X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fsign%2Fmod.rs;h=5912b7b84e16e393daffb3a144c6b12ee2e4331b;hb=9bd1cc76609e14c286477522cf2b56f17bd4346d;hp=5b42796a94f9586fe2dd42fd7210fada4be7297f;hpb=6016101ac8ff31275f31f68eef8d33e94b19c0b1;p=rust-lightning

diff --git a/lightning/src/sign/mod.rs b/lightning/src/sign/mod.rs
index 5b42796a..5912b7b8 100644
--- a/lightning/src/sign/mod.rs
+++ b/lightning/src/sign/mod.rs
@@ -30,13 +30,12 @@ use bitcoin::secp256k1::{KeyPair, PublicKey, Scalar, Secp256k1, SecretKey, Signi
 use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature};
 use bitcoin::secp256k1::schnorr;
-use bitcoin::{PackedLockTime, secp256k1, Sequence, Witness};
+use bitcoin::{PackedLockTime, secp256k1, Sequence, Witness, Txid};
 
 use crate::util::transaction_utils;
 use crate::util::crypto::{hkdf_extract_expand_twice, sign, sign_with_aux_rand};
 use crate::util::ser::{Writeable, Writer, Readable, ReadableArgs};
 use crate::chain::transaction::OutPoint;
-use crate::events::bump_transaction::HTLCDescriptor;
 use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
 use crate::ln::{chan_utils, PaymentPreimage};
 use crate::ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction, ClosingTransaction};
@@ -107,6 +106,12 @@ impl_writeable_tlv_based!(DelayedPaymentOutputDescriptor, {
 	(12, channel_value_satoshis, required),
 });
 
+pub(crate) const P2WPKH_WITNESS_WEIGHT: u64 = 1 /* num stack items */ +
+	1 /* sig length */ +
+	73 /* sig including sighash flag */ +
+	1 /* pubkey length */ +
+	33 /* pubkey */;
+
 /// Information about a spendable output to our "payment key".
 ///
 /// See [`SpendableOutputDescriptor::StaticPaymentOutput`] for more details on how to spend this.
@@ -121,20 +126,52 @@ pub struct StaticPaymentOutputDescriptor {
 	pub channel_keys_id: [u8; 32],
 	/// The value of the channel which this transactions spends.
 	pub channel_value_satoshis: u64,
+	/// The necessary channel parameters that need to be provided to the re-derived signer through
+	/// [`ChannelSigner::provide_channel_parameters`].
+	///
+	/// Added as optional, but always `Some` if the descriptor was produced in v0.0.117 or later.
+	pub channel_transaction_parameters: Option<ChannelTransactionParameters>,
 }
 impl StaticPaymentOutputDescriptor {
+	/// Returns the `witness_script` of the spendable output.
+	///
+	/// Note that this will only return `Some` for [`StaticPaymentOutputDescriptor`]s that
+	/// originated from an anchor outputs channel, as they take the form of a P2WSH script.
+	pub fn witness_script(&self) -> Option<Script> {
+		self.channel_transaction_parameters.as_ref()
+			.and_then(|channel_params|
+				 if channel_params.channel_type_features.supports_anchors_zero_fee_htlc_tx() {
+					let payment_point = channel_params.holder_pubkeys.payment_point;
+					Some(chan_utils::get_to_countersignatory_with_anchors_redeemscript(&payment_point))
+				 } else {
+					 None
+				 }
+			)
+	}
+
 	/// The maximum length a well-formed witness spending one of these should have.
 	/// Note: If you have the grind_signatures feature enabled, this will be at least 1 byte
 	/// shorter.
-	// Calculated as 1 byte legnth + 73 byte signature, 1 byte empty vec push, 1 byte length plus
-	// redeemscript push length.
-	pub const MAX_WITNESS_LENGTH: usize = 1 + 73 + 34;
+	pub fn max_witness_length(&self) -> usize {
+		if self.channel_transaction_parameters.as_ref()
+			.map(|channel_params| channel_params.channel_type_features.supports_anchors_zero_fee_htlc_tx())
+			.unwrap_or(false)
+		{
+			let witness_script_weight = 1 /* pubkey push */ + 33 /* pubkey */ +
+				1 /* OP_CHECKSIGVERIFY */ + 1 /* OP_1 */ + 1 /* OP_CHECKSEQUENCEVERIFY */;
+			1 /* num witness items */ + 1 /* sig push */ + 73 /* sig including sighash flag */ +
+				1 /* witness script push */ + witness_script_weight
+		} else {
+			P2WPKH_WITNESS_WEIGHT as usize
+		}
+	}
 }
 impl_writeable_tlv_based!(StaticPaymentOutputDescriptor, {
 	(0, outpoint, required),
 	(2, output, required),
 	(4, channel_keys_id, required),
 	(6, channel_value_satoshis, required),
+	(7, channel_transaction_parameters, option),
 });
 
