Editing Kidney swaps (section)

= Atomic kidney-swaps =

On a centralized exchange kidney-swaps can easily be accomplished since the exchange ends up with full control over the coins. But how would you accomplish this on a decentralized exchange where all of the traders are anonymous and assumed-to-be highly adversarial?

On Ethereum this algorithm is trivial since you can write arbitrary contracts with ease. Simply create an escrow contract that receives deposits and acts on a signed message to do some action between N parties. This can all be directly enforceable so there is no need for a third-party

But the question is – how would you accomplish this very same contract on legacy blockchains where the assets are on separate blockchains and where said blockchains have very poor support for complex contracts?

Micro-payment channels are obviously out for this. Traders can easily cut off other parties and leave someone else holding useless assets. So what about cross-chain contracts? Well, these never really worked that well for the stated purpose anyway – the idea was to link separate blockchains but such blockchains have poor support for complex transactions so the contract would either be considered invalid or never confirm.

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