研究成果

学術論文誌

  • Identity-based Encryption with Hierarchical Key-Insulation in the Standard Model
    著者
    J. Shikata and Y. Watanabe
    雑誌名
    Designs, Codes and Cryptography
    87
    5
    ページ
    1005–1033
    出版社
    Springer
    発行年
    2019
    Abstract

    A key exposure problem is unavoidable since it seems human error can never be eliminated completely, and key-insulated encryption is one of the cryptographic solutions to the problem. At Asiacrypt’05, Hanaoka et al. introduced hierarchical key-insulation functionality, which is attractive functionality that enhances key exposure resistance, and proposed an identity-based hierarchical key-insulated encryption (hierarchical IKE) scheme in the random oracle model. In this paper, we first propose the hierarchical IKE scheme in the standard model (i.e., without random oracles). Our hierarchical IKE scheme is secure under the symmetric external Diffie–Hellman (SXDH) assumption, which is a static assumption. 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.