Data encryption method for use in satellite-ground communication system

The embodiment of the invention provides a data encryption method for use in a satellite-ground communication system. The method comprises the following steps: determining an authentication parametertuple according to an access request sent by a first terminal, transmitting the authentication parameter tuple to a first access point in a data transmission path of the first terminal in order that the first access point performs bidirectional authentication on the first terminal according to the authentication parameter tuple, and negotiating a first session key with the first terminal when thebidirectional authentication is successful; and generating a first encrypted random number and transmitting the first encrypted random number to the first terminal in order that the first access pointnegotiates a second session key with a second access point in the data transmission path according to the first access point. According to the method provided by the embodiment of the invention, datatransmitted in an access ne