NTT Fellows/Senior Distinguished Researchers/Distinguished Researchers

NTT Fellow Dr.Tatsuaki Okamoto
  • Fellow

    Dr.Tatsuaki Okamoto

  • Secure Platform Laboratories
    Cryptography & Information Security Laboratories,
    NTT Research, Inc.
  • Research subject:Cryptography
  • Date of designation:April 1, 2007.

    Research subject:Cryptography

    Publications - Books

    • "Cryptography, Zero-Knowledge Proofs and Number Theory" (Kyoritsu-Shuppan, 1995)
    • "Cryptography" (Sangyo-Tosho, 1997)
    • "graphy and Information Security" (Nikkei-BP, 1998)
    • "Information Security" (Denki-Tsushin-Kyokai, 2000)
    • Japanese translation of "Modern Cryptography, Probabilistic Proofs and Psudorandomness (O.Goldreich)" (Springer-Verlag, Tokyo, 2001)

    Awards

    • IEICE Best Achievement Award (Kobayashi memorial award) (1993)
    • Research Achievement Awards of NTT (1992 and 1995)
    • Distinguished services of research award from Science and Technology Agency, Japan (1997)
    • Telecomm technology award from the Telecommunications Advancement Foundation, Japan (1998)
    • NTT R&D Fellow (1999)
    • Technology award from Nikkei-BP Press (2000)
    • IEICE Fellow (2003)
    • Certicom ECC Technology Award (2007)
    • METI Award (2008)
    • IACR Distinguished Lecturer (2009)
    • IISEC Information Security Cultural Award (2009)
    • IEICE Distinguished Achievement and Contributions Award (2011)
    • JSIAM Fellow (2011)
    • Medal with Purple Ribbon (2012)
    • IACR Fellow (2015)
    • IEICE Paper Award (2016, 2017)
    • RSA Conference Award (2017)
    • JSIAM Achievement Award (2017)
    • Asahi Prize (2019)

    Professional Services

    Board Member of Societies

    • President of the Japan Society of Industrial and Applied Mathematics (JSIAM) (2007-2008)
    • Director of IACR (International Association of Cryptology Research: 1999-2001)
    • Director of IEICE (the Institute of Electronics, Information and Communication Engineers, Japan: 2001-2003)
    • Director of JSIAM (1999-2007)
    • Chairperson of ISEC (the Information Security Research Group) of IEICE (1999-2000)

    Committee Member

    • Steering Committee Member of PKC, TCC and Pairing Conference.
    • (Associate) Editor of Journal of Cryptology.
    • Program (co-)Chair of ICICS'97, ASIACRYPT'2000, ICICS'01, CT-RSA'04, MAPTIC'05, PKC'07, Pairing'07, CANS'07, FC’15, ProvSec’17.
    • General (co-)Chair of TCC'13, and ProvSec’15.
    • Program Committees Member of Eurocrypt'92, Crypto'93, Eurocrypt'94, ASIACRYPT'94, Eurocrypt'96, Crypto'97, PKC'98, PKC'99, PKC'01, Crypto'01, CT-RSA'02, PKC'02, Crypto'02, ICICS'02, PKC'03, CT-RSA'03, CCC'03, ICISC'03, FC'04, Crypto'04, Eurocrypt'05, ICALP'05, Mycrypt'05, CT-RSA'06, FC'06, ICALP'06. PQCrypto'06, SECRYPT'06, FC'07, ProvSec'07, Indocrypt'07, ACCS'08, TCC'08, SCN'08,ASIACRYPT'08,SAC'08,ProvSec'08,ICISC'08,CANS'08,IWSEC'08,Eurocrypt'09, CosyProofs'09, Pairing'09, ProvSec'09, Eurocrypt'10, ACNS' 10, ProvSec'10,CT-RSA' 11, Eurocrypt'11, CT-RSA' 12, Crypto’12,ASIACRYPT'12,PKC’13, ProvSec’13, ACISP’14, FC’14, ASIACRYPT'15, ArcticCrypt'16, ASIACRYPT'16, ASIACRYPT'17, ISC'17.
    • Member of several Committees of Japanese government including the CRYPTREC (Evaluation of Cryptographic Techniques) committee.

