Dual system encryption was first proposed by Waters as a powerful method to prove full security for identity-based encryption (IBE) schemes and its extensions. To construct fully secure schemes, the application of dual system encryption is considered and a generic construction of fully secure schemes is presented. The construction combines a dual system encryption IBE scheme with a normal secure scheme and produces a new scheme which can be proven secure by dual system encryption. Based on the proposed generic construction, an instantiation, which is a hierarchical identity-based encryption (HIBE) scheme with constant ciphertext size, is presented. This scheme is more efficient than Waters’ original dual system encryption HIBE scheme, and it is proven fully secure under the Decision BDH and Decision Linear assumptions.