WE　(Witness　Encryption)　is　a　new　kind　of　encryption　scheme　without　key　generation.　The　original　security　definition　of　WE　does　not　consider　the　scenario　where　the　instance　belongs　to　the　NP　language　L,　but　the　adversary　does　not　know　any　witness　for　this　fact.　This　could　be　a　problem　in　many　applications　of　WE.　We　strengthen　the　security　definition　of　WE　by　considering　this　scenario,　and　present　a　theoretical　construction　based　on　the　original　WE　scheme　and　hard　subset　membership　problem.　Demonstrate　the　advantage　ofthe　new　concept　by　constructing　an　IBE　scheme　based　on　WE　with　simplified　construction　and　security　proof.　©　2016　ICIC　International.