中文摘要：

CLEFIA（named after the French word 'Clef' meaning 'Key'） is an efficient,highly secure block cipher proposed by SONY Corporation in the 14 th International Workshop on Fast Software Encryption（FSE-2007） and many cryptanalyses have been used to analyze it.According to the property of CLEFIA,a new technique Sandwich-Boomerang cryptanalysis is used on it.An 8-round Sandwich-Boomerang distinguisher of CLEFIA is constructed using the best differential characteristic of CLEFIA.And then,based on the distinguisher,an attack against 10-round CLEFIA is proposed.The number of chosen plaintexts required is 2119(or 2120) and the time complexity is 2120(or 2121).Compared with a 7-round impossible Boomerang distinguisher presented by Choy in the 4th International Workshop on Security（IWSEC-2009）,the differential characteristics used in the attack are all the best ones,so it is believed that the attack is the best result that the Boomerang attacks can get on CLEFIA at present.

英文摘要：

CLEFIA （ named after the French word ＂Clef＂ meaning ＂Key＂ ） is an efficient, highly secure block cipher proposed by SONY Corporation in the 14th International Workshop on Fast Software En- cryption （ FSE-2007 ） and many cryptanalyses have been used to analyze it. According to the proper- ty of CLEFIA, a new technique Sandwich-Boomerang cryptanalysis is used on it. An 8-round Sand- wich-Boomerang distinguisher of CLEFIA is constructed using the best differential characteristic of CLEFIA. And then, based on the distinguisher, an attack against 10-round CLEFIA is proposed. The number of chosen plaintexts required is 2^119（or 2^120） and the time complexity is 2^120（or 2^121）. Compared with a 7-round impossible Boomerang distinguisher presented by Choy in the 4th Interna- tional Workshop on Security （IWSEC-2009） , the differential characteristics used in the attack are all the best ones, so it is believed that the attack is the best result that the Boomerang attacks can get on CLEFIA at present.