Add InputSequence abstraction for input sequences

Author: MatthewLM

coinlib/CHANGELOG.md

@@ -5,7 +5,11 @@ secp256k1-coinlib fork.
 
 - Adds MuSig2 support with `MuSigPublicKeys` and `MuSigStatefulSigningSession`.
 - Includes adaptor signature support when using MuSig2 with
-- `SchnorrAdaptorSignature`.
+  `SchnorrAdaptorSignature`.
+- Adds `InputSequence` abstraction for input sequences. Input sequences are now
+    `0xfffffffe` by default and enforce locktimes.
+- Adds `locktimeIsEnforced` to `Transaction` to determine if the locktime is in
+    effect.
 - Moves to underlying secp256k1-coinlib.
 - Removed dependency to wasm_interop that had a broken js dependency.
 - Fixes `extraEntropy` being ignored for `Secp256k1Base.schnorrSign`.

coinlib/lib/src/coinlib_base.dart

@@ -54,6 +54,7 @@ export 'package:coinlib/src/tx/inputs/p2sh_multisig_input.dart';
 export 'package:coinlib/src/tx/inputs/p2wpkh_input.dart';
 export 'package:coinlib/src/tx/inputs/pkh_input.dart';
 export 'package:coinlib/src/tx/inputs/raw_input.dart';
+export 'package:coinlib/src/tx/inputs/sequence.dart';
 export 'package:coinlib/src/tx/inputs/taproot_input.dart';
 export 'package:coinlib/src/tx/inputs/taproot_key_input.dart';
 export 'package:coinlib/src/tx/inputs/taproot_script_input.dart';

coinlib/lib/src/tx/inputs/input.dart

@@ -6,19 +6,23 @@ import 'input_signature.dart';
 import 'p2pkh_input.dart';
 import 'p2sh_multisig_input.dart';
 import 'raw_input.dart';
+import 'sequence.dart';
 import 'witness_input.dart';
 
 /// The base class for all inputs, providing the [Input.match] factory
 /// constructor to determine the appropriate subclass from a [RawInput]
 abstract class Input with Writable {
 
-  static const sequenceFinal = 0xffffffff;
-
   OutPoint get prevOut;
   Uint8List get scriptSig;
-  int get sequence;
-
-  /// True when the input is fully signed and ready for broadcast
+  InputSequence get sequence;
+
+  /// True when the input is fully signed where it is possible to determine so.
+  ///
+  /// This doesn't mean the input is valid.
+  ///
+  /// [RawInput]s will set this to true as it is not known if they are
+  /// completed.
   bool get complete;
 
   /// The maximum total size when fully signed via the default hash type

coinlib/lib/src/tx/inputs/legacy_input.dart

@@ -2,19 +2,19 @@ import 'package:coinlib/src/crypto/ec_private_key.dart';
 import 'package:coinlib/src/crypto/ecdsa_signature.dart';
 import 'package:coinlib/src/tx/sighash/legacy_signature_hasher.dart';
 import 'package:coinlib/src/tx/sign_details.dart';
-import 'input.dart';
 import 'input_signature.dart';
 import 'p2pkh_input.dart';
 import 'p2sh_multisig_input.dart';
 import 'raw_input.dart';
+import 'sequence.dart';
 
 /// Inputs that are not witness inputs: [P2PKHInput] and [P2SHMultisigInput].
 abstract class LegacyInput extends RawInput {
 
   LegacyInput({
     required super.prevOut,
     required super.scriptSig,
-    super.sequence = Input.sequenceFinal,
+    super.sequence = InputSequence.enforceLocktime,
   });
 
   /// Signs the input given the sign [details] and [key].

coinlib/lib/src/tx/inputs/legacy_witness_input.dart

@@ -3,8 +3,8 @@ import 'package:coinlib/src/crypto/ecdsa_signature.dart';
 import 'package:coinlib/src/tx/sighash/witness_signature_hasher.dart';
 import 'package:coinlib/src/tx/sign_details.dart';
 import 'package:coinlib/src/tx/transaction.dart';
-import 'input.dart';
 import 'input_signature.dart';
+import 'sequence.dart';
 import 'witness_input.dart';
 
 /// Represents v0 witness program inputs
@@ -13,7 +13,7 @@ abstract class LegacyWitnessInput extends WitnessInput {
   LegacyWitnessInput({
     required super.prevOut,
     required super.witness,
-    super.sequence = Input.sequenceFinal,
+    super.sequence = InputSequence.enforceLocktime,
   });
 
   /// Signs the input given the [details] and [key]. Should throw

coinlib/lib/src/tx/inputs/p2pkh_input.dart

@@ -4,11 +4,11 @@ import 'package:coinlib/src/scripts/operations.dart';
 import 'package:coinlib/src/scripts/programs/p2pkh.dart';
 import 'package:coinlib/src/scripts/script.dart';
 import 'package:coinlib/src/tx/sign_details.dart';
-import 'input.dart';
 import 'input_signature.dart';
 import 'legacy_input.dart';
 import 'pkh_input.dart';
 import 'raw_input.dart';
+import 'sequence.dart';
 
