Cryptology ePrint Archive: Report 2014/408
Bootstrapping BGV Ciphertexts with a Wider Choice of p and q
Emmanuela Orsini and Joop van de Pol and Nigel P. Smart
Abstract: We describe a method to bootstrap a packed BGV ciphertext which
does not depend (as much) on any special properties of the plaintext and
ciphertext moduli. Prior “efficient” methods such as that of Gentry et al.
(PKC 2012) required a ciphertext modulus q which was close to a power
of the plaintext modulus p. This enables our method to be applied in a
larger number of situations. Our basic bootstrapping technique makes
use of a representation based on polynomials of the group (Zq,+) over the
finite field Fp , followed by polynomial interpolation of the reduction
mod p map over the coefficients of the algebraic group.
This technique is then extended to the full BGV packed ciphertext
space, using a method whose depth depends only logarithmically on
the number of packed elements. This method may be of interest as
an alternative to the method of Alperin-Sheriff and Peikert (CRYPTO
2013). To aid efficiency we utilize the ring/field switching technique of
Gentry et al (SCN 2012, JCS 2013).
Category / Keywords: public-key cryptography / FHE, Bootstrapping
Original Publication (in the same form): IET Information Security
Date: received 2 Jun 2014, last revised 22 Feb 2016
Contact author: emmanuela orsini at bristol ac uk; nigel@cs bris ac uk; Joop VandePol@bristol ac uk
Available format(s): PDF | BibTeX Citation
Version: 20160222:110121 (All versions of this report)
Short URL: ia.cr/2014/408
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