Abstract: The blockchain-based system for selecting a winner from among weighted candidates comprises: a server comprising secret voting smart contract comprising a ballot, and a plurality of candidates each having a particular weighted value; and a digital wallet having a digital identification and capable of communicating with the server. The secret voting smart contract is coded so as to be suitable for publishing and executing in a blockchain network, and a voter in possession of a digital wallet can, using the digital wallet, access a secret voting smart contract on the server to browse a plurality of candidates and vote by casting a ballot. The weighted value assigned to each candidate is determined on the basis of the level of completion of a task, and of the degree of participation and contribution thereto, the task being of a set type provided by the server.

Abstract: The apparatus for managing cyptocurrency rewarded for a response selected via lottery comprises: memory for storing commands; and a processor for executing actions in accordance with the commands. The actions executed in accordance with the commands comprise: transmitting, to a server, responses to a questionnaire associated with an advertisement after same transmitted to a client device is viewed; selecting one or more responses from among the responses transmitted from users; informing the client device that transmitted the selected response of the selection which includes a reward; receiving, from the client device that received the selection notification, information concerning receiving cryptocurrency; and paying cryptocurrency, which is legal tender, corresponding to the reward.