Toshio Tokita Tohru Sorimachi Mitsuru Matsui Linear Cryptanalysis of LOKI and s<sup>2</sup>DES. 293-303 1994 conf/asiacrypt/1994 ASIACRYPT db/conf/asiacrypt/asiacrypt94.html#TokitaSM94 http://dx.doi.org/10.1007/BFb0000442