Zcash team recently reported on the news about Atomic Trades development.
— Zcash Company (@zcashco) 11 сентября 2017 г.
We are excited to announce that we have been working on a command-line tool that executes atomic trades between Zcash t-addrs and Bitcoin addresses. Several people have come up with XCAT protocols. Loosely speaking, they all rely on a mechanism where for one side to obtain their coins, a secret must be revealed that will enable the second party to also redeem their coins. There are many variants of this basic idea.
The current version requires the user to run Bitcoin and Zcash full nodes, but a light-client version is in progress.
What is Atomic Trades?
Cross-chain atomic trades (for which we have coined the acronym “XCATs”) remove the need for a single point of trust for trades between different cryptocurrencies. They rely on clever protocols that automatically exchange funds across two chains only if both participants hold up their end of the deal, and refund both participants otherwise.
The problem of atomic cross-chain trading is one where (at least) two parties, Alice and Bob, own coins in separate cryptocurrencies, and want to exchange them without having to trust a third party (centralized exchange).
A non-atomic trivial solution would have Alice send her Bitcoins to Bob, and then have Bob send another cryptocurrency to Alice - but Bob has the option of going back on his end of the bargain and simply not following through with the protocol, ending up with both Bitcoins and the altcoin.