Cryptology ePrint Archive: Report 2020/412

Fixslicing: A New GIFT Representation

Alexandre Adomnicai and Zakaria Najm and Thomas Peyrin

Abstract: The GIFT family of lightweight block ciphers, published at CHES 2017, offers excellent hardware performance figures and has been used, in full or in part, in several candidates of the ongoing NIST lightweight cryptography competition. However, implementation of GIFT in software seems complex and not efficient due to the bit permutation composing its linear layer (a feature shared with PRESENT cipher). In this article, we exhibit a new non-trivial representation of the GIFT family of block ciphers over several rounds. This new representation, that we call fixslicing, allows extremely efficient software bitsliced implementations of GIFT, using only a few rotations, surprisingly placing GIFT as a very efficient candidate on micro-controllers. Our constant time implementations show that, on ARM Cortex-M3, 128-bit data can be ciphered with only about 800 cycles for GIFT-64 and about 1300 cycles for GIFT-128 (assuming pre-computed round keys). In particular, this is much faster than the impressive PRESENT implementation published at CHES 2017 that requires 2116 cycles in the same setting, or the current best AES constant time implementation reported that requires 1617 cycles. This work impacts GIFT, but also improves software implementations of all other cryptographic primitives directly based on it or strongly related to it.

Category / Keywords: implementation / GIFT, bitslicing, fixslicing, lightweight encryption

Original Publication (with minor differences): IACR-CHES-2020

Date: received 11 Apr 2020, last revised 8 Oct 2020

Contact author: alexandre adomnicai at ntu edu sg

Available format(s): PDF | BibTeX Citation

Note: Resize additional illustrations in Appendix B

Version: 20201008:091544 (All versions of this report)

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