Delete EcdsaChannelSigner::sign_holder_anchor_input

Author: tankyleo

lightning/src/events/bump_transaction.rs

@@ -119,11 +119,9 @@ pub enum BumpTransactionEvent {
 	/// broadcast first, as the child anchor transaction depends on it.
 	///
 	/// The consumer should be able to sign for any of the additional inputs included within the
-	/// child anchor transaction. To sign its anchor input, an [`EcdsaChannelSigner`] should be
-	/// re-derived through [`AnchorDescriptor::derive_channel_signer`]. The anchor input signature
-	/// can be computed with [`EcdsaChannelSigner::sign_holder_anchor_input`], which can then be
-	/// provided to [`build_anchor_input_witness`] along with the `funding_pubkey` to obtain the
-	/// full witness required to spend.
+	/// child anchor transaction. To sign its anchor input, a [`ChannelSigner`] should be
+	/// re-derived through [`AnchorDescriptor::derive_channel_signer`]. The anchor input witness
+	/// can be computed with [`ChannelSigner::spend_holder_anchor_output`].
 	///
 	/// It is possible to receive more than one instance of this event if a valid child anchor
 	/// transaction is never broadcast or is but not with a sufficient fee to be mined. Care should
@@ -142,9 +140,8 @@ pub enum BumpTransactionEvent {
 	/// an empty `pending_htlcs`), confirmation of the commitment transaction can be considered to
 	/// be not urgent.
 	///
-	/// [`EcdsaChannelSigner`]: crate::sign::ecdsa::EcdsaChannelSigner
-	/// [`EcdsaChannelSigner::sign_holder_anchor_input`]: crate::sign::ecdsa::EcdsaChannelSigner::sign_holder_anchor_input
-	/// [`build_anchor_input_witness`]: crate::ln::chan_utils::build_anchor_input_witness
+	/// [`ChannelSigner`]: crate::sign::ChannelSigner
+	/// [`ChannelSigner::spend_holder_anchor_output`]: crate::sign::ChannelSigner::spend_holder_anchor_output
 	ChannelClose {
 		/// The `channel_id` of the channel which has been closed.
 		channel_id: ChannelId,

lightning/src/sign/ecdsa.rs

@@ -67,19 +67,6 @@ pub trait EcdsaChannelSigner: ChannelSigner {
 	fn sign_closing_transaction(
 		&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>,
 	) -> Result<Signature, ()>;
-	/// Computes the signature for a commitment transaction's anchor output used as an
-	/// input within `anchor_tx`, which spends the commitment transaction, at index `input`.
-	///
-	/// An `Err` can be returned to signal that the signer is unavailable/cannot produce a valid
-	/// signature and should be retried later. Once the signer is ready to provide a signature after
-	/// previously returning an `Err`, [`ChannelMonitor::signer_unblocked`] must be called on its
-	/// monitor or [`ChainMonitor::signer_unblocked`] called to attempt unblocking all monitors.
-	///
-	/// [`ChannelMonitor::signer_unblocked`]: crate::chain::channelmonitor::ChannelMonitor::signer_unblocked
-	/// [`ChainMonitor::signer_unblocked`]: crate::chain::chainmonitor::ChainMonitor::signer_unblocked
-	fn sign_holder_anchor_input(
-		&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
-	) -> Result<Signature, ()>;
 	/// Signs a channel announcement message with our funding key proving it comes from one of the
 	/// channel participants.
 	///

