Photo credit: Patricia Kuharic

Beyond Smarts: Toward Correct, Private, Data-Rich Smart Contracts


Smart contracts are applications that run on and inherit the special properties of blockchains. These properties alone, though, do not make smart contracts broadly useful. Persistence prevents tampering, but makes errors irreversible. Transparency supports behavioral assurances, but at the cost of confidentiality.

Happily, combining blockchains with complementary technologies can more closely approximate what users ultimately want from smart contracts. I’ll discuss the previously dismissed idea of N-version programming and how it can place bug bounties on a principled footing as a tool for securing smart contracts. I’ll also explore blockchain applications of trusted execution environments (TEEs) such as Intel SGX. By addressing the confidentiality and performance deficits of blockchains, TEEs can spawn performant, trustworthy cryptocurrency exchanges, privacy-preserving smart contracts, secure off-chain data feeds or oracles, and much more.


Ari Juels is a Professor at Cornell Tech (Jacobs Institute) in New York City, and Computer Science faculty member at Cornell University. He is a Co-Director of the Initiative for CryptoCurrencies and Contracts (IC3). He was previously the Chief Scientist of RSA. For more details, visit

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