Abstract: In a data encrypting/decrypting system both the encoding and decoding stations are receptive of a common source of time varying digital signals. The digital signals in the encoding station are applied to one or both of circuits for encrypting data supplied to the encoding station and spreading the spectrum of a carrier which is modulated by the encrypted data. The digital signals in the decoding station are applied to one or both of circuits for despreading the carrier transmitted by the encoding station and decrypting the received encrypted data. In the decoding station and optionally in the encoding station delays are interposed between the circuits therein and the reception point of the digital signals of values such that the digital signals arrive at the decoding station circuit(s) in synchronism with when data encoded in accordance with a particular digital signal arrives at the decoding station.