Abstract
This paper describes a linear analysis of Blowfish (a block cipher designed by B. Schneier in 1993), and Khufu (a cipher designed by R.C. Merkle in 1989). The nonlinear cipher components of these ciphers are key dependent, and thus, unknown to unauthorized entities. Nonetheless, we estimate the fraction of user keys that generate weak nonlinear components (namely, with large enough bias). As far as we are aware of this paper reports the first known-plaintext (and ciphertext-only) attacks on these ciphers.
Research funded by FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) under contract 2005/02102-9.
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Nakahara, J. (2007). A Linear Analysis of Blowfish and Khufu. In: Dawson, E., Wong, D.S. (eds) Information Security Practice and Experience. ISPEC 2007. Lecture Notes in Computer Science, vol 4464. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-72163-5_3
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DOI: https://doi.org/10.1007/978-3-540-72163-5_3
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