    PhD Committee Member

    • ETH (Switzerland) for Michael Stadler (supervised by Prof. Ueli Maurer) (1996.5)
    • ENST (France) for Pascal Paillier (supervised by Dr. David Naccache) (1999.9)
    • JAIST(Japan) for Takeshi Okamoto (supervised by Prof. Atsuko Miyaji) (2001.12)
    • UPC (Spain) for Javier Herranz (supervised by Prof. German Saez) (2005.4)
    • Seoul National University (Korea) for Namsu Jho and Eunsun Yoo (supervised by Prof. Myung-Hwan Kim) (2007.6)
    • Kyoto University (Japan) for Mitsuo Okada (supervised by Prof. Toshio Okabe) (2011.6)
    • ENS (France) for Mehdi Tibouch (supervised by Dr. David Naccache) (2011.9)
    • Seoul National University (Korea) for Hyung Tae Lee (supervised by Prof. Jung Hee Cheon) (2012.11)

    Teaching

    • 1999-2004 Guest Professor, University of Tokyo (Grad. School of Mathematical Science)
    • 2001-2018 Guest Professor, Kyoto University (Grad. School of Informatica)
    • 2003-2010 Guest Professor, Tsukuba University (Grad. School of System and Info. Eng.)
    • 2001-2019 Guest Lecturer, Chuo University (Grad. School of Mathematics)
    • 2011 Guest Lecturer, University of Electro-Communications (Grad. School of Mathematics)

