The authors construct a fully secure HIBE scheme with short cipher-texts. The previous construction of the researchers was only proven to be secure in the selective model, under a non-static assumption which depended on the depth of the hierarchy. To obtain full security, they apply the dual system encryption concept recently introduced by waters. A straightforward application of this technique is insufficient to achieve short ciphertexts, since the original instantiation of the technique includes tags that do not compress.