Use official feature bit for option_simple_taproot

Use the official feature bit and name for taproot channels and the
corresponding channel types. Activate taproot channels support by
default (without support for announcing such channels yet).

Author: t-bast

docs/release-notes/eclair-vnext.md

@@ -4,6 +4,28 @@
 
 ## Major changes
 
+### Taproot Channels (without announcements)
+
+This release adds support for taproot channels, as specified in [the BOLTs](https://github.com/lightning/bolts/pull/995).
+Taproot channels improve privacy and cost less on-chain fees by using musig2 for the channel output.
+This release is fully compatible with the `lnd` implementation of taproot channels.
+
+We don't support public taproot channels yet, as the gossip mechanism for this isn't finalized yet.
+It is thus only possible to open "private" (unannounced) taproot channels.
+You may follow progress on the specification for public taproot channels [here](https://github.com/lightning/bolts/pull/1059).
+
+This feature is active by default. To disable it, add the following to your `eclair.conf`:
+
+```conf
+eclair.features.option_simple_taproot = disabled
+```
+
+To open a taproot channel with a node that supports the `option_simple_taproot` feature, use the following command:
+
+```sh
+$ eclair-cli open --nodeId=<node_id> --fundingSatoshis=<funding_amount> --channelType=simple_taproot_channel --announceChannel=false
+```
+
 ### Remove support for non-anchor channels
 
 We remove the code used to support legacy channels that don't use anchor outputs or taproot.

eclair-core/src/main/resources/reference.conf

@@ -88,6 +88,7 @@ eclair {
     option_zeroconf = disabled
     keysend = disabled
     option_simple_close = optional
+    option_simple_taproot = optional
     trampoline_payment_prototype = disabled
     async_payment_prototype = disabled
     on_the_fly_funding = disabled

eclair-core/src/main/scala/fr/acinq/eclair/Features.scala

@@ -312,6 +312,11 @@ object Features {
     val mandatory = 60
   }
 
+  case object SimpleTaprootChannels extends Feature with InitFeature with NodeFeature with ChannelTypeFeature {
+    val rfcName = "option_simple_taproot"
+    val mandatory = 80
+  }
+
   case object PhoenixZeroReserve extends Feature with InitFeature with ChannelTypeFeature with PermanentChannelFeature {
     val rfcName = "phoenix_zero_reserve"
     val mandatory = 128
@@ -351,11 +356,6 @@ object Features {
     val mandatory = 564
   }
 
-  case object SimpleTaprootChannelsStaging extends Feature with InitFeature with NodeFeature with ChannelTypeFeature {
-    val rfcName = "option_simple_taproot_staging"
-    val mandatory = 180
-  }
-
   /**
    * Activate this feature to provide on-the-fly funding to remote nodes, as specified in bLIP 36: https://github.com/lightning/blips/blob/master/blip-0036.md.
    * TODO: add NodeFeature once bLIP is merged.
@@ -399,8 +399,8 @@ object Features {
     ZeroConf,
     KeySend,
     SimpleClose,
+    SimpleTaprootChannels,
     SimpleTaprootChannelsPhoenix,
-    SimpleTaprootChannelsStaging,
     WakeUpNotificationClient,
     TrampolinePaymentPrototype,
     AsyncPaymentPrototype,
@@ -421,6 +421,7 @@ object Features {
     TrampolinePaymentPrototype -> (PaymentSecret :: Nil),
     KeySend -> (VariableLengthOnion :: Nil),
     SimpleClose -> (ShutdownAnySegwit :: Nil),
+    SimpleTaprootChannels -> (ChannelType :: SimpleClose :: Nil),
     SimpleTaprootChannelsPhoenix -> (ChannelType :: SimpleClose :: Nil),
     AsyncPaymentPrototype -> (TrampolinePaymentPrototype :: Nil),
     OnTheFlyFunding -> (SplicePrototype :: Nil),

eclair-core/src/main/scala/fr/acinq/eclair/NodeParams.scala

@@ -131,7 +131,7 @@ case class NodeParams(nodeKeyManager: NodeKeyManager,
     // We use the most likely commitment format, even though there is no guarantee that this is the one that will be used.
     val commitmentFormat = if (Features.canUseFeature(localFeatures, remoteFeatures, Features.SimpleTaprootChannelsPhoenix)) {
       PhoenixSimpleTaprootChannelCommitmentFormat
-    } else if (Features.canUseFeature(localFeatures, remoteFeatures, Features.SimpleTaprootChannelsStaging)) {
+    } else if (Features.canUseFeature(localFeatures, remoteFeatures, Features.SimpleTaprootChannels)) {
       ZeroFeeHtlcTxSimpleTaprootChannelCommitmentFormat
     } else {
       ZeroFeeHtlcTxAnchorOutputsCommitmentFormat

