Improved Fully Adaptive Decentralized MA-ABE for NC1 from MDDH

We improve the first and the only existing prime-order fully adaptively secure decentralized Multi-Authority Attribute-Based Encryption (MA-ABE) scheme for NC1 in Datta-Komargodski-Waters [Eurocrypt '23]. Compared with Datta-Komargodski-Waters, our decentralized MA-ABE scheme extra enjoys shorter parameters and meanwhile supports many-use of attribute. Shorter parameters is always the goal for Attribute-Based Encryption (ABE), and many-use of attribute is a native property of decentralized MA-ABE for NC1. Our scheme relies on the Matrix Decision Diffie-Hellman (MDDH) assumption and is in the random oracle model, as Datta-Komargodski-Waters.