Katsuyuki OKEYA


Sole Inversion Precomputation for Elliptic Curve Scalar Multiplications
Erik DAHMEN Katsuyuki OKEYA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2010/06/01
Vol. E93-A  No. 6  pp. 1140-1147
Type of Manuscript:  Special Section PAPER (Special Section on Discrete Mathematics and Its Applications)
Category: Cryptography and Information Security
Keyword: 
affine coordinateselliptic curve cryptosystemprecomputationscalar multiplication
 Summary | Full Text:PDF(374.2KB)

Recursive Double-Size Modular Multiplications from Euclidean and Montgomery Multipliers
Masayuki YOSHINO Katsuyuki OKEYA Camille VUILLAUME 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2010/01/01
Vol. E93-A  No. 1  pp. 180-187
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Mathematics
Keyword: 
modular multiplicationRSAefficient implementationlow-end devicedouble-size technique
 Summary | Full Text:PDF(234.7KB)

Faster Double-Size Bipartite Multiplication out of Montgomery Multipliers
Masayuki YOSHINO Katsuyuki OKEYA Camille VUILLAUME 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2009/08/01
Vol. E92-A  No. 8  pp. 1851-1858
Type of Manuscript:  Special Section PAPER (Special Section on Discrete Mathematics and Its Applications)
Category: Theory
Keyword: 
Montgomery multiplicationdouble-size techniqueRSAefficient implementationsmartcard
 Summary | Full Text:PDF(347.5KB)

Side Channel Attacks against Hash-Based MACs with PGV Compression Functions
Katsuyuki OKEYA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2008/01/01
Vol. E91-A  No. 1  pp. 168-175
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Side Channel Attacks
Keyword: 
(keyed) hash functionHMACNMACPGV constructionside channel attacksdifferential power analysis (DPA)reverse DPA
 Summary | Full Text:PDF(202.4KB)

Montgomery Multiplication with Twice the Bit-Length of Multipliers
Masayuki YOSHINO Katsuyuki OKEYA Camille VUILLAUME 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2008/01/01
Vol. E91-A  No. 1  pp. 203-210
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Implementation
Keyword: 
Montgomery multiplicationRSAcrypto-coprocessorsmartcard
 Summary | Full Text:PDF(236.2KB)

A New Upper Bound for the Minimal Density of Joint Representations in Elliptic Curve Cryptosystems
Erik DAHMEN Katsuyuki OKEYA Tsuyoshi TAKAGI 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2007/05/01
Vol. E90-A  No. 5  pp. 952-959
Type of Manuscript:  Special Section PAPER (Special Section on Discrete Mathematics and Its Applications)
Category: 
Keyword: 
elliptic curve cryptosystemjoint sparse formleft-to-rightmulti-scalar multiplicationshamir method
 Summary | Full Text:PDF(248.3KB)

Enhanced Exhaustive Search Attack on Randomized BSD Type Countermeasure
Dong-Guk HAN Katsuyuki OKEYA Tae Hyun KIM Yoon Sung HWANG Beomin KIM Young-Ho PARK 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2006/05/01
Vol. E89-A  No. 5  pp. 1316-1327
Type of Manuscript:  Special Section PAPER (Special Section on Discrete Mathematics and Its Applications)
Category: 
Keyword: 
elliptic curve cryptosystemside channel attacksSPADPABSD representationHa-Moon countermeasureEbeid-Hasan countermeasureAgagliate et al.'s countermeasure
 Summary | Full Text:PDF(387.1KB)

Defeating Simple Power Analysis on Koblitz Curves
Camille VUILLAUME Katsuyuki OKEYA Tsuyoshi TAKAGI 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2006/05/01
Vol. E89-A  No. 5  pp. 1362-1369
Type of Manuscript:  Special Section PAPER (Special Section on Discrete Mathematics and Its Applications)
Category: 
Keyword: 
elliptic curve cryptosystemsKoblitz curvessmartcardside channel attacksSPA countermeasure
 Summary | Full Text:PDF(257.3KB)

Security Analysis of the SPA-Resistant Fractional Width Method
Katsuyuki OKEYA Tsuyoshi TAKAGI Camille VUILLAUME 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2006/01/01
Vol. E89-A  No. 1  pp. 161-168
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Elliptic Curve Cryptography
Keyword: 
elliptic curve cryptosystemssmartcardfractional windowside channel attacksflexibilitydiscrete logarithm problem
 Summary | Full Text:PDF(167KB)

Cryptanalysis of Ha-Moon's Countermeasure of Randomized Signed Scalar Multiplication
Katsuyuki OKEYA Dong-Guk HAN 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2005/05/01
Vol. E88-A  No. 5  pp. 1140-1147
Type of Manuscript:  Special Section PAPER (Special Section on Discrete Mathematics and Its Applications)
Category: 
Keyword: 
elliptic curve cryptosystemsside channel attacksSPADPAHa-Moon's countermeasurefinite Markov chain
 Summary | Full Text:PDF(169KB)

On the Importance of Protecting Δ in SFLASH against Side Channel Attacks
Katsuyuki OKEYA Tsuyoshi TAKAGI Camille VUILLAUME 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2005/01/01
Vol. E88-A  No. 1  pp. 123-131
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Tamper-Resistance
Keyword: 
asymmetric signatureSFLASHside channel attacksSHA-1C*C*--hidden monomial problem
 Summary | Full Text:PDF(294.3KB)

SCA-Resistant and Fast Elliptic Scalar Multiplication Based on wNAF
Katsuyuki OKEYA Tsuyoshi TAKAGI 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2004/01/01
Vol. E87-A  No. 1  pp. 75-84
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Asymmetric Cipher
Keyword: 
elliptic curve cryptosystemside channel attackswidth-w NAFsmart card
 Summary | Full Text:PDF(468.2KB)

A Simple Power Attack on a Randomized Addition-Subtraction Chains Method for Elliptic Curve Cryptosystems
Katsuyuki OKEYA Kouichi SAKURAI 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2003/05/01
Vol. E86-A  No. 5  pp. 1171-1180
Type of Manuscript:  Special Section PAPER (Special Section on Discrete Mathematics and Its Applications)
Category: 
Keyword: 
elliptic curve cryptosystemsside channel attacksrandomized addition-subtraction chains countermeasureSPA attacktiming attack
 Summary | Full Text:PDF(319.8KB)

Use of Montgomery Trick in Precomputation of Multi-Scalar Multiplication in Elliptic Curve Cryptosystems
Katsuyuki OKEYA Kouichi SAKURAI 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2003/01/01
Vol. E86-A  No. 1  pp. 98-112
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Asymmetric Ciphers
Keyword: 
elliptic curve cryptographymulti-scalar multiplicationprecomputationMontgomery tricksimultaneous
 Summary | Full Text:PDF(305.4KB)

A Scalar Multiplication Algorithm with Recovery of the y-Coordinate on the Montgomery Form and Analysis of Efficiency for Elliptic Curve Cryptosystems
Katsuyuki OKEYA Kouichi SAKURAI 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2002/01/01
Vol. E85-A  No. 1  pp. 84-93
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
elliptic curve cryptosystemMontgomery formfast scalar multiplicationy-coordinate recovery
 Summary | Full Text:PDF(267.9KB)