eclair-core/src/main/scala/fr/acinq/eclair/channel/ChannelFeatures.scala

@@ -95,14 +95,14 @@ object ChannelTypes {
     override def commitmentFormat: CommitmentFormat = ZeroFeeHtlcTxAnchorOutputsCommitmentFormat
     override def toString: String = s"anchor_outputs_zero_fee_htlc_tx${if (scidAlias) "+scid_alias" else ""}${if (zeroConf) "+zeroconf" else ""}"
   }
-  case class SimpleTaprootChannelsStaging(scidAlias: Boolean = false, zeroConf: Boolean = false) extends SupportedChannelType {
+  case class SimpleTaprootChannel(scidAlias: Boolean = false, zeroConf: Boolean = false) extends SupportedChannelType {
     override def features: Set[ChannelTypeFeature] = Set(
       if (scidAlias) Some(Features.ScidAlias) else None,
       if (zeroConf) Some(Features.ZeroConf) else None,
-      Some(Features.SimpleTaprootChannelsStaging),
+      Some(Features.SimpleTaprootChannels),
     ).flatten
     override def commitmentFormat: CommitmentFormat = ZeroFeeHtlcTxSimpleTaprootChannelCommitmentFormat
-    override def toString: String = s"simple_taproot_channel_staging${if (scidAlias) "+scid_alias" else ""}${if (zeroConf) "+zeroconf" else ""}"
+    override def toString: String = s"simple_taproot_channel${if (scidAlias) "+scid_alias" else ""}${if (zeroConf) "+zeroconf" else ""}"
   }
 
   case class UnsupportedChannelType(featureBits: Features[InitFeature]) extends ChannelType {
@@ -127,10 +127,10 @@ object ChannelTypes {
     AnchorOutputsZeroFeeHtlcTx(zeroConf = true),
     AnchorOutputsZeroFeeHtlcTx(scidAlias = true),
     AnchorOutputsZeroFeeHtlcTx(scidAlias = true, zeroConf = true),
-    SimpleTaprootChannelsStaging(),
-    SimpleTaprootChannelsStaging(zeroConf = true),
-    SimpleTaprootChannelsStaging(scidAlias = true),
-    SimpleTaprootChannelsStaging(scidAlias = true, zeroConf = true),
+    SimpleTaprootChannel(),
+    SimpleTaprootChannel(zeroConf = true),
+    SimpleTaprootChannel(scidAlias = true),
+    SimpleTaprootChannel(scidAlias = true, zeroConf = true),
     SimpleTaprootChannelsPhoenix,
   ).map {
     channelType => Features(channelType.features.map(_ -> FeatureSupport.Mandatory).toMap) -> channelType
@@ -150,7 +150,9 @@ object ChannelTypes {
 
   /** Returns our preferred channel type for public channels, if supported by our peer. */
   def preferredForPublicChannels(localFeatures: Features[InitFeature], remoteFeatures: Features[InitFeature]): Option[SupportedChannelType] = {
-    if (Features.canUseFeature(localFeatures, remoteFeatures, Features.AnchorOutputsZeroFeeHtlcTx)) {
+    if (Features.canUseFeature(localFeatures, remoteFeatures, Features.SimpleTaprootChannels)) {
+      Some(SimpleTaprootChannel(scidAlias = Features.canUseFeature(localFeatures, remoteFeatures, Features.ScidAlias)))
+    } else if (Features.canUseFeature(localFeatures, remoteFeatures, Features.AnchorOutputsZeroFeeHtlcTx)) {
       Some(AnchorOutputsZeroFeeHtlcTx(scidAlias = Features.canUseFeature(localFeatures, remoteFeatures, Features.ScidAlias)))
     } else {
       None

eclair-core/src/test/scala/fr/acinq/eclair/channel/InteractiveTxBuilderSpec.scala

