Public-key　encryption　with　keyword　search　(PEKS)　enables　users　to　search　over　encrypted　data　and　retrieve　target　data　efficiently.　However,　most　of　existing　PEKS　schemes　are　vulnerable　to　adversaries　equipped　with　quantum　computers　in　the　near　future,　and　even　incur　complex　certificate　management　procedures　due　to　the　public　key　infrastructure　(PKI).　To　this　end,　we　propose　a　proxy-oriented　identity-based　encryption　with　keyword　search　(PO-IBEKS)　scheme　from　lattices　for　cloud　storage,　which　is　post-quantum　secure.　In　PO-IBEKS,　an　original　data　owner　authorizes　a　proxy　to　encrypt　sensitive　data　as　well　as　corresponding　keywords　and　upload　ciphertexts　to　clouds,　which　alleviates　the　data　processing　burden　on　the　original　data　owner.　Besides,　PO-IBEKS　can　resist　inside　keyword　guessing　attacks　(IKGA)　from　misbehaved　cloud　servers　by　integrating　the　learning　with　errors　(LWE)　encryption　and　preimage　sampleable　function.　Each　entity　in　PO-IBEKS　is　identified　with　her/his　recognizable　information,　thereby　eliminating　managing　certificates.　Formal　security　analysis　proves　that　PO-IBEKS　can　achieve　ciphertext　indistinguishability,　existential　unforgeability,　and　delegation　security.　Experimental　results　demonstrate　PO-IBEKS　is　much　more　practical　when　compared　with　existing　schemes.　©　2019　Elsevier　Inc.