Cryptology ePrint Archive: Report 2020/228

Optimal Broadcast Encryption from Pairings and LWE

Shweta Agrawal and Shota Yamada

Abstract: Boneh, Waters and Zhandry (CRYPTO 2014) used multilinear maps to provide a solution to the long-standing problem of public-key broadcast encryption (BE) where all parameters in the system are small. In this work, we improve their result by providing a solution that uses only bilinear maps and Learning With Errors (LWE). Our scheme is fully collusion-resistant against any number of colluders, and can be generalized to an identity-based broadcast system with short parameters. Thus, we reclaim the problem of optimal broadcast encryption from the land of “Obfustopia”.

Our main technical contribution is a ciphertext policy attribute based encryption (CP-ABE) scheme which achieves special efficiency properties – its ciphertext size, secret key size, and public key size are all independent of the size of the circuits supported by the scheme. We show that this special CP-ABE scheme implies BE with optimal parameters; but it may also be of independent interest. Our constructions rely on a novel interplay of bilinear maps and LWE, and are proven secure in the generic group model.

Category / Keywords: public-key cryptography / broadcast encryption, lattices, pairings

Original Publication (in the same form): IACR-EUROCRYPT-2020

Date: received 20 Feb 2020

Contact author: shweta a at gmail com,yamada-shota@aist go jp

Available format(s): PDF | BibTeX Citation

Version: 20200221:121031 (All versions of this report)

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