Ensuring Flexibility and Sustainability of the Zcash Development Fund - Draft

[daira]

@conradoplg

I don’t see how could this be implemented. How would it know where to send the ZEC to? Unless it would not directly send but allow Orchard holders to claim a % of the reward in each block based on the total Orchard pool at the time of that block. But there’s no way to know how much ZEC they hold unless in zero knowledge, and that would require changing the circuit and that totally won’t happen in time for the next halvening. (I could be totally wrong about all of this though)

@zkcroc

A possible method [of implementing a return on holding ZEC in Orchard] has been briefly discussed here

@daira

Another way to do it is to have the note commit to a fixed-point representation of \frac{\mathsf{v}}{\mathsf{compoundedValue}}. For example, suppose that we start out with \mathsf{compoundedValue} as 100000000, representing 1.0 in fixed point. Each time we read the value from an Orchard note we multiply it by \frac{\mathsf{compoundedValue}}{100000000}, and each time we write the value we multiply it by \frac{100000000}{\mathsf{compoundedValue}}. The effect is essentially the same as before [in this comment], except that now we don’t have to keep track of the compounded value as part of the commitments. All existing notes automatically have the correct value at the activation block for this change.

Just to clarify, this approach does require a circuit change: when I refer to reading the value from, or writing it to, an Orchard note, that is in the circuit statement. This scheme is simpler than requiring additional transactions, but it would require significant analysis in terms of both circuit security and economic effects, which I believe is probably not feasible in the planned NU6 timeframe.