 /// Describes the necessary information to spend a spendable output.
@@ -201,15 +238,23 @@ pub enum SpendableOutputDescriptor {
 	/// [`DelayedPaymentOutputDescriptor::to_self_delay`] contained here to
 	/// [`chan_utils::get_revokeable_redeemscript`].
 	DelayedPaymentOutput(DelayedPaymentOutputDescriptor),
-	/// An output to a P2WPKH, spendable exclusively by our payment key (i.e., the private key
-	/// which corresponds to the `payment_point` in [`ChannelSigner::pubkeys`]). The witness
-	/// in the spending input is, thus, simply:
+	/// An output spendable exclusively by our payment key (i.e., the private key that corresponds
+	/// to the `payment_point` in [`ChannelSigner::pubkeys`]). The output type depends on the
+	/// channel type negotiated.
+	///
+	/// On an anchor outputs channel, the witness in the spending input is:
+	/// ```bitcoin
+	/// <BIP 143 signature> <witness script>
+	/// ```
+	///
+	/// Otherwise, it is:
 	/// ```bitcoin
 	/// <BIP 143 signature> <payment key>
 	/// ```
 	///
 	/// These are generally the result of our counterparty having broadcast the current state,
-	/// allowing us to claim the non-HTLC-encumbered outputs immediately.
+	/// allowing us to claim the non-HTLC-encumbered outputs immediately, or after one confirmation
+	/// in the case of anchor outputs channels.
 	StaticPaymentOutput(StaticPaymentOutputDescriptor),
 }
 
@@ -229,6 +274,9 @@ impl SpendableOutputDescriptor {
 	///
 	/// Note that this does not include any signatures, just the information required to
 	/// construct the transaction and sign it.
+	///
+	/// This is not exported to bindings users as there is no standard serialization for an input.
+	/// See [`Self::create_spendable_outputs_psbt`] instead.
 	pub fn to_psbt_input(&self) -> bitcoin::psbt::Input {
 		match self {
 			SpendableOutputDescriptor::StaticOutput { output, .. } => {
@@ -280,13 +328,22 @@ impl SpendableOutputDescriptor {
 			match outp {
 				SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
 					if !output_set.insert(descriptor.outpoint) { return Err(()); }
+					let sequence =
+						if descriptor.channel_transaction_parameters.as_ref()
+							.map(|channel_params| channel_params.channel_type_features.supports_anchors_zero_fee_htlc_tx())
+							.unwrap_or(false)
+						{
+							Sequence::from_consensus(1)
+						} else {
+							Sequence::ZERO
+						};
 					input.push(TxIn {
 						previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
 						script_sig: Script::new(),
-						sequence: Sequence::ZERO,
+						sequence,
 						witness: Witness::new(),
 					});
-					witness_weight += StaticPaymentOutputDescriptor::MAX_WITNESS_LENGTH;
+					witness_weight += descriptor.max_witness_length();
 					#[cfg(feature = "grind_signatures")]
 					{ witness_weight -= 1; } // Guarantees a low R signature
 					input_value += descriptor.output.value;
@@ -343,6 +400,151 @@ impl SpendableOutputDescriptor {
 	}
 }
 
