Mimblewimble allows for a very simple coin shuffling protocol [1] with the following properties:

* Users submit self-spends throughout the day. No interaction needed for shuffling.

* Shuffling is performed at the end of the day by a set of mixnodes that cannot steal any coins.

* Invalid self-spends are automatically filtered out. No need to abort or restart the shuffling.

* As long as at least one mixnode is honest, then no one learns the input output links.

* The size of the shuffle is limited only by blocksize and could easily be over a thousand.

* Each shuffle only grows the chainsize by a constant, thanks to Mimblewimble cut-through.


We welcome review of the proposal.

[1] https://forum.grin.mw/t/mimblewimble-coinswap-proposal