Re: [ANN] [ZOI] Zoin - Zerocoin based privacy - CPU

Also dev what's the difference between lyra2 and lyra2-zoin? why create a different flavor? When I check the Lyra2 code, I don't see any differences though.

The Lyra algorithm is the same, it just uses different parameters. Originally ZCoin had unsustainable parameters for Lyra, as explained here:

https://bitcointalk.org/index.php?topic=1671060.msg16863305#msg16863305

If ZCoin didn't change the algo, it would have needed more and more memory and got slower and slower until most machines would not be able to do the hash.

Zoin had to change the original ZCoin algo for this reason.

It's nice that Zoin improved ZCoin. Why do we use Lyra2 here at all? Any adavantages? Would it be the same to use scrypt or X11 etc as PoW while still keeping the zerocoin features?

The algo could be changed yes. Lyra was kept because it is heavy on memory usage, which favours CPU mining and this could make GPU implementation inefficient. Previous versions of hash algos based on lyra2 used parameters that were too small to give problems for GPU. And ZCoins version was/is too extreme. We'll see what the outcome is, but if we decide to change the algo, it could be implemented as a hard fork.