scispace - formally typeset
Search or ask a question
Author

Shinichi Kawamura

Bio: Shinichi Kawamura is an academic researcher from Toshiba. The author has contributed to research in topics: Encryption & Key (cryptography). The author has an hindex of 26, co-authored 132 publications receiving 2002 citations. Previous affiliations of Shinichi Kawamura include National Institute of Advanced Industrial Science and Technology & Panasonic.


Papers
More filters
Book ChapterDOI
14 May 2000
TL;DR: The main contribution of this paper is to provide a new RNS base extension algorithm, which can be adapted to an existing standard radix interface of RSA cryptosystem.
Abstract: This paper proposes a fast parallel Montgomery multiplication algorithm based on Residue Number Systems (RNS). It is easy to construct a fast modular exponentiation by applying the algorithm repeatedly. To realize an efficient RNS Montgomery multiplication, the main contribution of this paper is to provide a new RNS base extension algorithm. Cox-Rower Architecture described in this paper is a hardware suitable for the RNS Montgomery multiplication. In this architecture, a base extension algorithm is executed in parallel by plural Rower units controlled by a Cox unit. Each Rower unit is a single-precision modular multiplier-and-accumulator, whereas Cox unit is typically a 7 bit adder. Although the main body of the algorithm processes numbers in an RNS form, efficient procedures to transform RNS to or from a radix representation are also provided. The exponentiation algorithm can, thus, be adapted to an existing standard radix interface of RSA cryptosystem.

176 citations

Book ChapterDOI
14 May 2001
TL;DR: An implementation of RSA cryptosystem using the RNS Montgomery multiplication is described, and an implementation method using the Chinese Remainder Theorem (CRT) is presented.
Abstract: We proposed a fast parallel algorithm of Montgomery multiplication based on Residue Number Systems (RNS). An implementation of RSA cryptosystem using the RNS Montgomery multiplication is described in this paper. We discuss how to choose the base size of RNS and the number of parallel processing units. An implementation method using the Chinese Remainder Theorem (CRT) is also presented. An LSI prototype adopting the proposed Cox-Rower Architecture achieves 1024- bit RSA transactions in 4.2 msec without CRT and 2.4 msec with CRT, when the operating frequency is 80 MHz and the total number of logic gates is 333 KG for 11 parallel processing units.

128 citations

Patent
29 Jun 2001
TL;DR: In this paper, an encryption scheme for block data is proposed, which consists of a first processing unit randomizing the block data in units of first portions obtained by dividing the block datasets, and a second processing unit diffusing the output from the first unit with respect to a second portion of the block dataset which is wider than the first portion.
Abstract: An encryption apparatus for block data, comprises a first processing unit randomizing the block data in units of first portions obtained by dividing the block data, and a second processing unit diffusing the block data output from the first processing unit with respect to a second portion of the block data which is wider than the first portion. The first processing unit comprises first nonlinear processing units nonlinearly transforming the block data in units of the first portions. The second processing unit comprises a first linear diffusion processing unit linearly diffusing the second portion of the block data. At least one of the first nonlinear processing units comprises second nonlinear processing units nonlinearly transforming the block data in units of the first portions, and a second linear diffusion processing unit linearly diffusing the second portion of the block data.

75 citations

Journal ArticleDOI
TL;DR: A record high bit rate prototype QKD system providing a total of 878 Gbit of secure key data over a 34 day period corresponding to a sustained key rate of around 300 kbit/s is reported.
Abstract: Securing information in communication networks is an important challenge in today's world. Quantum Key Distribution (QKD) can provide unique capabilities towards achieving this security, allowing intrusions to be detected and information leakage avoided. We report here a record high bit rate prototype QKD system providing a total of 878 Gbit of secure key data over a 34 day period corresponding to a sustained key rate of around 300 kbit/s. The system was deployed over a standard 45 km link of an installed metropolitan telecommunication fibre network in central Tokyo. The prototype QKD system is compact, robust and automatically stabilised, enabling key distribution during diverse weather conditions. The security analysis includes an efficient protocol, finite key size effects and decoy states, with a quantified key failure probability of e = 10⁻¹⁰.