@@ -480,7 +480,7 @@ class InteractiveTxBuilderSpec extends TestKitBaseClass with AnyFunSuiteLike wit
     val targetFeerate = FeeratePerKw(2500 sat)
     val fundingA = 150_000 sat
     val utxosA = Seq(80_000 sat, 120_000 sat)
-    withFixture(ChannelTypes.SimpleTaprootChannelsStaging(), fundingA, utxosA, 0 sat, Nil, targetFeerate, 660 sat, 0, RequireConfirmedInputs(forLocal = false, forRemote = false)) { f =>
+    withFixture(ChannelTypes.SimpleTaprootChannel(), fundingA, utxosA, 0 sat, Nil, targetFeerate, 660 sat, 0, RequireConfirmedInputs(forLocal = false, forRemote = false)) { f =>
       import f._
 
       alice ! Start(alice2bob.ref)
@@ -1997,7 +1997,7 @@ class InteractiveTxBuilderSpec extends TestKitBaseClass with AnyFunSuiteLike wit
     val utxosA = Seq(340_000 sat, 40_000 sat, 35_000 sat)
     val fundingB1 = 80_000 sat
     val utxosB = Seq(290_000 sat, 20_000 sat, 15_000 sat)
-    withFixture(ChannelTypes.SimpleTaprootChannelsStaging(), fundingA1, utxosA, fundingB1, utxosB, targetFeerate, 660 sat, 0, RequireConfirmedInputs(forLocal = false, forRemote = false)) { f =>
+    withFixture(ChannelTypes.SimpleTaprootChannel(), fundingA1, utxosA, fundingB1, utxosB, targetFeerate, 660 sat, 0, RequireConfirmedInputs(forLocal = false, forRemote = false)) { f =>
       import f._
 
       val probe = TestProbe()
@@ -2385,7 +2385,7 @@ class InteractiveTxBuilderSpec extends TestKitBaseClass with AnyFunSuiteLike wit
   }
 
   test("invalid tx_signatures (missing shared input signature, taproot)") {
-    testTxSignaturesMissingSharedInputSigs(ChannelTypes.SimpleTaprootChannelsStaging())
+    testTxSignaturesMissingSharedInputSigs(ChannelTypes.SimpleTaprootChannel())
   }
 
   test("invalid commitment index") {

eclair-core/src/test/scala/fr/acinq/eclair/channel/states/ChannelStateTestsHelperMethods.scala

@@ -263,8 +263,8 @@ trait ChannelStateTestsBase extends Assertions with Eventually {
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.DualFunding))(_.updated(Features.DualFunding, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.SimpleClose))(_.updated(Features.SimpleClose, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.AnchorOutputsPhoenix))(_.removed(Features.AnchorOutputsZeroFeeHtlcTx).updated(Features.AnchorOutputs, FeatureSupport.Optional))
-      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaprootPhoenix))(_.removed(Features.SimpleTaprootChannelsStaging).updated(Features.SimpleTaprootChannelsPhoenix, FeatureSupport.Optional).updated(Features.PhoenixZeroReserve, FeatureSupport.Optional))
-      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaproot))(_.updated(Features.SimpleTaprootChannelsStaging, FeatureSupport.Optional))
+      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaproot))(_.updated(Features.SimpleTaprootChannels, FeatureSupport.Optional))
+      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaprootPhoenix))(_.removed(Features.SimpleTaprootChannels).updated(Features.SimpleTaprootChannelsPhoenix, FeatureSupport.Optional).updated(Features.PhoenixZeroReserve, FeatureSupport.Optional))
     )
     val nodeParamsB1 = nodeParamsB.copy(features = nodeParamsB.features
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.DisableWumbo))(_.removed(Features.Wumbo))
@@ -275,8 +275,8 @@ trait ChannelStateTestsBase extends Assertions with Eventually {
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.SimpleClose))(_.updated(Features.SimpleClose, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.DisableSplice))(_.removed(Features.SplicePrototype))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.AnchorOutputsPhoenix))(_.removed(Features.AnchorOutputsZeroFeeHtlcTx).updated(Features.AnchorOutputs, FeatureSupport.Optional))
-      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaprootPhoenix))(_.removed(Features.SimpleTaprootChannelsStaging).updated(Features.SimpleTaprootChannelsPhoenix, FeatureSupport.Optional).updated(Features.PhoenixZeroReserve, FeatureSupport.Optional))
-      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaproot))(_.updated(Features.SimpleTaprootChannelsStaging, FeatureSupport.Optional))
+      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaproot))(_.updated(Features.SimpleTaprootChannels, FeatureSupport.Optional))
+      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaprootPhoenix))(_.removed(Features.SimpleTaprootChannels).updated(Features.SimpleTaprootChannelsPhoenix, FeatureSupport.Optional).updated(Features.PhoenixZeroReserve, FeatureSupport.Optional))
     )
     (nodeParamsA1, nodeParamsB1)
   }
@@ -287,8 +287,8 @@ trait ChannelStateTestsBase extends Assertions with Eventually {
 
