## Cryptology ePrint Archive: Report 2017/691

Universal Forgery and Key Recovery Attacks: Application to FKS, FKD and Keyak

Fanbao Liu and Fengmei Liu

Abstract: In this paper, we provide a security analysis of the Full-State Keyed Sponge (FKS), Full-State Keyed Duplex (FKD) and Keyak, one of the third-round CAESAR candidates, in the classic setting and the quantum model, respectively. In the classic setting, we present an universal forgery attack that can be implemented in $O(2^{c/2})$ queries, where $c$ is the capacity.

In the quantum model, by utilizing the Simon's algorithm, we propose an efficient universal forgery attack to FKS, FKD and Keyak with complexity of $O(c)$. Moreover, we also propose an efficient key recovery attack that can be implemented in $O(c)$. Such attacks show that FKS, FKD and Keyak is completely broken in the quantum model.

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Date: received 6 Jul 2017, last revised 18 Jul 2017

Contact author: lfbjantie at 163 com

Available format(s): PDF | BibTeX Citation

Short URL: ia.cr/2017/691

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