+/// The parameters required to derive a channel signer via [`SignerProvider`].
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct ChannelDerivationParameters {
+	/// The value in satoshis of the channel we're attempting to spend the anchor output of.
+	pub value_satoshis: u64,
+	/// The unique identifier to re-derive the signer for the associated channel.
+	pub keys_id: [u8; 32],
+	/// The necessary channel parameters that need to be provided to the re-derived signer through
+	/// [`ChannelSigner::provide_channel_parameters`].
+	pub transaction_parameters: ChannelTransactionParameters,
+}
+
+impl_writeable_tlv_based!(ChannelDerivationParameters, {
+    (0, value_satoshis, required),
+    (2, keys_id, required),
+    (4, transaction_parameters, required),
+});
+
+/// A descriptor used to sign for a commitment transaction's HTLC output.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct HTLCDescriptor {
+	/// The parameters required to derive the signer for the HTLC input.
+	pub channel_derivation_parameters: ChannelDerivationParameters,
+	/// The txid of the commitment transaction in which the HTLC output lives.
+	pub commitment_txid: Txid,
+	/// The number of the commitment transaction in which the HTLC output lives.
+	pub per_commitment_number: u64,
+	/// The key tweak corresponding to the number of the commitment transaction in which the HTLC
+	/// output lives. This tweak is applied to all the basepoints for both parties in the channel to
+	/// arrive at unique keys per commitment.
+	///
+	/// See <https://github.com/lightning/bolts/blob/master/03-transactions.md#keys> for more info.
+	pub per_commitment_point: PublicKey,
+	/// The feerate to use on the HTLC claiming transaction. This is always `0` for HTLCs
+	/// originating from a channel supporting anchor outputs, otherwise it is the channel's
+	/// negotiated feerate at the time the commitment transaction was built.
+	pub feerate_per_kw: u32,
+	/// The details of the HTLC as it appears in the commitment transaction.
+	pub htlc: HTLCOutputInCommitment,
+	/// The preimage, if `Some`, to claim the HTLC output with. If `None`, the timeout path must be
+	/// taken.
+	pub preimage: Option<PaymentPreimage>,
+	/// The counterparty's signature required to spend the HTLC output.
+	pub counterparty_sig: Signature
+}
+
+impl_writeable_tlv_based!(HTLCDescriptor, {
+	(0, channel_derivation_parameters, required),
+	(1, feerate_per_kw, (default_value, 0)),
+	(2, commitment_txid, required),
+	(4, per_commitment_number, required),
+	(6, per_commitment_point, required),
+	(8, htlc, required),
+	(10, preimage, option),
+	(12, counterparty_sig, required),
+});
+
+impl HTLCDescriptor {
+	/// Returns the outpoint of the HTLC output in the commitment transaction. This is the outpoint
+	/// being spent by the HTLC input in the HTLC transaction.
+	pub fn outpoint(&self) -> bitcoin::OutPoint {
+		bitcoin::OutPoint {
+			txid: self.commitment_txid,
+			vout: self.htlc.transaction_output_index.unwrap(),
+		}
+	}
+
+	/// Returns the UTXO to be spent by the HTLC input, which can be obtained via
+	/// [`Self::unsigned_tx_input`].
+	pub fn previous_utxo<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> TxOut {
+		TxOut {
+			script_pubkey: self.witness_script(secp).to_v0_p2wsh(),
+			value: self.htlc.amount_msat / 1000,
+		}
+	}
+
+	/// Returns the unsigned transaction input spending the HTLC output in the commitment
+	/// transaction.
+	pub fn unsigned_tx_input(&self) -> TxIn {
+		chan_utils::build_htlc_input(
+			&self.commitment_txid, &self.htlc, &self.channel_derivation_parameters.transaction_parameters.channel_type_features
+		)
+	}
+
+	/// Returns the delayed output created as a result of spending the HTLC output in the commitment
+	/// transaction.
+	pub fn tx_output<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> TxOut {
+		let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
+		let broadcaster_keys = channel_params.broadcaster_pubkeys();
+		let counterparty_keys = channel_params.countersignatory_pubkeys();
+		let broadcaster_delayed_key = chan_utils::derive_public_key(
+			secp, &self.per_commitment_point, &broadcaster_keys.delayed_payment_basepoint
+		);
+		let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
+			secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint
+		);
+		chan_utils::build_htlc_output(
+			self.feerate_per_kw, channel_params.contest_delay(), &self.htlc,
+			channel_params.channel_type_features(), &broadcaster_delayed_key, &counterparty_revocation_key
+		)
+	}
+
+	/// Returns the witness script of the HTLC output in the commitment transaction.
+	pub fn witness_script<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> Script {
+		let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
+		let broadcaster_keys = channel_params.broadcaster_pubkeys();
+		let counterparty_keys = channel_params.countersignatory_pubkeys();
+		let broadcaster_htlc_key = chan_utils::derive_public_key(
+			secp, &self.per_commitment_point, &broadcaster_keys.htlc_basepoint
+		);
+		let counterparty_htlc_key = chan_utils::derive_public_key(
+			secp, &self.per_commitment_point, &counterparty_keys.htlc_basepoint
+		);
+		let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
+			secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint
+		);
+		chan_utils::get_htlc_redeemscript_with_explicit_keys(
+			&self.htlc, channel_params.channel_type_features(), &broadcaster_htlc_key, &counterparty_htlc_key,
+			&counterparty_revocation_key,
+		)
+	}
+
+	/// Returns the fully signed witness required to spend the HTLC output in the commitment
+	/// transaction.
+	pub fn tx_input_witness(&self, signature: &Signature, witness_script: &Script) -> Witness {
+		chan_utils::build_htlc_input_witness(
+			signature, &self.counterparty_sig, &self.preimage, witness_script,
+			&self.channel_derivation_parameters.transaction_parameters.channel_type_features
+		)
+	}
+
+	/// Derives the channel signer required to sign the HTLC input.
+	pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
+	where
+		SP::Target: SignerProvider<Signer = S>
+	{
+		let mut signer = signer_provider.derive_channel_signer(
+			self.channel_derivation_parameters.value_satoshis,
+			self.channel_derivation_parameters.keys_id,
+		);
+		signer.provide_channel_parameters(&self.channel_derivation_parameters.transaction_parameters);
+		signer
+	}
+}
+
 /// A trait to handle Lightning channel key material without concretizing the channel type or
 /// the signature mechanism.
 pub trait ChannelSigner {
@@ -429,31 +631,26 @@ pub trait EcdsaChannelSigner: ChannelSigner {
 	/// This is required in order for the signer to make sure that the state has moved
 	/// forward and it is safe to sign the next counterparty commitment.
 	fn validate_counterparty_revocation(&self, idx: u64, secret: &SecretKey) -> Result<(), ()>;
-	/// Creates a signature for a holder's commitment transaction and its claiming HTLC transactions.
+	/// Creates a signature for a holder's commitment transaction.
 	///
 	/// This will be called
 	/// - with a non-revoked `commitment_tx`.
 	/// - with the latest `commitment_tx` when we initiate a force-close.
-	/// - with the previous `commitment_tx`, just to get claiming HTLC
-	///   signatures, if we are reacting to a [`ChannelMonitor`]
-	///   [replica](https://github.com/lightningdevkit/rust-lightning/blob/main/GLOSSARY.md#monitor-replicas)
-	///   that decided to broadcast before it had been updated to the latest `commitment_tx`.
 	///
 	/// This may be called multiple times for the same transaction.
 	///
 	/// An external signer implementation should check that the commitment has not been revoked.
-	///
-	/// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
+	//
 	// TODO: Document the things someone using this interface should enforce before signing.
-	fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction,
-		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()>;
-	/// Same as [`sign_holder_commitment_and_htlcs`], but exists only for tests to get access to
-	/// holder commitment transactions which will be broadcasted later, after the channel has moved
-	/// on to a newer state. Thus, needs its own method as [`sign_holder_commitment_and_htlcs`] may
-	/// enforce that we only ever get called once.
+	fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction,
+		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
+	/// Same as [`sign_holder_commitment`], but exists only for tests to get access to holder
+	/// commitment transactions which will be broadcasted later, after the channel has moved on to a
+	/// newer state. Thus, needs its own method as [`sign_holder_commitment`] may enforce that we
+	/// only ever get called once.
 	#[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
-	fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction,
-		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()>;
+	fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction,
+		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
 	/// Create a signature for the given input in a transaction spending an HTLC transaction output
 	/// or a commitment transaction `to_local` output when our counterparty broadcasts an old state.
 	///
@@ -494,11 +691,14 @@ pub trait EcdsaChannelSigner: ChannelSigner {
 		secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
 	/// Computes the signature for a commitment transaction's HTLC output used as an input within
 	/// `htlc_tx`, which spends the commitment transaction at index `input`. The signature returned
-	/// must be be computed using [`EcdsaSighashType::All`]. Note that this should only be used to
-	/// sign HTLC transactions from channels supporting anchor outputs after all additional
-	/// inputs/outputs have been added to the transaction.
+	/// must be be computed using [`EcdsaSighashType::All`].
+	///
+	/// Note that this may be called for HTLCs in the penultimate commitment transaction if a
+	/// [`ChannelMonitor`] [replica](https://github.com/lightningdevkit/rust-lightning/blob/main/GLOSSARY.md#monitor-replicas)
+	/// broadcasts it before receiving the update for the latest commitment transaction.
 	///
 	/// [`EcdsaSighashType::All`]: bitcoin::blockdata::transaction::EcdsaSighashType::All
+	/// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
 	fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize,
 		htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<secp256k1::All>
 	) -> Result<Signature, ()>;
@@ -838,42 +1038,68 @@ impl InMemorySigner {
 
