In the event of a complete disconnection of the Internet, one of the main problems is communication with friends and relatives. Hong Kong’s experience shows that decentralized P2P messengers that work without the Internet using mesh network Wi-Fi Direct, Bluetooth, Apple Multipeer Connectivity Framework, ANT +, LoRa, etc.
For effective communication, the application must be downloaded by the maximum number of people before the beginning of the blockade of the Internet. Otherwise, you will have to search for files after the blockade. A person with the necessary files will become a real authority in the office or in the classroom (as it was in Belarus in August 2020 – people actually came to get Psiphon files from other micro-districts of the city).
Apps like FireChat create a mesh network using Bluetooth and direct connections over Wi-Fi. They provide the exchange of messages and photos offline between devices located at a distance of about 60 meters from each other.
All users form a single network, which expands with the increase in the number of devices. On the way to the recipient (s), messages are passed from one device to another.
In other words, you just need to get 60 meters closer to the nearest user – and you can send a message to anyone. Each user is a node on the network. Without Internet.
Therefore, the more people use the application, the larger the network, and the better it works. By the way, this is the fundamental difference between mesh systems and most other computer networks and network technologies, including cellular networks.
If any node of the mesh network suddenly goes online, then messages in a packet from all users will go to recipients all over the world.
It is especially convenient if channels or rooms in the messenger are created automatically and unite people who are next to each other (apartment building, stadium, concert hall).
Almost any mesh network can be adapted to transfer text messages, even a network of Apple AirTag geotags, which are actually not intended for communication between people, but for finding lost things. In May 2021, hackers managed to decrypt AirTag traffic and send arbitrary text over the Apple Find My network under the guise of original encrypted messages with GPS coordinates. The transfer rate was 3 bytes per second. Network latency – from 1 to 60 minutes.