 /// An input for a Pay-to-Public-Key-Hash output ([P2PKH]). This contains the
 /// public key that should match the hash in the associated output. It is either
@@ -28,7 +28,7 @@ class P2PKHInput extends LegacyInput with PKHInput {
     required super.prevOut,
     required this.publicKey,
     this.insig,
-    super.sequence = Input.sequenceFinal,
+    super.sequence = InputSequence.enforceLocktime,
   }) : super(
     scriptSig: Script([
       if (insig != null) ScriptPushData(insig.bytes),

coinlib/lib/src/tx/inputs/p2sh_multisig_input.dart

@@ -11,10 +11,10 @@ import 'package:coinlib/src/tx/sighash/legacy_signature_hasher.dart';
 import 'package:coinlib/src/tx/sighash/sighash_type.dart';
 import 'package:coinlib/src/tx/sign_details.dart';
 import 'package:coinlib/src/tx/transaction.dart';
-import 'input.dart';
 import 'input_signature.dart';
 import 'legacy_input.dart';
 import 'raw_input.dart';
+import 'sequence.dart';
 
 /// An input for a Pay-to-Script-Hash output ([P2SH]) with a multisig
 /// redeemScript and any number of required signatures. It can be signed with
@@ -29,7 +29,7 @@ class P2SHMultisigInput extends LegacyInput {
     required super.prevOut,
     required this.program,
     Iterable<ECDSAInputSignature> sigs = const [],
-    super.sequence = Input.sequenceFinal,
+    super.sequence = InputSequence.enforceLocktime,
   }) : sigs = List.unmodifiable(sigs), super(
     scriptSig: Script([
       ScriptOp.fromNumber(0),

coinlib/lib/src/tx/inputs/p2wpkh_input.dart

@@ -3,11 +3,11 @@ import 'package:coinlib/src/crypto/ec_private_key.dart';
 import 'package:coinlib/src/crypto/ec_public_key.dart';
 import 'package:coinlib/src/scripts/programs/p2wpkh.dart';
 import 'package:coinlib/src/tx/sign_details.dart';
-import 'input.dart';
 import 'input_signature.dart';
 import 'pkh_input.dart';
 import 'raw_input.dart';
 import 'legacy_witness_input.dart';
+import 'sequence.dart';
 
 /// An input for a Pay-to-Witness-Public-Key-Hash output ([P2WPKH]). This
 /// contains the public key that should match the hash in the associated output.
@@ -28,7 +28,7 @@ class P2WPKHInput extends LegacyWitnessInput with PKHInput {
     required super.prevOut,
     required this.publicKey,
     this.insig,
-    super.sequence = Input.sequenceFinal,
+    super.sequence = InputSequence.enforceLocktime,
   }) : super(
     witness: [
       if (insig != null) insig.bytes,

coinlib/lib/src/tx/inputs/raw_input.dart

@@ -1,11 +1,11 @@
 import 'dart:typed_data';
-import 'package:coinlib/src/common/checks.dart';
 import 'package:coinlib/src/common/serial.dart';
 import 'package:coinlib/src/tx/outpoint.dart';
 import 'package:coinlib/src/tx/sighash/sighash_type.dart';
 import 'package:coinlib/src/tx/transaction.dart';
 import 'input.dart';
 import 'input_signature.dart';
+import 'sequence.dart';
 
 /// A transaction input without any associated witness data that acts as the
 /// base for all other inputs as all inputs include a outpoint, script and
@@ -17,7 +17,7 @@ class RawInput extends Input {
   @override
   final Uint8List scriptSig;
   @override
-  final int sequence;
+  final InputSequence sequence;
 
   static SigHashType checkHashTypeNotSchnorr(SigHashType type) {
     if (type.schnorrDefault) {
@@ -31,21 +31,19 @@ class RawInput extends Input {
   RawInput({
     required this.prevOut,
     required this.scriptSig,
-    this.sequence = Input.sequenceFinal,
-  }) {
-    checkUint32(sequence, "this.sequence");
-  }
+    this.sequence = InputSequence.enforceLocktime,
+  });
 
   RawInput.fromReader(BytesReader reader)
     : prevOut = OutPoint.fromReader(reader),
     scriptSig = reader.readVarSlice(),
-    sequence = reader.readUInt32();
+    sequence = InputSequence.fromValue(reader.readUInt32());
 
   @override
   void write(Writer writer) {
     prevOut.write(writer);
     writer.writeVarSlice(scriptSig);
-    writer.writeUInt32(sequence);
+    writer.writeUInt32(sequence.value);
   }
 
   /// Always true as a simple [RawInput] is assumed to be fully signed as there

coinlib/lib/src/tx/inputs/sequence.dart

@@ -0,0 +1,42 @@
+import 'package:coinlib/src/common/checks.dart';
+import 'package:coinlib/src/tx/transaction.dart';
+
+/// Represents the sequence field of an input. Inputs should generally use
+/// [enforceLocktime] to ensure that any given locktime will function correctly.
+/// This is also the default behaviour of the Peercoin client.
+///
+/// To set BIP68 relative locktimes, use [InputSequence.fromValue]. There is no
+/// high-level abstraction for this yet.
+class InputSequence {
+
+  final int value;
+
+  const InputSequence._(this.value);
+
+  /// The usual sequence value that requires the [Transaction.locktime] to be
+  /// enforced.
+  static const enforceLocktime = InputSequence._(0xfffffffe);
+
+  /// An input which does not enforce the [Transaction.locktime]. If all inputs
+  /// have this sequence, the transaction locktime will be ignored.
+  static const finalWithoutLocktime = InputSequence._(0xffffffff);
+
+  /// Set a specific value for the sequence.
+  InputSequence.fromValue(this.value) {
+    checkUint32(value, "this.value");
+  }
+
+  /// True if this input requires enforcement of the [Transaction.locktime].
+  bool get locktimeIsEnforced => value < finalWithoutLocktime.value;
+
+  @override
+  String toString() => value.toString();
+
+  @override
+  bool operator ==(Object other)
+    => (other is InputSequence) && value == other.value;
+
+  @override
+  int get hashCode => value;
+
+}