    Publications

    Journal papers

    1. A Digital Signature Scheme Based on Polynomial Operations, (with A. Shiraishi), Systems and Computers in Japan, 17, 5, pp.36-44 (1986) translated from IECE Transactions, J68-D, 5, pp.1157-1164 (1985).
    2. A Single Public-Key Authentication Scheme for Multiple Users, Systems and Computers in Japan, 18, 10, pp.14-24 (1987) translated from IECE Transactions, J69-D, 10, pp.1481-1489 (1986).
    3. Fast Public-Key Cryptosystem Using Congruent Polynomial Equations, Electronics Letters, 22, 11, pp.581-582 (1986).
    4. Modification of a Public-Key Cryptosystem, Electronics Letters, 23, 16, pp.814-815 (1987).
    5. Practical Extension of the Fiat-Shamir Scheme, (with K. Ohta), Electronics Letters, 24, 15, pp.955-956 (1988).
    6. A Digital Multisignature Scheme Using Bijective Public-key Cryptosystems, ACM Transactions on Computer Systems, Vol.6, No.8, pp.432-441 (1988).
    7. Membership Authentication for Hierarchical Multigroups Using a Mater Key, (with K. Ohta), IEICE Transactions, Vol. E-73, No.7, pp.1107-1110 (1990).
    8. A Fast Signature Scheme Based on Congruential Polynomial Operations, IEEE Transactions on Information Theory, Vol.IT-36, No.1, pp.47-53 (1990).
    9. Abuse of Undeniable Signatures and Their Countermeasures, (with K. Ohta and A. Fujioka), IEICE Transactions, Vol. E74, No.8, pp.2109-2113 (1991).
    10. Interactive Bi-proof Systems and Undeniable Signature Schemes, (with A. Fujioka and K. Ohta) IEICE Transactions, Vol. E-75-D, No. 1, pp. 102-109 (1992).
    11. Reducing Elliptic Curve Logarithms to Logarithms in a Finite Field, (with A. Menezes and S. Vanstone), IEEE Transactions on Information Theory, Vol.IT-39, No.5 (1993).
    12. On the Complexity of the Discrete Logarithm for a General Finite, (with K. Sakurai and H. Shizuya), IEICE Transactions, Vol. E79-A , No. 1, pp. 61-65 (1996).
    13. One-Time Zero-Knowledge Authentication and Untraceable Cash, (with K. Ohta), IEICE Transactions, Vol. E81-A, No. 1 (1998).
    14. Security of the Modified Fiat-Shamir Schemes, (with K. Ohta), IEICE Transactions, Vol. E81-A, No. 1 (1998).
    15. Escraw Cash Systems, (with E. Fujisaki), IEICE Transactions, Vol. E81-A (1998), No. 1 (1998).
    16. Threshold Key-Recovery Systems for RSA, IEICE Transactions, Vol. E82-A, No. 1 (1999).
    17. Statistical Zero-Knowledge Protocols to Prove Modular] Polynomial Relations, (with E. Fujisaki), IEICE Transactions, Vol. E82-A, No. 1 (1999).
    18. Multi-Signature Schemes Secure against Active Insider Attacks, (with K. Ohta), IEICE Transactions, Vol. E82-A, No. 1 (1999).
    19. On Relationships between Statistical Zero-Knowledge Proofs, Journal of Comput. and System Sciences, 60, pp.47-108 (1999).
    20. How to Enhance the Security of Public-Key Encryptions at Minimum Cost, (with E. Fujisaki), IEICE Transactions, Vol. E83-A, No. 1, pp.147-165 (2000).
    21. A Signature Scheme with Message Recovery as Secure as Discrete Logarithm, (with M. Abe), IEICE Transactions, Vol. E84-A, No. 1 (2001).
    22. A Chosen-Cipher Secure Encryption Scheme Tightly As Secure As Factoring, (with E. Fujisaki), IEICE Transactions, Vol. E84-A, No. 1 (2001).
    23. How to Enhance the Security of Public-Key Encryption at Minimum Cost, (with E. Fujisaki), IEICE Transactions, Vol. E83-A, No.1, pp. 24-32(2000).
    24. A Chosen-Cipher Secure Encryption Scheme Tightly as Secure as Factoring, (with E. Fujisaki), IEICE Transactions, Vol. E84-A, No.1, pp. 179-187(2001).
    25. A Signature Scheme with Message Recovery as Secure as Discrete Logarithm, (with M. Abe), IEICE Transactions, Vol. E84-A, No.1, pp. 197-204(2001).
    26. Delegation Chains Secure up to Constant Length, (with M. Abe), IEICE Transactions, Vol. E85-A, No.1, pp. 110-116(2002).
