Masayuki Abe Eike Kiltz Tatsuaki Okamoto Chosen Ciphertext Security with Optimal Ciphertext Overhead. 355-371 2008 ASIACRYPT http://dx.doi.org/10.1007/978-3-540-89255-7_22 conf/asiacrypt/2008 db/conf/asiacrypt/asiacrypt2008.html#AbeKO08