A packet leaving with seven relays to spend.
03 — Encryption
Three levels, and one of them is none
Most apps claim encryption everywhere. This one cannot, and says so. What is private is genuinely private; what is public is public because being readable is the only way it does its job.
Direct messages
Noise Protocol XX
A one-to-one conversation is encrypted between the two phones. The phones relaying it in between carry the bytes and cannot read them. The recipient has to accept before a conversation starts, and a decline or a block survives a restart.
Password channels
AES-256-GCM
A channel locked with a password is readable by everyone who knows that password, and by nobody else. The password never leaves the devices that were told it.
Lobby and 긴급
Plaintext, deliberately
The public channels are in the clear on purpose. An SOS travels through the emergency channel, and a stranger who might actually come and help has to be able to read it. Encrypting it would make it useless.
04 — SOS
One tap, your location, everyone in range
An SOS goes out on the emergency channel with your GPS coordinates attached, and every JaenanTok phone that can hear it — directly or through a relay — shows it. The location is put into that message and carried over Bluetooth. It is never uploaded and never stored anywhere but the phones that received it.
This is not a rescue service. An SOS reaches phones in range, not dispatchers. When a call is possible, call 112 or 119 first — this is for when it is not.
Prewritten phrases, because typing is the first thing that goes when your hands are shaking.
05 — Limits
What it cannot do for you
These are properties of the design, not gaps waiting to be filled. Knowing them before an emergency is the difference between a useful tool and a false sense of safety.
It cannot promise delivery
There is no server to hold a message until the other phone comes back, and no receipt to tell you it landed. If nobody is in range, the message simply does not go. Call 112 or 119 whenever calling is possible.
Relay is off until you turn it on
Carrying other people’s messages costs your battery, so the app will not do it behind your back. Relaying is a switch in Settings, off by default — which also means the mesh only works if enough people turn it on.
Seven hops, then it stops
Every packet carries a hop budget and is dropped when it runs out. That ceiling is what stops a message circulating forever through a dense crowd.
Nobody is moderating in real time
With no server there is no one reading messages centrally. The app ships a keyword filter, blocking and reporting, and they run on your device — which is honest, but it is not the same as supervision.
06 — Build
Underneath
- Transport
- Bluetooth Low Energy, dual-role
- Direct messages
- Noise Protocol XX
- Password channels
- AES-256-GCM
- Packet authentication
- Ed25519
- Relay ceiling
- 7 hops, opt-in
- Storage
- SQLite on device
- Backend
- None
- Platforms
- iOS 15+ · Android 8.0+
- Languages
- 한국어 · English · 日本語 · 中文
- Age rating
- 17+