Abstract: A method includes obtaining identification data indicative of a subject's identity; identifying the subject using a computer system based on the identification data; obtaining, using one or more sensors, a plurality of authentication data each separately indicative of the subject's identity, at least one of the authentication data being obtained passively; individually analyzing each one of the plurality of authentication data using the computer system; and validating or denying the subject's identity, using the computer system, based on the analysis of the authentication data. Systems for authenticating a subject's identity are also disclosed.