Secret signaling system with means for preventing key disclosure

In a signaling system for transmitting with secrecy signals of varying amplitude, means to encipher said signals comprising means to produce variable key currents and means to combine said signals with said key currents to produce said transmission combination signal and key currents, and means to impress variations upon the key current in response to zero signal value.

In a plural station communication system, means at each station to encipher signals for secret transmission to the other station or stations of the system including sources of duplicate key currents at the several stations together with means for combining said key currents with signals to be sent, and means for transmitting from each station in response to zero signal value a key current having a characteristic individual to that station and different from that of any other of said stations, each key current having a characteristic which varies in highly irregular and substantially fortuitous manner.

In a secret communicating system in which outgoing signals are enciphered by means of key waves and incoming signals are deciphered by means of key waves, a source of duplicate key waves at each station for use in enciphering and diciphering signals, and means at each station operating in response to pauses between outgoing signal elements for superposing variations upon the key waves thereat, said means causing the variations so superposed at any station to differ in distinguishable manner from the variations superposed at the other station or stations.

In a secret communication system for signal currents having a finite number of different magnitudes one of which is zero, means to encipher said signal currents comprising means to convert each value of signal current other than zero to current of some one of a finite number of magnitudes on a fortuitous basis and means operative when the signal current has zero value for variably producing output current of some one of said finite number of magnitudes.

In a secret communication system for signals, means to translate signal values other than zero into pulses, automatic enciphering means for enciphering said pulses, meanns to translate zero value of signal into pulses of any one of a plurality of different characters, means to determine on an irregular basis the character of pulses into which the zero signal value is so translated, and means to impress said last pulses upon said enciphering means.

In a secret communication system having a plurality of stations, means to send between stations a succession of designations of instantaneous signal values, means at each station to encipher the signals, means at each station to decipher received signals, means to produce a different designation of zero signal value to be sent from each station and means at all other stations for receiving said last designations and translating them into zero received signal value.

In a signal privacy communication system, means at a station to supply a variable key with which to encipher signals for transmission from such station, means to determine a characteristic of said key, means to transmit signals enciphered by said key in each of a succession of definitely timed intervals, and means for periodically sending in one such timed interval a special enciphered signal indicating the characteristic of said key that is used for enciphering said signals.

In a signal privacy communication system, means at a station to encipher signals in accordance with a secret key for transmission, means to determine a characteristic of said key, means to encipher elements of said signals in successively timed intervals in accordance with said secret key, and means for sending from time to time in one of such intervals an enciphered indication of the characteristic of said key that is used for enciphering signal elements sent in other of said intervals.

In a secret signal communication system, a source of variable key currents at a station, means to encipher signals in accordance with said key currents for transmission, means to impress a variation on said key currents to alter their character, a plurality of communication channels for transmitting the enciphered signals, a special communication channel, and means to transmit over said special channel indications of the variations impressed upon said key currents.

In a secret signal communication system for signals having a definite number of discrete values including zero, transmitting means for said signals including means to translate each signal value other than zero into a current of definite character for transmission, means to provide additionally a plurality of different characters of currents, and means controlled in response to zero value of signal for automatically selecting any one of said different characters of currents for transmission.

In a signal privacy communication system, means at a sending station for enciphering outgoing signals in accordance with a secret key wave, means to generate any one of a given plurality by key waves of different character at said station for use in enciphering said signals, means to select a key wave for use, and means for sending to a distant station in time intervals when the signal has zero value an indication of the key wave that has been selected for use.