Functional　encryption　(FE)　is　a　vast　new　paradigm　for　encryption　scheme　which　allows　tremendous　flexibility　in　accessing　encrypted　data.　In　a　FE　scheme,　a　user　can　learn　specific　function　of　encrypted　messages　by　restricted　functional　key　and　reveals　nothing　else　about　the　messages.　Besides　the　standard　notion　of　data　privacy　in　FE,　it　should　protect　the　privacy　of　the　function　itself　which　is　also　crucial　for　practical　applications.　In　this　paper,　we　construct　a　secret　key　FE　scheme　for　the　inner　product　functionality　using　asymmetric　bilinear　pairing　groups　of　prime　order.　Compared　with　the　existing　similar　schemes,　our　construction　reduces　both　necessary　storage　and　computational　complexity　by　a　factor　of　2　or　more.　It　achieves　simulation-based　security,　security　strength　which　is　higher　than　that　of　indistinguishability-based　security,　against　adversaries　who　get　hold　of　an　unbounded　number　of　ciphertext　queries　and　adaptive　secret　key　queries　under　the　External　Decisional　Linear　(XDLIN)　assumption　in　the　standard　model.　In　addition,　we　implement　the　secret　key　inner　product　scheme　and　compare　the　performance　with　the　similar　schemes.