A method of transmitting and receiving data in which cipher-transmission of digital information data for which forbidden codes including timing identification codes are predetermined can be carried out with enciphered digital information data without containing undesirable forbidden code. Digital information data contained in word sequence data which also contain time reference code data composed of the timing identification codes are subjected to enciphering process without producing the forbidden code to produce the enciphered digital information data which do not contain any forbidden code. Enciphered word sequence data are constituted with the enciphered digital information data and the time reference code data to be transmitted.
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