It's possible in Bitcoin too and not just for the kind of trivial program you could plausible execute in a public blockchain. https://bitcoincore.org/en/2016/02

It's possible in Bitcoin too and not just for the kind of trivial program you could plausible execute in a public blockchain. https://bitcoincore.org/en/2016/02/26/zero-knowledge-contingent-payments-announcement/ https://bitcoincore.org/en/2016/02/26/zero-knowledge-conting... (And to not put too fine a point on it: the existing track record of ethereum smart contracts suggests that if such a bounty had been created there it would have simply been stolen due to contract/vm flaws by now.)