Jack Dorsey, co-founder of Twitter and Square and founder of Bluesky, is back with another potentially disruptive and decentralized app: bitchat.Like Twitter and Bluesky, bitchat is a social app, but its not a social media platform. Instead, bitchat is a peer-to-peer messaging app, and is unique among the myriad of messaging options available already, as it does not operate over the internet. Rather than connect to wifi or a cellular network, bitchat is designed to operate over Bluetooth, specifically Bluetooth Low Energy (BLE) mesh networks. In theory, it would allow bitchat to function even when networks are down. In the event you can't connect to either cellular or wifi, bitchat would still function. (Though expanding satellite communications may give bitchat a run for its money.)How does bitchat work?According to the apps white paper, bitchatrelies on the devices running it to communicate with each other over BLE. As such, your device connects to another user's device within Bluetooth range, their device connects to another in Bluetooth range, and so on. "Local clusters" are made up of the device within Bluetooth range (typically 33 feet, though the white paper says roughly 30), where "bridge nodes" can connect those clusters when they overlap in range. With enough devices, you create a network where one user is able to message another well outside the usual Bluetooth range.It's sort of like how networks like Apple's Find My work. Products like AirTags communicate via Bluetooth with other devices on the Find My network. But where an iPhone will connect to the internet to ultimate update your AirTag's location, bitchat never needs to connect to the internet: It's all Bluetooth based.The design also accounts for users that are unavailable at the time you send a message. If you send it to a regular user, the message will be cached for up to 12 hours before sending, though messages you send to "favorite peers" can be cached indefinitely. Direct messages are end-to-end encrypted, while group messages (yes, bitchat supports group messaging) can be password protected if you so choose. You can set group messages, or "channels," with a channel name prefixed with a # (e.g. #channelname), and you can transfer the ownership of a group chat if you wish.Bitchat might not be secure at this timeWhile Dorsey suggests the app has user privacy and security in mind, it isn't perfect. The app's github page even presents a warning at the top, reading: "Private message and channel features have not received external security review and may contain vulnerabilities. Do not use for sensitive use cases, and do not rely on its security until it has been reviewed. Work in progress. Public local chat (the main feature) has no security concerns." According to TechCrunch, that warning was not present when the app first launched.TechCrunch highlights a number of security concerns testers have discovered while using the app. One found that it is possible to pretend to be another users' contact, and trick the app into marking them as a "Favorite" contacta feature that is supposed to guarantee the contact is who they say they are. Another user raised an issue with the app's "forward secrecy" feature, which is supposed to prevent bad actors from successfully breaking encryption even if they access the encryption key for your message. Still another found a security flaw that might allow a bad actor to overflow memory to another location, which could enable hacking.It's clear that the app has a ways to go to iron out its privacy and security functions, so, at this time, it might not be the best idea to try it outor, at least, to send sensitive information. How to try bitchatIf you're okay taking on the security risks, you can try out bitchat todaythough set up is a bit complicated. There is a TestFlight beta program for iPhone and Mac, but it's full.Bitchat's GitHub page has three options for setup on Mac: You can get things up and running via XcodeGen, which is the recommended method; Swift Package Manager; or start a manual Xcode Project by copying over all Swift files from the bitchat directory on GitHub. Personally, I'll wait until the app is fully realized on iPhone and Mac before giving it a shot. But if there are any peers in your area on bitchat, you'll be able to start chatting.