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fix: correct Particl transaction serialization and signing #9

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fix: correct Particl transaction serialization and signing #9

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62 changes: 41 additions & 21 deletions lib/src/transaction.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -275,6 +275,37 @@ class Transaction {
: 0)) as int;
}

int _byteLengthParticl(bool _ALLOW_WITNESS) {
// Particl wire format header: version (2 bytes) + locktime (4 bytes) = 6.
// No SegWit marker/flag bytes.
// Each output has a varint type prefix.
// Witness is always present for Particl-versioned txns with inputs.
var hasWitness = _ALLOW_WITNESS && ins.isNotEmpty;

return (6 +
varuint.encodingLength(ins.length) +
varuint.encodingLength(outs.length) +
ins.fold(0, (sum, input) => sum + 40 + varSliceSize(input.script!)) +
outs.fold(
0,
(sum, output) =>
sum +
varuint.encodingLength(1) +
8 +
varSliceSize(output.script!)) +
(payload != null ? varSliceSize(payload!) : 0) +
(hasWitness
? ins.fold(0, (sum, input) {
if (input.witness == null) {
input.witness = [];
return sum + varuint.encodingLength(0);
} else {
return sum + vectorSize(input.witness!);
}
})
: 0)) as int;
}

int vectorSize(List<Uint8List> someVector) {
var length = someVector.length;
return varuint.encodingLength(length) +
Expand Down Expand Up @@ -432,7 +463,7 @@ class Transaction {
[Uint8List? buffer, initialOffset, bool _ALLOW_WITNESS = false]) {

// _ALLOW_WITNESS is used to separate witness part when calculating tx id
buffer ??= Uint8List(_byteLength(_ALLOW_WITNESS));
buffer ??= Uint8List(_byteLengthParticl(_ALLOW_WITNESS));

// Any changes made to the ByteData will also change the buffer, and vice versa.
// https://api.dart.dev/stable/2.7.1/dart-typed_data/ByteBuffer/asByteData.html
Expand All @@ -454,21 +485,6 @@ class Transaction {
offset += 4;
}

void writeUInt16(i) {
bytes.setUint16(offset, i, Endian.little);
offset += 2;
}

void writeInt32(i) {
bytes.setInt32(offset, i, Endian.little);
offset += 4;
}

void writeInt16(i) {
bytes.setInt16(offset, i, Endian.little);
offset += 2;
}

void writeUInt64(i) {
bytes.setUint64(offset, i, Endian.little);
offset += 8;
Expand All @@ -491,8 +507,11 @@ class Transaction {
});
}

writeInt32(version);
writeUInt16(locktime);
// Particl header: 2-byte version + 4-byte locktime.
// Matches Particl Core: s << GetVersion(); s << GetType(); s << nLockTime;
writeUInt8(version & 0xFF);
writeUInt8((version >> 8) & 0xFF);
writeUInt32(locktime);

writeVarInt(ins.length);
ins.forEach((txIn) {
Expand All @@ -514,9 +533,10 @@ class Transaction {
writeVarSlice(txOut.script);
});

if (_ALLOW_WITNESS && hasWitnesses()) {
ins.forEach((txInt) {
writeVector(txInt.witness);
// Particl always includes witness for Particl-versioned txns with inputs.
if (_ALLOW_WITNESS && ins.isNotEmpty) {
ins.forEach((txIn) {
writeVector(txIn.witness ?? []);
});
}

Expand Down
23 changes: 16 additions & 7 deletions lib/src/transaction_builder.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -137,6 +137,7 @@ class TransactionBuilder {
int? witnessValue,
Uint8List? witnessScript,
int? hashType,
bool isParticl = false,
String overridePrefix = ''}) {
// TODO checkSignArgs

Expand Down Expand Up @@ -237,24 +238,32 @@ class TransactionBuilder {
.data
.output;
} else if (type == SCRIPT_TYPES['P2PKH']) {
var prevOutScript = pubkeyToOutputScript(ourPubKey, network);
input.prevOutType = SCRIPT_TYPES['P2PKH'];
var p2pkhScript = pubkeyToOutputScript(ourPubKey, network);
// Particl requires all inputs to use witness format (empty scriptSig,
// sig+pubkey in witness), even for P2PKH prevouts. BIP143 is used
// for all Particl signing with the P2PKH script as the scriptCode.
input.prevOutType =
isParticl ? SCRIPT_TYPES['P2WPKH'] : SCRIPT_TYPES['P2PKH'];
if (isParticl) input.hasWitness = true;
input.signatures = [null];
input.pubkeys = [ourPubKey];
input.signScript = prevOutScript;
input.signScript = p2pkhScript;
} else {
// TODO other type
}
} else {
var prevOutScript = pubkeyToOutputScript(ourPubKey, network);
input.prevOutType = SCRIPT_TYPES['P2PKH'];
var p2pkhScript = pubkeyToOutputScript(ourPubKey, network);
input.prevOutType =
isParticl ? SCRIPT_TYPES['P2WPKH'] : SCRIPT_TYPES['P2PKH'];
if (isParticl) input.hasWitness = true;
input.signatures = [null];
input.pubkeys = [ourPubKey];
input.signScript = prevOutScript;
input.signScript = p2pkhScript;
}
}
var signatureHash;
if (input.hasWitness != null && input.hasWitness!) {
// Particl always uses BIP143 sighash for all input types.
if (isParticl || (input.hasWitness != null && input.hasWitness!)) {
signatureHash =
_tx.hashForWitnessV0(vin, input.signScript!, input.value!, hashType);
} else {
Expand Down