Paper 2006/362

Construction of a Hybrid (Hierarchical) Identity-Based Encryption Protocol Secure Against Adaptive Attacks

Palash Sarkar and Sanjit Chatterjee


The current work considers the problem of obtaining a hierarchical identity-based encryption (HIBE) protocol which is secure against adaptive key extraction and decryption queries. Such a protocol is obtained by modifying an earlier protocol by Chatterjee and Sarkar (which, in turn, is based on a protocol due to Waters) which is secure only against adaptive key extraction queries. The setting is quite general in the sense that random oracles are not used and security is based on the hardness of the decisional bilinear Diffie-Hellman (DBDH) problem. In this setting, the new construction provides the most efficient (H)IBE protocol known till date. The technique for answering decryption queries in the proof is based on earlier work by Boyen, Mei and Waters. Ciphertext validity testing is done indirectly through a symmetric authentication algorithm in a manner similar to the Kurosawa-Desmedt public key encryption protocol. Additionally, we perform symmetric encryption and authentication by a single authenticated encryption algorithm.

Note: Corrects a few errors in the previous version and discusses the relation of the construction to some work appearing after the last posting.

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Published elsewhere. An abridged version of this paper has appeared in the proceedings of ProvSec 2007
Hierarchical Identity based encryptionCCA-securitypairing
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palash @ isical ac in
2008-03-07: last of 4 revisions
2006-10-25: received
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      author = {Palash Sarkar and Sanjit Chatterjee},
      title = {Construction of a Hybrid (Hierarchical) Identity-Based Encryption Protocol Secure Against Adaptive Attacks},
      howpublished = {Cryptology ePrint Archive, Paper 2006/362},
      year = {2006},
      note = {\url{}},
      url = {}
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