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Cryptanalysis of Stream Cipher COS (2,128) Mode I
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Abstract: | Filiol and Fontaine recently proposed a family of stream ciphers named COS. COS is based on nonlinear feedback shift registers and was claimed to be with high cryptographic strength. Babbage showed that COS $(2,128)$ Mode II is extremely weak. But Babbage's attack is too expensive to break the COS $(2,128)$ Mode I (the complexity is around $2^{52}$). In this paper, we show that the COS $(2,128)$ Mode I is too weak. With about $2^{16}$-bit known plaintext, the secret information could be recovered with small amount of memory and computation time (less than one second on a Pentium IV Processor). |
BibTeX
@misc{eprint-2002-11530, title={Cryptanalysis of Stream Cipher COS (2,128) Mode I}, booktitle={IACR Eprint archive}, keywords={secret-key cryptography / stream ciphers, cryptanalysis, COS}, url={http://eprint.iacr.org/2002/005}, note={ hongjun@krdl.org.sg 11691 received 3 Jan 2002}, author={Hongjun Wu and Feng Bao}, year=2002 }