I remember this system ... (Score 1)

I vauguely recall a system where the transmitter would send clear text, and the legitimate reciever would create random interference. The legit reciever knew what kind of interference it was generating, so it could filter it out and retrieve the message. The result of this setup is a situation where there can be only one reciever; if someone tried to intercept the transmission they'd just get garbage.

Does anyone know if this is feasible?