Traceable and retrievable identity-based encryption

Man Ho Au, Qiong Huang, Joseph K. Liu, Willy Susilo, Duncan S. Wong, Guomin Yang

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

40 Citations (Scopus)


Very recently, the concept of Traceable Identity-based Encryption (IBE) scheme (or Accountable Authority Identity based Encryption scheme) was introduced in Crypto 2007. This concept enables some mechanisms to reduce the trust of a private key generator (PKG) in an IBE system. The aim of this paper is threefold. First, we discuss some subtleties in the first traceable IBE scheme in the Crypto 2007 paper. Second, we present an extension to this work by having the PKG's master secret key retrieved automatically if more than one user secret key are released. This way, the user can produce a concrete proof of misbehaviour of the PKG in the court. In contrast to previous approach, our idea gives strong incentive for the PKG to strengthen the security of the system since if someone can successfully release a user's secret key, it means that his security is also compromised. We present a formal model to capture our idea. Third, we present an efficient construction based on Gentry's IBE that satisfies our model and prove its security. Our construction is proven secure in the random oracle model. Nevertheless, we should emphasize that the aim of this paper is to introduce the new model to strengthen the IBE system.

Original languageEnglish
Title of host publicationApplied Cryptography and Network Security - 6th International Conference, ACNS 2008, Proceedings
Number of pages17
Publication statusPublished - 30 Jun 2008
Externally publishedYes
EventInternational Conference on Applied Cryptography and Network Security 2008 - New York, United States of America
Duration: 3 Jun 20086 Jun 2008
Conference number: 6th (Proceedings)

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume5037 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


ConferenceInternational Conference on Applied Cryptography and Network Security 2008
Abbreviated titleACNS 2008
Country/TerritoryUnited States of America
CityNew York
Internet address


  • Identity-based Encryption
  • PKG
  • Retrievability
  • Traceability
  • Trust

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