 	/// Returns the counterparty's pubkeys.
 	///
-	/// Will panic if [`ChannelSigner::provide_channel_parameters`] has not been called before.
-	pub fn counterparty_pubkeys(&self) -> &ChannelPublicKeys { &self.get_channel_parameters().counterparty_parameters.as_ref().unwrap().pubkeys }
+	/// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
+	/// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
+	pub fn counterparty_pubkeys(&self) -> Option<&ChannelPublicKeys> {
+		self.get_channel_parameters()
+			.and_then(|params| params.counterparty_parameters.as_ref().map(|params| &params.pubkeys))
+	}
+
 	/// Returns the `contest_delay` value specified by our counterparty and applied on holder-broadcastable
 	/// transactions, i.e., the amount of time that we have to wait to recover our funds if we
 	/// broadcast a transaction.
 	///
-	/// Will panic if [`ChannelSigner::provide_channel_parameters`] has not been called before.
-	pub fn counterparty_selected_contest_delay(&self) -> u16 { self.get_channel_parameters().counterparty_parameters.as_ref().unwrap().selected_contest_delay }
+	/// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
+	/// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
+	pub fn counterparty_selected_contest_delay(&self) -> Option<u16> {
+		self.get_channel_parameters()
+			.and_then(|params| params.counterparty_parameters.as_ref().map(|params| params.selected_contest_delay))
+	}
+
 	/// Returns the `contest_delay` value specified by us and applied on transactions broadcastable
 	/// by our counterparty, i.e., the amount of time that they have to wait to recover their funds
 	/// if they broadcast a transaction.
 	///
-	/// Will panic if [`ChannelSigner::provide_channel_parameters`] has not been called before.
-	pub fn holder_selected_contest_delay(&self) -> u16 { self.get_channel_parameters().holder_selected_contest_delay }
+	/// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
+	/// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
+	pub fn holder_selected_contest_delay(&self) -> Option<u16> {
+		self.get_channel_parameters().map(|params| params.holder_selected_contest_delay)
+	}
+
 	/// Returns whether the holder is the initiator.
 	///
-	/// Will panic if [`ChannelSigner::provide_channel_parameters`] has not been called before.
-	pub fn is_outbound(&self) -> bool { self.get_channel_parameters().is_outbound_from_holder }
+	/// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
+	/// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
+	pub fn is_outbound(&self) -> Option<bool> {
+		self.get_channel_parameters().map(|params| params.is_outbound_from_holder)
+	}
+
 	/// Funding outpoint
 	///
-	/// Will panic if [`ChannelSigner::provide_channel_parameters`] has not been called before.
-	pub fn funding_outpoint(&self) -> &OutPoint { self.get_channel_parameters().funding_outpoint.as_ref().unwrap() }
+	/// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
+	/// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
+	pub fn funding_outpoint(&self) -> Option<&OutPoint> {
+		self.get_channel_parameters().map(|params| params.funding_outpoint.as_ref()).flatten()
+	}
+
 	/// Returns a [`ChannelTransactionParameters`] for this channel, to be used when verifying or
 	/// building transactions.
 	///
-	/// Will panic if [`ChannelSigner::provide_channel_parameters`] has not been called before.
-	pub fn get_channel_parameters(&self) -> &ChannelTransactionParameters {
-		self.channel_parameters.as_ref().unwrap()
+	/// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
+	/// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
+	pub fn get_channel_parameters(&self) -> Option<&ChannelTransactionParameters> {
+		self.channel_parameters.as_ref()
 	}
+
 	/// Returns the channel type features of the channel parameters. Should be helpful for
 	/// determining a channel's category, i. e. legacy/anchors/taproot/etc.
 	///
-	/// Will panic if [`ChannelSigner::provide_channel_parameters`] has not been called before.
-	pub fn channel_type_features(&self) -> &ChannelTypeFeatures {
-		&self.get_channel_parameters().channel_type_features
+	/// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
+	/// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
+	pub fn channel_type_features(&self) -> Option<&ChannelTypeFeatures> {
+		self.get_channel_parameters().map(|params| &params.channel_type_features)
 	}
+
 	/// Sign the single input of `spend_tx` at index `input_idx`, which spends the output described
 	/// by `descriptor`, returning the witness stack for the input.
 	///
@@ -891,18 +1117,36 @@ impl InMemorySigner {
 		if !spend_tx.input[input_idx].script_sig.is_empty() { return Err(()); }
 		if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint() { return Err(()); }
 
