This disclosure is directed to embodiments of systems and methods for controlling the access to files or other data. In some of the disclosed embodiments, a computing system receives a request for access to data by a first device operated by a first user, and determines that an identity of a second user associated with the data is to be authenticated to allow access to the data by the first device. The computing system invokes an authentication process to authenticate the identity of the second user based on an input provided to a second device by the second user and, based on that authentication process, determines that the identity of the second user has been authenticated based on the first input. The computing system then provides access to the data by the first device based at least in part on authentication of the identity of the second user. The authentication process may, for example, authenticate the identity of the second user based on a biometric input provided by the second user.