Speaker:Dr. Meicheng Liu is an associate researcher at the Institute of Information Engineering of the Chinese Academy of Sciences. His research interests are in cryptographic algorithm design and analysis. He received his PhD from the Institute of Information Engineering, Chinese Academy of Sciences in 2013, and was a postdoctoral researcher at Nanyang Technological University in Singapore from 2015 to 2016. He has made a series of valuable academic achievements in cryptographic functions, sequence ciphers, SHA-3 security analysis, etc. and published many papers in well-known journals and conferences such as IEEE Trans. Inf. Theory and CRYPTO, EUROCRYPT, ASIACRYPT, FSE, etc. He has won the Dean's Award of Excellence from the Chinese Academy of Sciences, one hundred outstanding doctoral dissertations of the Chinese Academy of Sciences, and the Outstanding Youth Award of the Chinese Cryptographic Association.

Date:November 29, 2019

Time:14:00—17:30

Location:Room 320, Block D, Ganchang Building, Qingdao Campus

Abstract:

The report mainly introduces the research progress of security analysis of nonlinear feedback cryptosystems. It first briefly analyzes the research progress of the security analysis of nonlinear feedback cryptosystems in the past 10 years, and then introduces the works of nonlinear feedback cryptosystems on the algebraic number estimation, distinguisher and key recovery attacks, etc. The speaker will propose the concept of numerical mapping to establish an efficient algebraic evaluation model for nonlinear feedback cryptosystems, and provide a linear time-space complexity estimation algorithm for sequential cryptographic algorithms such as Trivium, etc., and then apply them to the security evaluation of algorithms such as Trivium and Grain. The report will also propose a new attack method named related cubic attacks, and explore how to convert weak key distinguisher with low threats into key recovery attacks with high threats, and then apply numerical mapping techniques to Trivium, etc. It helps to get the result of 835 rounds of Trivium's actual partial key recovery attack. The achievements were published in the stand conference of Crypto 2017 and Eurocrypt 2018.

Inviter:Prof. Meiqin Wang

Edited by:Jinsong L