SIGNAL PROTECTION AND RETRIEVAL BY NON-LINEAR ANALOG MODULATION

A method is disclosed wherein an analog message signal is received with a finite length. An analog key signal is also received having a finite length at least as long as the analog message signal. An encryption carrier is generated ant then an encryption operation initiated to encrypt the analog message. First, the encryption carrier is modulated with the analog key signal, generating an encryption dynamic carrier. Then, the analog message signal is mixed with the encryption dynamic carrier, with the mixing process initiated at an initial key starting point of the analog key signal and an initial message starting point. An encrypted message signal is output from the mixing process, which encrypted message signal has a starting point that coincides with both the message starting point and the key starting point and an encrypted message end point coinciding with the encrypted message signal end point.