Multi-Input Functional Encryption for Inner Products
Romain Gay
Abstract:
We present new constructions of multi-input functional encryption (MIFE) schemes for the inner-product functionality that improve the state of the art solution of Abdalla et al. (Eurocrypt 2017). Namely, we put forward a novel methodology to convert single-input functional encryption for inner products into multi-input schemes for the same functionality. Our transformation is surprisingly simple, general, and efficient. In particular, it does not require pairings and it can be instantiated with all known single-input schemes. This leads to two main advances. First, we enlarge the set of assumptions this primitive can be based on, notably obtaining new MIFEs for inner products from plain DDH, LWE and Composite Residuosity. Second, we obtain the first MIFE schemes from standard assumptions where decryption works efficiently even for messages of super-polynomial size. Finally, we will present an extension where functional secret keys are generated in a decentralized way, without relying on a trusted third party.
Bio:
Romain Gay is a third year PhD candidate at ENS, Paris, under the supervision of Michel Abdalla and Hoeteck Wee. He works on Functional Encryption, and Attribute Based Encryption, which allows fine-grained access control of encrypted data.