Yasufumi Hashimoto

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It is well known that the problem to solve a set of randomly chosen multivariate quadratic equations over a finite field is NP-hard. However, when the number of variables is much larger than the number of equations, it is not necessarily difficult to solve equations. In fact, when n ≥ m(m+1) (n, m are the numbers of variables and equations respectively) and(More)
It is well known that if the higher half bits of a prime factor are known or the secret key is small enough then the RSA cryptosystem is broken (e.g. [Coppersmith, J. Cryptology, 1997] and [Boneh-Durfee, Eurocrypt'99]). Recently, Sarkar-Maitra-Sarkar [Cryptology ePrint Archiv, 2008/315] proposed attacks against RSA under the conditions that the higher bits(More)
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