Systems, methods, and software products provide increased trust in authentication of a user to an authentication server when a trusted witness client device witnesses the authentication of the user on the user's root client device. Both the root and the witness client devices cooperate to present the user with an interactive task during the authentications and each client device independently captures movement of the user performing the interactive task, during which, the user is authenticated to the root client device. An increased level of trust in the authentication of the user is achieved by the authentication server when the captured movements match expected movements of the user performing the interactive task and the authentication server has proof that the witness client devices witnessed a successful authentication.