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Research Duration

April, 2011 - March, 2014

Research Representative

Lihua Wang

Senior Researcher
Security Fundamentals Laboratory
Network Security Research Institute
National Institute of Information and Communications Technology

E-Mail : wlh(at)nict.go.jp

Motivation and Research Objectives

We investigated cryptographic technologies with long-term usability from two aspects - improvement in safety and/or applicability - on the following two issues:

Issue 1.    Post-Quantum Cryptography

The development of quantum computation casts serious threats to the security of most existing public-key cryptosystems. Cryptosystems that are secure against quantum attacks and can be run on traditional computers are desirable and known as post-quantum cryptosystems. Lattice-based cryptography and non-commutative cryptography are two promising alternatives that have the potential advantage of resisting quantum attacks. This is important because existing quantum analysis algorithms cannot efficiently attack corresponding assumptions, for example, the learning with error (LWE) assumption in Lattice-based cryptosystems and the conjugacy search problem (CSP) in some special non-commutative algebraic constructions.

We aim at designing post-quantum authentication and encryption systems, such as the signcryptosystem from Lattice-based cryptosystems and the CSP-based DHIES (Diffie-Hellman Integrated Encryption Scheme), and evaluating their security and efficiency.

Issue 2.    Practical Cryptography for Cloud Security

Public cloud storage service provides several benefits, including availability (being able to access data from anywhere) and reliability, at a relatively low cost. However, while a private cloud is managed and owned by the customer and located on the premises, a public cloud is owned and managed by an external cloud service provider and data are outside the customer’s control and could potentially be granted to untrusted parties. An adoptable cloud storage service should aim to achieve the best of both worlds by providing the security of a private cloud and the functionality and cost savings of a public cloud, therefore providing confidentiality, integrity, and encrypted data sharing, among other features.

We aim at constructing practical cryptosystems for cloud security in proxy cryptosystems with revocation, threshold encryption, a secret sharing scheme, and position authentication using homomorphic encryption, among others.

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