A system for performing authentication of a first user to a second user includes the ability for the first user to submit multiple instances of authentication data which are evaluated and then used to generate an overall level of confidence in the claimed identity of the first user. The individual authentication instances are evaluated based upon: the degree of match between the user provided by the first user during the authentication and the data provided by the first user during his enrollment; the inherent reliability of the authentication technique being used; the circumstances surrounding the generation of the authentication data by the first user; and the circumstances surrounding the generation of the enrollment data by the first user. This confidence level is compared with a required trust level which is based at least in part upon the requirements of the second user, and the authentication result is based upon this comparison.