Witness Encryption with (Weak) Unique Decryption and Message Indistinguishability: Constructions and Applications

Paper in proceeding, 2019

In this paper, we investigate WE scheme with the unique decryption and message indistinguishability, as well as its compelling applications. Our contributions are three-fold: (i) we first propose the notion of WE with MI and weak unique decryption, and give a construction based on public-coin differing-inputs obfuscation (diO), pseudorandom generator, and the Goldreich-Levin hard-core predicate; (ii) We show that our WE with MI and weak unique decryption can be used to construct a 4-round non-black-box honest-verifier zero-knowledge argument protocol; and (iii) We present a WE scheme with unique decryption and MI based on public-coin diO and weak auxiliary input multi-bit output point obfuscation (AIMPO). Moreover, we show that using our WE with unique decryption, we can get rid of the limitation of honest-verifier zero-knowledge property, thus yielding a 4-round non-black-box zero-knowledge argument.