Privatizing the Volume and Timing of Blockchain Transactions

With current state-of-the-art privacy-preserving blockchain solutions, users can submit transactions to a blockchain while maintaining full anonymity and not leaking the contents of the transaction through cryptographic techniques like zero-knowledge proofs and homomorphic encryption. However, the architecture of a blockchain consists of a decentralized network where every network participant maintains their own local copy of the blockchain and updates it upon every added transaction. As a result, the volume of blockchain transactions and the timestamp of each blockchain transaction for an application is publicly available. This is problematic for applications with time-sensitive or volume-sensitive outcomes because users may want this information to be privatized, such as not leaking the lateness of student examinations. However, this is not possible with existing blockchain research. In this thesis, we propose a blockchain system for multi-party applications that does not leak any useful information from the volume and timing metadata of the application's transactions, including maintaining the privacy of a time-sensitive or volume-sensitive outcome. We achieve this by adding sufficient noise using indistinguishable decoy transactions such that an adversary cannot deduce which transactions actually impacted the outcome of the application. This is facilitated in a manner where anyone can publicly verify the application's execution to be correct, fair, and honest. We demonstrate and evaluate our approach by implementing a Dutch auction that supports decoy bid transactions on a private Ethereum blockchain network.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Computer Science & Applications

Department dc:contributor.department

Computer Science and Applications

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2023

Author dc:creator

• Miller, Trevor John

Chair dc:contributor.committeechair

• Hoang, Thang

Committee members dc:contributor.committeemember

• Heath, Lenwood S.
• Gao, Peng

• blockchain
• privacy
• zero-knowledge
• timestamp

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

vt_gsexam:36549

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/114132