In recent years, the blockchain has become a hot spot, it includes features such as decentralization, publicity, independence, security, and anonymity. Among them, anonymity means that the identity information of the block nodes on the blockchain can be transmitted in an anonymous manner and it doesn't need to be verified.
In the real social environment, it is difficult to easily determine whether the other is trustworthy when we meet with strangers, indeed, this situation is even more so on the block chain.
In the digital signature system, the user's public key must be trusted by a third party to issue a public key certificate. This certificate is used to prove the validity of the user's public key. However, it is difficult to find a reliable third party in such point-to-point network and may be contrary to the de-centered nature of the blockchain.
Take the online shopping as an example, internet fraud is very common in recent years, malevolent sellers acquire good and excellent evaluations via undesirable tricks and penny antes so as to trick buyers out of confidence.
During the shopping processes, people usually tend to choose certain
commodities recommended by friends and have confidence in strange sellers on the basis of evaluation from persons they trust. PGP [1] is featured with similar characters.
By making digital signatures via the users’ private keys against the public keys of others, the digital signatures and the public keys are consequently stored in the key ring and owners of the public keys shall subject to the owners’ trust degree. When the
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signature of one user, PGP will judge whether to believe in the public key offered by the strange email or not, according to the trust degrees set by users in the key ring.
Our research motivation is inspired by the PGP trust network web of trust and the concept of owner trust degrees, we expect to establish a decentralized trust evaluation mechanism that doesn't need a trusted third-party and it can reduce the probability of being fraud.
1.2 Research Purpose
In view of the smart contract based on the blockchain [2] technology, the block chain thereof is public, transparent and cannot be changed or counterfeited. Hence, the use of the smart contract for implement trust evaluation mechanism can ensure that the calculation of the relevant parameters cannot be changed or counterfeited, and all users can verify the relevant transaction information in the smart contract. Before trading with a target user, the user can figure out the credibility of the target user via the mechanism and take the result to serve as the reference base for transactions with the target user.
1.3 Research Contribution
In the current online shopping, we can use the seller's transaction evaluation to understand whether a seller is trustworthy or not. In particular, most of seller
transaction evaluations contain the product name, the product amount, the person who gave the evaluation, the evaluation comments, and the evaluation scores. However, when we look at the seller's transaction evaluation, the page usually shows a lot of evaluations. Because there are too many transaction evaluations, so buyers often only
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look at the seller's evaluation score as a basis for trading. In addition, the seller's evaluation score is recorded by many strangers, although these strangers may be just the normal person, fraud is very common in recent years. The malicious seller can get the good evaluation by the bad way, so we question the existing evaluation
mechanism.
In our mechanism, we use the path algorithm to calculate whether the user and the seller have the direct relationship or indirect relationship between them and show the interpersonal network relationship between them. Hence, users can know via which friends to build the relationship with the seller.
In addition, we also use this relevant information to calculate seller's trust degree, and to get a more valuable value of the trust score.
In this paper, we use the Ethereum to develop smart contracts and store all the transactions recorded in smart contracts. Hence, all users can verify the transaction information to ensure that the relevant parameters cannot be tamped. In this way to protect the rights and interests of users.
1.4 Organization
This paper has six chapters. In the first chapter, we describe the research
motivation, research purpose, research contribution, and the organization of paper. In the second chapter, we introduce the background and related works, among them, include the related documents of digital signature, digital certificate, PGP, elliptic curve cryptography, blockchain, smart contract, the small world problem, Dijkstra algorithm and trust calculation. In the third chapter, we introduce the reputation-based trust evaluation mechanism for decentralized environments proposed in this paper.
The fourth chapter is the implementation of reputation-based trust evaluation
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mechanism and shopping platform. In the fifth chapter, we compare our trust
evaluation mechanism with others trust evaluation mechanism. In the sixth chapter is the conclusion of this paper and the future work.