A data transfer method, comprising: at an electronic device having one or more processors and memory storing program modules to be executed by the one or more processors: obtaining a plurality of data packets that comply with a specific data format corresponding to a network access protocol, wherein each data packet comprises a respective header that further includes at least one data field which is identifiable by a receiver device which does not have a communication connection established with a wireless access point that transmits the data packet; arranging a service set identifier, SSID, data set in the at least one data field of the plurality of data packets according to a link layer data structure, wherein the SSID data set at least comprises a SSID and a SSID password, and the SSID identifies a wireless network that is accessible when the SSID password is verified; and encrypting the plurality of data packets that include the SSID data set; sending the plurality of encrypted data packets to the wireless access point; and transmitting, by the wireless access point, the plurality of encrypted data packets via a wireless channel from which a receiver device monitoring wireless signals in space acquires the SSID data set from the at least one data field of the plurality of encrypted data packets. at an electronic device having one or more processors and memory storing program modules to be executed by the one or more processors: obtaining a plurality of data packets that comply with a specific data format corresponding to a network access protocol, wherein each data packet comprises a respective header that further includes at least one data field which is identifiable by a receiver device which does not have a communication connection established with a wireless access point that transmits the data packet; arranging a service set identifier, SSID, data set in the at least one data field of the plurality of data packets according to a link layer data structure, wherein the SSID data set at least comprises a SSID and a SSID password, and the SSID identifies a wireless network that is accessible when the SSID password is verified; and encrypting the plurality of data packets that include the SSID data set; sending the plurality of encrypted data packets to the wireless access point; and obtaining a plurality of data packets that comply with a specific data format corresponding to a network access protocol, wherein each data packet comprises a respective header that further includes at least one data field which is identifiable by a receiver device which does not have a communication connection established with a wireless access point that transmits the data packet; arranging a service set identifier, SSID, data set in the at least one data field of the plurality of data packets according to a link layer data structure, wherein the SSID data set at least comprises a SSID and a SSID password, and the SSID identifies a wireless network that is accessible when the SSID password is verified; and encrypting the plurality of data packets that include the SSID data set; sending the plurality of encrypted data packets to the wireless access point; and transmitting, by the wireless access point, the plurality of encrypted data packets via a wireless channel from which a receiver device monitoring wireless signals in space acquires the SSID data set from the at least one data field of the plurality of encrypted data packets.