Cryptology ePrint Archive: Report 2014/051

An Equivalence-Preserving Transformation of Shift Registers

Elena Dubrova

Abstract: The Fibonacci-to-Galois transformation is useful for reducing the propagation delay of feedback shift register-based stream ciphers and hash functions. In this paper, we extend it to handle Galois-to-Galois case as well as feedforward connections. This makes possible transforming Trivium stream cipher and increasing its keystream data rate by 27\% without any penalty in area. The presented transformation might open new possibilities for cryptanalysis of Trivium, since it induces a class of stream ciphers which generate the same set of keystreams as Trivium, but have a different structure.

Category / Keywords: foundations / Feedback shift register, NLFSR, Fibonacci configuration, Galois configuration, stream cipher

Original Publication (with minor differences): Sequences and Their Applications - SETA'2014, Springer

Date: received 22 Jan 2014, last revised 18 Nov 2014

Contact author: dubrova at kth se

Available format(s): PDF | BibTeX Citation

Version: 20141118:094815 (All versions of this report)

Short URL: ia.cr/2014/051

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