Embodiments of the present disclosure provide a data transmission method, apparatus, and device. The method includes: performing, by a terminal, encryption and integrity protection on a data packet by using a public key of a network device and a private key of the terminal, where the data packet includes user data; and sending, by the terminal, the data packet to the network device, to send the user data to a server by using the network device. Encryption and integrity protection are performed on the data packet respectively by using the public key of the network device and the private key of the terminal, and when no radio resource control RRC connection is established, the data packet is sent to the network device.