In　this　paper,　we　propose　a　privacy-preserving　e-health　system,　which　is　a　fusion　of　Internet-of-things　(IoT),　big　data　and　cloud　storage.　The　medical　IoT　network　monitors　patient＇s　physiological　data,　which　are　aggregated　to　electronic　health　record　(EHR).　The　medical　big　data　that　contains　a　large　amount　of　EHRs　are　outsourced　to　cloud　platform.　In　the　proposed　system,　the　patient　distributes　an　IoT　group　key　to　the　medical　nodes　in　an　authenticated　way　without　interaction　round.　The　IoT　messages　are　encrypted　using　the　IoT　group　key　and　transmitted　to　the　patient,　which　can　be　batch　authenticated　by　the　patient.　The　encrypted　EHRs　are　shared　among　patient　and　different　data　users　in　a　fine-grained　access　control　manner.　A　novel　keyword　match　based　policy　update　mechanism　is　designed　to　enable　flexible　access　policy　updating　without　privacy　leakage.　Extensive　comparison　and　simulation　results　demonstrate　that　the　algorithms　in　the　proposed　system　are　efficient.　Comprehensive　analysis　is　provided　to　prove　its　security.　©　2018　Elsevier　B.V.