Key-aggregate cryptosystem for scalable data sharing in cloud storage

Cheng Kang Chu, Sherman S.M. Chow, Wen-Guey Tzeng, Jianying Zhou, Robert H. Deng

Research output: Contribution to journalArticlepeer-review

168 Scopus citations


Data sharing is an important functionality in cloud storage. In this paper, we show how to securely, efficiently, and flexibly share data with others in cloud storage. We describe new public-key cryptosystems that produce constant-size ciphertexts such that efficient delegation of decryption rights for any set of ciphertexts are possible. The novelty is that one can aggregate any set of secret keys and make them as compact as a single key, but encompassing the power of all the keys being aggregated. In other words, the secret key holder can release a constant-size aggregate key for flexible choices of ciphertext set in cloud storage, but the other encrypted files outside the set remain confidential. This compact aggregate key can be conveniently sent to others or be stored in a smart card with very limited secure storage. We provide formal security analysis of our schemes in the standard model. We also describe other application of our schemes. In particular, our schemes give the first public-key patient-controlled encryption for flexible hierarchy, which was yet to be known.

Original languageEnglish
Article number6497048
Pages (from-to)468-477
Number of pages10
JournalIEEE Transactions on Parallel and Distributed Systems
Issue number2
StatePublished - 1 Feb 2014


  • Cloud storage
  • data sharing
  • key-aggregate encryption
  • patient-controlled encryption

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