Crypt-DAC: Cryptographically Enforced Dynamic Access Control in the Cloud

Saiyu Qi, Yuanqing Zheng

Research output: Journal article publicationJournal articleAcademic researchpeer-review

18 Citations (Scopus)


Enabling cryptographically enforced access controls for data hosted in untrusted cloud is attractive for many users and organizations. However, designing efficient cryptographically enforced dynamic access control system in the cloud is still challenging. In this paper, we propose Crypt-DAC, a system that provides practical cryptographic enforcement of dynamic access control. Crypt-DAC revokes access permissions by delegating the cloud to update encrypted data. In Crypt-DAC, a file is encrypted by a symmetric key list which records a file key and a sequence of revocation keys. In each revocation, a dedicated administrator uploads a new revocation key to the cloud and requests it to encrypt the file with a new layer of encryption and update the encrypted key list accordingly. Crypt-DAC proposes three key techniques to constrain the size of key list and encryption layers. As a result, Crypt-DAC enforces dynamic access control that provides efficiency, as it does not require expensive decryption/re-encryption and uploading/re-uploading of large data at the administrator side, and security, as it immediately revokes access permissions. We use formalization framework and system implementation to demonstrate the security and efficiency of our construction.

Original languageEnglish
Article number8676350
Pages (from-to)765-779
Number of pages15
JournalIEEE Transactions on Dependable and Secure Computing
Issue number2
Publication statusPublished - 1 Mar 2021


  • Access control
  • cloud
  • revocation

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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