AWARDEE OF TECHNOLOGICAL SCIENCES PRIZE

ZENG KENCHENG

Abstract

Prof. Zeng Kencheng, a cryptologist, was born in 1927 and graduated from Tsinghua University in 1950.  Started to work in the University of Science and Technology of China since 1958.  His main area of scientific interest is the design and analysis of private key cryptosystems.
In the middle of the 80s, he and the laboratory he belonged to collaborated with a certain institute of the Ministery of Post and Telegram in establishing a stream cipher system.  The cipher stream was made particularly hard to analyze by combining the data-stream with a pseudo-random sequence determined by the key.  By this, they won a rank Ⅱ National Science and Technology Progress Prize in 1988.
In the aspect of cryptanalysis, they succeeded to break the so-called “Stop and Go” system of Beth and Piper in 1989.  A special feature of this system is that it has high linearcomplexity and its breaking means that high linear complexity of a system is only a necessary condition for its security, but not sufficient.
In 1993, the laboratory won a Rank I National Science and Technology Progress Prize by a cycle of research papers on cryptological problems.  Among others, part of these papers were devoted to the discussion of ring-derived binary sequences.  It turns out that ring derivation is a good method for obtaining qualified pseudo-random sequences, and some of these sequences have already been put in practical use.
With regard to block ciphers and other problems of cryptology, things are somewhat different.  Here one needs algorithms which are not only highly secure, but also very fast.  For example, since Biham broke the famous DES in the early 90s, there appeared among the cryptologists a heat of designing new block cipher systems to replace it.  This has been simply a campaign of security and speed.  Zeng and his laboratory have also their own scheme.  But it is not fast enough, and the security aspect is insufficiently considered.  So one cannot say that they have succeeded to establish a block cipher system.