| 研究実績の概要 |
We followed the plan in the original application. Overall, we published several papers on international cryptographic conferences and journals, including the flag-ship cryptographic conference ASIACRYPT 2014, and famous security conference SCN 2014. We also attend several conferences and presented our paper. Our main research achievements can be categorized in the following two aspects.
1.We analyzed the security of public key encryption under the side-channel attacks and proposed a stronger security model, i.e., chosen-ciphertext security under post-challenge attacks. We then gave a generic construction to satisfy the security.
2.We analyzed the security of very basic cryptographic problems, called one-more cryptographic problems. We compared their hardness with existing well-known cryptographic problems, and presented black-box separations.
Through the above research, we explore factors affecting perfect implementations, including bad randomness usage and new attacks, find possible approaches to overcome them, and design more secure and efficient cryptographic protocols that are very useful in the design of advanced security systems and are easy to be implemented in practice.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
We did research just as the plans in the application. The main reasons are as follows. 1) We already analyzed the security of public key encryption under side channel attacks, and presented stronger security models. This exactly achieved the research purpose. This also laid a good foundation for the further research in this fiscal year. In the meantime, we did some joint research with several researchers from abroad, which will help to complete our research project. 2) In order to collect enough research information and trace the most updated research in our field, Zhang also attended several famous conferences including workshop for real-world crypto. Zhang also had classes in a summer-school to learn updated knowledge about cryptography.
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| 今後の研究の推進方策 |
The problems of imperfect randomness and side channel attacks also have great influence on real-world cryptographic protocols in existing security infrastructure. To achieve the above objective (b), I intend to analyze globally deployed cryptographic protocols such as SSL/TLS, the IEEE wireless communication standards (WPA, WPA2) and SSH, disk encryption (including BitLocker, TrueCrypt, and FileVault). I plan to provide a formal analysis of these cryptographic protocols in an appropriate security model, highlight potential weaknesses (especially with respect to weak randomness and side-channel attacks), develop improved protocol specifications supported by formal security arguments, and securely implement them in the real world. This research is an extension and application of the research in previous year. I intend to further apply the above research results to real-world applications, e.g., privacy-preserving database search, which is closely related to a project applied by my host researcher. I plan to design cryptographic protocols that on one hand achieve advanced functionalities for database search, and on the other hand, satisfy higher security guarantees even against imperfect randomness and side-channel attacks. In addition, I will analyze the main bottleneck that affects efficiency and find appropriate techniques to bypass the bottleneck.
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