1. A method implemented by one or more computing devices, the method comprising: receiving a biological characteristic image uploaded by a terminal; verifying a digital watermark included in the biological characteristic image, the digital watermark being generated based on device identification information and/or user identification information of the terminal; and determining whether the biological characteristic image is usable based at least in part on a result of the verifying, the biological characteristic image being usable in the terminal only when the terminal corresponds to a device from which the biological characteristic image is generated.