    27. RSA-OAEP Is Secure under the RSA Assumption, (with E. Fujisaki, D. Pointcheval, and J. Stern), Journal of Cryptology, Vol. 17 (2004).
    28. A Universally Composable Secure Channel Based on the KEM-DEM Framework, (with W. Nagao and Y. Manabe), IEICE Transactions, Vol. E89-A, No.1, pp. 28-38 (2006).
    29. An optimistic fair exchange protocol and its security in the universal composability framework, (with Y. Okada and Y. Manabe), IJACT Transactions, Vol. 1, No. 1, pp. 70-77, (2008).
    30. On the Equivalence of Several Security Notions of KEM and DEM, (with W. Nagao and Y. Manabe), IEICE Transactions, Vol. E91-A, No.1, pp. 283-297, (2008).
    31. Universally Composable Identity-Based Encryption, (with R. Nishimaki and Y. Manabe), IEICE Transactions, Vol. E91-A, No.1, pp. 262-271, (2008).
    32. Chosen Ciphertext Security with Optimal Ciphertext Overhead, (with M. Abe and E. Kiltz), IEICE Transactions, Vol. E93-A, No.1, pp. 22-33, (2010).
    33. An eCK-secure Authenticated Key Exchange Protocol without Random Oracles, (with D. Moriyama), KSII Transactions, Vol. 5, No.3, pp. 607-625, (2011).
    34. Meta-envy-free Cake-cutting and Pie-cutting Protocols, (with Y. Manabe), JIP Transactions, Vol. 20, No.3, pp. 686-693, (2012).
    35. Efficient (Hierarchical) Inner-Product Encryption Tightly Reduced from the Decisional Linear Assumption, (with K. Takashima), IEICE Transactions, Vol. E96-A, No.1, pp. 42-52 (2013).
    36. Efficient Secure Auction Protocols Based on the Boneh-Goh-Nissim Encryption, (with T. Mitsunaga and Y. Manabe), IEICE Transactions, Vol. E96-A, No.1, pp. 68-75, (2013).
    37. Message Recovery Signature Schemes from Sigma-Protocols, (with M. Abe and K. Suzuki), IEICE Transactions, Vol. E96-A, No.1, 92-100, (2013).
    38. Secure Integration of Asymmetric and Symmetric Encryption Schemes, (with E. Fujisaki), J. Cryptology Vol. 26, No.1, pp. 80-101, (2013)
    39. Efficient Attribute-Based Signatures for Non-Monotone Predicates in the Standard Model, (with K. Takashima), IEEE Transactions on Cloud Computing, Vol.2, No.4, pp. 409-421, (2014).
    40. A Cryptographic Moving-Knife Cake-Cutting Protocol with High Social Surplus. (with Y. Manabe and R. Otsuka), Journal of Information Processing, Volume 23, pp. 299-304 (2015).
    41. Dual Pairing Vector Spaces and Their Applications, (with K. Takashima), IEICE Transactions, Vol.98-A, No. 1, pp.3-15, (2015).
    42. Achieving short ciphertexts or short secret-keys for adaptively secure general inner-product encryption, (with K. Takashima), Des. Codes Cryptography, Vol. 77, Issue2, pp.725-771(2015).
    43. A Secure M + 1st Price Auction Protocol Based on Bit Slice Circuits, (with T. Mitsunaga and Y. Manabe), IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Volume 99-A, No8. pp.1591-1599 (2016)
    44. Adaptively Attribute-Hiding (Hierarchical) Inner Product Encryption, (with K. Takashima), IEICE Transactions, Vol.99-A, No.1, pp.92-117 (2016).
    45. Packing Messages and Optimizing Bootstrapping in GSW-FHE, (with R. Hiromasa and M. Abe), IEICE Transactions, Vol. 99-A, No. 1, pp.73-82 (2016).
    46. Fully Secure Functional Encryption with a Large Class of Relations from the Decisional Linear Assumption, . (with K. Takashima), Journal of Cryptology, Volume 32, No.4, pp.1491-1573 (2019).
    47. Decentralized Attribute-Based Encryption and Signatures, (with K. Takashima), IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Volume 103-A, No.1, pp. 41-73 (2020).
    48. Efficient Inner Product Functional Encryption with Full-Hiding Security, (with J. Tomida and M. Abe), EICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Volume 103-A, No.1, pp. 33-40 (2020).

