Tatsuaki OKAMOTO


A Secure M + 1st Price Auction Protocol Based on Bit Slice Circuits
Takuho MITSUNAGA Yoshifumi MANABE Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2016/08/01
Vol. E99-A  No. 8  pp. 1591-1599
Type of Manuscript:  PAPER
Category: Cryptography and Information Security
Keyword: 
secure auction protocolM+1st price auctionBoneh-Goh-Nissim encryptionmix-and-match protocol
 Summary | Full Text:PDF(757.8KB)

Adaptively Attribute-Hiding (Hierarchical) Inner Product Encryption
Tatsuaki OKAMOTO Katsuyuki TAKASHIMA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2016/01/01
Vol. E99-A  No. 1  pp. 92-117
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
functional encryptioninner product encryptionattribute-hiding
 Summary | Full Text:PDF(750.1KB)

Packing Messages and Optimizing Bootstrapping in GSW-FHE
Ryo HIROMASA Masayuki ABE Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2016/01/01
Vol. E99-A  No. 1  pp. 73-82
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
lattice-based cryptographyfully homomorphic encryptionbootstrappingSIMD operations
 Summary | Full Text:PDF(860.3KB)

Dual Pairing Vector Spaces and Their Applications
Tatsuaki OKAMOTO Katsuyuki TAKASHIMA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2015/01/01
Vol. E98-A  No. 1  pp. 3-15
Type of Manuscript:  INVITED PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
bilinear pairingsdual pairing vector spacesDPVSfunctional encryptionattribute-based encryptioninner-product encryptionattribute-based signatures
 Summary | Full Text:PDF(561.1KB)

Message Recovery Signature Schemes from Sigma-Protocols
Masayuki ABE Tatsuaki OKAMOTO Koutarou SUZUKI 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2013/01/01
Vol. E96-A  No. 1  pp. 92-100
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Public Key Based Protocols
Keyword: 
message recovery signaturesSigma-protocolchosen message attacks
 Summary | Full Text:PDF(328.4KB)

Efficient Secure Auction Protocols Based on the Boneh-Goh-Nissim Encryption
Takuho MITSUNAGA Yoshifumi MANABE Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2013/01/01
Vol. E96-A  No. 1  pp. 68-75
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Public Key Based Protocols
Keyword: 
secure auction1st price auction2nd price auctionBoneh-Goh-Nissim encryptionmix-and-match protocol
 Summary | Full Text:PDF(673.5KB)

Efficient (Hierarchical) Inner-Product Encryption Tightly Reduced from the Decisional Linear Assumption
Tatsuaki OKAMOTO Katsuyuki TAKASHIMA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2013/01/01
Vol. E96-A  No. 1  pp. 42-52
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Public Key Based Protocols
Keyword: 
functional encryptioninner-product encryptionattribute-hidingtight security reductionshort ciphertexts/secret-keys
 Summary | Full Text:PDF(310.4KB)

Chosen Ciphertext Security with Optimal Ciphertext Overhead
Masayuki ABE Eike KILTZ Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2010/01/01
Vol. E93-A  No. 1  pp. 22-33
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Public Key Cryptography
Keyword: 
chosen-ciphertext securityOAEPciphertext overhead
 Summary | Full Text:PDF(259.8KB)

On the Equivalence of Several Security Notions of KEM and DEM
Waka NAGAO Yoshifumi MANABE Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2008/01/01
Vol. E91-A  No. 1  pp. 283-297
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Security Notions
Keyword: 
universal composabilityKEMDEMISOIND-CCA2NM-CCA2IND-P2-C2NM-P2-C2
 Summary | Full Text:PDF(286.4KB)

Universally Composable Identity-Based Encryption
Ryo NISHIMAKI Yoshifumi MANABE Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2008/01/01
Vol. E91-A  No. 1  pp. 262-271
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Security Notions
Keyword: 
identity-based encryptionIND-ID-CCA2universal composition
 Summary | Full Text:PDF(240.5KB)

A Universally Composable Secure Channel Based on the KEM-DEM Framework
Waka NAGAO Yoshifumi MANABE Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2006/01/01
Vol. E89-A  No. 1  pp. 28-38
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Public Key Cryptography
Keyword: 
universally composableKEMDEMISOIND-CCA2NM-CCA2
 Summary | Full Text:PDF(218.6KB)

Security and Performance Evaluation of ESIGN and RSA on IC Cards by Using Byte-Unit Modular Algorithms
Chung-Huang YANG Hikaru MORITA Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2005/03/01
Vol. E88-B  No. 3  pp. 1244-1248
Type of Manuscript:  LETTER
Category: Fundamental Theories for Communications
Keyword: 
digital signatureESIGNPKIsmartcardsmodular arithmetic
 Summary | Full Text:PDF(165.9KB)

Delegation Chains Secure up to Constant Length
Masayuki ABE Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2002/01/01
Vol. E85-A  No. 1  pp. 110-116
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
proxy signaturedelegation chainsID-based signaturesrandom oracles
 Summary | Full Text:PDF(235KB)

A Chosen-Cipher Secure Encryption Scheme Tightly as Secure as Factoring
Eiichiro FUJISAKI Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2001/01/01
Vol. E84-A  No. 1  pp. 179-187
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
chosen-cipher securityfactoringrandom oracleexact security
 Summary | Full Text:PDF(265.5KB)

