Identity-based Hierarchical Key-insulated Encryption without Random Oracles

Yohei Watanabe; Junji Shikata

Paper 2015/1254

Identity-based Hierarchical Key-insulated Encryption without Random Oracles

Yohei Watanabe and Junji Shikata

Abstract

Key-insulated encryption is one of the effective solutions to a key exposure problem. At Asiacrypt'05, Hanaoka et al. proposed an identity-based hierarchical key-insulated encryption (hierarchical IKE) scheme. Although their scheme is secure in the random oracle model, it has a ``hierarchical key-updating structure,'' which is attractive functionality that enhances key exposure resistance. In this paper, we first propose the hierarchical IKE scheme without random oracles. Our hierarchical IKE scheme is secure under the symmetric external Diffie-Hellman (SXDH) assumption, which is known as the simple and static one. Particularly, in the non-hierarchical case, our construction is the first IKE scheme that achieves constant-size parameters including public parameters, secret keys, and ciphertexts. Furthermore, we also propose the first public-key-based key-insulated encryption (PK-KIE) in the hierarchical setting by using our technique.

Note: Modified constructions and security proofs due to bugs in the proofs.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: A minor revision of an IACR publication in PKC 2016
Keywords: Key-insulated encryption Hierarchical identity-based encryption Asymmetric pairing
Contact author(s): watanabe @ uec ac jp
History: 2017-01-05: last of 4 revisions; 2016-01-02: received; See all versions
Short URL: https://ia.cr/2015/1254
License: CC BY

BibTeX

@misc{cryptoeprint:2015/1254,
      author = {Yohei Watanabe and Junji Shikata},
      title = {Identity-based Hierarchical Key-insulated Encryption without Random Oracles},
      howpublished = {Cryptology {ePrint} Archive, Paper 2015/1254},
      year = {2015},
      url = {https://eprint.iacr.org/2015/1254}
}