Chronobank LaborX’s decentralised reputation system

  • LaborX’s decentralised reputation system relies on three roles — the Evaluator, Verifier and Provider — in addition to the worker and client.

    Online community-based business services are gaining increasing popularity due to the rapid development of computer networking technologies. However, such applications are still struggling to obtain wider acceptance by mainstream users due to a number of unresolved issues including trust, security and privacy.

    Trust, in such community services, mainly addresses whether a remote user — called a trustee — behaves as expected by an interested user (the trustor), through the activity of other users called recommenders. A ‘trust graph’ consists of a trustor, a trustee, recommenders, and the trust relationships among them.

    In LaborX, in addition to the commonly-used roles of Worker and Client, we have introduced another three roles — Evaluator, Verifier and Provider. Together, these will serve the purpose of recommenders.

    The Evaluator. The highest-ranked members of a community will be able to evaluate and confirm relevant skills of workers, building a chain of trust. In this way, clients can be sure that the assigned worker has all the required skills for completing the job. Workers will be required to have a high rating and sufficient activity points in order to become an Evaluator. Evaluators may verify and endorse skills of other workers, ensuring clients have a more accurate description of their potential workforce. Workers with skills endorsements will typically have a greater chance of being selected for any given job by the LaborX core. After performing a worker’s skill assessment, the Evaluator publishes a record on the blockchain. The Evaluator’s profile displays statistics of appraised workers, and the Evaluator’s reputation among LaborX users will depend on this.

    The Verifier. This is a worker who offers services to verify clients and workers in a particular region. The fundamental role of a Verifier is to check required documents for their respective areas, such as work permits, certificates, injury insurance or other types of relevant cover. These entities are essential for ensuring local laws are observed, enhancing security, and potentially minimising spam issues. Both parties (clients and workers) may choose either a single Verifier or multiple Verifiers to review their documents, based on their rating and popularity. Each worker has a public profile and private data. The public profile is readily available on the blockchain and is accessible to everyone. Private data is verified and electronically signed by a Verifier. It is only available to a client after they enter into a contract with the worker.

    The Provider. This is an entity who has created a job board. The nature of the blockchain means that participants are pseudonymous by default. This opens opportunities for spammers, marketing bots and other parties whose behaviour would be disruptive to LaborX. The decentralisation of the system means that there is no single authority who can ban these problematic groups. A proposed solution is to give participants the ability to create job boards, where the creator is also the moderator. Each board would have a rating given to it by other participants, and every participant who has the required minimum of activity points would be able to vote jobs up or down on the boards. The job board creator will be able to appoint other members as moderators. Board members with sufficient activity points to contribute to the process would be able to flag any suspicious entry for review and receive activity points for helpful reports. The boards would be filtered by tags and sorted by rating in the client application to remove/filter all junk boards easily. The job board creators also can enforce requirements for the clients and workers who want to use their board. For example, they could include a requirement that an applicant has obtained verification by one of the listed Verifiers; has a specified minimum rating; has performed a job in a defined field of work; will accept payment in a given cryptocurrency; is located in specified area, etc.

    We have also introduced two metrics:rating and activity points. The first describes how well a client or worker has performed their duties and is dictated by their partners. The second is a points system based on all LaborX activity.

    The better the individual’s rating (based on previous work), the higher the price they are able to demand for an hour of work. After a job is completed, both client and worker are asked to rate each other. The rating is in a range between 1 and 10, where 1 corresponds to a total disaster and 10 represents exceptional work.

    The rating system will be time and quantity sensitive: older ratings will contribute less to the current rating than recent ones (that is, more recent ratings are more heavily weighted). This means, for example, that a bad rating accrued a year ago by a worker can be fully offset by a series of recent good ratings, thus restoring the reputation of the worker.

    Activity points are used only in the LaborX DApp and have a crucial security role in limiting the amount of available functionality to newcomers. This limits threats such as spamming, posting advertisements with dubious links, or attackers attempting to overload the system with a large number of job postings.

    Every new user begins with a single activity point, which will automatically increase when performing various actions inside the app. An alternative way to gain activity points is by verifying one’s identity by various means, or by passing a skill assessment with an Evaluator. The activity points count will always be greater than or equal to 1.

    When our research on the reputation development algorithm was almost complete, community members pointed out us to the vulnerability to a sybil attack. In order to protect the system from sybil attack, we considered our TIME as reputation tokens which have a fixed supply. Reputation tokens will determine the probabilities to be drawn as an arbitrator or a jury. They would be valuable because arbitrators and jury members will be granted arbitration fees. Arbitrators and jury members behaving dishonestly will lose a proportion of their tokens, while those behaving honestly will win reputation tokens over time. Another way to resolve conflict situations between worker and client and provide an additional level of trust will be external arbitrary service integration, which is under active negotiation at the moment. This will be the first step in addressing a sybil attack.

    Another step in reputation algorithm improvement will be further development of the trust chain. The idea behind this is social rating points collection against all LaborX members, in relation to each other with recommendations promotions, based on relations weight approximation.

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