    International conference papers

    1. Modification of the Fiat-Shamir Scheme, (with K. Ohta), the proceedings of Crypto'88, LNCS 403, Springer-Verlag, pp.232-243 (1990).
    2. Divertible Zero Knowledge Interactive Proofs and Commutative Random Self-Reducibility, (with K. Ohta), the proceedings of Eurocrypt'89, LNCS, Springer-Verlag, pp.134-149 (1990).
    3. Disposable Zero-Knowledge Authentications and Their Applications to Untraceable Electronic Cash, (with K. Ohta), the proceedings of Crypto'89, LNCS, Springer-Verlag, pp.481-496 (1990).
    4. Membership Authentication for Hierarchical Multigroups Using the Extended Fiat-Shamir Scheme, (with K. Ohta and K. Koyama), the proceedings of Eurocrypt'90, LNCS 473, Springer-Verlag, pp.446-457 (1991).
    5. How to Utilize the Randomness of Zero-Knowledge Proofs, (with K. Ohta), the proceedings of Crypto'90, LNCS 537, Springer-Verlag, pp.456-475 (1991).
    6. ESIGN: An Efficient Digital Signature Implementation for Smart Cards, (with A. Fujioka and S. Miyaguchi), the proceedings of Eurocrypt'91, LNCS 547, Springer-Verlag, pp.446-457 (1992).
    7. Interactive Bi-Proof Systems and Undeniable Signature Schemes, with A. Fujioka and K. Ohta, the proceedings of Eurocrypt'91, LNCS 547, Springer-Verlag, pp.243-256 (1992).
    8. Direct Zero Knowledge Proofs of Computational Power in Five Rounds, (with D. Chaum and K. Ohta), the proceedings of Eurocrypt'91, LNCS 547, Springer-Verlag, pp.96-105 (1992).
    9. Reducing Elliptic Curve Logarithms to Logarithms in a Finite Field, (with A. Menezes and S. Vanstone), the proceedings of STOC, pp.80-89 (1991).
    10. Universal Electronic Cash, (with K. Ohta), the proceedings of Crypto'91, LNCS 576, Springer-Verlag, pp.324-337 (1992).
    11. Efficient Algorithms for the Construction of Hyperelliptic Cryptosystems, (with K. Sakurai), the proceedings of Crypto'91, LNCS 576, Springer-Verlag, pp.267-278 (1992).
    12. New Public-Key Schemes Based on Elliptic Curves over the Ring Z_n, (with K. Koyama, U.M. Maurer, and S.A. Vanstone), the proceedings of Crypto'91, LNCS 576, Springer-Verlag, pp.252-266 (1992).
    13. An Extension of Zero-Knowledge Proofs and Its Applications, the proceedings of ASIACRYPT'91, LNCS 739, Springer-Verlag, pp. 368-381(1992).
    14. A Digital Multisignature Scheme Based on the Fiat-Shamir Scheme, (with K. Ohta), the proceedings of ASIACRYPT'91, LNCS 739, Springer-Verlag, pp. 139-148 (1992).
    15. How Intractable Is the Discrete Logarithm for a General Finite Group, (with K. Sakurai and H. Shizuya), the proceedings of Eurocrypt'92, LNCS 658, Springer-Verlag, pp.420-428 (1993).
    16. Secure Bit Commitment Function against Divertibility, (with K. Ohta and A. Fujioka), the proceedings of Eurocrypt'92, LNCS 658, Springer-Verlag, pp.324-340 (1993).
    17. An Efficient Digital Signature Scheme Based on an Elliptic Curve over the Ring Z_n, (with A. Fujioka and E. Fujisaki), the proceedings of Crypto'92, LNCS, Springer--Verlag, pp.54-65 (1993).
    18. Provably Secure and Practical Identification Schemes and Corresponding Signature Schemes, the proceedings of Crypto'92, LNCS, Springer--Verlag, pp.31-53 (1993).
    19. A Practical Secret Voting Scheme for Large Scale Elections, (with A. Fujioka and K. Ohta), the proceedings of Auscrypt'92, LNCS, Springer--Verlag (1993).
    20. On Key Distribution and Authentication in Mobile Radio Networks, (with C. Park, K.Kurosawa, and S. Tsujii), the proceedings of Eurocrypt'93, LNCS, Springer-Verlag (1994).
    21. Survey of Digital Signature Schemes, (with K. Ohta),the proceedings of SPRC (the symposium on State and Progress of Research in Cryptography), Rome, pp.17-29 (1993),
    22. On the Relationship among Cryptographic Physical Assumptions, the Proceedings of ISAAC'93, LNCS 762, Springer-Verlag, pp. 369-378 (1993).
    23. Designated Confirmer Signatures and Public-Key Encryption Are Equivalent, the proceedings of Crypto'94, LNCS 839, Springer-Verlag, pp. 61-74 (1995).
