Title
Ring switching in BGV-Style homomorphic encryption
Abstract
The security of BGV-style homomorphic encryption schemes over polynomial rings relies on rings of very large dimension. This large dimension is needed because of the large modulus-to-noise ratio in the key-switching matrices that are used for the top few levels of the evaluated circuit. However, larger noise (and hence smaller modulus-to-noise ratio) is used in lower levels of the circuit, so from a security standpoint it is permissible to switch to lower-dimension rings, thus speeding up the homomorphic operations for the lower levels of the circuit. However, implementing such ring-switching is nontrivial, since these schemes rely on the ring algebraic structure for their homomorphic properties. A basic ring-switching operation was used by Brakerski, Gentry and Vaikuntanathan, over polynomial rings of the form $\mathbb{Z}[X]/(X^{2^n}+1)$, in the context of bootstrapping. In this work we generalize and extend this technique to work over any cyclotomic ring and show how it can be used not only for bootstrapping but also during the computation itself (in conjunction with the "packed ciphertext" techniques of Gentry, Halevi and Smart).
Year
DOI
Venue
2012
10.1007/978-3-642-32928-9_2
security and cryptography for networks
Keywords
DocType
Volume
cyclotomic ring,bgv-style homomorphic encryption scheme,basic ring-switching operation,lower level,large modulus-to-noise ratio,ring algebraic structure,bgv-style homomorphic encryption,large dimension,polynomial ring,homomorphic property,homomorphic operation
Conference
2012
Citations 
PageRank 
References 
17
1.25
13
Authors
4
Name
Order
Citations
PageRank
Craig Gentry19520380.03
Shai Halevi27203442.70
Chris Peikert33840154.98
Nigel P. Smart42808177.13