New methods for the implementation of statistical cipher feedback mode

Zhang, Liang (2008) New methods for the implementation of statistical cipher feedback mode. Masters thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (8MB)

Abstract

In this thesis, we investigate a recently proposed mode of operation for block ciphers, referred to as statistical cipher feedback (SCFB) mode. SCFB mode is designed for high speed stream-oriented transmission where it is necessary to recover from any number of bit slips or insertions in the communication channel, that is, SCFB has the capability of self-synchronization. SCFB mode is a hybrid of CFB mode and OFB mode, and hence, it has a higher throughput than CFB mode and can obtain self-synchronization while OFB mode cannot. As a result, SCFB mode can be applied physical layer security for applications such as SONET/SDH. -- In this thesis, SCFB mode using both serial transfer and parallel transfer is implemented in hardware. Additionally, we have implemented pipelined SCFB mode based on parallel transfer in hardware as well. The hardware implementation of these SCFB structures is thoroughly investigated. Throughout this research, VHDL and ModelSim SE 6.0 are used in the process of hardware design and verification. Further these SCFB modes which have been implemented are synthesized by using Synopsys tool (version 2002 and 2004) targeting to ASICs! based on 0.18 micron CMOS technology based on the TSMC (Taiwan Semiconductor Manufacturing Company) process supported by Canadian Microelectronics Corporation (CMC). -- As an outcome of our result, we have created a new modified version of SCFB mode, which we refer to as pipelined SCFB mode. Pipelined SCFB mode applies a block cipher, which has pipelined architecture, and Counter(CTR) mode instead of OFB mode which is used in conventional SCFB mode. -- Based on the synthesis results, the throughput of the SCFB using serial transfer and parallel transfer (block transfer size equal to 4 bits) can reach 100 Mbps and 222 Mbps, respectively. The total number of gates of these two SCFB systems are 41600 and 43697, respectively. For the pipelined SCFB mode, the throughput and area complexity are 333 Mbps and 189963 gates. -- The performance analysis of pipelined SCFB mode is also provided with respect to characteristics such as synchronization recovery delay (SRD) and error propagation factor (EPF). Moreover, the analysis of system queues such as the number of bits in the plaintext queue, the queue size requirements and probability of queue overflow is also provided. -- Among these different implementations, the pipelined SCFB mode based on parallel transfer mode can obtain the highest throughput and the SCFB mode using serial transfer mode has the lowest area complexity. Hence, the pipelined SCFB mode using parallel transfer is more suitable for high speed physical layer security.

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