Functional Encryption with Bounded Collusions via Multi-party Computation

We construct a functional encryption scheme secure against an a-priori bounded polynomial number of collusions for the class of all polynomial-size circuits. Our constructions require only semantically secure public-key encryption schemes and pseudorandom generators computable by small-depth circuits (known to be implied by most concrete intractability assumptions). For certain special cases such as predicate encryption schemes with public index, the construction requires only semantically secure encryption schemes, which is clearly the minimal necessary assumption. Our constructions rely heavily on techniques from secure multi-party computation and randomized encodings. All our constructions are secure under a strong, adaptive simulationbased definition of functional encryption.

• Type: Journal
• Year: 2012
• Where: CRYPTO
• Authors: Sergey Gorbunov, Vinod Vaikuntanathan, Hoeteck Wee
• Keywords: CRYPTO 2012, Cryptology, Intractability Assumptions, Polynomial Number, Polynomial Size