Currently, users of Bitcoin and other non-privacy coins are using mixing services. However, even for non-custodial services there are many risks, caused by dropping on networking traffic, adversarial partners or even mixing service.
As a solution, non-interactive mixer comes. In this case Alice just puts her coin on the blockchain and waits for Bob. Coin's contract allows Bob to spend Alice's coin as well as Bob's coin but only if two outputs of the transactions would be properly mixed and indistinguishable for external observer.
A paper on such a mixer (with my co-authorship) appeared online recently
https://eprint.iacr.org/2020/560 , but for Ergo there's proof-of-concept mixer already (made ny anonymous dev "anon92048"):
https://github.com/anon92048/ergo-mixer-webFor Bitcoin, a little bit similar scheme called SNICKER is coming, but currently in form of early draft. Also, it still requires for some offchain public bulletin board.
There are some wallets coming with such mixer built in, such as Cypra wallet:
https://cypra.io/Thus a gap between privacy and non-privacy coins become more narrow.
Please let me know what do you think on that.
