iUC-Secure Distributed File Transfer from Standard Attribute-Based Encryption

Attribute-Based Encryption ( \(\textsf {ABE}\) ) stands as a cryptographic cornerstone, enabling access control to messages based on user attributes. The security definition of standard \(\textsf {ABE}\) is shown to be impossible in Universal Composability (UC) against an active adversary. To overcome this issue, existing formal UC security definitions of \(\textsf {ABE}\) rely on additional properties for \(\textsf {ABE}\) , necessary to prove security against an active adversary, excluding standard \(\textsf {ABE}\) by definition. In light of the composability feature offered by UC and the absence of ideal functionality tailored for standard \(\textsf {ABE}\) , we propose the two following contributions: (1) We construct the first ideal functionality \(\mathcal {F}_{\textsf{ABE}}\) for \(\textsf {ABE}\) which, under reasonable hypothesis against static corruption, can be realized using an \(\text {IND-CCA2}\) -secure \(\textsf {ABE}\) scheme; and (2) our \(\mathcal {F}_{\textsf{ABE}}\) leads us to propose a protocol solving a simple yet highly practical, world-scaled company-focused problem: efficient file transfer. The proposed construction provides data integrity, sender authentication, attribute-based file access, featured with constant data size transferred between users. This is achieved by relying on two efficient building blocks: \(\textsf {ABE}\) and signature, which are layered atop of the hash-based distributed storage system \(\textsf{IPFS}\) . Our protocol, strengthened by a formal security definition and analysis under the Universally Composable (UC) framework called iUC, is proved to realize our problem-oriented authenticated attribute-based file transfer ideal functionality. Finally, we implement our proposal with a proof-of-concept written in Rust, and show it is practical and efficient.