Efficient solution to verify kernel uniqueness + better absolute timelocks

[johndavies24]

I think this thread is a nice thing for people to refresh their memory about some of our prior conversations on payjoins

PayJoin (P2EP) in Grin

Say Alice wants to send 2 Grin to Bob. A simple transaction looks like the following. Alice spends a 5 Grin output, Bob receives 2 Grin and Alice receives 3 Grin in change. 5 Grin -> 2 Grin 3 Grin Even with hidden values the structure leaks “direction” with one output presumably a “change” output. Alice has ownership of the spent output and the new change output and further analysis may reveal this shared ownership. If the change output is identified then the direction of flow o…