Patent ID: 8453222

Claim:
A computer-implemented method for user authentication, comprising: storing on a non-transitory computer-readable storage medium server data synchronized with client data on one or more client devices associated with a user; receiving an authentication request for authenticating the user; identifying a level of authentication associated with the authentication request from a plurality of levels of authentication; transmitting a data request to the one or more client devices, the data request requesting attributes of the client data, the requested attributes of the client data determined responsive to the level of authentication associated with the authentication request; receiving from the one or more client devices the requested attributes of the client data; verifying the received attributes of the client data based on the stored server data to determine whether the received attributes meet the level of authentication associated with the authentication request; responsive to the received attributes meeting the level of authentication associated with the authentication request, determining that the user is successfully authenticated; and responsive to the received attributes not meeting the level of authentication associated with the authentication request, requesting additional attributes of the client data for verification.