zk-Agreements: A Privacy-Preserving Way to Establish Deterministic Trust in Confidential Agreements

2025-10-22

AI Summary

Digital transactions require computable legal agreements that simultaneously support automated enforcement and clause confidentiality; however, natural-language contracts lack verifiability, while existing smart contracts expose sensitive terms due to on-chain transparency. This paper introduces zk-agreements—a novel executable contract framework that integrates zero-knowledge proofs (ZKPs) and secure two-party computation (2PC). ZKPs ensure privacy of contractual content and compliance conclusions, while 2PC enables collaborative verification over parties’ private inputs. A blockchain-based smart contract guarantees tamper-proof execution. Crucially, zk-agreements achieves deterministic, privacy-preserving compliance verification and automatic enforcement—without revealing original clauses or private inputs—thereby resolving the fundamental tension between transparency and confidentiality in blockchain systems. To our knowledge, this is the first infrastructure enabling verifiable, executable, and auditable legal agreements for high-privacy digital commerce.

Technology Category

• Multiagent Systems: Mechanism Design
• Natural Language Processing: Ethics — Bias, Fairness, Transparency & Privacy
• Machine Learning: Privacy

Application Category

• Security and Privacy: Cryptocurrency and smart contracts
• Economics, Online Markets and Human Computation: Economic aspects of blockchain and cryptocurrencies
• Responsible Web: Data and user privacy-enhancing technologies for the Web

Abstract

Digital transactions currently exceed trillions of dollars annually, yet traditional paper-based agreements remain a bottleneck for automation, enforceability, and dispute resolution. Natural language contracts introduce ambiguity, require manual processing, and lack computational verifiability, all of which hinder efficient digital commerce. Computable legal contracts, expressed in machine-readable formats, offer a potential solution by enabling automated execution and verification. Blockchain-based smart contracts further strengthen enforceability and accelerate dispute resolution; however, current implementations risk exposing sensitive agreement terms on public ledgers, raising serious privacy and competitive intelligence concerns that limit enterprise adoption. We introduce zk-agreements, a protocol designed to transition from paper-based trust to cryptographic trust while preserving confidentiality. Our design combines zero-knowledge proofs to protect private agreement terms, secure two-party computation to enable private compliance evaluation, and smart contracts to guarantee automated enforcement. Together, these components achieve both privacy preservation and computational enforceability, resolving the fundamental tension between transparency and confidentiality in blockchain-based agreements.

Problem

• Establish deterministic trust in confidential agreements privately
• Resolve tension between transparency and confidentiality in blockchain
• Enable automated enforcement while protecting sensitive agreement terms

Innovation

• Zero-knowledge proofs protect private agreement terms
• Secure two-party computation enables private compliance evaluation
• Smart contracts guarantee automated enforcement of agreements