A Survey on Additive Synchronous Stream Ciphers

PhD Qualifying Examination


Title: "A Survey on Additive Synchronous Stream Ciphers"

by

Miss Wenpei Si


Abstract:

Both stream ciphers and block ciphers can be used to provide data 
confidentiality service. Stream ciphers are preferred in many 
applications, since they can destroy statistical properties of natural 
languages to some extent. As an important type of stream ciphers, additive 
synchronous stream ciphers (ASSCs) are simple in structure and have many 
security properties. This survey investigates various ASSCs proposed in 
the past studies and their cryptographic aspects, in order to provide a 
basic knowledge of ASSCs as well as their state-of-the-art developments. 
The survey is also expected to inspire us with our future research. Some 
common attacks on ASSCs and associated design criteria are first examined. 
An overview of binary ASSCs based on natural sequence generators is 
subsequently performed. Then the ASSCs based on other generators are 
introduced and analyzed briefly. The survey results indicate that the 
Legendre cipher and the two-prime cipher of order 2 exhibit a slow 
performance and could only be used for offline applications, although 
these two stream ciphers are simple in structure and have relatively more 
proven security properties than other known ones. On the other hand, the 
security properties of ASSCs using the generators based on permutations, 
which are also simple in structure, have not attracted much attention so 
far. This type of ASSCs may have many interesting provable security 
properties and better performance, and it looks to be an interesting 
research topic.


Date:                   Wednesday, 16 February 2011

Time:                   2:00pm - 4:00pm

Venue:                  Room 4480
                        lifts 25/26

Committee Members:	Prof. Cunsheng Ding (Supervisor)
                        Dr. Ke Yi (Chairperson)
 			Dr. Lei Chen
 			Dr. Wai-Ho Mow (ECE)


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