A Broadcast Authenticated Encryption with Keyword Search in the Standard Model: Tightly Secure in Multi-User, Multi-Challenge Settings
Cryptography and Security
Summary
The authors focus on improving a type of encryption called BAEKS by considering more realistic scenarios where multiple users and multiple challenges exist simultaneously. They introduce a stronger security definition that covers these complex settings and show this also provides protection against forgery. They then create a new version of BAEKS using bilinear pairing groups and prove its security under standard cryptographic assumptions. Additionally, their construction can be simplified for a single user while remaining efficient. The authors also implemented and tested their scheme to show its practical performance.
Authors
Sayantan Mukherjee
Abstract
However, no known work considered the functionality requirement in its most realistic setting. We propose a new security definition of BAEKS in the multi-user (with adaptive corruptions) and multi-challenge (both in terms of ciphertext and trapdoor in an interleaved manner) settings. We also study the question of the unforgeability of BAEKS. In fact, our strong hiding requirement already implies a significant amount of unforgeability. We then propose a new BAEKS construction in the bilinear pairing groups. We prove this scheme achieves adaptive tight full-hiding security under (almost) standard MDDH assumptions. Restricting our BAEKS construction for a single receiver also gives an efficient and tightly secure PAEKS construction. We further run experiments to implement and evaluate our scheme.