Privacy Amplification from Non-malleable Codes

Chattopadhyay, E and Kanukurthi, B and Obbattu, SLB and Sekar, S (2019) Privacy Amplification from Non-malleable Codes. In: 20th International Conference on Cryptology in India, INDOCRYPT 2019, 15- 18 December 2019, Hyderabad, pp. 318-337.

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Abstract

Non-malleable Codes give us the following property: their codewords cannot be tampered into codewords of related messages. Privacy Amplification allows parties to convert their weak shared secret into a fully hidden, uniformly distributed secret key, while communicating on a fully tamperable public channel. In this work, we show how to construct a constant round privacy amplification protocol from any augmented split-state non-malleable code. Existentially, this gives us another primitive (in addition to optimal non-malleable extractors) whose optimal construction would solve the long-standing open problem of building constant round privacy amplification with optimal entropy loss and min-entropy requirement. Instantiating our code with the current best known NMC gives us an 8-round privacy amplification protocol with entropy loss (Formula Presented) and min-entropy requirement (Formula Presented), where (Formula Presented) is the security parameter and n is the length of the shared weak secret. In fact, for our result, even the weaker primitive of Non-malleable Randomness Encoders suffice. We view our result as an exciting connection between two of the most fascinating and well-studied information theoretic primitives, non-malleable codes and privacy amplification.

Item Type:	Conference Paper
Publication:	Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Publisher:	Springer
Additional Information:	The copyright for this article belongs to Springer.
Keywords:	Cryptography; Entropy, Non-malleable; Non-malleable codes; Non-malleable extractors; Optimal construction; Optimal entropy; Privacy amplification; Security parameters; Shared secrets, Codes (symbols)
Department/Centre:	Division of Electrical Sciences > Computer Science & Automation Division of Physical & Mathematical Sciences > Mathematics
Date Deposited:	05 Dec 2022 05:56
Last Modified:	05 Dec 2022 05:56
URI:	https://eprints.iisc.ac.in/id/eprint/78208

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