Abstract: A system, method and computer program product are provided for authenticating a user. The method includes receiving, such as from an authenticator, a set of at least one label identifying at least one element of an authentication matrix. The authentication matrix includes a plurality of elements, each element capable of being identified by a label. Then, a passcode is formulated, such as by the client, based upon the element(s) identified by the received set of label(s). Thereafter, the client is authenticated based upon the formulated passcode, such as by the authenticator. The set of label(s) can be received, the passcode can be formulated, and the client can be authenticated a plurality of times. In such instances, to permit the passcode to dynamically change, each set of label(s) received can differ from each previously received set of label(s).