PoTS: A Secure Proof of TEE-Stake for Permissionless Blockchains

Abstract

Proof of Stake (PoS) blockchain protocols emerged as a promising alternative to the largely energy-wasteful proof of work mechanisms currently in place. In contrast to computing power, however, “stake” is a virtual resource that can be replicated or reused, opening the door to attack vectors that have no counterpart in a PoW setting, and are much harder to defeat. We present PoTS (Proof of TEE-Stake), a novel PoS protocol that leverages properties of trusted execution environments (TEEs) to limit the attack surface of malicious validators, and employs techniques such as forward security to guarantee protection against posterior-corruption attacks. We show that PoTS is secure against nothing at stake, grinding, and long range attacks down to realistic hardware assumptions on TEE and well-established cryptographic assumptions, and retains reasonable security even in face of compromised TEEs. We evaluate the performance of our proposal by means of implementation. Our evaluation results demonstrate that PoTS offers an excellent trade-off between security and performance.