Our construction combines three building blocks: a (computational) nearly linear secret sharing scheme with compact shares which we construct from LWE, an inner-product functional encryption scheme with special properties which is constructed from the bilinear Matrix Decision Diffie Hellman (MDDH) assumption, and a certain form of hyperplane obfuscation, which is constructed using the KOALA assumption. While similar to that of Agrawal and Yamada, our construction provides a new understanding of how to decompose the construction into simpler, modular building blocks with concrete and easy-to-understand security requirements for each one. We believe this sheds new light on the requirements for optimal broadcast encryption, which may lead to new constructions in the future.
Category / Keywords: public-key cryptography / Broadcast Encryption, learning with errors, bilinear maps, optimal parameter size, standard model Original Publication (with minor differences): IACR-TCC-2020 Date: received 26 Sep 2020, last revised 26 Sep 2020 Contact author: shota yamada enc at gmail com Available format(s): PDF | BibTeX Citation Version: 20200930:073916 (All versions of this report) Short URL: ia.cr/2020/1179