Chosen-Ciphertext Secure Multi-Identity and Multi-Attribute Pure FHE

Tapas Pal; Ratna Dutta

Paper 2020/1382

Chosen-Ciphertext Secure Multi-Identity and Multi-Attribute Pure FHE

Tapas Pal and Ratna Dutta

Abstract

A multi-identity pure fully homomorphic encryption (MIFHE) enables a server to perform arbitrary computation on the ciphertexts that are encrypted under different identities. In case of multi-attribute pure FHE (MAFHE), the ciphertexts are associated with different attributes. Clear and McGoldrick (CANS 2014) gave the first chosen-plaintext attack secure MIFHE and MAFHE based on indistinguishability obfuscation. In this study, we focus on building MIFHE and MAFHE which are se- cure under type 1 of chosen-ciphertext attack (CCA1) security model. In particular, using witness pseudorandom functions (Zhandry, TCC 2016) and multi-key pure FHE or MFHE (Mukherjee and Wichs, EUROCRYPT 2016) we propose the following constructions: – CCA secure identity-based encryption (IBE) that enjoys an optimal size ciphertexts, which we extend to a CCA1 secure MIFHE scheme. – CCA secure attribute-based encryption (ABE) having an optimal size ciphertexts, which we transform into a CCA1 secure MAFHE scheme. By optimal size, we mean that the bit-length of a ciphertext is the bit-length of the message plus a security parameter multiplied with a constant. Known constructions of multi-identity(attribute) FHEs are either leveled, that is, support only bounded depth circuit evaluations or secure in a weaker CPA security model. With our new approach, we achieve both CCA1 security and evaluation on arbitrary depth circuits for multi-identity(attribute) FHE schemes.

Note: It is the extended version of the paper accepted in CANS 2020. It includes appendices that contain security analysis of ABE and MAFHE.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: Published elsewhere. Minor revision. CANS 2020 https://cans2020.at/accepted-papers/
Keywords: witness pseudorandom function identity-based encryption attribute- based encryption fully homomorphic encryption
Contact author(s): tapas pal @ iitkgp ac in
History: 2020-11-10: received
Short URL: https://ia.cr/2020/1382
License: CC BY

BibTeX

@misc{cryptoeprint:2020/1382,
      author = {Tapas Pal and Ratna Dutta},
      title = {Chosen-Ciphertext Secure Multi-Identity and Multi-Attribute Pure {FHE}},
      howpublished = {Cryptology {ePrint} Archive, Paper 2020/1382},
      year = {2020},
      url = {https://eprint.iacr.org/2020/1382}
}