75 citations

Journal ArticleDOI
TL;DR: Four efficient server-aided computation protocols for the modular exponentiation operation are proposed and it is shown that the most efficient one ever proposed to provide the highest security level is shown.
Abstract: Four efficient server-aided computation protocols for the modular exponentiation operation are proposed. The server-aided computation protocol is a two-party protocol between the client and the server. This protocol has two objectives. The first is to allow the client to borrow the computational power from the server to reduce the computation time. Note that the server is powerful, but restricted to polynomial time. The second objective is to keep the client's exponent secret from the server. Efficient and secure protocols which disclose no knowledge about the secret exponent are proposed. The protocols are based on efficient exponentiation algorithms. The computation time depends on the server's power and the speed of the channel between the client and the server. The normalized computation time is introduced and used to evaluate the protocols. It is shown that, for typical parameters, the protocol is the most efficient one ever proposed to provide the highest security level. >

66 citations


Cited by
More filters
Book ChapterDOI
15 Aug 1999
TL;DR: In this paper, the authors examine specific methods for analyzing power consumption measurements to find secret keys from tamper resistant devices. And they also discuss approaches for building cryptosystems that can operate securely in existing hardware that leaks information.
Abstract: Cryptosystem designers frequently assume that secrets will be manipulated in closed, reliable computing environments. Unfortunately, actual computers and microchips leak information about the operations they process. This paper examines specific methods for analyzing power consumption measurements to find secret keys from tamper resistant devices. We also discuss approaches for building cryptosystems that can operate securely in existing hardware that leaks information.

6,757 citations

Book ChapterDOI
04 Oct 2019
TL;DR: Permission to copy without fee all or part of this material is granted provided that the copies arc not made or distributed for direct commercial advantage.
Abstract: Usually, a proof of a theorem contains more knowledge than the mere fact that the theorem is true. For instance, to prove that a graph is Hamiltonian it suffices to exhibit a Hamiltonian tour in it; however, this seems to contain more knowledge than the single bit Hamiltonian/non-Hamiltonian.In this paper a computational complexity theory of the “knowledge” contained in a proof is developed. Zero-knowledge proofs are defined as those proofs that convey no additional knowledge other than the correctness of the proposition in question. Examples of zero-knowledge proof systems are given for the languages of quadratic residuosity and 'quadratic nonresiduosity. These are the first examples of zero-knowledge proofs for languages not known to be efficiently recognizable.

1,962 citations

Patent
01 Aug 2008
TL;DR: In this article, the oxide semiconductor film has at least a crystallized region in a channel region, which is defined as a region of interest (ROI) for a semiconductor device.
Abstract: An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

1,501 citations

Journal ArticleDOI
TL;DR: This review begins by reviewing protocols of quantum key distribution based on discrete variable systems, and considers aspects of device independence, satellite challenges, and high rate protocols based on continuous variable systems.
Abstract: Quantum cryptography is arguably the fastest growing area in quantum information science. Novel theoretical protocols are designed on a regular basis, security proofs are constantly improving, and experiments are gradually moving from proof-of-principle lab demonstrations to in-field implementations and technological prototypes. In this paper, we provide both a general introduction and a state-of-the-art description of the recent advances in the field, both theoretical and experimental. We start by reviewing protocols of quantum key distribution based on discrete variable systems. Next we consider aspects of device independence, satellite challenges, and protocols based on continuous-variable systems. We will then discuss the ultimate limits of point-to-point private communications and how quantum repeaters and networks may overcome these restrictions. Finally, we will discuss some aspects of quantum cryptography beyond standard quantum key distribution, including quantum random number generators and quantum digital signatures.

769 citations

Book
08 Aug 2003
TL;DR: This is the first comprehensive and integrated treatment of protocols for authentication and key establishment, which allows researchers and practitioners to quickly access a protocol for their needs and become aware of existing protocols which have been broken in the literature.
Abstract: Protocols for authentication and key establishment are the foundation for security of communications. The range and diversity of these protocols is immense, while the properties and vulnerabilities of different protocols can vary greatly.This is the first comprehensive and integrated treatment of these protocols. It allows researchers and practitioners to quickly access a protocol for their needs and become aware of existing protocols which have been broken in the literature.As well as a clear and uniform presentation of the protocols this book includes a description of all the main attack types and classifies most protocols in terms of their properties and resource requirements. It also includes tutorial material suitable for graduate students.

703 citations