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- Yasufumi Hashimoto, Kouichi Sakurai
- IACR Cryptology ePrint Archive
- 2008

- Hiroyuki Miura, Yasufumi Hashimoto, Tsuyoshi Takagi
- IEICE Transactions
- 2013

- Yasufumi Hashimoto
- IACR Cryptology ePrint Archive
- 2016

The unbalanced oil and vinegar signature scheme (UOV) is one of signature schemes whose public key is a set of multivariate quadratic forms. Recently, a new variant of UOV called Cubic UOV was proposed at Inscrypt 2015. It was claimed that the cubic UOV was more efficient than the original UOV and its security was enough. However, an equivalent secret key… (More)

- Yasufumi Hashimoto
- IEICE Transactions
- 2009

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)

- Yasufumi Hashimoto, Sadatsugu Ookuma, Eisuke Nishida
- Genes to cells : devoted to molecular & cellular…
- 2009

Lifespan is regulated by a complex combination of environmental and genetic factors. Autophagy, which is a bulk degradation system of macromolecules and organelles, has an important role in various biological events. In Caenorhabditis elegans, several autophagy genes have been shown to have a role in promoting longevity, but many other autophagy genes have… (More)

- Yasufumi Hashimoto, Tsuyoshi Takagi, Kouichi Sakurai
- IEICE Transactions
- 2011

General fault attacks on multivariate public key cryptosystems

Abstract In [Sa], it was proved that the Selberg zeta function for SL2(Z) is expressed in terms of the fundamental units and the class numbers of the primitive indefinite binary quadratic forms. The aim of this paper is to obtain similar arithmetic expressions of the logarithmic derivatives of the Selberg zeta functions for congruence subgroups of SL2(Z).… (More)

- Yasufumi Hashimoto
- IEICE Transactions
- 2014

We study splitting densities of primitive elements of a discrete subgroup Γ̃ of a connected non-compact semisimple Lie group G of real rank one with finite center in another larger such Γ. When the corresponding cover of such locally symmetric negative curved spaces is regular, the densities can be easily obtained from the results of [Sa] or [Su]. Our main… (More)

- Yasufumi Hashimoto
- IACR Cryptology ePrint Archive
- 2015

Multi-HFE (Chen et al., 2009) is one of cryptosystems whose public key is a set of multivariate quadratic forms over a finite field. Its quadratic forms are constructed by a set of multivariate quadratic forms over an extension field. Recently, Bettale et al. (2013) have studied the security of HFE and multi-HFE against the min-rank attack and found that… (More)