-		let remotepubkey = self.pubkeys().payment_point;
-		let witness_script = bitcoin::Address::p2pkh(&::bitcoin::PublicKey{compressed: true, inner: remotepubkey}, Network::Testnet).script_pubkey();
+		let remotepubkey = bitcoin::PublicKey::new(self.pubkeys().payment_point);
+		// We cannot always assume that `channel_parameters` is set, so can't just call
+		// `self.channel_parameters()` or anything that relies on it
+		let supports_anchors_zero_fee_htlc_tx = self.channel_type_features()
+			.map(|features| features.supports_anchors_zero_fee_htlc_tx())
+			.unwrap_or(false);
+
+		let witness_script = if supports_anchors_zero_fee_htlc_tx {
+			chan_utils::get_to_countersignatory_with_anchors_redeemscript(&remotepubkey.inner)
+		} else {
+			Script::new_p2pkh(&remotepubkey.pubkey_hash())
+		};
 		let sighash = hash_to_message!(&sighash::SighashCache::new(spend_tx).segwit_signature_hash(input_idx, &witness_script, descriptor.output.value, EcdsaSighashType::All).unwrap()[..]);
 		let remotesig = sign_with_aux_rand(secp_ctx, &sighash, &self.payment_key, &self);
-		let payment_script = bitcoin::Address::p2wpkh(&::bitcoin::PublicKey{compressed: true, inner: remotepubkey}, Network::Bitcoin).unwrap().script_pubkey();
+		let payment_script = if supports_anchors_zero_fee_htlc_tx {
+			witness_script.to_v0_p2wsh()
+		} else {
+			Script::new_v0_p2wpkh(&remotepubkey.wpubkey_hash().unwrap())
+		};
 
