Fast correlation attack on streamcipher ABC v3  

作　　者：ZHANG HaiNa LI Lin WANG XiaoYun 

机构地区：[1]Key Laboratory of Cryptographic Technology and Information Security, Ministry of Education, ShandongUniversity, Jinan 250100, China [2]Center for Advanced Study, Tsinghua University, Beijing 100084, China

出　　处：《Science in China(Series F)》2008年第7期936-947,共12页中国科学（F辑英文版）

基　　金：the National Natural Science Foundation of China (Grant Nos.90604036 and 60525201);the 973 Project (Grant No.2007CB807902)

摘　　要：ABC v3 is a stream cipher submitted to the ECRYPT eStream project and has entered the second evaluation phase. Its key length is 128 bits. In this paper, we find large numbers of new weak keys of ABC family and introduce a method to search for them, and then apply a fast correlation attack to break ABC v3 with weak keys. We show that there are at least 2^103.71 new weak keys in ABC v3. Recovering the internal state of a weak key requires 236.05 keystream words and 2^50.56 operations. The attack can be applied to ABC vl and v2 with the same complexity as that of ABC v3. However, the number of weak keys of ABC vl as well as ABC v2 decreases to 2^97 ＋ 20^95.19,It reveals that ABC v3 incurs more weak keys than that of ABC vl and v2.ABC v3 is a stream cipher submitted to the ECRYPT eStream project and has entered the second evaluation phase. Its key length is 128 bits. In this paper, we find large numbers of new weak keys of ABC family and introduce a method to search for them, and then apply a fast correlation attack to break ABC v3 with weak keys. We show that there are at least 2^103.71 new weak keys in ABC v3. Recovering the internal state of a weak key requires 236.05 keystream words and 2^50.56 operations. The attack can be applied to ABC vl and v2 with the same complexity as that of ABC v3. However, the number of weak keys of ABC vl as well as ABC v2 decreases to 2^97 ＋ 20^95.19,It reveals that ABC v3 incurs more weak keys than that of ABC vl and v2.

关 键 词：CRYPTANALYSIS stream cipher fast correlation attack ABC v3 

分 类 号：TN918[电子电信—通信与信息系统]