Data transmission method and device

An embodiment of the present invention provides a data transmission method and device. The method comprises a step of sending an instruction to a second device through a first device, wherein the instruction is used for instructing the second device to generate a random number, a step of receiving the random number fed by the second device through the first device and obtaining an encrypted ciphertext based on the random number, a built-in encryption algorithm and an identification number, a step of sending the encrypted ciphertext to the second device through the first device such that the second device determines an identification number based on the generated random number, the built-in encryption algorithm and the encrypted ciphertext and performs matching verification with a pre-stored identification number, a step of allowing the first device to send data to be transmitted to the second device when the first device obtains information of verification pass fed by the second device. The identification num