Cryptology ePrint Archive: Report 2021/751

Grain-128AEADv2: Strengthening the Initialization Against Key Reconstruction

Martin Hell and Thomas Johansson and Alexander Maximov and Willi Meier and Hirotaka Yoshida

Abstract: Properties of the Grain-128AEAD key re-introduction, as part of the cipher initialization, are analyzed and discussed. We consider and analyze several possible alternatives for key re-introduction and identify weaknesses, or potential weaknesses, in them. Our results show that it seems favorable to separate the state initialization, the key re-introduction, and the $A/R$ register initialization into three separate phases. Based on this, we propose a new cipher initialization and update the cipher version to Grain-128AEADv2. It can be noted that previously reported and published analysis of the cipher remains valid also for this new version.

Category / Keywords: secret-key cryptography / Grain-128AEADv2, stream ciphers, NIST, differentials

Date: received 4 Jun 2021

Contact author: martin hell at eit lth se

Available format(s): PDF | BibTeX Citation

Version: 20210607:062911 (All versions of this report)

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