Generalized Feed Forward Shift Registers and Their Application to Secure Scan Design

Katsuya FUJIWARA  Hideo FUJIWARA  

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E96-D   No.5   pp.1125-1133
Publication Date: 2013/05/01
Online ISSN: 1745-1361
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Dependable Computing
Keyword: 
design-for-testability,  scan design,  shift register equivalents,  shift register quasi-equivalents,  generalized feed-forward shift registers,  security,  scan-based side-channel attack,  

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Summary: 
In this paper, we introduce generalized feed-forward shift registers (GF2SR) to apply them to secure and testable scan design. Previously, we introduced SR-equivalents and SR-quasi-equivalents which can be used in secure and testable scan design, and showed that inversion-inserted linear feed-forward shift registers (I2LF2SR) are useful circuits for the secure and testable scan design. GF2SR is an extension of I2LF2SR and the class is much wider than that of I2LF2SR. Since the cardinality of the class of GF2SR is much larger than that of I2LF2SR, the security level of scan design with GF2SR is much higher than that of I2LF2SR. We consider how to control/observe GF2SR to guarantee easy scan-in/out operations, i.e., state-justification and state-identification problems are considered. Both scan-in and scan-out operations can be overlapped in the same way as the conventional scan testing, and hence the test sequence for the proposed scan design is of the same length as the conventional scan design. A program called WAGSR (Web Application for Generalized feed-forward Shift Registers) is presented to solve those problems.