Separate out the methods that would apply to any channel into a ChannelSigner, leaving the implementation-dependent ones in EcdsaChannelSigner.

arik-so · arik-so · commit 2539e40870b3 · 2023-01-18T13:12:01.000-08:00
diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs
@@ -75,7 +75,7 @@ pub struct DelayedPaymentOutputDescriptor {
 	/// The revocation point specific to the commitment transaction which was broadcast. Used to
 	/// derive the witnessScript for this output.
 	pub revocation_pubkey: PublicKey,
-	/// Arbitrary identification information returned by a call to [`EcdsaChannelSigner::channel_keys_id`].
+	/// Arbitrary identification information returned by a call to [`ChannelSigner::channel_keys_id`].
 	/// This may be useful in re-deriving keys used in the channel to spend the output.
 	pub channel_keys_id: [u8; 32],
 	/// The value of the channel which this output originated from, possibly indirectly.
@@ -107,7 +107,7 @@ pub struct StaticPaymentOutputDescriptor {
 	pub outpoint: OutPoint,
 	/// The output which is referenced by the given outpoint.
 	pub output: TxOut,
-	/// Arbitrary identification information returned by a call to [`EcdsaChannelSigner::channel_keys_id`].
+	/// Arbitrary identification information returned by a call to [`ChannelSigner::channel_keys_id`].
 	/// This may be useful in re-deriving keys used in the channel to spend the output.
 	pub channel_keys_id: [u8; 32],
 	/// The value of the channel which this transactions spends.
@@ -172,15 +172,15 @@ pub enum SpendableOutputDescriptor {
 	///
 	/// To derive the delayed payment key which is used to sign this input, you must pass the
 	/// holder [`InMemorySigner::delayed_payment_base_key`] (i.e., the private key which corresponds to the
-	/// [`ChannelPublicKeys::delayed_payment_basepoint`] in [`EcdsaChannelSigner::pubkeys`]) and the provided
+	/// [`ChannelPublicKeys::delayed_payment_basepoint`] in [`ChannelSigner::pubkeys`]) and the provided
 	/// [`DelayedPaymentOutputDescriptor::per_commitment_point`] to [`chan_utils::derive_private_key`]. The public key can be
 	/// generated without the secret key using [`chan_utils::derive_public_key`] and only the
-	/// [`ChannelPublicKeys::delayed_payment_basepoint`] which appears in [`EcdsaChannelSigner::pubkeys`].
+	/// [`ChannelPublicKeys::delayed_payment_basepoint`] which appears in [`ChannelSigner::pubkeys`].
 	///
 	/// To derive the [`DelayedPaymentOutputDescriptor::revocation_pubkey`] provided here (which is
 	/// used in the witness script generation), you must pass the counterparty
 	/// [`ChannelPublicKeys::revocation_basepoint`] (which appears in the call to
-	/// [`EcdsaChannelSigner::provide_channel_parameters`]) and the provided
+	/// [`ChannelSigner::provide_channel_parameters`]) and the provided
 	/// [`DelayedPaymentOutputDescriptor::per_commitment_point`] to
 	/// [`chan_utils::derive_public_revocation_key`].
 	///
@@ -191,7 +191,7 @@ pub enum SpendableOutputDescriptor {
 	/// [`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 [`EcdsaChannelSigner::pubkeys`]). The witness
+	/// which corresponds to the `payment_point` in [`ChannelSigner::pubkeys`]). The witness
 	/// in the spending input is, thus, simply:
 	/// ```bitcoin
 	/// <BIP 143 signature> <payment key>
@@ -212,18 +212,14 @@ impl_writeable_tlv_based_enum!(SpendableOutputDescriptor,
 	(2, StaticPaymentOutput),
 );
 
