The keyed duplex construction was introduced by Bertoni et al. (SAC 2011) and recently generalized to full-state absorption by Mennink et al. (ASIACRYPT 2015). We present a generalization of the full-state keyed duplex that natively supports multiple instances by design, and perform a security analysis that improves over that of Mennink et al. in terms of a more modular security analysis and a stronger and more adaptive security bound. Via the introduction of an additional parameter to the analysis, our bound demonstrates a significant security improvement in case of nonce-respecting adversaries. Furthermore, by supporting multiple instances by design, instead of adapting the security model to it, we manage to derive a security bound that is largely independent of the number of instances.

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STMicroelectronics, Belgium
International Conference on the Theory and Application of Cryptology and Information Security
Centrum Wiskunde & Informatica, Amsterdam (CWI), The Netherlands

Daemen, J, Mennink, B.J.M, & Van Assche, G. (2017). Full-state keyed duplex with built-in multi-user support. In Lecture Notes in Computer Science/Lecture Notes in Artificial Intelligence (pp. 606–637). doi:10.1007/978-3-319-70697-9_21