    24. Simultaneous Secret Exchange Protocols Based on General Assumptions, (with K. Ohta), the Proceedings of the ACM Conference on Computer and Communications Security (1994).
    25. Zero-Knowledge Proofs of Computational Power in the Shared String Model, (with A. De Santis and G. Persiano), the proceedings of ASIACRYPT'94, LNCS, Springer-Verlag (1995).
    26. Single-Term Divisible Electronic Coins, (with T. Eng), the proceedings of Eurocrypt'94, LNCS 950, Springer-Verlag, pp.306-319 (1995).
    27. Honest Verifier vs Dishonest Verifier in Public Coin Zero-Knowledge Proofs, (with I. Damgaard, O. Goldreich and A. Wigderson), the proceedings of Crypto'95}, LNCS 963, Springer--Verlag, pp.325--338 (1995).
    28. An Efficient Divisible Electronic Cash Scheme, the proceedings of Crypto'95, LNCS 963, Springer-Verlag, pp.438-451 (1995).
    29. Practical Escrow Cash Systems, (with E. Fujisaki), the proceedings of Security Protocols Workshop, LNCS 1189, Springer-Verlag, pp. 33-48 (1996).
    30. On Relationships between Statistical Zero-Knowledge Proofs, the proceedings of STOC, pp.649-658 (1996).
    31. An Electronic Voting Scheme, the proceedings of IFIP'96, IT Tools (1996).
    32. Receipt-Free Electronic Voting Schemes for Large Scale Elections, the proceedings of Security Protocols Workshop, LNCS 1361, Springer-Verlag, pp.25-36 (1997).
    33. Threshold Key-Recovery Systems for RSA, the proceedings of Security Protocols Workshop, LNCS 1361, Springer-Verlag, pp.192-200 (1997).
    34. Statistical Zero-Knowledge Protocols to Prove Polynomial Relations, (with E. Fujisaki), the proceedings of Crypto'97, LNCS1294, Springer-Verlag, pp16-30 (1997).
    35. Keeping the SZK-Verifier Honest Uncondi tionally, (with G. DiCrescenzo and M. Yung), the proceedings of Crypto'97, LNCS 1294, pp31-45 Springer-Verlag (1997).
    36. Lower Bounds on Term-Based Divisible Cash Systems, (with M. Yung), the proceedings of PKC'98, LNCS 1431, Springer-Verlag, pp72-82 (1998).
    37. NTT's Public-Key Cryptosystem and Electronic Money System, (with H.Kawahara and K.Koyama), the proceedings of PKS'98, Certicom (1998).
    38. Security of an Identity-Based Cryptosystem and the Related Reductions, (with S. Uchiyama), the proceedings of Eurocrypt'98, LNCS 1403, Springer-Verlag, pp546-560 (1998).
    39. A Practical and Provably Secure Scheme for Publicly Secret Sharing and Its Application, (with E. Fujisaki), the proceedings of Eurocrypt'98, LNCS 1403, Springer-Verlag, pp32-46 (1998).
    40. A Public-Key Cryptosystem as Secure as Factoring, (with S. Uchiyama), the proceedings of Eurocrypt'98, LNCS 1403, Springer-Verlag, pp308-318 (1998).
    41. On Concrete Security Treatment of Signature Schemes Derived from Identification, (with K. Ohta), the proceedings of Crypto'98, LNCS 1462, Springer-Verlag, pp354-369 (1998).
    42. EPOC: Efficient Probabilistic Public-Key Encryption, (with S.Uchiyama and E.Fujisaki), IEEE P1363 (1998).
    43. TSH-ESIGN: Efficient Digital Signature Scheme Using Trisection Size Hash, (with E.Fujisaki and H.Morita), IEEE P1363a (1998).
    44. Provable Security of Practical Public-Key Encryption Scheme, the proceedings of JWIS98 (1998).
    45. Oblivious Transfer Channels and Dealing Channels, DMTCS'99 (1999).
    46. How to Enhance the Security of Public-Key Encryptions at Minimum Cost, (with E. Fujisaki), the proceedings of PKC'99, LNCS 1560, Springer-Verlag, pp.53-68 (1999).
    47. Secure Integration of Asymmetric and Symmetric Encryption Schemes, (with E. Fujisaki), the proceedings of Crypto’99, LNCS 1666, Springer-Verlag, pp.537-554 (1999).
    48. A Signature Scheme with Message Recovery as Secure as Discrete Logarithm, (with M. Abe), the proceedings of ASIACRYPTo’99, LNCS 1716, Springer-Verlag, pp.378-389 (1999).
    49. Quantum Public-Key Cryptosystems, (with K.Tanaka and S.Uchiyama), the proceedings of Crypto 2000, LNCS 1880, Springer-Verlag, pp.147-165 (2000).
