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Comment by natosaichek | Hacker News Reader

One of the cool things about Ethereum is that you can build your non-turing-complete contract software on Eth, and use Eth to check your NTC-Eth contracts. I can't think of anything stopping you from doing this right now. Maybe you or other people can weigh in on why it's not feasible?

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The ETH language semantics aren't what I'd want for verification proofs, even restricted to a subset. It's possible there are conflicts between the execution model and what would be required for verified, secure contracts.

Similarly, Id want a proof-checked VM for the currency, which ETH is pretty far from supporting.

So verified-ETH would be a larger, more bug-prone project than starting from first principles, developing a language and VM in parallel. (Also, starting a new project gives a chance to change the economics and/or technology used; depending on your views, this might be a benefit.)

https://tezos.com/pdf/language.txt

Yoichi Hirai has built a formal definition of the EVM in Coq which makes it possible to produce formal proofs of an Ethereum smart contract's correctness:

https://medium.com/@pirapira/ethereum-virtual-machine-for-co...

Thanks for showing me this!

I either missed it or it didn't exist last time I looked in to ETH. (About a year ago, pre-DAO.)

Either way, this is a major component of what I'd like to see in smart contracts! (The other two major pieces being a verified VM that supports that spec, and a developer library of "standard" contract pieces -- I don't recall being impressed by directly coding for the EVM, and easy-to-use contracts require a library of "standard legalese".)

Glad to see ETH is putting in the effort.

Most welcome! It was just released so you wouldn't have seen it last year. There was a major push toward more secure smart contacts, in particular using formal verification, after the DAO hack, and the efforts continue to this day.

Using my definition of EVM, I think it's already possible to create a small verified compiler.

My priority is on keeping the formal definition in sync with the Yellow Paper and the implementations.

It's a surprise to see you here! :) Thanks for the explanation. Good luck with your work!

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