public void RebaseKeyPaths(PSBT psbt)
{
foreach (var rebase in GetPSBTRebaseKeyRules())
{
psbt.RebaseKeyPaths(rebase.AccountKey, rebase.AccountKeyPath);
}
}
public void RebaseKeyPaths(PSBT psbt)
{
foreach (var rebase in GetPSBTRebaseKeyRules())
{
psbt.RebaseKeyPaths(rebase.AccountKey, rebase.AccountKeyPath, rebase.MasterFingerprint);
}
}
private static PSBT Sign(Party party, DerivationStrategyBase derivationStrategy, PSBT psbt)
{
psbt = psbt.Clone();
// NBXplorer does not have knowledge of the account key path, KeyPath are private information of each peer
// NBXplorer only derive 0/* and 1/* on top of provided account xpubs,
// This mean that the input keypaths in the PSBT are in the form 0/* (as if the account key was the root)
// RebaseKeyPaths modifies the PSBT by adding the AccountKeyPath in prefix of all the keypaths of the PSBT
// Note that this is not necessary to do this if the account key is the same as root key.
// Note that also that you don't have to do this, if you do not pass the account key path in the later SignAll call.
// however, this is best practice to rebase the PSBT before signing.
// If you sign with an offline device (hw wallet), the wallet would need the rebased PSBT.
psbt.RebaseKeyPaths(party.AccountExtPubKey, party.AccountKeyPath);
Console.WriteLine("A PSBT is a data structure with all information for a wallet to sign.");
var spend = psbt.GetBalance(derivationStrategy, party.AccountExtPubKey, party.AccountKeyPath);
Console.WriteLine($"{party.PartyName}, Do you agree to sign this transaction spending {spend}?");
// Ok I sign
psbt.SignAll(derivationStrategy, // What addresses to derive?
party.RootExtKey.Derive(party.AccountKeyPath), // With which account private keys?
party.AccountKeyPath); // What is the keypath of the account private key. If you did not rebased the keypath like before, you can remove this parameter
return(psbt);
}
public async Task <IActionResult> CreatePSBT(
[ModelBinder(BinderType = typeof(NetworkModelBinder))]
NBXplorerNetwork network,
[ModelBinder(BinderType = typeof(DerivationStrategyModelBinder))]
DerivationStrategyBase strategy,
[FromBody]
JObject body)
{
if (body == null)
{
throw new ArgumentNullException(nameof(body));
}
CreatePSBTRequest request = ParseJObject <CreatePSBTRequest>(body, network);
if (strategy == null)
{
throw new ArgumentNullException(nameof(strategy));
}
var repo = RepositoryProvider.GetRepository(network);
var utxos = await GetUTXOs(network.CryptoCode, strategy, null);
var txBuilder = request.Seed is int s?network.NBitcoinNetwork.CreateTransactionBuilder(s)
: network.NBitcoinNetwork.CreateTransactionBuilder();
if (Waiters.GetWaiter(network).NetworkInfo?.GetRelayFee() is FeeRate feeRate)
{
txBuilder.StandardTransactionPolicy.MinRelayTxFee = feeRate;
}
txBuilder.OptInRBF = request.RBF;
if (request.LockTime is LockTime lockTime)
{
txBuilder.SetLockTime(lockTime);
txBuilder.OptInRBF = true;
}
var availableCoinsByOutpoint = utxos.GetUnspentCoins(request.MinConfirmations).ToDictionary(o => o.Outpoint);
if (request.IncludeOnlyOutpoints != null)
{
var includeOnlyOutpoints = request.IncludeOnlyOutpoints.ToHashSet();
availableCoinsByOutpoint = availableCoinsByOutpoint.Where(c => includeOnlyOutpoints.Contains(c.Key)).ToDictionary(o => o.Key, o => o.Value);
}
if (request.ExcludeOutpoints?.Any() is true)
{
var excludedOutpoints = request.ExcludeOutpoints.ToHashSet();
availableCoinsByOutpoint = availableCoinsByOutpoint.Where(c => !excludedOutpoints.Contains(c.Key)).ToDictionary(o => o.Key, o => o.Value);
}
txBuilder.AddCoins(availableCoinsByOutpoint.Values);
foreach (var dest in request.Destinations)
{
if (dest.SweepAll)
{
txBuilder.SendAll(dest.Destination);
}
else
{
txBuilder.Send(dest.Destination, dest.Amount);
if (dest.SubstractFees)
{
txBuilder.SubtractFees();
}
}
}
(Script ScriptPubKey, KeyPath KeyPath)change = (null, null);
bool hasChange = false;
// We first build the transaction with a change which keep the length of the expected change scriptPubKey
// This allow us to detect if there is a change later in the constructed transaction.
