Cryptology ePrint Archive: Report 2018/753

Decentralized Policy-Hiding Attribute-Based Encryption with Receiver Privacy

Yan Michalevsky and Marc Joye

Abstract: Attribute-based encryption (ABE) enables limiting access to encrypted data to users with certain attributes. Different aspects of ABE were studied, such as the multi-authority setting (MA-ABE), and policy hiding, meaning the access policy is unknown to unauthorized parties. However, no practical scheme so far provably provides both properties, which are often desirable in real-world applications: supporting decentralization, while hiding the access policy. We present the first practical decentralized ABE scheme with a proof of being policy-hiding. Our construction is based on a decentralized inner-product predicate encryption scheme, introduced in this paper, which hides the encryption policy. It results in an ABE scheme supporting conjunctions, disjunctions and threshold policies, that protects the access policy from parties that are not authorized to decrypt the content. Further, we address the issue of receiver privacy. By using our scheme in combination with vector commitments, we hide the overall set of attributes possessed by the receiver from individual authorities, only revealing the attribute that the authority is controlling. Finally, we propose randomizing-polynomial encodings that immunize the scheme in the presence of corrupt authorities.

Category / Keywords: public-key cryptography / attribute-based encryption

Original Publication (with major differences): European Symposium on Research in Computer Security

Date: received 15 Aug 2018, last revised 23 Oct 2019

Contact author: yanm2 at cs stanford edu

Available format(s): PDF | BibTeX Citation

Note: Updated the definition of the masking term mu_i to be a (k+1)-dimensional vector.

Version: 20191023:181104 (All versions of this report)

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