Information providing device, method, program and recording medium, and user authentication device, method, program and recording medium

A user authentication device comprising: a provider association unit which makes a plurality of authentication providers, including first and second authentication providers, be associated with each other, the provider association unit comprising: a first unit causing the first authentication provider to perform, in response to a first authentication request, a first user authentication based on a first user identification data that is specified in the first authentication request; and a second unit causing the second authentication provider to perform, in response to a second authentication request related to a user approved by the first user authentication, a second user authentication based on a second user identification data that is correlated with the first user identification data.