A system and method for authentication are described herein. An authentication request is received at a combiner proxy (350). The combiner proxy (350), is arranged to receive a user authentication request, receive one or more share values from one or more communications devices (330A, . . . , 330N) where each of the communications devices (330A, . . . 330N) stores at least one share value of a set of share values and determine if one or more share values that have been received from the communications devices (330A, . . . , 330N) meet a quantitative criteria. The combiner proxy (350) is arranged to authenticate the user if the received share values meet the quantitative criteria.