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MECURY: Practical Cross-Chain Exchange via Trusted Hardware

Xiaoqing Wen, Quanbi Feng, Jianyu Niu, Yinqian Zhang, Chen Feng

TL;DR

MERCURY is presented, a practical cryptocurrency exchange that is trust-minimized and efficient without online-client requirements, and leverages Trusted Execution Environments (TEEs) to shield participants from malicious behaviors, eliminating the reliance on trusted participants and making on-chain verification efficient.

Abstract

The proliferation of blockchain-backed cryptocurrencies has sparked the need for cross-chain exchanges of diverse digital assets. Unfortunately, current exchanges suffer from high on-chain verification costs, weak threat models of central trusted parties, or synchronous requirements, making them impractical for currency trading applications. In this paper, we present MERCURY, a practical cryptocurrency exchange that is trust-minimized and efficient without online-client requirements. MERCURY leverages Trusted Execution Environments (TEEs) to shield participants from malicious behaviors, eliminating the reliance on trusted participants and making on-chain verification efficient. Despite the simple idea, building a practical TEE-assisted cross-chain exchange is challenging due to the security and unavailability issues of TEEs. MERCURY tackles the unavailability problem of TEEs by implementing an efficient challenge-response mechanism executed on smart contracts. Furthermore, MERCURY utilizes a lightweight transaction verification mechanism and adopts multiple optimizations to reduce on-chain costs. Comparative evaluations with XClaim, ZK-bridge, and Tesseract demonstrate that MERCURY significantly reduces on-chain costs by approximately 67.87%, 45.01%, and 47.70%, respectively.

MECURY: Practical Cross-Chain Exchange via Trusted Hardware

TL;DR

MERCURY is presented, a practical cryptocurrency exchange that is trust-minimized and efficient without online-client requirements, and leverages Trusted Execution Environments (TEEs) to shield participants from malicious behaviors, eliminating the reliance on trusted participants and making on-chain verification efficient.

Abstract

The proliferation of blockchain-backed cryptocurrencies has sparked the need for cross-chain exchanges of diverse digital assets. Unfortunately, current exchanges suffer from high on-chain verification costs, weak threat models of central trusted parties, or synchronous requirements, making them impractical for currency trading applications. In this paper, we present MERCURY, a practical cryptocurrency exchange that is trust-minimized and efficient without online-client requirements. MERCURY leverages Trusted Execution Environments (TEEs) to shield participants from malicious behaviors, eliminating the reliance on trusted participants and making on-chain verification efficient. Despite the simple idea, building a practical TEE-assisted cross-chain exchange is challenging due to the security and unavailability issues of TEEs. MERCURY tackles the unavailability problem of TEEs by implementing an efficient challenge-response mechanism executed on smart contracts. Furthermore, MERCURY utilizes a lightweight transaction verification mechanism and adopts multiple optimizations to reduce on-chain costs. Comparative evaluations with XClaim, ZK-bridge, and Tesseract demonstrate that MERCURY significantly reduces on-chain costs by approximately 67.87%, 45.01%, and 47.70%, respectively.
Paper Structure (23 sections, 4 theorems, 6 figures, 5 tables, 1 algorithm)

This paper contains 23 sections, 4 theorems, 6 figures, 5 tables, 1 algorithm.

Table of Contents

  1. Introduction
  2. Related Work
  3. Problem Statement, Model and Challenges
  4. Problem Statement
  5. System Model
  6. System Goals
  7. Challenges
  8. Building Blocks
  9. Mercury Design
  10. Overview
  11. System Initialization
  12. Cross-Chain Exchange
  13. Safe Redemption
  14. Transaction Verification inside TEE
  15. Vault Liquidity and Rewards
  16. ...and 8 more sections

Key Result

Lemma 1

If $tx_S$ is confirmed on the blockchain $\mathcal{S}$, $tx_T$ must be confirmed on the blockchain $\mathcal{T}$.

Figures (6)

  • Figure 1: An example of the cross-chain exchange for Alice to exchange 1 ETH for 2500 EOS.
  • Figure 2: An architectural overview of Mercury. A client transfers currencies from the chain $\mathcal{S}$ to the chain $\mathcal{T}$.
  • Figure 3: The design of the challenge-response protocol. Case I represents the normal-case operation, whereas case II represents the case of failures. The red cross represents the process that cannot be completed when operators fail.
  • Figure 4: On-chain cost of the Transfer function with varying numbers of operators and transactions.
  • Figure 5: Transaction processing performance with varying different numbers of operators and batch size in LAN and WAN.
  • ...and 1 more figures

Theorems & Definitions (8)

  • Lemma 1
  • proof
  • Lemma 2
  • proof
  • Theorem 1: Atomicity
  • proof
  • Theorem 2: No online-client Requirement
  • proof