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

Speaker:
Giorgia Azzurra Marson, NEC Laboratories Europe, Germany

Abstract:
The widespread adoption of cryptocurrencies, such as Bitcoin, highlights a severe limitation of the Proof of Work (PoW) consensus mechanism currently in place in most blockchain protocols: it is extremely energy wasteful. A promising alternative to PoW is Proof of Stake (PoS), which allows nodes to reach consensus in the network based on the stake they own, rather than the computational effort they invest. In contrast to computing power, however, “stake” is a virtual resource and can therefore be replicated or reused, opening the door to attack vectors that have no counterpart in a PoW setting, and are much harder to defeat.
In this talk I will present PoTS, “Proof of TEE-Stake”, a novel PoS protocol that leverages properties of Trusted Execution Environments (TEEs), such as Intel SGX, to limit the attack surface of malicious nodes, and employs the paradigm of forward security to also guarantee robustness to posterior-corruption attacks. I will discuss the security components of PoTS which enable protection against nothing at stake, grinding, and long range attacks down to realistic hardware assumptions on TEEs and well-established cryptographic assumptions.

Biography:
Giorgia Azzurra Marson received her Master of Science in Mathematics from Sapienza University of Rome, Italy, in 2011, and her PhD degree in Computer Science from TU Darmstadt, Germany, in 2016. At TU Darmstadt, she worked in the Cryptoplexity team led by Marc Fischlin, focusing mostly on modeling channel security from a cryptographic perspective.
After working as a postdoctoral researcher at Ruhr University Bochum, in the Crypto group led by Eike Kiltz, she joined the Security Group of NEC Laboratories Europe, where she is working currently, in 2017.
Her research interests include blockchain and distributed systems security, machine learning security, and cryptography.

Host: Prof. Patrick Eugster