Fast correlation attacks on certain stream ciphers
Journal of Cryptology
Key-Dependent S-Boxes and Differential Cryptanalysis
Designs, Codes and Cryptography
Proceedings of the Third International Workshop on Fast Software Encryption
Differential-linear attacks against the stream cipher Phelix
FSE'07 Proceedings of the 14th international conference on Fast Software Encryption
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ABC v2 is a software-efficient stream cipher with 128-bit key. In this paper, we apply a fast correlation attack to break ABC v2 with weak keys. There are about 296 weak keys in ABC v2. The complexity to identify a weak key and to recover the internal state of a weak key is low: identifying one weak key from about 232 random keys requires 6460 keystream bytes and 213.5 operations for each random key. Recovering the internal state of a weak key requires about 219.5 keystream bytes and 232.8 operations. A similar attack can be applied to break ABC v1 with much lower complexity than the previous attack on ABC v1.