## Cryptology ePrint Archive: Report 2009/284

Privacy-aware Attribute-based Encryption with User Accountability

Jin Li, Kui Ren, Bo Zhu, and Zhiguo Wan

Abstract: As a new public key primitive, attribute-based encryption (ABE) is envisioned to be a promising tool for implementing fine-grained access control. To further address the concern of user access privacy, privacy-aware ABE schemes are being developed to achieve hidden access policy recently. For the purpose of secure access control, there is, however, still one critical functionality missing in the existing ABE schemes, which is user accountability. Currently, no ABE scheme can completely prevent the problem of illegal key sharing among users. In this paper, we tackle this problem by firstly proposing the notion of accountable, anonymous, and ciphertext-policy ABE (CP-A$^3$BE, in short) and then giving out a concrete construction. We start by improving the state-of-the-art of anonymous CP-ABE to obtain shorter public parameters and ciphertext length. In the proposed CP-A$^3$BE construction, user accountability can be achieved in black-box model by embedding additional user-specific information into the attribute private key issued to that user, while still maintaining hidden access policy. The proposed constructions are provably secure.

Category / Keywords: public-key cryptography / Access control, Anonymity, Attribute-based, Ciphertext-policy, Accountability

Date: received 15 Jun 2009, last revised 6 Jul 2009

Contact author: jli25 at iit edu

Available format(s): Postscript (PS) | Compressed Postscript (PS.GZ) | PDF | BibTeX Citation

Short URL: ia.cr/2009/284

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