Simple and Efficient FE for Quadratic Functions

Junqing Gong; Haifeng Qian

Paper 2020/1026

Simple and Efficient FE for Quadratic Functions

Junqing Gong and Haifeng Qian

Abstract

This paper presents the first functional encryption schemes for quadratic functions (or degree-2 polynomials) achieving simulation-based security in the semi-adaptive model with constant-size secret key. The unique prior construction with the same security guarantee by Gay [PKC 20] has secret keys of size linear in the message size. They also enjoy shorter ciphertexts: - our first scheme is based on bilateral DLIN (decisional linear) assumption as Gay's scheme and the ciphertext is 15% shorter; - our second scheme based on SXDH assumption and bilateral DLIN assumption is more efficient; it has 67% shorter ciphertext than previous SXDH-based scheme with selective indistinguishability security by Baltico et al. [CRYPTO 17]; the efficiency is comparable to their second scheme in the generic group model. Technically, we roughly combine Wee's ``secret-key-to-public-key'' compiler [TCC 17] with Gay's paradigm [PKC 20]. We avoid (partial) function-hiding inner-product functional encryption used in Gay's work and make our schemes conceptually simpler.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: Preprint. MINOR revision.
Contact author(s): jqgong @ sei ecnu edu cn
hfqian @ cs ecnu edu cn
History: 2020-08-27: received
Short URL: https://ia.cr/2020/1026
License: CC BY

BibTeX

@misc{cryptoeprint:2020/1026,
      author = {Junqing Gong and Haifeng Qian},
      title = {Simple and Efficient {FE} for Quadratic Functions},
      howpublished = {Cryptology {ePrint} Archive, Paper 2020/1026},
      year = {2020},
      url = {https://eprint.iacr.org/2020/1026}
}