We consider authentication to be a function of three (03) parameters: K, P and B Auth = F (K(), P(), B()) with K being something users know, P something users possess and B a biometric information of the user What the user knows yields id1; what he has yields id2 and finally what he is yields id3. The identity of the user is then composed of id1, id2 and id3 as on shown on Figure 2, which is stored in the data structure (of type linked list). ID = id1; id2; id3

ID1 = ID.id1 
ID2 = ID.id2 
ID3 = ID.id3