Securely Trading Unverifiable Information without Trust

TL;DR

This paper introduces SMind, a trust-free protocol for secure, truthful, and fair trading of unverifiable information using peer prediction, secure multi-party computation, and smart contracts, eliminating the need for trusted intermediaries.

Contribution

The paper presents SMind, a novel trust-free protocol enabling secure and truthful information trading without a trusted center, leveraging advanced cryptographic and economic tools.

Findings

SMind ensures high-quality information is securely sold at fair prices.

The protocol prevents low-quality sellers from earning unfairly.

It guarantees that only the buyer learns the information after trade.

Abstract

In future, information may become one of the most important assets in economy. However, unlike common goods (e.g. clothing), information is troublesome in trading since the information commodities are \emph{vulnerable}, as they lose their values immediately after revelation, and possibly unverifiable, as they can be subjective. By authorizing a trusted center (e.g. Amazon) to help manage the information trade, traders are ``forced'' to give the trusted center the ability to become an information monopolist. To this end, we need a trust-free (i.e. without a trusted center and with only strategic traders) unverifiable information trade protocol such that it 1) motivates the sellers to provide high quality information, and the buyer to pay for the information with a fair price (truthful); 2) except the owner, the information is known only to its buyer if the trade is executed (secure). In an unverifiable information trade scenario (e.g. a medical company wants to buy experts' opinions on multiple difficult medical images with unknown pathological truth from several hospitals), we design a trust-free, truthful, and secure protocol, Smart Info-Dealer (SMind), for information trading, by borrowing three cutting-edge tools that include peer prediction, secure multi-party computation, and smart contract. With SMind, without a trusted center, a seller with high-quality information is able to sell her information securely at a fair price and those with low-quality information cannot earn extra money with poor information or steal information from other sellers. We believe SMind will help describe a free and secure information trade scenario in the future.