Paper 2019/045
Leakage-resilient Identity-based Encryption in Bounded Retrieval Model with Nearly Optimal Leakage-Ratio
Ryo Nishimaki and Takashi Yamakawa
Abstract
We propose new constructions of leakage-resilient public-key encryption (PKE) and identity-based 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 $\ell/|\textsf{sk}|$ leakage-ratio where $|\textsf{sk}|$ denotes a bit-length of a secret key. Several PKE/IBE schemes in the BRM are known. However, none of these constructions achieve a constant leakage-ratio under a standard assumption in the standard model. Our PKE/IBE schemes are the first schemes in the BRM that achieve leakage-ratio $1-\epsilon$ for any constant $\epsilon>0$ under standard assumptions in the standard model. As previous works, we use identity-based hash proof systems (IB-HPS) to construct IBE schemes in the BRM. It is known that a parameter for IB-HPS called the universality-ratio is translated into the leakage-ratio of the resulting IBE scheme in the BRM. We construct an IB-HPS with universality-ratio $1-\epsilon$ for any constant $\epsilon>0$ based on any inner-product predicate encryption (IPE) scheme with compact secret keys. Such IPE schemes exist under the $d$-linear, subgroup decision, learning with errors, or computational bilinear Diffie-Hellman assumptions. As a result, we obtain IBE schemes in the BRM with leakage-ratio $1-\epsilon$ 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
- Leakage-resilienceBounded retrieval modelIdentity-based EncryptionIdentity-based hash proof system
- Contact author(s)
-
takashi yamakawa ga @ hco ntt co jp
ryo nishimaki zk @ hco ntt co jp - History
- 2019-01-31: revised
- 2019-01-25: 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 = {Leakage-resilient Identity-based Encryption in Bounded Retrieval Model with Nearly Optimal Leakage-Ratio}, howpublished = {Cryptology {ePrint} Archive, Paper 2019/045}, year = {2019}, url = {https://eprint.iacr.org/2019/045} }