Answer
First the devices are paired. Users compare security codes so that the public key really belongs to the chosen target device. The confidential text is then encrypted for this target and signed by the sender. A QR code can contain the complete encrypted transfer; Bluetooth transfer between supported WithinCells devices is also planned.
On the target, the content is entered once via an intended output channel, on Android in particular via the WithinCells keyboard. Transfer and input are two separate steps. Encryption protects the content during transfer, but not against an already compromised sender or target device, or against later input being observed. Users should compare pairing codes and not accept unknown or unchecked QR codes.
As of 3 September 2026
Further reading
Related topic: WithinCells