A terminal to be connected to a network has: a data acquisition unit for acquiring first data from the network; an extraction unit for extracting second data regarding a physical quantity in accordance with the first data; a random number generation unit for generating a random number in accordance with the second data; and an enciphering unit for enciphering the first data in accordance with the random number. The terminal has further a counter unit for counting the number of the first data, wherein the random number generation unit generates a random number in accordance with the second data or a value counted by the counter unit.