> send data out but is physically unable to receive That's a "data diode". The chat system that uses data diodes is "Tinfoil Chat". https://cs.helsinki.fi/u/o

> send data out but is physically unable to receive That's a "data diode". The chat system that uses data diodes is "Tinfoil Chat". https://cs.helsinki.fi/u/oottela/tfc.pdf https://cs.helsinki.fi/u/oottela/tfc.pdf It should be very robust against attack, but be careful to note the exact features that TFC provides, which are a bit unusual.