    50. Provably Secure Partially Blind Signatures, (with M.Abe), the proceedings of Crypto 2000, LNCS 1880, Springer-Verlag, pp.271- 286 (2000).
    51. The Gap-Problems: a New Class of Problems for the Security of Cryptographic Schemes, (with D. Pointcheval), the proceedings of PKC’01, LNCS 1992, Springer-Verlag, pp.104-118 (2001).
    52. REACT: Rapid Enhanced-security Asymmetric Cryptosystem Transform, (with D. Pointcheval), the proceedings of Cryptographers’ Track at RSA Conference’01 (CT-RSA’01), LNCS 2020, Springer-Verlag, pp.159-175 (2001).
    53. RSA-OAEP is Secure under the RSA Assumption, (with E. Fujisaki, D. Pointcheval and J. Stern), the proceedings of Crypto’01, LNCS 2139, Springer-Verlag, pp.260-274 (2001).
    54. A New Approach to Knapsack Cryptosystems (Extended Abstract), (with K. Tanaka), the proceedings of WISA2002, Vol.3, pp.33-42 (2002).
    55. Almost Uniform Density of Power Residues and the Provable Security of ESIGN, (with J. Stern), the proceedings of ASIACRYPT 2003, LNCS 2894, Springer, pp.287--301 (2003).
    56. Resource Bounded Unprovability of Computational Lower Bounds, the Proceedings of Workshop on Cryptography and Related Mathematics, Chuo University, ePrint Archive 2003/187, IACR, http://eprint.iacr.org/ (2003).
    57. An RSA Family of Trap-door Permutations with a Common Domain and Its Application, (with R. Hayashi and K. Tanaka), the proceedings of PKC'04, LNCS, Springer-Verlag (2004).
    58. A Universal Composable Channel Based on the KEM-DEM Framework, (with W. Nagao and Y. Manabe) the proceedings of TCC'05, LNCS, Springer-Verlag (2005).
    59. Efficient Blind and Partially Blind Signatures Without Random Oracles, the proceedings of TCC'06, LNCS, Springer-Verlag (2006).
    60. Cryptography Based on Bilinear Maps, the proceedings of AAECC-16} LNCS 3857, Springer-Verlag, pp.35-50 (2006).
    61. On Pairing-Based Cryptosystems, the proceedings of Vietcrypt'06, LNCS 4341, Springer-Verlag, pp.50-66 (2006).
    62. Universally Composable Identity-Based Encryption, (with R. Nishimaki and Y. Manabe) the proceedings of Vietcrypt'06, LNCS 4341, Springer-Verlag, pp.337-353 (2006).
    63. Authenticated Key Exchange and Key Encapsulation in the Standard Model, the proceedings of ASIACRYPT 2007, LNCS 4833, Springer-Verlag, pp.474-484, (2007).
    64. Relationship of Three Cryptographic Channels in the UC Framework, (with W. Nagao and Y. Manabe) the proceedings of ProvSec 2008, LNCS 5324, Springer-Verlag, pp. 268-282, (2008).
    65. Homomorphic Encryption and Signatures from Vector Decomposition, (with K. Takashima) the proceedings of Pairing 2008, LNCS 5209, Springer-Verlag, pp.57-74, (2008).
    66. An Efficient Anonymous Credential System, (with N. Akagi and Yoshifumi Manabe) the proceedings of Financial Cryptography 2008, LNCS 5143, Springer-Verlag, pp. 272-286, (2008).
    67. Chosen Ciphertext Security with Optimal Ciphertext Overhead, (with M. Abe and E. Kiltz) the proceedings of ASIACRYPT 2008, LNCS 5350, Springer-Verlag, pp. 355-371, (2008).
    68. Compact CCA-Secure Encryption for Messages of Arbitrary Length, (with M. Abe) the proceedings of PKC 2009, LNCS 5443, Springer Springer-Verlag, pp. 377-392, (2009).
    69. An eCK-Secure Authenticated Key Exchange Protocol without Random Oracles, (with D. Moriyama) the proceedings of ProvSec 2009, LNCS 5848, Springer Springer-Verlag, pp. 154-167, (2009).
    70. Hierarchical Predicate Encryption for Inner-Products, (with K. Takashima) the proceedings of ASIACRYPT 2009, LNCS 5912, Springer Springer-Verlag, pp. 214-231, (2009).
    71. Meta-Envy-Free Cake-Cutting Protocols, (with Y. Manabe) the proceedings of MFCS 2010, LNCS 6281, Springer-Verlag, pp. 501-512, (2010).
    72. Efficient Secure Auction Protocols Based on the Boneh-Goh-Nissim Encryption, (with T. Mitsunaga and Y. Manabe) the proceedings of IWSEC 2010, LNCS6434, Springer-Verlag, pp. 149-163, (2010).
