Non-malleable randomness encoders and their applications

Kanukurthi, B and Obbattu, SLB and Sekar, S (2018) Non-malleable randomness encoders and their applications. In: 37th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2018, 29 April 2018 through 3 May 2018, Tel Aviv, pp. 589-617.

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Abstract

Non-malleable Codes (NMCs), introduced by Dziembowski, Peitrzak and Wichs (ITCS 2010), serve the purpose of preventing “related tampering” of encoded messages. The most popular tampering model considered is the 2-split-state model where a codeword consists of 2 states, each of which can be tampered independently. While NMCs in the 2-split state model provide the strongest security guarantee, despite much research in the area we only know how to build them with poor rate ($$\varOmega (\frac{1}{logn})$$, where n is the codeword length). However, in many applications of NMCs one only needs to be able to encode randomness i.e., security is not required to hold for arbitrary, adversarially chosen messages. For example, in applications of NMCs to tamper-resilient security, the messages that are encoded are typically randomly generated secret keys. To exploit this, in this work, we introduce the notion of “Non-malleable Randomness Encoders” (NMREs) as a relaxation of NMCs in the following sense: NMREs output a random message along with its corresponding non-malleable encoding. Our main result is the construction of a 2-split state, rate-$$\frac{1}{2}$$ NMRE. While NMREs are interesting in their own right and can be directly used in applications such as in the construction of tamper-resilient cryptographic primitives, we also show how to use them, in a black-box manner, to build a 3-split-state (standard) NMCs with rate$$\frac{1}{3}$$. This improves both the number of states, as well as the rate, of existing constant-rate NMCs.

Item Type:	Conference Paper
Publication:	Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Publisher:	Springer Verlag
Additional Information:	The copyright for this article belongs to the International Association for Cryptologic Research.
Keywords:	Cryptography; Encoding (symbols); Random processes; Technology transfer, Black boxes; Codeword length; Constant rate; Cryptographic primitives; Non-malleable; Non-malleable codes; Number of state; State modeling, Signal encoding
Department/Centre:	Division of Electrical Sciences > Computer Science & Automation Division of Physical & Mathematical Sciences > Mathematics
Date Deposited:	26 Aug 2022 06:29
Last Modified:	26 Aug 2022 06:29
URI:	https://eprints.iisc.ac.in/id/eprint/76082

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