Ryuichi SAKAI


A Construction of Public-Key Cryptosystem Based on Singular Simultaneous Equations
Masao KASAHARA Ryuichi SAKAI 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2005/01/01
Vol. E88-A  No. 1  pp. 74-80
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Public Key Cryptography
Keyword: 
public-key cryptosystemsingular simultaneous equationsmultivariate polynomials
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A Construction of Public Key Cryptosystem for Realizing Ciphertext of Size 100 Bit and Digital Signature Scheme
Masao KASAHARA Ryuichi SAKAI 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2004/01/01
Vol. E87-A  No. 1  pp. 102-109
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Asymmetric Cipher
Keyword: 
public key cryptosystemsimultaneous equationsmultivariate polynomialdigital signature
 Summary | Full Text:PDF(298.1KB)

A New Traitor Tracing
Shigeo MITSUNARI Ryuichi SAKAI Masao KASAHARA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2002/02/01
Vol. E85-A  No. 2  pp. 481-484
Type of Manuscript:  PAPER
Category: Information Security
Keyword: 
traitor tracingWeil pairingelliptic curve
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Person Authentication Scheme with Image of Face Casted by Light from Various Directions
Ryuichi SAKAI Nobuyuki KOMORI Masaaki TAKAMATSU 
Publication:   IEICE TRANSACTIONS on Information and Systems
Publication Date: 2001/07/01
Vol. E84-D  No. 7  pp. 885-888
Type of Manuscript:  Special Section LETTER (Special Issue on Biometric Person Authentication)
Category: 
Keyword: 
face recognitionperson authenticationvarying light
 Summary | Full Text:PDF(636.1KB)

A New Product-Sum Type Public Key Cryptosystem Based on Reduced Bases
Daisuke SUZUKI Yasuyuki MURAKAMI Ryuichi SAKAI Masao KASAHARA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2001/01/01
Vol. E84-A  No. 1  pp. 326-330
Type of Manuscript:  Special Section LETTER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
low-density attackproduct-sum type public key cryptosystemsreduced base
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A New Probabilistic ID-Based Non-interactive Key Sharing Scheme
Yasuyuki MURAKAMI Ryuichi SAKAI Masao KASAHARA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2000/01/25
Vol. E83-A  No. 1  pp. 2-9
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
IDkey sharingnon-interactiveID-based non-interactive key sharing scheme (ID-NIKS)linear attackcollusion attack
 Summary | Full Text:PDF(429.7KB)

On Ambiguity in Coppersmith' Attacking Method a against NIKS-TAS Scheme
Shigeo TSUJII Kiyomichi ARAKI Masao KASAHARA Eiji OKAMOTO Ryuichi SAKAI Yasuo MAEDA Tomohiko YAGISAWA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1996/01/25
Vol. E79-A  No. 1  pp. 66-75
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
modulo degeneracycryptanalysisID-based key sharingNIKS-TAS
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A New Class of Non-interactive ID-Based Key Sharing Schemes and Its Performances
Ryuichi SAKAI Masao KASAHARA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1995/01/25
Vol. E78-A  No. 1  pp. 51-58
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
key sharingID informationcommon keycryptosysteminformation security
 Summary | Full Text:PDF(557.2KB)

New Key Generation Algorithm for RSA Cryptosystem
Ryuichi SAKAI Masakatu MORII Masao KASAHARA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 1994/01/25
Vol. E77-A  No. 1  pp. 89-97
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
cryptographypublic-key cryptosystemRSAkey generation algorithmprimality test
 Summary | Full Text:PDF(693.6KB)