    73. Fully Secure Functional Encryption: Attribute-Based Encryption and (Hierarchical) Inner Product Encryption, (with A. B. Lewko, A. Sahai, K. Takashima and B. Waters) the proceedings of EUROCRYPT 2010, LNCS 6110, Springer-Verlag, pp. 62-91, (2010).
    74. Fully Secure Functional Encryption with General Relations from the Decisional Linear Assumption, (with K. Takashima) the proceedings of CRYPTO 2010, LNCS 6223, Springer-Verlag, pp. 191-208, (2010).
    75. Efficient Attribute-Based Signatures for Non-monotone Predicates in the Standard Model, (with K. Takashima) the proceedings of PKC 2011, LNCS 6571, Springer-Verlag, pp. 35-52, (2011).
    76. A Secure M + 1st Price Auction Protocol Based on Bit Slice Circuits, (with T. Mitsunaga and Y. Manabe) the proceedings of IWSEC 2011, LNCS 7038, Springer-Verlag, pp. 51-64, (2011).
    77. Leakage resilient eCK-secure key exchange protocol without random oracles, (with D. Moriyama) the proceedings of ASIACCS 2011, pp. 441-447, (2011).
    78. Achieving Short Ciphertexts or Short Secret-Keys for Adaptively Secure General Inner-Product Encryption, (with K. Takashima) the proceedings of CANS 2011, LNCS 7092, Springer-Verlag, pp. 138-159, (2011).
    79. Some Key Techniques on Pairing Vector Spaces, (with K. Takashima) the proceedings of AFRICACRYPT 2011, LNCS 6737, Springer-Verlag, pp. 380-382, (2011).
    80. A Cryptographic Moving-Knife Cake-Cutting Protocol, (with Y. Manabe) the proceedings of IWIGP 2012, pp. 15-23, (2012).
    81. Efficient Concurrent Oblivious Transfer in Super-Polynomial-Simulation Security, (with S. Kiyoshima and Y. Manabe) the proceedings of IWSEC 2012, LNCS 7631, Springer-Verlag, pp. 216-232, (2012).
    82. Adaptively Attribute-Hiding (Hierarchical) Inner Product Encryption, (with K. Takashima) the proceedings of EUROCRYPT 2012, LNCS 7237, Springer-Verlag, pp. 591-608, (2012).
    83. Fully Secure Unbounded Inner-Product and Attribute-Based Encryption, (with K. Takashima) the proceedings of ASIACRYPT 2012, LNCS 7658, Springer-Verlag, pp. 349-366, (2012).
    84. Decentralized Attribute-Based Signatures, (with K. Takashima) the proceedings of PKC 2013, LNCS 7778, Springer-Verlag, pp. 125-142, (2013).
    85. Constant-Round Black-Box Construction of Composable Multi-Party Computation Protocol, (with S. Kiyoshima and Y. Manabe) the proceedings of TCC 2014, LNCS 8349, Springer-Verlag, pp. 343-367, (2014).
    86. Packing Messages and Optimizing Bootstrapping in GSW-FHE, (with R. Hiromasa and M. Abe) the proceedings of PKC 2015, LNCS 9020, Springer-Verlag, pp. 699-715, (2015).
    87. New Realizations of Somewhere Statistically Binding Hashing and Positional Accumulators. (with K. Pietrzak, B. Waters, D. Wichs) the proceedings of ASIACRYPT 2015, LNCS 9452, Springer-Verlag, pp 121-145 (2015).
    88. Efficient Functional Encryption for Inner-Product Values with Full-Hiding Security, (with J. Tomida and M. Abe), ISC 2016: 408-425 (2016).
    89. Signature Schemes with Randomized Verification (with C. Freitag, R. Goyal, S. Hohenberger, V. Koppulaand, E. Lee, J. Tran, B. Waters), ACNS 2017: 379-389 (2017).
    90. Full-Hiding (Unbounded) Multi-input Inner Product Functional Encryption from the k-Linear Assumption, (with P. Datta and J. Tomida), Public Key Cryptography 2018: 245-277 (2018).
    91. Adaptively Simulation-Secure Attribute-Hiding Predicate Encryption, (with P. Datta and K. Takashima), ASIACRYPT 2018: 640-672 (2018).
    92. Efficient Attribute-Based Signatures for Unbounded Arithmetic Branching Programs. (with P. Datta and K. Takashima), Public Key Cryptography 2019: 127-158 (2019).

    Academic Activities

    • Director of IACR (1998-2000)
    • Director of IEICE (2001-2003)
    • President of JSIAM (2007- )

    Visiting Professor

    • Visiting Assistant Professor of Univ. of Waterloo (Canada) (1989-1990)
    • Visiting Researcher of Bell Labs (USA) (1994-1995)
    • Guest Professor of Univ. of Tokyo (1999-2004)
    • Guest Professor of Kyoto Univ. (2001- )

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