RouTEE: Secure, Scalable, and Efficient Off-Chain Payments using Trusted Execution Environments

We propose a trusTEE-chain, a highly scalable payment system on a centralized host with trusted execution environments (TEEs) that can provide confidentiality and integrity. Our implementation of trusTEE-chain called RouTEE is an open-sourced TEE application which can provide a unified solution for the existing issues of payment systems. That is, although RouTEE is run by a host, its data including payment details can be concealed from the host. Also, RouTEE does not require its own collateral, but receives deposits from users and makes payments. Users do not have to verify the whole blockchain but only the block headers asynchronously, and they can go indefinitely offline without worrying about financial losses. Finally, RouTEE is highly scalable since its payment throughput is limited only by the TEE performance. Although TEEs can simplify the solution, TEEs alone are not enough because the host can possibly misbehave by feeding fake blocks to RouTEE or aborting its operation. By introducing a novel protocol and incentive model, RouTEE makes a rational host behave honestly. We also propose solutions for fault failures, compromised TEEs, and irrational hosts. RouTEE works for any UTXO-based blockchain and requires only the digital signatures, thus highly portable. Our implementation of RouTEE using Intel SGX on Bitcoin shows that RouTEE achieves a high throughput even with frequent data backups, for more than 150K users.