12 Result(s)

Article

Chosen-ciphertext secure code-based threshold public key encryptions with short ciphertext

Threshold public-key encryption (threshold PKE) has various useful applications. A lot of threshold PKE schemes are proposed based on RSA, Diffie–Hellman and lattice, but to the best of our knowledge, code-based ...

Kota Takahashi, Keitaro Hashimoto, Wakaha Ogata in Designs, Codes and Cryptography (2024)

Chapter and Conference Paper

Relationship Between Standard Model Plaintext Awareness and Message Hiding

Recently, Bellare and Palacio succeeded in defining the plaintext awareness, which is also called PA2, in the standard model. They propose three valiants of the standard model PA2 named perfect, statistical, a...

Isamu Teranishi, Wakaha Ogata in Advances in Cryptology – ASIACRYPT 2006 (2006)

Chapter and Conference Paper

The Security of the FDH Variant of Chaum’s Undeniable Signature Scheme

In this paper, we first introduce a new kind of adversarial goal called forge-and-impersonate in undeniable signature schemes. Note that forgeability does not necessarily imply impersonation ability. We then clas...

Wakaha Ogata, Kaoru Kurosawa, Swee-Huay Heng in Public Key Cryptography - PKC 2005 (2005)

Chapter and Conference Paper

Bounds for Robust Metering Schemes and Their Relationship with A²-code

A metering scheme allows a correct counting on the number of hits that a Web site received during a certain period. In this paper, we first derive tight lower bounds on the communication complexity |V ...

Wakaha Ogata, Kaoru Kurosawa in Advances in Cryptology — ASIACRYPT 2002 (2002)

Chapter and Conference Paper

Bit-Slice Auction Circuit

In this paper, we introduce a bit-slice approach for auctions and present a more efficient circuit than the normal approach for the highest-price auction. Our circuit can be combined with any auction protocol bas...

Kaoru Kurosawa, Wakaha Ogata in Computer Security — ESORICS 2002 (2002)

Chapter and Conference Paper

IND-CCA Public Key Schemes Equivalent to Factoring n =pq

Indistinguishability against adaptive hosen ciphertext attack (IND-CCA2) is the strongest notion for security of public key schemes. In this paper, we present the first IND-CCA2 schemes whose securities are eq...

Kaoru Kurosawa, Wakaha Ogata, Toshihiko Matsuo… in Public Key Cryptography (2001)

Chapter and Conference Paper

Provably Secure Metering Scheme

Naor and Pinkas introduced metering schemes at Eurocrypt ’98 in order to decide on advertisement fees for web servers. In the schemes, any server should be able to construct a proof to be sent to an audit agency ...

Wakaha Ogata, Kaoru Kurosawa in Advances in Cryptology — ASIACRYPT 2000 (2000)

Article

On a Fallacious Bound for Authentication Codes

We show that the lower bound on substitution success probability P _S provided by Theorem 3.8 in De Soete's paper [4], which appeared earlier in this journal, ...

Carlo Blundo, Alfredo De Santis, Kaoru Kurosawa, Wakaha Ogata in Journal of Cryptology (1999)

Chapter and Conference Paper

Optimum Secret Sharing Scheme Secure against Cheating

Tompa and Woll considered a problem of cheaters in (k, n) threshold secret sharing schemes. We first derive a tight lower bound on the size of shares |V _i| for this problem: |V _i| ...

Wakaha Ogata, Kaoru Kurosawa in Advances in Cryptology — EUROCRYPT ’96 (1996)

Chapter and Conference Paper

t-Cheater Identifiable (k, n) Threshold Secret Sharing Schemes

In this paper, we show that there exists a t-cheater identifiable (k, n) threshold secret sharing scheme such as follows for cheating probability ε > 0. If k ≥ 3t + 1, then

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Kaoru Kurosawa, Satoshi Obana, Wakaha Ogata in Advances in Cryptology — CRYPT0’ 95 (1995)

Chapter and Conference Paper

Nonperfect Secret Sharing Schemes and Matroids

This paper shows that nonperfect secret sharing schemes (NSS) have matroid structures and presents a direct link between the secret sharing matroids and entropy for both perfect and nonperfect schemes. We defi...

Kaoru Kurosawa, Koji Okada, Keiichi Sakano… in Advances in Cryptology — EUROCRYPT ’93 (1994)

Chapter and Conference Paper

General public key residue cryptosystems and mental poker protocols

This paper presents a general method how to construct public key cryptosystems based on the r-th residue problem. Based on the proposed method, we present the first mental poker protocol which can shuffle any set...

Kaoru Kurosawa, Yutaka Katayama, Wakaha Ogata… in Advances in Cryptology — EUROCRYPT ’90 (1991)