lightning/src/sign/mod.rs

@@ -1033,7 +1033,16 @@ pub trait ChannelSigner {
 		}
 	}
 
-	/// Spend the holder anchor output
+	/// Computes the signature for a commitment transaction's anchor output used as an
+	/// input within `anchor_tx`, which spends the commitment transaction, at index `input`.
+	///
+	/// An `Err` can be returned to signal that the signer is unavailable/cannot produce a valid
+	/// signature and should be retried later. Once the signer is ready to provide a signature after
+	/// previously returning an `Err`, [`ChannelMonitor::signer_unblocked`] must be called on its
+	/// monitor or [`ChainMonitor::signer_unblocked`] called to attempt unblocking all monitors.
+	///
+	/// [`ChannelMonitor::signer_unblocked`]: crate::chain::channelmonitor::ChannelMonitor::signer_unblocked
+	/// [`ChainMonitor::signer_unblocked`]: crate::chain::chainmonitor::ChainMonitor::signer_unblocked
 	fn spend_holder_anchor_output(
 		&self, anchor_tx: &Transaction, input_idx: usize, secp_ctx: &Secp256k1<secp256k1::All>,
 	) -> Result<Witness, ()>;
@@ -1829,10 +1838,19 @@ impl ChannelSigner for InMemorySigner {
 	fn spend_holder_anchor_output(
 		&self, anchor_tx: &Transaction, input_idx: usize, secp_ctx: &Secp256k1<secp256k1::All>,
 	) -> Result<Witness, ()> {
-		let anchor_sig =
-			EcdsaChannelSigner::sign_holder_anchor_input(self, anchor_tx, input_idx, secp_ctx)?;
-		let funding_pubkey = self.pubkeys().funding_pubkey;
-		Ok(chan_utils::build_anchor_input_witness(&funding_pubkey, &anchor_sig))
+		let funding_pubkey = &self.pubkeys().funding_pubkey;
+		let witness_script = chan_utils::get_anchor_redeemscript(funding_pubkey);
+		let sighash = sighash::SighashCache::new(anchor_tx)
+			.p2wsh_signature_hash(
+				input_idx,
+				&witness_script,
+				Amount::from_sat(ANCHOR_OUTPUT_VALUE_SATOSHI),
+				EcdsaSighashType::All,
+			)
+			.unwrap();
+		let sig =
+			sign_with_aux_rand(secp_ctx, &hash_to_message!(&sighash[..]), &self.funding_key, &self);
+		Ok(chan_utils::build_anchor_input_witness(funding_pubkey, &sig))
 	}
 }
 
@@ -1922,22 +1940,6 @@ impl EcdsaChannelSigner for InMemorySigner {
 		))
 	}
 
-	fn sign_holder_anchor_input(
-		&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
-	) -> Result<Signature, ()> {
-		let witness_script =
-			chan_utils::get_anchor_redeemscript(&self.holder_channel_pubkeys.funding_pubkey);
-		let sighash = sighash::SighashCache::new(&*anchor_tx)
-			.p2wsh_signature_hash(
-				input,
-				&witness_script,
-				Amount::from_sat(ANCHOR_OUTPUT_VALUE_SATOSHI),
-				EcdsaSighashType::All,
-			)
-			.unwrap();
-		Ok(sign_with_aux_rand(secp_ctx, &hash_to_message!(&sighash[..]), &self.funding_key, &self))
-	}
-
 	fn sign_channel_announcement_with_funding_key(
 		&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>,
 	) -> Result<Signature, ()> {

lightning/src/util/test_channel_signer.rs

@@ -7,7 +7,6 @@
 // You may not use this file except in accordance with one or both of these
 // licenses.
 
-use crate::ln::channel::{ANCHOR_OUTPUT_VALUE_SATOSHI, MIN_CHAN_DUST_LIMIT_SATOSHIS};
 use crate::ln::chan_utils::{self, HTLCOutputInCommitment, ChannelPublicKeys, HolderCommitmentTransaction, CommitmentTransaction, ChannelTransactionParameters, TrustedCommitmentTransaction, ClosingTransaction, TxCreationKeys};
 use crate::ln::channel_keys::{HtlcKey};
 use crate::ln::msgs;
@@ -368,20 +367,6 @@ impl EcdsaChannelSigner for TestChannelSigner {
 		Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 	}
 
-	fn sign_holder_anchor_input(
-		&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
-	) -> Result<Signature, ()> {
-		debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
-		// As long as our minimum dust limit is enforced and is greater than our anchor output
-		// value, an anchor output can only have an index within [0, 1].
-		assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
-		#[cfg(test)]
-		if !self.is_signer_available(SignerOp::SignHolderAnchorInput) {
-			return Err(());
-		}
-		EcdsaChannelSigner::sign_holder_anchor_input(&self.inner, anchor_tx, input, secp_ctx)
-	}
-
 	fn sign_channel_announcement_with_funding_key(
 		&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
 	) -> Result<Signature, ()> {