1. A method for sequential authentication of a user, comprising: challenging said user with at least one knowledge challenge to obtain an intermediate authentication result, wherein said intermediate authentication result is based on one or more of false accept and false reject error probabilities for each knowledge challenge, wherein said false accept and false reject error probabilities for a current challenge are updated based on information from one or more previous challenges from one or more previous sessions prior to determining a final authentication result for said current challenge; and repeating said step of challenging said user with at least one knowledge challenge until a cumulative authentication result satisfies one or more criteria, wherein said cumulative authentication result is calculated based on a dynamic algorithm and wherein said dynamic algorithm is capable of being reconfigured during execution of said method, wherein one or more of said steps are performed by a processor.