// This defend against bug which can happen if one of the destination is the same as the expected change
// This assume that a script with only 0 can't be created from a strategy, nor by passing any data to explicitChangeAddress
if (request.ExplicitChangeAddress == null)
{
// The dummyScriptPubKey is necessary to know the size of the change
var dummyScriptPubKey = utxos.Unconfirmed.UTXOs.FirstOrDefault()?.ScriptPubKey ??
utxos.Confirmed.UTXOs.FirstOrDefault()?.ScriptPubKey ?? strategy.Derive(0).ScriptPubKey;
change = (Script.FromBytesUnsafe(new byte[dummyScriptPubKey.Length]), null);
}
else
{
change = (Script.FromBytesUnsafe(new byte[request.ExplicitChangeAddress.ScriptPubKey.Length]), null);
}
txBuilder.SetChange(change.ScriptPubKey);
PSBT psbt = null;
try
{
if (request.FeePreference?.ExplicitFeeRate is FeeRate explicitFeeRate)
{
txBuilder.SendEstimatedFees(explicitFeeRate);
}
else if (request.FeePreference?.BlockTarget is int blockTarget)
{
try
{
var rate = await GetFeeRate(blockTarget, network.CryptoCode);
txBuilder.SendEstimatedFees(rate.FeeRate);
}
catch (NBXplorerException e) when(e.Error.Code == "fee-estimation-unavailable" && request.FeePreference?.FallbackFeeRate is FeeRate fallbackFeeRate)
{
txBuilder.SendEstimatedFees(fallbackFeeRate);
}
}
else if (request.FeePreference?.ExplicitFee is Money explicitFee)
{
txBuilder.SendFees(explicitFee);
}
else
{
try
{
var rate = await GetFeeRate(1, network.CryptoCode);
txBuilder.SendEstimatedFees(rate.FeeRate);
}
catch (NBXplorerException e) when(e.Error.Code == "fee-estimation-unavailable" && request.FeePreference?.FallbackFeeRate is FeeRate fallbackFeeRate)
{
txBuilder.SendEstimatedFees(fallbackFeeRate);
}
}
psbt = txBuilder.BuildPSBT(false);
hasChange = psbt.Outputs.Any(o => o.ScriptPubKey == change.ScriptPubKey);
}
catch (NotEnoughFundsException)
{
throw new NBXplorerException(new NBXplorerError(400, "not-enough-funds", "Not enough funds for doing this transaction"));
}
if (hasChange) // We need to reserve an address, so we need to build again the psbt
{
if (request.ExplicitChangeAddress == null)
{
var derivation = await repo.GetUnused(strategy, DerivationFeature.Change, 0, request.ReserveChangeAddress);
change = (derivation.ScriptPubKey, derivation.KeyPath);
}
else
{
change = (request.ExplicitChangeAddress.ScriptPubKey, null);
}
txBuilder.SetChange(change.ScriptPubKey);
psbt = txBuilder.BuildPSBT(false);
}
var tx = psbt.GetOriginalTransaction();
if (request.Version is uint v)
{
tx.Version = v;
}
psbt = txBuilder.CreatePSBTFrom(tx, false, SigHash.All);
var outputsKeyInformations = repo.GetKeyInformations(psbt.Outputs.Where(o => !o.HDKeyPaths.Any()).Select(o => o.ScriptPubKey).ToArray());
