An information security processing method, comprising: sending, by a terminal device (100, 300), an uplink message to a second network device; receiving, by the terminal device (100, 300), a downlink message from the second network device, the downlink message is a message that is generated by a first network device (200, 400) based on the uplink message and on which security processing is performed by the first network device (200, 400) based on first time information, wherein the security processing comprises at least one of encryption or integrity protection, and the first time information is time information determined by the first network device (200, 400) based on a time point at which the uplink message is received; and performing (106, 208), by the terminal device (100, 300), security verification on the downlink message, wherein the security verification comprises at least one of decryption or integrity protection verification; and wherein the performing, by the terminal device (100, 300), of the security verification on the downlink message comprises: performing, by the terminal device (100, 300), the security verification on the downlink message based on second time information, wherein the second time information is time information determined by the terminal device (100, 300) based on a time point at which the uplink message is sent; and when the security verification performed (106, 208) by the terminal device (100, 300) on the downlink message fails, determining, by the terminal device (100, 300), that the second network device is a fake network device. sending, by a terminal device (100, 300), an uplink message to a second network device; receiving, by the terminal device (100, 300), a downlink message from the second network device, the downlink message is a message that is generated by a first network device (200, 400) based on the uplink message and on which security processing is performed by the first network device (200, 400) based on first time information, wherein the security processing comprises at least one of encryption or integrity protection, and the first time information is time information determined by the first network device (200, 400) based on a time point at which the uplink message is received; and performing (106, 208), by the terminal device (100, 300), security verification on the downlink message, wherein the security verification comprises at least one of decryption or integrity protection verification; and wherein the performing, by the terminal device (100, 300), of the security verification on the downlink message comprises: performing, by the terminal device (100, 300), the security verification on the downlink message based on second time information, wherein the second time information is time information determined by the terminal device (100, 300) based on a time point at which the uplink message is sent; and when the security verification performed (106, 208) by the terminal device (100, 300) on the downlink message fails, determining, by the terminal device (100, 300), that the second network device is a fake network device. performing, by the terminal device (100, 300), the security verification on the downlink message based on second time information, wherein the second time information is time information determined by the terminal device (100, 300) based on a time point at which the uplink message is sent; and when the security verification performed (106, 208) by the terminal device (100, 300) on the downlink message fails, determining, by the terminal device (100, 300), that the second network device is a fake network device.