I’ve been exploring VUTXOs and have a couple of general questions regarding their behavior.
1. Consolidation on Each Round
I’ve noticed that when I participate in a round, all my VUTXOs get consolidated into a single one. This makes ARK function more like an account-based model rather than a UTXO-based system. I understand this is done to reduce on-chain fees, but it significantly impacts privacy—allowing recipients to see the entire balance.
Has there been any consideration for implementing coin control features? Perhaps introducing upper/lower limits to avoid excessive consolidation during rounds?
2. Recovering Funds After VTUXO Expiration
I don’t fully understand why VTUXOs expire, though I realize it’s necessary for the implementation. However, when I let my VTUXOs expire by waiting a week, my funds weren’t lost.
Could you clarify me:
Why is expiration necessary?
Is there a way to recover my balance after expiration? If so, what level of trust is involved in the recovery process?
Note that bark is both a command-line interface and a Rust-API that wallet developers can use. At the moment developers can implement coin-selection themselves.
It might be useful to add some more flexibility to the CLI. I’ve created an issue.
Expiration
The expiration is technically required. The core idea of Ark is that we want to save expensive blockspace. The expiration ensures the full tree doesn’t need to be published to the blockchain.
In the current implementation the Ark Server is allowing you to use expired VTXOs.
However, an expired VTXO is not as good. A refresh VTXO comes with a unilateral exit that ensures you can get your money back. Once a VTXO expires their is no guarantee whatsoever that you can still exit your VTXO
Using Ark will inevitably require ongoing costs to maintain a balance. But if your app is managing refreshes properly (refreshing near expiry), costs should be totally manageable. We’ll have some projections out on this soon.
Ark is intended for “spending” money, and any long-term savings should still be held on-chain. If Ark were ever to become popular for savings, then you’d probably see the emergence of Ark servers offering much longer expiry times to cater to that (less refreshes required, but more expensive to spend).