Fast correlation attack on streamcipher ABC v3

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.

Fast correlation attack on stream cipher ABC v3

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 2~(36.05) keystream words and 2~(50.56) operations. The attack can be applied to ABC v1 and v2 with the same complexity as that of ABC v3. However, the number of weak keys of ABC v1 as well as ABC v2 decreases to 2~(97) 2~(95.19). It reveals that ABC v3 incurs more weak keys than that of ABC v1 and v2.