     val scidAlias = canUse(Features.ScidAlias) && !announceChannel // alias feature is incompatible with public channel
     val zeroConf = canUse(Features.ZeroConf)
-    if (canUse(Features.SimpleTaprootChannelsStaging)) {
-      ChannelTypes.SimpleTaprootChannelsStaging(scidAlias, zeroConf)
+    if (canUse(Features.SimpleTaprootChannels)) {
+      ChannelTypes.SimpleTaprootChannel(scidAlias, zeroConf)
     } else if (canUse(Features.SimpleTaprootChannelsPhoenix)) {
       ChannelTypes.SimpleTaprootChannelsPhoenix
     } else if (canUse(Features.AnchorOutputsZeroFeeHtlcTx)) {

eclair-core/src/test/scala/fr/acinq/eclair/channel/states/a/WaitForOpenChannelStateSpec.scala

@@ -78,7 +78,7 @@ class WaitForOpenChannelStateSpec extends TestKitBaseClass with FixtureAnyFunSui
   test("recv OpenChannel (simple taproot channels)", Tag(ChannelStateTestsTags.OptionSimpleTaproot)) { f =>
     import f._
     val open = alice2bob.expectMsgType[OpenChannel]
-    assert(open.channelType_opt.contains(ChannelTypes.SimpleTaprootChannelsStaging()))
+    assert(open.channelType_opt.contains(ChannelTypes.SimpleTaprootChannel()))
     alice2bob.forward(bob)
     awaitCond(bob.stateName == WAIT_FOR_FUNDING_CREATED)
     assert(bob.stateData.asInstanceOf[DATA_WAIT_FOR_FUNDING_CREATED].commitmentFormat == ZeroFeeHtlcTxSimpleTaprootChannelCommitmentFormat)
@@ -88,7 +88,7 @@ class WaitForOpenChannelStateSpec extends TestKitBaseClass with FixtureAnyFunSui
   test("recv OpenChannel (simple taproot channels, missing nonce)", Tag(ChannelStateTestsTags.OptionSimpleTaproot)) { f =>
     import f._
     val open = alice2bob.expectMsgType[OpenChannel]
-    assert(open.channelType_opt.contains(ChannelTypes.SimpleTaprootChannelsStaging()))
+    assert(open.channelType_opt.contains(ChannelTypes.SimpleTaprootChannel()))
     assert(open.commitNonce_opt.isDefined)
     alice2bob.forward(bob, open.copy(tlvStream = open.tlvStream.copy(records = open.tlvStream.records.filterNot(_.isInstanceOf[ChannelTlv.NextLocalNonceTlv]))))
     val error = bob2alice.expectMsgType[Error]

eclair-core/src/test/scala/fr/acinq/eclair/wire/protocol/LightningMessageCodecsSpec.scala

@@ -304,7 +304,7 @@ class LightningMessageCodecsSpec extends AnyFunSuite {
       defaultEncoded ++ hex"0000" ++ hex"0107 04400000101000" -> defaultOpen.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty), ChannelTlv.ChannelTypeTlv(ChannelTypes.AnchorOutputs(scidAlias = true, zeroConf = true)))),
       defaultEncoded ++ hex"0000" ++ hex"0107 04400000401000" -> defaultOpen.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty), ChannelTlv.ChannelTypeTlv(ChannelTypes.AnchorOutputsZeroFeeHtlcTx(scidAlias = true, zeroConf = true)))),
       // taproot channel type + nonce
-      defaultEncoded ++ hex"0000" ++ hex"01 17 1000000000000000000000000000000000400000000000" ++ hex"04 42 2062534ccb3be5a8997843f3b6bc530a94cbc60eceb538674ceedd62d8be07f2dfa5df6acf3ded7444268d56925bb2c33afe71a55f4fa88f3985451a681415930f6b" -> defaultOpen.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty), ChannelTlv.ChannelTypeTlv(ChannelTypes.SimpleTaprootChannelsStaging(scidAlias = true)), ChannelTlv.NextLocalNonceTlv(nonce)))
+      defaultEncoded ++ hex"0000" ++ hex"01 0b 0100000000400000000000" ++ hex"04 42 2062534ccb3be5a8997843f3b6bc530a94cbc60eceb538674ceedd62d8be07f2dfa5df6acf3ded7444268d56925bb2c33afe71a55f4fa88f3985451a681415930f6b" -> defaultOpen.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty), ChannelTlv.ChannelTypeTlv(ChannelTypes.SimpleTaprootChannel(scidAlias = true)), ChannelTlv.NextLocalNonceTlv(nonce)))
     )
 
