Paper 2015/827

Unbounded Hierarchical Identity-Based Encryption with Efficient Revocation

Geumsook Ryu, Kwangsu Lee, Seunghwan Park, and Dong Hoon Lee


Hierarchical identity-based encryption (HIBE) is an extension of identity-based encryption (IBE) where an identity of a user is organized as a hierarchical structure and a user can delegate the private key generation to another user. Providing a revocation mechanism for HIBE is highly necessary to keep a system securely. Revocable HIBE (RHIBE) is an HIBE scheme that can revoke a user's private key if his credential is expired or revealed. In this paper, we first propose an unbounded HIBE scheme where the maximum hierarchy depth is not limited and prove its selective security under a q-type assumption. Next, we propose an efficient unbounded RHIBE scheme by combining our unbounded HIBE scheme and a binary tree structure, and then we prove its selective security. By presenting the unbounded RHIBE scheme, we solve the open problem of Seo and Emura in CT-RSA 2015.

Available format(s)
Public-key cryptography
Publication info
Preprint. MINOR revision.
Hierarchical identity-based encryptionRevocationUnbounded hierarchy depthBilinear maps
Contact author(s)
madeby_r @ korea ac kr
guspin @ korea ac kr
2015-08-26: received
Short URL
Creative Commons Attribution


      author = {Geumsook Ryu and Kwangsu Lee and Seunghwan Park and Dong Hoon Lee},
      title = {Unbounded Hierarchical Identity-Based Encryption with Efficient Revocation},
      howpublished = {Cryptology ePrint Archive, Paper 2015/827},
      year = {2015},
      note = {\url{}},
      url = {}
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