Abstract:In this paper,LOKI97 is analyzed using linear cryptanalysis.The results show that LOKI97 does not meet the needs of AES (advanced encryption standard).Using algorithm 1 of linear cryptanalysis,the authors can get the 92-bit subkey with 250 known-plaintexts and the success rate is 0.977; using algorithm 2 of linear cryptanalysis,it is possible to break LOKI97 with 245 known-plaintexts and the success rate is 0.967.