-/// A trait to sign Lightning channel transactions as described in
-/// [BOLT 3](https://github.com/lightning/bolts/blob/master/03-transactions.md).
-///
-/// Signing services could be implemented on a hardware wallet and should implement signing
-/// policies in order to be secure. Please refer to the [VLS Policy
-/// Controls](https://gitlab.com/lightning-signer/validating-lightning-signer/-/blob/main/docs/policy-controls.md)
-/// for an example of such policies.
-pub trait EcdsaChannelSigner {
+/// A trait to handle Lightning channel key material without concretizing the channel type or
+/// the signature mechanism.
+pub trait ChannelSigner {
 	/// Gets the per-commitment point for a specific commitment number
 	///
 	/// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
 	fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey;
+
 	/// Gets the commitment secret for a specific commitment number as part of the revocation process
 	///
 	/// An external signer implementation should error here if the commitment was already signed
@@ -234,6 +230,7 @@ pub trait EcdsaChannelSigner {
 	/// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
 	// TODO: return a Result so we can signal a validation error
 	fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
+
 	/// Validate the counterparty's signatures on the holder commitment transaction and HTLCs.
 	///
 	/// This is required in order for the signer to make sure that releasing a commitment
@@ -249,12 +246,35 @@ pub trait EcdsaChannelSigner {
 	/// irrelevant or duplicate preimages.
 	fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction,
 		preimages: Vec<PaymentPreimage>) -> Result<(), ()>;
+
 	/// Returns the holder's channel public keys and basepoints.
 	fn pubkeys(&self) -> &ChannelPublicKeys;
+
 	/// Returns an arbitrary identifier describing the set of keys which are provided back to you in
 	/// some [`SpendableOutputDescriptor`] types. This should be sufficient to identify this
 	/// [`EcdsaChannelSigner`] object uniquely and lookup or re-derive its keys.
 	fn channel_keys_id(&self) -> [u8; 32];
+
+	/// Set the counterparty static channel data, including basepoints,
+	/// `counterparty_selected`/`holder_selected_contest_delay` and funding outpoint.
+	///
+	/// This data is static, and will never change for a channel once set. For a given [`ChannelSigner`]
+	/// instance, LDK will call this method exactly once - either immediately after construction
+	/// (not including if done via [`SignerProvider::read_chan_signer`]) or when the funding
+	/// information has been generated.
+	///
+	/// channel_parameters.is_populated() MUST be true.
+	fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters);
+}
+
+/// A trait to sign Lightning channel transactions as described in
+/// [BOLT 3](https://github.com/lightning/bolts/blob/master/03-transactions.md).
+///
+/// Signing services could be implemented on a hardware wallet and should implement signing
+/// policies in order to be secure. Please refer to the [VLS Policy
+/// Controls](https://gitlab.com/lightning-signer/validating-lightning-signer/-/blob/main/docs/policy-controls.md)
+/// for an example of such policies.
+pub trait EcdsaChannelSigner: ChannelSigner {
 	/// Create a signature for a counterparty's commitment transaction and associated HTLC transactions.
 	///
 	/// Note that if signing fails or is rejected, the channel will be force-closed.
@@ -395,16 +415,6 @@ pub trait EcdsaChannelSigner {
 	fn sign_channel_announcement_with_funding_key(
 		&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
 	) -> Result<Signature, ()>;
-	/// Set the counterparty static channel data, including basepoints,
-	/// `counterparty_selected`/`holder_selected_contest_delay` and funding outpoint.
-	///
-	/// This data is static, and will never change for a channel once set. For a given [`EcdsaChannelSigner`]
-	/// instance, LDK will call this method exactly once - either immediately after construction
-	/// (not including if done via [`SignerProvider::read_chan_signer`]) or when the funding
-	/// information has been generated.
-	///
-	/// channel_parameters.is_populated() MUST be true.
-	fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters);
 }
 
 /// A writeable signer.
@@ -511,7 +521,7 @@ pub trait SignerProvider {
 	/// To derive a new `Signer`, a fresh `channel_keys_id` should be obtained through
 	/// [`SignerProvider::generate_channel_keys_id`]. Otherwise, an existing `Signer` can be
 	/// re-derived from its `channel_keys_id`, which can be obtained through its trait method
-	/// [`EcdsaChannelSigner::channel_keys_id`].
+	/// [`ChannelSigner::channel_keys_id`].
 	fn derive_channel_signer(&self, channel_value_satoshis: u64, channel_keys_id: [u8; 32]) -> Self::Signer;
 
 	/// Reads a [`Signer`] for this [`SignerProvider`] from the given input stream.
@@ -620,38 +630,38 @@ impl InMemorySigner {
 
