K. Y. Cheong Takeshi Koshiba Shohei Nishiyama Strengthening the Security of Distributed Oblivious Transfer. 377-388 2009 ACISP http://dx.doi.org/10.1007/978-3-642-02620-1_26 conf/acisp/2009 db/conf/acisp/acisp2009.html#CheongKN09