Abstract
In this paper, we propose several selective-identity chosen-ciphertext attack (IND-sID-CCA) secure identity based key encapsulation (IB-KEM) schemes that are provably secure under the computational bilinear Diffie-Hellman (CBDH) assumption in the standard model. Our schemes compare favorably to previous results in efficiency. With delicate modification, our schemes can be strengthened to be full-identity CCA secure easily.