private Dictionary <int, WitScript> SignCoinJoin(ClientRound ongoingRound, Transaction unsignedCoinJoin)
{
TxOut[] myOutputs = unsignedCoinJoin.Outputs
.Where(x => x.ScriptPubKey == ongoingRound.Registration.ChangeAddress.ScriptPubKey ||
ongoingRound.Registration.ActiveOutputs.Select(y => y.Address.ScriptPubKey).Contains(x.ScriptPubKey))
.ToArray();
Money amountBack = myOutputs.Sum(y => y.Value);
// Make sure change is counted.
Money minAmountBack = ongoingRound.CoinsRegistered.Sum(x => x.Amount); // Start with input sum.
// Do outputs.lenght + 1 in case the server estimated the network fees wrongly due to insufficient data in an edge case.
Money networkFeesAfterOutputs = ongoingRound.State.FeePerOutputs * (ongoingRound.Registration.AliceClient.RegisteredAddresses.Length + 1); // Use registered addresses here, because network fees are decided at inputregistration.
Money networkFeesAfterInputs = ongoingRound.State.FeePerInputs * ongoingRound.Registration.CoinsRegistered.Count();
Money networkFees = networkFeesAfterOutputs + networkFeesAfterInputs;
minAmountBack -= networkFees; // Minus miner fee.
IOrderedEnumerable <(Money value, int count)> indistinguishableOutputs = unsignedCoinJoin.GetIndistinguishableOutputs(includeSingle: false).OrderByDescending(x => x.count);
foreach ((Money value, int count)denomPair in indistinguishableOutputs)
{
var mineCount = myOutputs.Count(x => x.Value == denomPair.value);
Money denomination = denomPair.value;
int anonset = Math.Min(110, denomPair.count); // https://github.com/zkSNACKs/WalletWasabi/issues/1379
Money expectedCoordinatorFee = denomination.Percentage(ongoingRound.State.CoordinatorFeePercent * anonset);
for (int i = 0; i < mineCount; i++)
{
minAmountBack -= expectedCoordinatorFee; // Minus expected coordinator fee.
}
}
// If there's no change output then coordinator protection may happened:
bool gotChange = myOutputs.Select(x => x.ScriptPubKey).Contains(ongoingRound.Registration.ChangeAddress.ScriptPubKey);
if (!gotChange)
{
Money minimumOutputAmount = Money.Coins(0.0001m); // If the change would be less than about $1 then add it to the coordinator.
Money baseDenomination = indistinguishableOutputs.First().value;
Money onePercentOfDenomination = baseDenomination.Percentage(1m); // If the change is less than about 1% of the newDenomination then add it to the coordinator fee.
Money minimumChangeAmount = Math.Max(minimumOutputAmount, onePercentOfDenomination);
minAmountBack -= minimumChangeAmount; // Minus coordinator protections (so it won't create bad coinjoins.)
}
if (amountBack < minAmountBack && !amountBack.Almost(minAmountBack, Money.Satoshis(1000))) // Just in case. Rounding error maybe?
{
Money diff = minAmountBack - amountBack;
throw new NotSupportedException($"Coordinator did not add enough value to our outputs in the coinjoin. Missing: {diff.Satoshi} satoshis.");
}
var signedCoinJoin = unsignedCoinJoin.Clone();
signedCoinJoin.Sign(
ongoingRound
.CoinsRegistered
.Select(x =>
(x.Secret ??= KeyManager.GetSecrets(SaltSoup(), x.ScriptPubKey).Single())
.PrivateKey
.GetBitcoinSecret(Network)),
ongoingRound
.Registration
.CoinsRegistered
.Select(x => x.GetCoin()));
var myDic = new Dictionary <int, WitScript>();
for (int i = 0; i < signedCoinJoin.Inputs.Count; i++)
{
var input = signedCoinJoin.Inputs[i];
if (ongoingRound.CoinsRegistered.Select(x => x.GetOutPoint()).Contains(input.PrevOut))
{
myDic.Add(i, signedCoinJoin.Inputs[i].WitScript);
}
}
return(myDic);
}
