We show that such WE schemes can be generically constructed from smooth projective hash functions (SPHFs). In terms of concrete instantiations of SPHFs (and thus WE), we target languages of statements proven in the popular Groth-Sahai (GS) non-interactive witness-indistinguishable/zero-knowledge proof framework. This allows us to provide a novel way to encrypt. In particular, encryption is with respect to a GS proof and efficient decryption can only be done by the respective prover. The so obtained constructions are entirely practical. To illustrate our techniques, we apply them in context of privacy-preserving exchange of information.
Category / Keywords: public-key cryptography / witness encryption, smooth projective hash functions, Groth-Sahai proofs, encryption, privacy Original Publication (with minor differences): Designs, Codes and Cryptography Date: received 4 Nov 2015, last revised 9 Jan 2018 Contact author: david derler at iaik tugraz at Available format(s): PDF | BibTeX Citation Version: 20180109:145938 (All versions of this report) Short URL: ia.cr/2015/1073