Bootstrapping BGV ciphertexts with a wider choice of p and q. Issue 6 (1st November 2016)

• Record Type: Journal Article
• Authors: Orsini, Emmanuela; van de Pol, Joop; Smart, Nigel P.
• Is Part Of: IET information security. Volume 10:Issue 6(2016)
• Page Start: 348
• Page End: 357
• Publication Date: 2016-11-01
• Subjects: cryptography -- interpolation -- polynomials; plaintext modulus -- bootstrapping technique -- polynomial interpolation -- reduction mod p map -- full BGV packed ciphertext space; Computer security -- Periodicals; Cryptography -- Periodicals; Computer networks -- Security measures -- Periodicals; Database security -- Periodicals; 005.8
• DOI: 10.1049/iet-ifs.2015.0505
• Languages: English
• ISSNs: 1751-8709

Abstract

Abstract : The authors 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 the authors' method to be applied in a larger number of situations. The authors' basic bootstrapping technique makes use of a representation based on polynomials of the group Z q + over the finite field F p, 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, the authors utilise the ring/field switching technique of Gentry et al . (SCN 2012, JCS 2013).