var utxosByOutpoint = utxos.GetUnspentUTXOs().ToDictionary(u => u.Outpoint);
// Maybe it is a change that we know about, let's search in the DB
if (hasChange && change.KeyPath == null)
{
var keyInfos = await repo.GetKeyInformations(new[] { request.ExplicitChangeAddress.ScriptPubKey });
if (keyInfos.TryGetValue(request.ExplicitChangeAddress.ScriptPubKey, out var kis))
{
var ki = kis.FirstOrDefault(k => k.DerivationStrategy == strategy);
if (ki != null)
{
change = (change.ScriptPubKey, kis.First().KeyPath);
}
}
}
var pubkeys = strategy.GetExtPubKeys().Select(p => p.AsHDKeyCache()).ToArray();
var keyPaths = psbt.Inputs.Select(i => utxosByOutpoint[i.PrevOut].KeyPath).ToList();
if (hasChange && change.KeyPath != null)
{
keyPaths.Add(change.KeyPath);
}
var fps = new Dictionary <PubKey, HDFingerprint>();
foreach (var pubkey in pubkeys)
{
// We derive everything the fastest way possible on multiple cores
pubkey.Derive(keyPaths.ToArray());
fps.TryAdd(pubkey.GetPublicKey(), pubkey.GetPublicKey().GetHDFingerPrint());
}
foreach (var input in psbt.Inputs)
{
var utxo = utxosByOutpoint[input.PrevOut];
foreach (var pubkey in pubkeys)
{
var childPubKey = pubkey.Derive(utxo.KeyPath);
NBitcoin.Extensions.TryAdd(input.HDKeyPaths, childPubKey.GetPublicKey(), Tuple.Create(fps[pubkey.GetPublicKey()], utxo.KeyPath));
}
}
await Task.WhenAll(psbt.Inputs
.Select(async(input) =>
{
if (input.WitnessUtxo == null) // We need previous tx
{
var prev = await repo.GetSavedTransactions(input.PrevOut.Hash);
if (prev?.Any() is true)
{
input.NonWitnessUtxo = prev[0].Transaction;
}
}
}).ToArray());
var outputsKeyInformationsResult = await outputsKeyInformations;
foreach (var output in psbt.Outputs)
{
foreach (var keyInfo in outputsKeyInformationsResult[output.ScriptPubKey].Where(o => o.DerivationStrategy == strategy))
{
foreach (var pubkey in pubkeys)
{
var childPubKey = pubkey.Derive(keyInfo.KeyPath);
NBitcoin.Extensions.TryAdd(output.HDKeyPaths, childPubKey.GetPublicKey(), Tuple.Create(fps[pubkey.GetPublicKey()], keyInfo.KeyPath));
}
}
}
if (request.RebaseKeyPaths != null)
{
foreach (var rebase in request.RebaseKeyPaths)
{
if (rebase.AccountKeyPath == null)
{
throw new NBXplorerException(new NBXplorerError(400, "missing-parameter", "rebaseKeyPaths[].accountKeyPath is missing"));
}
if (rebase.AccountKey == null)
{
throw new NBXplorerException(new NBXplorerError(400, "missing-parameter", "rebaseKeyPaths[].accountKey is missing"));
}
psbt.RebaseKeyPaths(rebase.AccountKey, rebase.AccountKeyPath, rebase.MasterFingerprint);
}
}
var resp = new CreatePSBTResponse()
{
PSBT = psbt,
ChangeAddress = hasChange ? change.ScriptPubKey.GetDestinationAddress(network.NBitcoinNetwork) : null
};
return(Json(resp, network.JsonSerializerSettings));
}