     for ((encoded, expected) <- testCases) {
@@ -378,7 +378,7 @@ class LightningMessageCodecsSpec extends AnyFunSuite {
       defaultEncoded ++ hex"0000" -> defaultAccept.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty))), // empty upfront_shutdown_script
       defaultEncoded ++ hex"0000" ++ hex"0100" -> defaultAccept.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty), ChannelTlv.ChannelTypeTlv(ChannelTypes.UnsupportedChannelType(Features.empty)))), // empty upfront_shutdown_script with channel type
       defaultEncoded ++ hex"0004 01abcdef" -> defaultAccept.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(hex"01abcdef"))), // non-empty upfront_shutdown_script
-      defaultEncoded ++ hex"0000" ++ hex"01 17 1000000000000000000000000000000000000000000000" ++ hex"04 42 2062534ccb3be5a8997843f3b6bc530a94cbc60eceb538674ceedd62d8be07f2dfa5df6acf3ded7444268d56925bb2c33afe71a55f4fa88f3985451a681415930f6b" -> defaultAccept.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty), ChannelTlv.ChannelTypeTlv(ChannelTypes.SimpleTaprootChannelsStaging()), ChannelTlv.NextLocalNonceTlv(nonce))), // empty upfront_shutdown_script with taproot channel type and nonce
+      defaultEncoded ++ hex"0000" ++ hex"01 0b 0100000000000000000000" ++ hex"04 42 2062534ccb3be5a8997843f3b6bc530a94cbc60eceb538674ceedd62d8be07f2dfa5df6acf3ded7444268d56925bb2c33afe71a55f4fa88f3985451a681415930f6b" -> defaultAccept.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty), ChannelTlv.ChannelTypeTlv(ChannelTypes.SimpleTaprootChannel()), ChannelTlv.NextLocalNonceTlv(nonce))), // empty upfront_shutdown_script with taproot channel type and nonce
       defaultEncoded ++ hex"0004 01abcdef" ++ hex"0103401000" -> defaultAccept.copy(tlvStream = TlvStream(ChannelTlv.UpfrontShutdownScriptTlv(hex"01abcdef"), ChannelTlv.ChannelTypeTlv(ChannelTypes.AnchorOutputsZeroFeeHtlcTx()))), // non-empty upfront_shutdown_script with channel type
       defaultEncoded ++ hex"0000 0302002a 050102" -> defaultAccept.copy(tlvStream = TlvStream(Set[AcceptChannelTlv](ChannelTlv.UpfrontShutdownScriptTlv(ByteVector.empty)), Set(GenericTlv(UInt64(3), hex"002a"), GenericTlv(UInt64(5), hex"02")))), // empty upfront_shutdown_script + unknown odd tlv records
       defaultEncoded ++ hex"0002 1234 0303010203" -> defaultAccept.copy(tlvStream = TlvStream(Set[AcceptChannelTlv](ChannelTlv.UpfrontShutdownScriptTlv(hex"1234")), Set(GenericTlv(UInt64(3), hex"010203")))), // non-empty upfront_shutdown_script + unknown odd tlv records

eclair-node/src/main/scala/fr/acinq/eclair/api/handlers/Channel.scala

@@ -37,10 +37,10 @@ trait Channel {
     ChannelTypes.AnchorOutputsZeroFeeHtlcTx(zeroConf = true),
     ChannelTypes.AnchorOutputsZeroFeeHtlcTx(scidAlias = true),
     ChannelTypes.AnchorOutputsZeroFeeHtlcTx(scidAlias = true, zeroConf = true),
-    ChannelTypes.SimpleTaprootChannelsStaging(),
-    ChannelTypes.SimpleTaprootChannelsStaging(zeroConf = true),
-    ChannelTypes.SimpleTaprootChannelsStaging(scidAlias = true),
-    ChannelTypes.SimpleTaprootChannelsStaging(scidAlias = true, zeroConf = true),
+    ChannelTypes.SimpleTaprootChannel(),
+    ChannelTypes.SimpleTaprootChannel(zeroConf = true),
+    ChannelTypes.SimpleTaprootChannel(scidAlias = true),
+    ChannelTypes.SimpleTaprootChannel(scidAlias = true, zeroConf = true)
   ).map(ct => ct.toString -> ct).toMap // we use the toString method as name in the api
 
   val open: Route = postRequest("open") { implicit t =>