An authentication technique with a teaching phase and authentication phase. In the teaching phase, authentication information is collected for a user in at least two categories, wherein one category relates to measurable physical characteristics of the user, another category relates to communication resources available to the user; and a third category relates to knowledge possessed by the user. In the authentication phase, some of the collected authentication information is used to formulate challenge(s) for presentation to the user. Response(s) to the formulated challenge(s) is/are received from the user and correctness of the received response is determined based at least partially on comparison with at least a portion of the collected authentication information. A correctness metric is calculated for the response(s). The user is authenticated if the correctness metric meets or exceeds a first threshold value.