Disclosed herein are methods, systems, and apparatus, including computer programs encoded on computer storage media, for hiding copyright information in a display screen. One of the methods includes generating, by a computing device, a unique identifier (ID) based on copyright information associated with a digital content, wherein the copyright information and the digital content are recorded on a blockchain of a blockchain network; determining one or more attributes associated with the display screen; and converting the unique ID to a digital watermark based on the one or more attributes, the digital watermark not being apparent to an unaided human eye when displayed in the display screen and enables retrieval of the copyright information from the blockchain based on the unique ID.