Publication Date
5-2024
Date of Final Oral Examination (Defense)
12-12-2023
Type of Culminating Activity
Dissertation
Degree Title
Doctor of Philosophy in Computing
Department Filter
Computer Science
Department
Computer Science
Supervisory Committee Chair
Gaby G. Dagher, Ph.D.
Supervisory Committee Member
Jyh-Haw Yeh, Ph.D.
Supervisory Committee Member
Min Long, Ph.D.
Abstract
Secure multiparty computation is a major field of research in modern cryptography. It allows for the creation of a protocol that maintains the privacy of the inputs and ensures that violation of the protocol results in no undue benefit to the violator or detriment to an honest party. These protocols can be used in many fields. In this dissertation, we explore the application of the mechanisms of secure party computation in the context of peer-to-peer lending, fair exchange with cryptocurrencies, consensus, and electronic voting. In all these areas, honesty of execution and fairness in the outcome should be assured or verifiable, especially if the other parties are not trusted. In this dissertation, we designed protocols to solve the above-mentioned problems, analyzed their efficiency and scalability, and proved their security.
First, we present a platform called ZeroLender for peer-to-peer lending in Bitcoin. Our protocol utilizes zero-knowledge proofs to achieve unlinkability between lenders and borrowers while securing payments in both directions against potential malicious behavior of the ZeroLender as well as the lenders and covert action by the borrowers. We prove by simulation that our protocol is privacy-preserving. Based on our experiments, we show that the runtime and transcript size of our protocol scale linearly with respect to the number of lenders and repayments.
Second, we propose a generic framework for atomic swap, called PolySwap, that enables fair exchange of assets between two {heterogeneous sets of blockchains}. Our construction preserves the anonymity of the swap by preventing transactions from being linked to each other or be distinguishable from other transactions on the blockchain and does not require any scripting capability in the blockchain, all without requiring a third party. We provide construction details of secret sharing signatures for ECDSA, Schnorr, and CryptoNote-style Ring signatures. Additionally, we provide an alternative contingency protocol, allowing parties to exchange to and from blockchains that do not support any form of time-locked escape transactions. We prove that PolySwap is secure against malicious adversaries, and is privacy-preserving against passive observers. We conducted experiments to demonstrate the efficiency of the protocol.
Third, we propose ACCORD, a consensus protocol consisting of three distinct components: an asynchronous quorum selection procedure to designate the creators of future blocks, a block creation protocol run by the quorum to prevent omissions in the presence of honest quorum members, and a decentralized arbitration protocol to ensure consensus by voting. We implemented the protocol and conducted experiments to demonstrate scalability, robustness, and fairness.
Finally, we introduce ORBIT, a cryptographic voting protocol that uses hidden credentials and mutable identities through ciphertext manipulation to prevent coercion. This enables voters to submit dummy ballots that are indistinguishable from genuine ones, thus enabling them to evade potential coercers, as well as preventing a fully compromised government from determining their voting preferences. ORBIT is blockchain-based, allowing government verifiers to process incoming ballots as they are submitted. We implemented ORBIT and performed experiments that illustrate its linear scaling in relation to three key variables: election size, the number of ring members within the anonymity set, and the number of ballots.
DOI
https://doi.org/10.18122/td.2214.boisestate
Recommended Citation
Holmes, Joshua, "Secure Multiparty Protocols on Blockchain with Fairness and Scalability" (2024). Boise State University Theses and Dissertations. 2214.
https://doi.org/10.18122/td.2214.boisestate