 	/// Returns the counterparty's pubkeys.
 	///
-	/// Will panic if [`EcdsaChannelSigner::provide_channel_parameters`] has not been called before.
+	/// 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 }
 	/// 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 [`EcdsaChannelSigner::provide_channel_parameters`] has not been called before.
+	/// 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 }
 	/// 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 [`EcdsaChannelSigner::provide_channel_parameters`] has not been called before.
+	/// 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 }
 	/// Returns whether the holder is the initiator.
 	///
-	/// Will panic if [`EcdsaChannelSigner::provide_channel_parameters`] has not been called before.
+	/// 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 }
 	/// Funding outpoint
 	///
-	/// Will panic if [`EcdsaChannelSigner::provide_channel_parameters`] has not been called before.
+	/// 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() }
 	/// Returns a [`ChannelTransactionParameters`] for this channel, to be used when verifying or
 	/// building transactions.
 	///
-	/// Will panic if [`EcdsaChannelSigner::provide_channel_parameters`] has not been called before.
+	/// 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()
 	}
 	/// Returns whether anchors should be used.
 	///
-	/// Will panic if [`EcdsaChannelSigner::provide_channel_parameters`] has not been called before.
+	/// Will panic if [`ChannelSigner::provide_channel_parameters`] has not been called before.
 	pub fn opt_anchors(&self) -> bool {
 		self.get_channel_parameters().opt_anchors.is_some()
 	}
@@ -725,7 +735,7 @@ impl InMemorySigner {
 	}
 }
 
-impl EcdsaChannelSigner for InMemorySigner {
+impl ChannelSigner for InMemorySigner {
 	fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
 		let commitment_secret = SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx)).unwrap();
 		PublicKey::from_secret_key(secp_ctx, &commitment_secret)
@@ -743,6 +753,18 @@ impl EcdsaChannelSigner for InMemorySigner {
 
 	fn channel_keys_id(&self) -> [u8; 32] { self.channel_keys_id }
 
+	fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
+		assert!(self.channel_parameters.is_none() || self.channel_parameters.as_ref().unwrap() == channel_parameters);
+		if self.channel_parameters.is_some() {
+			// The channel parameters were already set and they match, return early.
+			return;
+		}
+		assert!(channel_parameters.is_populated(), "Channel parameters must be fully populated");
+		self.channel_parameters = Some(channel_parameters.clone());
+	}
+}
+
+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();
@@ -871,16 +893,6 @@ impl EcdsaChannelSigner for InMemorySigner {
 		let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
 		Ok(sign(secp_ctx, &msghash, &self.funding_key))
 	}
-
-	fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
-		assert!(self.channel_parameters.is_none() || self.channel_parameters.as_ref().unwrap() == channel_parameters);
-		if self.channel_parameters.is_some() {
-			// The channel parameters were already set and they match, return early.
-			return;
-		}
-		assert!(channel_parameters.is_populated(), "Channel parameters must be fully populated");
-		self.channel_parameters = Some(channel_parameters.clone());
-	}
 }
 
 const SERIALIZATION_VERSION: u8 = 1;
diff --git a/lightning/src/chain/onchaintx.rs b/lightning/src/chain/onchaintx.rs
@@ -21,7 +21,7 @@ use bitcoin::hash_types::{Txid, BlockHash};
 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
 use bitcoin::secp256k1;
 