 		if payment_script != descriptor.output.script_pubkey { return Err(()); }
 
 		let mut witness = Vec::with_capacity(2);
 		witness.push(remotesig.serialize_der().to_vec());
 		witness[0].push(EcdsaSighashType::All as u8);
-		witness.push(remotepubkey.serialize().to_vec());
+		if supports_anchors_zero_fee_htlc_tx {
+			witness.push(witness_script.to_bytes());
+		} else {
+			witness.push(remotepubkey.to_bytes());
+		}
 		Ok(witness)
 	}
 
@@ -982,13 +1226,16 @@ impl ChannelSigner for InMemorySigner {
 	}
 }
 
+const MISSING_PARAMS_ERR: &'static str = "ChannelSigner::provide_channel_parameters must be called before signing operations";
+
 impl EcdsaChannelSigner for InMemorySigner {
 	fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, _preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 		let trusted_tx = commitment_tx.trust();
 		let keys = trusted_tx.keys();
 
 		let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
-		let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
+		let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
+		let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
 
 		let built_tx = trusted_tx.built_transaction();
 		let commitment_sig = built_tx.sign_counterparty_commitment(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx);
@@ -996,10 +1243,13 @@ impl EcdsaChannelSigner for InMemorySigner {
 
 		let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len());
 		for htlc in commitment_tx.htlcs() {
-			let channel_parameters = self.get_channel_parameters();
-			let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), self.holder_selected_contest_delay(), htlc, &channel_parameters.channel_type_features, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
-			let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, self.channel_type_features(), &keys);
-			let htlc_sighashtype = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
+			let channel_parameters = self.get_channel_parameters().expect(MISSING_PARAMS_ERR);
+			let holder_selected_contest_delay =
+				self.holder_selected_contest_delay().expect(MISSING_PARAMS_ERR);
+			let chan_type = &channel_parameters.channel_type_features;
+			let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), holder_selected_contest_delay, htlc, chan_type, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+			let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, chan_type, &keys);
+			let htlc_sighashtype = if chan_type.supports_anchors_zero_fee_htlc_tx() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
 			let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).segwit_signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, htlc_sighashtype).unwrap()[..]);
 			let holder_htlc_key = chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key);
 			htlc_sigs.push(sign(secp_ctx, &htlc_sighash, &holder_htlc_key));
@@ -1012,25 +1262,21 @@ impl EcdsaChannelSigner for InMemorySigner {
 		Ok(())
 	}
 
