Sark: Oblivious Integrity Without Global State

2025-12-23

AI Summary

This paper addresses the design challenge of Untrusted-State, Unforgeable, Stateful, and client-Oblivious (USO) asset systems—i.e., systems lacking global state, ensuring asset unforgeability, maintaining local state, and preserving client obliviousness. We propose Sark, a reference architecture comprising two core components: Sloop, a permissioned CFT blockchain, and Porters, a commitment-aggregation subsystem. Sark introduces a novel *stealthy state-update protocol* that decouples state maintenance from privacy preservation. We formalize the *Integrity Locus* concept within the CIA security model to rigorously characterize decentralization trade-offs and achieve, for the first time, *verifiable asset integrity without global state*. Experimental evaluation confirms feasibility: Sark guarantees both client obliviousness and integrity, while quantitatively exposing an inherent trade-off between Porters’ localized centrality and overall system availability.

Technology Category

• Data Mining & Knowledge Management: Representing, Reasoning, and Using Provenance, Trust
• Multiagent Systems: Mechanism Design
• Cognitive Modeling & Cognitive Systems: Agent Architectures

Application Category

• Security and Privacy: Blockchains and distributed ledgers
• Systems and Infrastructure for Web, Mobile and WoT: Decentralized Web and Fediverse systems
• Responsible Web: Social and technical mechanisms of refusal for web technologies and applications

Abstract

In this paper, we introduce Sark, a reference architecture implementing the Unforgeable, Stateful, and Oblivious (USO) asset system as described by Goodell, Toliver, and Nakib. We describe the motivation, design, and implementation of Sloop, a permissioned, crash fault-tolerant (CFT) blockchain that forms a subsystem of Sark, and the other core subsystems, Porters, which accumulate and roll-up commitments from Clients. We analyse the operation of the system using the 'CIA Triad': Confidentiality, Availability, and Integrity. We then introduce the concept of Integrity Locus and use it to address design trade-offs related to decentralization. Finally, we point to future work on Byzantine fault-tolerance (BFT), and mitigating the local centrality of Porters.

Problem

• Designs a USO asset system for unforgeable, stateful, oblivious integrity
• Implements a CFT blockchain and subsystems to manage commitments and confidentiality
• Addresses decentralization trade-offs using Integrity Locus and targets future BFT improvements

Innovation

• Architecture for unforgeable, stateful, oblivious assets
• Permissioned blockchain subsystem with crash fault tolerance
• Integrity Locus concept addressing decentralization trade-offs