Cryptographic Works of Dr. Kenji Koyama: In Memoria
Noboru KUNIHIRO Kazuo OHTA Tatsuaki OKAMOTO Routo TERADA Yukio TSURUOKA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2001/01/01
Vol. E84-A  No. 1  pp. 108-113
Type of Manuscript:  INVITED PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
modern cryptographykey managementzero-knowledge proofelliptic curve applications
 Summary | Full Text:PDF(216.8KB)

A Signature Scheme with Message Recovery as Secure as Discrete Logarithm
Masayuki ABE Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2001/01/01
Vol. E84-A  No. 1  pp. 197-204
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
digital signature with message recoveryrandom oracle modelconcrete security analysisprovable securityelliptic curve cryptosystem
 Summary | Full Text:PDF(227.2KB)

How to Enhance the Security of Public-Key Encryption at Minimum Cost
Eiichiro FUJISAKI Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2000/01/25
Vol. E83-A  No. 1  pp. 24-32
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
indistinguishabilitychosen-plaintext attackadaptive chosen-ciphertext attackrandom oracle model
 Summary | Full Text:PDF(362.7KB)

FOREWORD
Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2000/01/25
Vol. E83-A  No. 1  pp. 1-1
Type of Manuscript:  FOREWORD
Category: 
Keyword: 
 Summary | Full Text:PDF(12.7KB)

Multi-Signature Schemes Secure against Active Insider Attacks
Kazuo OHTA Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1999/01/25
Vol. E82-A  No. 1  pp. 21-31
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
digital signatureFiat-Shamir schemeSchnorr schemerandom oracle modelzero-knowledge interactive proofprovable security
 Summary | Full Text:PDF(219.6KB)

Statistical Zero-Knowledge Protocols to Prove Modular Polynomial Relations
Eiichiro FUJISAKI Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1999/01/25
Vol. E82-A  No. 1  pp. 81-92
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
bit commitmentstatistical zero-knowledgeargument of knowledge
 Summary | Full Text:PDF(249.3KB)

Threshold Key-Recovery Systems for RSA
Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1999/01/25
Vol. E82-A  No. 1  pp. 48-54
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
key recoverykey escrowsecret sharingthreshold scheme
 Summary | Full Text:PDF(144.7KB)

Security of the Extended Fiat-Shamir Schemes
Kazuo OHTA Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1998/01/25
Vol. E81-A  No. 1  pp. 65-71
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
the Fiat-Shamir schemezero-knowledge proofidentificationno-transferable informationdigital signatures
 Summary | Full Text:PDF(673.4KB)

Practical Escrow Cash Schemes
Eiichiro FUJISAKI Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1998/01/25
Vol. E81-A  No. 1  pp. 11-19
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
escrowtrusteeelectronic cashmoney launderingextortion crime
 Summary | Full Text:PDF(751.4KB)

One-Time Zero-Knowledge Authentications and Their Applications to Untraceable Electronic Cash
Tatsuaki OKAMOTO Kazuo OHTA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1998/01/25
Vol. E81-A  No. 1  pp. 2-10
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
electronic cashzero-knowledge proofsuntraceabilityoff-line cash
 Summary | Full Text:PDF(827.8KB)

On the Complexity of the Discrete Logarithm for a General Finite Group
Tatsuaki OKAMOTO Kouichi SAKURAI Hiroki SHIZUYA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1996/01/25
Vol. E79-A  No. 1  pp. 61-65
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
discrete logarithmcomputational complexitycryptography
 Summary | Full Text:PDF(504.7KB)

Interactive Bi-proof Systems and Undeniable Signature Schemes
Atsushi FUJIOKA Tatsuaki OKAMOTO Kazuo OHTA 
Publication:   IEICE TRANSACTIONS on Information and Systems
Publication Date: 1992/01/25
Vol. E75-D  No. 1  pp. 102-109
Type of Manuscript:  Special Section PAPER (Special Section on Theoretical Foundations of Computing)
Category: 
Keyword: 
interactive proof systemrandom self-reducibilityminimum knowledgenessdigital signature
 Summary | Full Text:PDF(644.7KB)

Elliptic Curve Cryptosytems and Their Applications
Kenji KOYAMA Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS on Information and Systems
Publication Date: 1992/01/25
Vol. E75-D  No. 1  pp. 50-57
Type of Manuscript:  Special Section PAPER (Special Section on Theoretical Foundations of Computing)
Category: 
Keyword: 
public-key cryptosystemelliptic curvefactoring
 Summary | Full Text:PDF(643.5KB)

Abuses of Undeniable Signatures and Their Countermeasures
Kazuo OHTA Tatsuaki OKAMOTO Atsushi FUJIOKA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1991/08/25
Vol. E74-A  No. 8  pp. 2109-2113
Type of Manuscript:  Special Section PAPER (Special Issue on Cryptography and Information Security)
Category: 
Keyword: 
 Summary | Full Text:PDF(384.9KB)

Membership Authentication for Hierarchical Multigroups Using a Master Secret Key
Kazuo OHTA Tatsuaki OKAMOTO 
Publication:   IEICE TRANSACTIONS (1976-1990)
Publication Date: 1990/07/25
Vol. E73-E  No. 7  pp. 1107-1110
Type of Manuscript:  Special Section PAPER (Special Issue on Cryptography and Information Security)
Category: Authentication Techniques
Keyword: 
 Summary | Full Text:PDF(364.9KB)