-	fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
+	fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 		let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
-		let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
+		let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
+		let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
 		let trusted_tx = commitment_tx.trust();
-		let sig = trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx);
-		let channel_parameters = self.get_channel_parameters();
-		let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), &self, secp_ctx)?;
-		Ok((sig, htlc_sigs))
+		Ok(trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx))
 	}
 
 	#[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
-	fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
+	fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 		let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
-		let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
+		let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
+		let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
 		let trusted_tx = commitment_tx.trust();
-		let sig = trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx);
-		let channel_parameters = self.get_channel_parameters();
-		let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), &self, secp_ctx)?;
-		Ok((sig, htlc_sigs))
+		Ok(trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx))
 	}
 
 	fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
@@ -1038,8 +1284,11 @@ impl EcdsaChannelSigner for InMemorySigner {
 		let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
 		let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint);
 		let witness_script = {
-			let counterparty_delayedpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().delayed_payment_basepoint);
-			chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.holder_selected_contest_delay(), &counterparty_delayedpubkey)
+			let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
+			let holder_selected_contest_delay =
+				self.holder_selected_contest_delay().expect(MISSING_PARAMS_ERR);
+			let counterparty_delayedpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &counterparty_keys.delayed_payment_basepoint);
+			chan_utils::get_revokeable_redeemscript(&revocation_pubkey, holder_selected_contest_delay, &counterparty_delayedpubkey)
 		};
 		let mut sighash_parts = sighash::SighashCache::new(justice_tx);
 		let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
@@ -1051,9 +1300,11 @@ impl EcdsaChannelSigner for InMemorySigner {
 		let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
 		let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint);
 		let witness_script = {
-			let counterparty_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint);
+			let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
+			let counterparty_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &counterparty_keys.htlc_basepoint);
 			let holder_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint);
-			chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, self.channel_type_features(), &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
+			let chan_type = self.channel_type_features().expect(MISSING_PARAMS_ERR);
+			chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, chan_type, &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
 		};
 		let mut sighash_parts = sighash::SighashCache::new(justice_tx);
 		let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
@@ -1077,9 +1328,11 @@ impl EcdsaChannelSigner for InMemorySigner {
 	fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 		let htlc_key = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key);
 		let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint);
-		let counterparty_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint);
+		let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
+		let counterparty_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &counterparty_keys.htlc_basepoint);
 		let htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint);
-		let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, self.channel_type_features(), &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey);
+		let chan_type = self.channel_type_features().expect(MISSING_PARAMS_ERR);
+		let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, chan_type, &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey);
 		let mut sighash_parts = sighash::SighashCache::new(htlc_tx);
 		let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
 		Ok(sign_with_aux_rand(secp_ctx, &sighash, &htlc_key, &self))
@@ -1087,7 +1340,8 @@ impl EcdsaChannelSigner for InMemorySigner {
 
 	fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 		let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
-		let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
+		let counterparty_funding_key = &self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR).funding_pubkey;
+		let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, counterparty_funding_key);
 		Ok(closing_tx.trust().sign(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
 	}
 
@@ -1353,9 +1607,11 @@ impl KeysManager {
 				SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
 					let input_idx = psbt.unsigned_tx.input.iter().position(|i| i.previous_output == descriptor.outpoint.into_bitcoin_outpoint()).ok_or(())?;
 					if keys_cache.is_none() || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id {
-						keys_cache = Some((
-							self.derive_channel_keys(descriptor.channel_value_satoshis, &descriptor.channel_keys_id),
-							descriptor.channel_keys_id));
+						let mut signer = self.derive_channel_keys(descriptor.channel_value_satoshis, &descriptor.channel_keys_id);
+						if let Some(channel_params) = descriptor.channel_transaction_parameters.as_ref() {
+							signer.provide_channel_parameters(channel_params);
+						}
+						keys_cache = Some((signer, descriptor.channel_keys_id));
 					}
 					let witness = Witness::from_vec(keys_cache.as_ref().unwrap().0.sign_counterparty_payment_input(&psbt.unsigned_tx, input_idx, &descriptor, &secp_ctx)?);
 					psbt.inputs[input_idx].final_script_witness = Some(witness);