Masayuki Fukumitsu

Hokkaido Information University

5Publications

6Citations

Publications 5

Newest*
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Published on Jan 1, 2019

Estimated H-index: 3

Published on Oct 1, 2018

Estimated H-index: 3

Estimated H-index: 3

Galindo and Garcia introduced a light-wight identity-based signature (IBS) based on Schnorr signature in AFRICACRYPT 2009. Despite the simple construction and the ef-ficiency of Galindo-Garcia IBS, to the best of our knowledge, their followers do not appear except the IBS scheme by Fukumitsu and Hasegawa in CANDAR’17. Although their IBS achieves the tight security, the efficiency is worse than Galindo-Garcia IBS. Their result suggests that Galindo-Garcia IBS utilizes some special properties of S...

Impossibility of the Provable Security of the Schnorr Signature from the One-More DL Assumption in the Non-programmable Random Oracle Model*
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Published on Oct 23, 2017

Estimated H-index: 3

Estimated H-index: 3

The security of the Schnorr signature was widely discussed. In the random oracle model (ROM), it is provable from the DL assumption, whereas there is a negative circumstantial evidence in the standard model. Fleischhacker, Jager and Schroder showed that the tight security of the Schnorr signature is unprovable from a strong cryptographic assumption, such as the One-more DL (OM-DL) assumption and the computational and decisional Diffie-Hellman assumption, in the ROM via a generic reduction as lon...

Published on Oct 1, 2016 in ISITA (International Symposium on Information Theory and its Applications)

Estimated H-index: 3

Estimated H-index: 3

We propose a generic construction of tightly secure signature schemes in the non-programmable random oracle model. Our construction employs the dual-mode commitment and the lossy identification schemes. Since there are many instantiation of lossy identification schemes, we can obtain many tightly secure signature schemes in the non-programmable random oracle model.

Impossibility on the Provable Security of the Fiat-Shamir-Type Signatures in the Non-programmable Random Oracle Model*
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Published on Sep 3, 2016

Estimated H-index: 3

Estimated H-index: 3

On the security of Fiat-Shamir (FS) type signatures, some negative circumstantial evidences were given in the non-programmable random oracle model (NPROM). Fischlin and Fleischhacker first showed an impossibility for specific FS-type signatures via a single-instance reduction. In ISC 2015, Fukumitsu and Hasegawa found another conditions to prove such an impossibility, however their result requires a strong condition on a reduction, i.e. a key-preserving reduction. In this paper, we focus on a no...

Published on Jul 7, 2014 in ACISP (Australasian Conference on Information Security and Privacy)

Estimated H-index: 3

Estimated H-index: 3

Estimated H-index: 10

We pose a question whether or not the standard RSA assumption is sufficient to prove the security of the strong RSA-based (SRSA-based, for short) signatures. In this paper, we show a negative circumstantial evidence for the question. Namely, several SRSA-based signatures cannot be proven to be sEUF-CMA, or even EUF-KOA, under the RSA assumption as far as a modulus-preserving algebraic reduction is concerned. Our result is obtained as an important application of the adaptive pseudo-free group int...

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