Fuente: Wipo "digitalization" Disclosed herein are methods, systems, and apparatus, including computer programs encoded on computer storage media, for controlling authorization of access to user data. One of the methods includes generating a first decentralized identifier based on information about a second decentralized identifier and information about a third decentralized identifier, in which the second decentralized identifier is associated with a first user, the third decentralized identifier is associated with a first blockchain that is configured to store records associated with the first user; registering a first set of records and the first decentralized identifier at a second blockchain, wherein the first set of records include data associated with the first user, and the first set of records are stored in the first consortium blockchain, the second blockchain includes one or more blockchain contracts configured to, upon execution, perform one or more operations associated with the first decentralized identifier, and registering the first set of records includes storing a hash value for each record in the first set of records in the second blockchain; and controlling authorization of access to the first set of records based on the first decentralized identifier, including in response to receiving a request to grant a second user access to a particular record in the first set of records, determining whether the request includes the first decentralized identifier.