Teechain: A Secure Payment Network with Asynchronous Blockchain Access

TL;DR

Teechain introduces an asynchronous layer-two payment network utilizing trusted execution environments and committee chains to enable high-throughput, secure off-chain transactions without requiring immediate blockchain access.

Contribution

It is the first layer-two payment network to execute off-chain transactions asynchronously using TEEs and committee chains, significantly improving throughput and security.

Findings

Achieves at least 33x higher transaction throughput than Lightning.

Handles over 1 million Bitcoin transactions per second with 30 machines.

Ensures secure off-chain transactions without immediate blockchain interaction.

Abstract

Blockchains such as Bitcoin and Ethereum execute payment transactions securely, but their performance is limited by the need for global consensus. Payment networks overcome this limitation through off-chain transactions. Instead of writing to the blockchain for each transaction, they only settle the final payment balances with the underlying blockchain. When executing off-chain transactions in current payment networks, parties must access the blockchain within bounded time to detect misbehaving parties that deviate from the protocol. This opens a window for attacks in which a malicious party can steal funds by deliberately delaying other parties' blockchain access and prevents parties from using payment networks when disconnected from the blockchain. We present Teechain, the first layer-two payment network that executes off-chain transactions asynchronously with respect to the underlying blockchain. To prevent parties from misbehaving, Teechain uses treasuries, protected by hardware trusted execution environments (TEEs), to establish off-chain payment channels between parties. Treasuries maintain collateral funds and can exchange transactions efficiently and securely, without interacting with the underlying blockchain. To mitigate against treasury failures and to avoid having to trust all TEEs, Teechain replicates the state of treasuries using committee chains, a new variant of chain replication with threshold secret sharing. Teechain achieves at least a 33x higher transaction throughput than the state-of-the-art Lightning payment network. A 30-machine Teechain deployment can handle over 1 million Bitcoin transactions per second.