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Thesis Defence: Constant-Time Zero-Knowledge Based Blockchain Bridge
August 3, 2023 at 2:00 pm - 5:00 pm
This event was rescheduled and has a new date as indicated.
Fatemeh Bagheriesfandabadi, supervised by Dr. Chen Feng, will defend their thesis titled “Constant-Time Zero-Knowledge Based Blockchain Bridge” in partial fulfillment of the requirements for the degree of Master of Applied Science in Electrical Engineering.
An abstract for Fatemeh Bagheriesfandabadi’s thesis is included below.
Defences are open to all members of the campus community as well as the general public. Please email chen.feng@ubc.ca to receive the Zoom link for this defence.
ABSTRACT
In recent years, the significance of Blockchain bridges has grown substantially, becoming a highly sought-after technological advancement. However, their architectural reliance on third-party entities for information relay has made them susceptible targets for malicious attacks. Conversely, zero-knowledge proofs and arguments of knowledge have demonstrated promising potential in addressing various challenges within the realms of blockchains and cryptography.
The principal challenge in developing secure bridges lies in the inherent necessity to depend on third-party entities for information relay between disparate chains. This requirement arises from the absence of common entities across different blockchains that can facilitate seamless connection. Consequently, trust must be placed in a third party. Several approaches have been explored and implemented to ensure bridge security while acknowledging the inevitability of third-party trust. One solution involves distributing trust among a set of third parties, operating under the assumption of an honest majority. Alternatively, employing zero-knowledge proofs offers another set of solutions to enhance the security of relayed information.
Recently, the ZkBridge protocol was introduced as a novel bridge implementation that leverages zero-knowledge proofs, while still relying on a group of trusted third parties for relaying the information that is encrypted using zero-knowledge algorithms. In this thesis, a novel adversarial attack is devised to expose security vulnerabilities in the ZkBridge protocol. Reliance on the relaying entities presents an exploitable vulnerability that could potentially disrupt the entire system.
The most significant contribution of this thesis is the proposal of a new bridge protocol design that mitigates the need for trust in third-party entities by delegating the responsibility of zero-knowledge calculations to the user. Furthermore, by selecting a proper zero-knowledge algorithm, the proposed design maintains a constant time complexity. This design offers improved efficiency and reduced complexity compared to existing ZkBridge implementations, while also circumventing the security flaws associated with the ZkBridge protocol.
