## Cryptology ePrint Archive: Report 2019/539

Iterated Truncated Differential for Internal Keyed Permutation of FlexAEAD

Mostafizar Rahman and Dhiman Saha and Goutam Paul

Abstract: In this draft, the internal keyed permutation of FlexAEAD has been analysed. In our analysis, we have first reported an iterated truncated differential for one round which holds with a probability of $2^{-7}$ and can penetrate same number of rounds as claimed by the designers with much less complexity which can be easily converted to a key-recovery attack. We have also reported a Super-Sbox construction in the internal permutation, which has been exploited using the Yoyo game to devise a 6-round deterministic distinguisher and a 7-round key recovery attack for 128-bit internal permutation. Similar attacks can be mounted for 64-bit and 256-bit internal permutation.

Category / Keywords: secret-key cryptography / FlexAEAD, Distinguisher, Iterated Differential , Yoyo , NIST lightweight cryptography project

Date: received 20 May 2019, last revised 21 May 2019

Contact author: mrahman454 at gmail com, dhiman@iitbhilai ac in

Available format(s): PDF | BibTeX Citation

Short URL: ia.cr/2019/539

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