We design, implement, and evaluate ZEXE, a ledger-based system where users can execute offline computations and subsequently produce transactions, attesting to the correctness of these computations, that satisfy two main properties. First, transactions hide all information about the offline computations. Second, transactions can be validated by anyone in constant time, regardless of the offline computation.
The core of ZEXE is a protocol for a new cryptographic primitive that we introduce, *decentralized private computation* (DPC). The security guarantees of DPC are concisely expressed via an ideal functionality, which our protocol provably achieves. In order to achieve an efficient implementation of our protocol, we leverage tools in the area of cryptographic proofs, including succinct zero knowledge proofs and recursive proof composition. Overall, transactions in ZEXE are 968 bytes *regardless of the offline computation*, and generating them takes less than 2 minutes plus a time that grows with the offline computation.
To facilitate real-world deployments, ZEXE also provides support for delegating the process of producing a transaction to an untrusted worker, and support for threshold transactions and blind transactions.
Category / Keywords: cryptographic protocols / decentralized computation; zero knowledge proofs; succinct arguments Date: received 8 Oct 2018 Contact author: alexch at berkeley edu Available format(s): PDF | BibTeX Citation Version: 20181014:133800 (All versions of this report) Short URL: ia.cr/2018/962