-use crate::chain::keysinterface::{EcdsaChannelSigner, EntropySource, SignerProvider};
+use crate::chain::keysinterface::{ChannelSigner, EntropySource, SignerProvider};
 use crate::ln::msgs::DecodeError;
 use crate::ln::PaymentPreimage;
 #[cfg(anchors)]
diff --git a/lightning/src/ln/chan_utils.rs b/lightning/src/ln/chan_utils.rs
@@ -1635,7 +1635,7 @@ mod tests {
 	use crate::ln::chan_utils::{get_htlc_redeemscript, get_to_countersignatory_with_anchors_redeemscript, CommitmentTransaction, TxCreationKeys, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, HTLCOutputInCommitment};
 	use bitcoin::secp256k1::{PublicKey, SecretKey, Secp256k1};
 	use crate::util::test_utils;
-	use crate::chain::keysinterface::{EcdsaChannelSigner, SignerProvider};
+	use crate::chain::keysinterface::{ChannelSigner, SignerProvider};
 	use bitcoin::{Network, Txid};
 	use bitcoin::hashes::Hash;
 	use crate::ln::PaymentHash;
diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
@@ -35,7 +35,7 @@ use crate::chain::BestBlock;
 use crate::chain::chaininterface::{FeeEstimator, ConfirmationTarget, LowerBoundedFeeEstimator};
 use crate::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, LATENCY_GRACE_PERIOD_BLOCKS};
 use crate::chain::transaction::{OutPoint, TransactionData};
-use crate::chain::keysinterface::{Sign, EntropySource, EcdsaChannelSigner, SignerProvider, NodeSigner, Recipient};
+use crate::chain::keysinterface::{Sign, EntropySource, ChannelSigner, SignerProvider, NodeSigner, Recipient};
 use crate::util::events::ClosureReason;
 use crate::util::ser::{Readable, ReadableArgs, Writeable, Writer, VecWriter};
 use crate::util::logger::Logger;
@@ -6871,7 +6871,7 @@ mod tests {
 	use crate::ln::chan_utils::{htlc_success_tx_weight, htlc_timeout_tx_weight};
 	use crate::chain::BestBlock;
 	use crate::chain::chaininterface::{FeeEstimator, LowerBoundedFeeEstimator, ConfirmationTarget};
-	use crate::chain::keysinterface::{EcdsaChannelSigner, InMemorySigner, EntropySource, SignerProvider};
+	use crate::chain::keysinterface::{ChannelSigner, InMemorySigner, EntropySource, SignerProvider};
 	use crate::chain::transaction::OutPoint;
 	use crate::util::config::UserConfig;
 	use crate::util::enforcing_trait_impls::EnforcingSigner;
diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs
@@ -17,7 +17,7 @@ use crate::chain::chaininterface::LowerBoundedFeeEstimator;
 use crate::chain::channelmonitor;
 use crate::chain::channelmonitor::{CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS, ANTI_REORG_DELAY};
 use crate::chain::transaction::OutPoint;
-use crate::chain::keysinterface::{EcdsaChannelSigner, EntropySource};
+use crate::chain::keysinterface::{ChannelSigner, EcdsaChannelSigner, EntropySource};
 use crate::ln::{PaymentPreimage, PaymentSecret, PaymentHash};
 use crate::ln::channel::{commitment_tx_base_weight, COMMITMENT_TX_WEIGHT_PER_HTLC, CONCURRENT_INBOUND_HTLC_FEE_BUFFER, FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE, MIN_AFFORDABLE_HTLC_COUNT};
 use crate::ln::channelmanager::{self, PaymentId, RAACommitmentOrder, PaymentSendFailure, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA};
diff --git a/lightning/src/util/enforcing_trait_impls.rs b/lightning/src/util/enforcing_trait_impls.rs
@@ -10,7 +10,7 @@
 use crate::ln::channel::{ANCHOR_OUTPUT_VALUE_SATOSHI, MIN_CHAN_DUST_LIMIT_SATOSHIS};
 use crate::ln::chan_utils::{HTLCOutputInCommitment, ChannelPublicKeys, HolderCommitmentTransaction, CommitmentTransaction, ChannelTransactionParameters, TrustedCommitmentTransaction, ClosingTransaction};
 use crate::ln::{chan_utils, msgs, PaymentPreimage};
-use crate::chain::keysinterface::{Sign, InMemorySigner, EcdsaChannelSigner};
+use crate::chain::keysinterface::{Sign, InMemorySigner, ChannelSigner, EcdsaChannelSigner};
 
 use crate::prelude::*;
 use core::cmp;
@@ -90,7 +90,7 @@ impl EnforcingSigner {
 	}
 }
 
-impl EcdsaChannelSigner for EnforcingSigner {
+impl ChannelSigner for EnforcingSigner {
 	fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
 		self.inner.get_per_commitment_point(idx, secp_ctx)
 	}
@@ -114,8 +114,15 @@ impl EcdsaChannelSigner for EnforcingSigner {
 	}
 
 	fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
+
 	fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
 
+	fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
+		self.inner.provide_channel_parameters(channel_parameters)
+	}
+}
+
+impl EcdsaChannelSigner for EnforcingSigner {
 	fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 		self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
 
@@ -228,10 +235,6 @@ impl EcdsaChannelSigner for EnforcingSigner {
 	) -> Result<Signature, ()> {
 		self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
 	}
-
-	fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
-		self.inner.provide_channel_parameters(channel_parameters)
-	}
 }
 
 impl Sign for EnforcingSigner {}
