A biometric identity confirmation system is based on both pulse wave shape data and spirometric data for the subject. During an initial enrollment mode, pulse wave shape and spirometric data for a known subject are used to generate subject characterization data for the known subject by computing an exemplar and selectively weighting portions of the exemplar based, for example, on repeatability or distinguishing characteristic features over the population of known subjects. During a subsequent identity authentication mode, pulse wave shape and spirometric data for a test subject are analyzed using the subject characterization data to confirm whether the identity of the test subject matches the known subject.