Academic lecture of College of Information Science and Technology / College of Cyber Security of Jinan University

Computing an LLL-reduced Basis of the Orthogonal Lattice

Lecture | November 11, 2018 | 9:00 a.m. | Room 124, Nahai Building

Speaker: Chen Jing-wei, associate researcher of Chongqing Institute of Green and Intelligence Technology, Chinese Academy of Sciences(CAS)

ABSTRACT
As a typical application, the Lenstra-Lenstra-Lovász lattice basis reduction algorithm (LLL) is used to compute a reduced basis of the orthogonal lattice for a given integer matrix, via reducing a special kind of lattice bases. With such bases in input, we propose a new technique, in this talk, for bounding from above the number of iterations required by the LLL algorithm. The main technical ingredient is a variant of the classical LLL potential, which could prove useful to understand the behavior of LLL. This talk is based on joint work with Damien Stehle and Gilles Villard.

ABOUT CHEN JING-WEI:
Chen Jing-wei was graduated from the Department of Mathematics of Southwest University with Bechlor’s degree in 2007. He visited Prof. Damien Stehle and Prof. Gilles Villard in LIP (CNRS-INRIA-ENS de Lyon) Lab as a China- Europe co-training doctoral student in 2012 and got his Doctor’s degree from Chengdu Institute of Computer Applications, CAS (the Institute was tatally transformed into Chengdu Information Technology of Chinese Academy of Sciences Co., Ltd. in 2001) in 2013. He is mainly engaged in Symbolic numeric hybrid computation and Lattice- based Cryptography research. He was elected to the West Light Foundation and Youth Innovation Promotion Association of CAS. He has published more than 20 papers in journals and conferences such as Mathematics of Computation, Science China Mathematics, Journal of Systems Science and Complexity, ISSAC, ISPEC, SNC and etc.

Ciphertext-Policy Attribute-Based Encryption with Equality Test and Outsourced Decryption

Lecture | November 11, 2018 | 09:00 a.m. | Nanhai Building Room 124
Speaker: Huang Qiong, South China Agricultural University

ABSTRACT:
In the cloud era people get used to store their data to the cloud server, and would use encryption technique to protect their sensitive data from leakage. However, encrypted data management is a challenging problem, for example, encrypted data classification. Besides, how to effectively control the access to the encrypted data is also an important problem. Ciphertext-policy attribute-based encryption with equality test (CP-ABEET) is an efficient solution to the aforementioned problems, which enjoys the advantage of attribute-based encryption, and in the meanwhile supports the test of whether two different ciphertexts contain the same message without the need of decryption. However, their scheme suffers from a high computation cost. In this work, we study how to outsource the heavy computation in CP-ABEET scheme to a third-party server. We introduce the notion of CP-ABEET supporting outsourced decryption (OCP-ABEET), which saves a lot of local computation loads of CP-ABEET. We propose a concrete construction of OCP-ABEET, and prove its security based on a reasonable number-theoretic assumption in the random oracle model. Compared with the existing CP-ABEET schemes, our scheme is more computationally efficient.

ABOUT HUANG QIONG:
Prof. Huang Qiong, a Ph.D supervisor, has been working at South China Agricultural University (SCAU) since 2011 after graduating from City University of Hong Kong with a doctoral degree in 2010. Huang’s research mainly focus on cryptography and information security. Awarded with Guangdong Nature and Science Fund for Distinguished Young Scholars, and selected as Outstanding Science Innovation Talent of Guangdong Special Support Program and Pearl River Science New Star of Guangzhou, She has led many projects supported by National Nature and Science Fund, and projects at provincial and ministerial level, and published over 80 papers across the years.
Working as vice president of College of Mathematics and Informatics of SCAU, she is also a member of Youth Working Committee of Chinese Association for Cryptologic Research, an executive committee member of China Computer Federation (Guangzhou Division), vice president of Guangzhou Computer Society, general secretary of Youth Working Committee, and deputy director of special committees of Guangdong Computer Society for Cloud Computing, Cyber Security, etc.
She has once been a member of program committee of over 40 international conferences and a peer reviewer of over 30 international academic journals. In 2016, she was entitled Talent Young Scholar of Institute of Higher Education supported by Fok Ying Tung Education Foundation of Ministry of Education of China and in 2017 she received New Star Award of ACM Guangzhou.

Related Cubic Attack and Numerical Mapping and Application

Lecture | November 11, 2018 | 9:00 a.m. | Meeting room 124 in Nanhai building,Jinan University

Speaker: Liu Meicheng, Associate Researcher Institute of Information engineering, CAS

ABSTRACT
This lecture mainly introduces the latest research results in the evaluation and safety analysis of the nonlinear feedback cryptosystem. The report will propose the concept of numerical mapping, establish an efficient evaluation model of algebraic number of nonlinear feedback cryptosystems, and give a method for estimating the linear spatiotemporal complexity of Trivium and other sequence cryptographic algorithms, and then apply it to the differentiated attack of Trivium and other algorithms. The report will also propose a new type of attack method-related cube attack, which converts the weakly threatened weak key distinguisher into a threat-hit key recovery attack, and then combines the numerical mapping technology with the cryptographic algorithm such as Trivium. 835 rounds of Trivium's actual partial key recovery attack. The main results of the report were published in the cryptography flagship conference Crypto 2017 and Eurocrypt 2018

ABOUT DENG LIU MEICHENG
Researcher Liu Meicheng’s research direction is the design and analysis of cryptographic algorithms. In 2013, he received his Ph.D. from the Chinese Academy of Sciences and was a postdoctoral researcher at Nanyang Technological University in Singapore from 2015 to 2016. He has obtained a series of valuable academic achievements in cryptographic functions, sequence ciphers and SHA-3 security analysis. He has published many papers in IEEE Trans. Inf. Theory and CRYPTO, EUROCRYPT, ASIACRYPT, FSE and other journals and conferences. He was awarded the Outstanding Award of the Chinese Academy of Sciences, and the Outstanding Youth Award of the Chinese Academy of Sciences.

Subsequences shared by de Bruijn sequences

Lecture | November 11, 2018 | 9:00a.m. | Room 124 in Nanhai builiding
Speaker: Jiang Yupeng, Institute of Information Engineering, Chinese Academy of Sciences

ABSTRACT
We consider sequences shared by two or more de Bruijn sequences. Such sequences are related to cross-join pairs. For a de Bruijn sequence, the de Bruijn sequences sharing a longest subsequence with it correspond to cross-join pairs with maximum diameter. Moreover, we find two de Bruijn sequences sharing a subsequence with length 2^n-2 if n>4.

ABOUT JIANG YUPENG
Dr.Jiang Yupeng is an associate research fellow of Institute of Information Engineering, Chinese Academy of Science. His main research field covers sequential cipher and its number theory. In 2013, Jiang recived his doctorate degree on applied mathematics from Academy of Mathematics and Systems Science, CAS and then became a postdoctoral research fellow in CAS Institute of Information Engineering. He has been working in the CAS Institute of Information Engineering since 2015. He has published more than 10 essays on SCI and is responsible for 3 projects including China postdoctor fund, the National Science Fund for Distinguished Young Scholars and the general fund.