Teechan: Payment Channels Using Trusted Execution Environments (1612.07766v2)

Abstract: Blockchain protocols are inherently limited in transaction throughput and latency. Recent efforts to address performance and scale blockchains have focused on off-chain payment channels. While such channels can achieve low latency and high throughput, deploying them securely on top of the Bitcoin blockchain has been difficult, partly because building a secure implementation requires changes to the underlying protocol and the ecosystem. We present Teechan, a full-duplex payment channel framework that exploits trusted execution environments. Teechan can be deployed securely on the existing Bitcoin blockchain without having to modify the protocol. It: (i) achieves a higher transaction throughput and lower transaction latency than prior solutions; (ii) enables unlimited full-duplex payments as long as the balance does not exceed the channel's credit; (iii) requires only a single message to be sent per payment in any direction; and (iv) places at most two transactions on the blockchain under any execution scenario. We have built and deployed the Teechan framework using Intel SGX on the Bitcoin network. Our experiments show that, not counting network latencies, Teechan can achieve 2,480 transactions per second on a single channel, with sub-millisecond latencies.

• The paper introduces Teechan, a framework using TEEs to build secure, high-throughput off-chain payment channels for Bitcoin without requiring protocol modifications.
• By leveraging Intel SGX, Teechan secures private keys within trusted enclaves, enabling trustless, high-efficiency payments with only two total on-chain transactions.
• Performance tests show Teechan achieves 2480 transactions/second and sub-millisecond latency on a single channel, demonstrating its potential for scalable Bitcoin use.

Teechan: Payment Channels Using Trusted Execution Environments

The paper introduces Teechan, an innovative framework designed to utilize trusted execution environments (TEEs) for establishing secure full-duplex payment channels on the Bitcoin blockchain without necessitating any modifications to the underlying protocol. This solution addresses crucial limitations inherent in Bitcoin's transaction throughput and latency, which have been exacerbated by its rising popularity and utilization across various industries.

Overview

Bitcoin's transaction throughput is fundamentally constrained by its protocol, particularly the block size and interval, allowing a maximum of 7 transactions per second. Traditional proposals to circumvent these limitations, such as increasing block size or reducing interval, could only offer modest improvements, and more radical alterations faced adoption resistance due to necessary modifications to the protocol. In contrast, Teechan leverages off-chain point-to-point payment channels to enhance both throughput and latency, an approach previously inhibited by implementation security issues.

Teechan Framework

Teechan channels utilize Intel SGX to create secure, trustless environments between two parties with ongoing financial interactions. This framework uniquely supports continuous full-duplex payments, imposing minimal blockchain transactions—limited to two, under any scenario—and requiring a single message exchange per payment. Significantly, while other solutions often necessitate protocol alterations or monitoring for invalidated states, Teechan circumvents such requirements due to the robust security provided by TEEs. These enclaves ensure that private keys associated with the channel remain securely within the enclave, protecting against a broad class of attacks even in the presence of compromised software or facilities external to the CPU package.

Performance Evaluation

The experimental results demonstrate Teechan's capability to sustain a throughput of 2480 transactions per second on a single channel with sub-millisecond latency—numbers that rival, if not exceed, traditional credit card processing systems. This performance indicates Teechan's potential to facilitate high-volume transactional applications with consistent reliability, thereby significantly enhancing the Bitcoin network's practical utility.

Implications and Future Work

The introduction of Teechan represents a substantial technical advance. It notably enhances Bitcoin's scalability through off-chain transactions while maintaining security without demanding protocol changes. These findings are pertinent for researchers focusing on blockchain performance optimization and practical deployment strategies. While the current paper provides compelling evidence for Teechan's efficacy, future work could explore integrating Teechan in multi-hop or network-based channel architectures similar to the Lightning Network, potentially further broadening its applicability.

In summary, Teechan offers a notable contribution to the field of scalable blockchain technologies by effectively addressing security and performance challenges, paving the way for more substantial adoption and use-case scenarios in decentralized financial transactions.