The coin days requirement should be reserved for usage by user option when there is an ongoing attack, as otherwise new users wont be able to trade.
Allow me to correct you on this non-sequitor. The newness of a user of a decentralized exchange doesn't require that user's UXTO is newly acquired.
I was thinking of someone that just got their first BTC locally. wouldnt that be too young to be used? maybe i dont understand the intended coinage well enough.
If we assume that a lot of new users will be using the DE, they will be coming from the CE. And maybe they never had a local wallet, so they do a withdraw. patiently wait the confirms so it is in the wallet, then start a trade (after all they are doing this to use the DE) and then told "sorry you have to wait X amount of time since your dont have the right time of utxo"
I really want to avoid having what is potentially a mainstream real world case have such an error message to be expected
James
You are building a DE so that should mean that users have some coins on a block chain that they wish to trade. Who knows how long ago they acquired those coins. The Coin Days Destroyed is the time (# of blocks) elapsed since the UXTO was created.
Since this is suggested to be a user configurable setting which they set only on their own decentralized client (which filters which counter parties they accept to start the DE protocol), then user whose UXTO is very young, can set the threshold so their UXTO fulfills the chosen threshold. If the threshold isn't high enough, they incur more risk of being jammed. But also note that while they are being jammed, their UXTO is aging, so they can continually increase their chosen threshold if necessary to foil an attacker.
There is no disadvantage to offering the feature. An error msg will never be shown. The only effect is the number of available counter parties may shrink as the threshold is raised, as well the risk of jam attack decreases as the threshold is raised.
There a many people who have dozens of different altcoins and no wallet for any of them, or just a few. In fact most people fall in that category, where they have a few alts they have local wallets and still they buy alts on exchanges they dont have wallets for, with the intent of converting them before withdrawing.
Good point that it can be done without any error messages, but just a gradual increase in the potential matches that are possible. Maybe we can have a sunrise type of graphics to show that the longer you wait the more trades are possible