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 submillisecond
latencies.