Paper 2019/045
Leakageresilient Identitybased Encryption in Bounded Retrieval Model with Nearly Optimal LeakageRatio
Ryo Nishimaki and Takashi Yamakawa
Abstract
We propose new constructions of leakageresilient publickey encryption (PKE) and identitybased encryption (IBE) schemes in the bounded retrieval model (BRM). In the BRM, adversaries are allowed to obtain at most $\ell$bit leakage from a secret key and we can increase $\ell$ only by increasing the size of secret keys without losing efficiency in any other performance measure. We call $\ell/\textsf{sk}$ leakageratio where $\textsf{sk}$ denotes a bitlength of a secret key. Several PKE/IBE schemes in the BRM are known. However, none of these constructions achieve a constant leakageratio under a standard assumption in the standard model. Our PKE/IBE schemes are the first schemes in the BRM that achieve leakageratio $1\epsilon$ for any constant $\epsilon>0$ under standard assumptions in the standard model. As previous works, we use identitybased hash proof systems (IBHPS) to construct IBE schemes in the BRM. It is known that a parameter for IBHPS called the universalityratio is translated into the leakageratio of the resulting IBE scheme in the BRM. We construct an IBHPS with universalityratio $1\epsilon$ for any constant $\epsilon>0$ based on any innerproduct predicate encryption (IPE) scheme with compact secret keys. Such IPE schemes exist under the $d$linear, subgroup decision, learning with errors, or computational bilinear DiffieHellman assumptions. As a result, we obtain IBE schemes in the BRM with leakageratio $1\epsilon$ under any of these assumptions. Our PKE schemes are immediately obtained from our IBE schemes.
Metadata
 Available format(s)
 Publication info
 Published by the IACR in PKC 2019
 Keywords
 LeakageresilienceBounded retrieval modelIdentitybased EncryptionIdentitybased hash proof system
 Contact author(s)

takashi yamakawa ga @ hco ntt co jp
ryo nishimaki zk @ hco ntt co jp  History
 20190131: revised
 20190125: received
 See all versions
 Short URL
 https://ia.cr/2019/045
 License

CC BY
BibTeX
@misc{cryptoeprint:2019/045, author = {Ryo Nishimaki and Takashi Yamakawa}, title = {Leakageresilient Identitybased Encryption in Bounded Retrieval Model with Nearly Optimal LeakageRatio}, howpublished = {Cryptology ePrint Archive, Paper 2019/045}, year = {2019}, note = {\url{https://eprint.iacr.org/2019/045}}, url = {https://eprint.iacr.org/2019/045} }