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SCIENCE CHINA Information Sciences, Volume 63 , Issue 9 : 192101(2020) https://doi.org/10.1007/s11432-018-9788-1

Rényi divergence on learning with errors

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  • ReceivedAug 7, 2018
  • AcceptedFeb 14, 2019
  • PublishedAug 10, 2020

Abstract

Many lattice-based schemes are built from the hardness of the learning with errors problem, which naturally comes in two flavors: the decision LWE and search LWE. In this paper, we investigate the decision LWE and search LWE by Rényi divergence respectively and obtain the following results: For decision LWE, we apply RD on LWE variants with different error distributions (i.e., center binomial distribution and uniform distribution, which are frequently used in the NIST PQC submissions) and prove the pseudorandomness in theory. As a by-product, we extend the so-called public sampleability property and present an adaptively public sampling property to the application of Rényi divergence on more decision problems. As for search LWE, we improve the classical reduction proof from GapSVP to LWE. Besides, as an independent interest, we also explore the intrinsic relation between the decision problem and search problem.


Acknowledgment

This work was supported in part by National Natural Science Foundation of China (Nos. 61772520, 61632020, 61472416, 61802392), Key Research Project of Zhejiang Province (Grant No. 2017C01062), and National Key Research and Development Program of China (Grant No. 2017yfb0802200).


Supplement

Appendixes A–C.


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  • Table 1  

    Table 1List of NIST submissions based on LWE with different error distributions

    Scheme Functionality Hard problem Error distribution
    Kyber [10] KEM/PKE MLWE Center binomial distribution
    NewHope [11] KEM/PKE RLWE Center binomial distribution
    LAC [12] KEM/PKE RLWE Center binomial distribution
    LIMA [13]KEM/PKE RLWE Center binomial distribution
    KINDI [14] KEM/PKE MLWE Uniform distribution
    Dilithium [15] Signature MLWE Uniform distribution

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