Sıfır bilgi ispatlarıyla blokzincir üzerinde merkeziyetsiz, mahremiyet koruyucu, kolektif ve çok amaçlı protokoller

In this thesis, we propose decentralized privacy-preserving cryptographic protocols on blockchain with zero-knowledge proofs for three essential problems. Firstly, the privacy-preserving payment problem refers to a specific group of transactions where a source address (i.e. sender) transfers a certain amount of tokens to a destination address (i.e. receiver) while still protecting the privacy of their balances and transaction details. We extend this problem to address multi-token payments as well. Secondly, the privacy-preserving aggregation problem refers to a multi-party computation where a group of blockchain addresses (i.e. aggregators) aggregate their data to reach global aggregation by protecting the privacy of their own data. We also extend this problem for prefix aggregation and to support for arbitrary numbers of aggregators. Thirdly, privacy-preserving multi-token bartering-based trading problem refers to a multi-party computation where a group of blockchain addresses (i.e. barterers) collectively exchanges a set of tokens for another set of tokens via proposing bids by protecting the privacy of their balances and bids. We extend this problem as multi-objective bartering using Bellman-Ford and pareto-domination. We propose the protocols of PTTS for the first problem, PVSS and PRFX for the second problem and PMTBS and zkMOBF for the third problem. We analyze the protocols in terms of their scalability (computational, communication and storage overheads) and their security (potential attacks and reduction proofs). We perform experimental study on Ethereum and Avalanche to measure gas consumption, proof generation/verification times and proof artifact size.