Implement DelayedPaymentBasepoint and DelayedPaymentKey wrappers to explicitly specify those types of keys in functions and structs allowing the language to verify what key is being used and enable idiomatic derivation of one key from another.

Author: yellowred

lightning/src/chain/channelmonitor.rs

@@ -35,7 +35,7 @@ use bitcoin::{secp256k1, EcdsaSighashType};
 use crate::ln::channel::INITIAL_COMMITMENT_NUMBER;
 use crate::ln::{PaymentHash, PaymentPreimage};
 use crate::ln::msgs::DecodeError;
-use crate::ln::chan_utils;
+use crate::ln::chan_utils::{self, DelayedPaymentKey, DelayedPaymentBasepoint};
 use crate::ln::chan_utils::{CommitmentTransaction, CounterpartyCommitmentSecrets, HTLCOutputInCommitment, HTLCClaim, ChannelTransactionParameters, HolderCommitmentTransaction, TxCreationKeys};
 use crate::ln::channelmanager::{HTLCSource, SentHTLCId};
 use crate::chain;
@@ -239,7 +239,7 @@ struct HolderSignedTx {
 	revocation_key: PublicKey,
 	a_htlc_key: PublicKey,
 	b_htlc_key: PublicKey,
-	delayed_payment_key: PublicKey,
+	delayed_payment_key: DelayedPaymentKey,
 	per_commitment_point: PublicKey,
 	htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Signature>, Option<HTLCSource>)>,
 	to_self_value_sat: u64,
@@ -276,7 +276,7 @@ impl HolderSignedTx {
 /// justice or 2nd-stage preimage/timeout transactions.
 #[derive(Clone, PartialEq, Eq)]
 struct CounterpartyCommitmentParameters {
-	counterparty_delayed_payment_base_key: PublicKey,
+	counterparty_delayed_payment_base_key: DelayedPaymentBasepoint,
 	counterparty_htlc_base_key: PublicKey,
 	on_counterparty_tx_csv: u16,
 }
@@ -2923,9 +2923,10 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 		let revocation_pubkey = chan_utils::derive_public_revocation_key(
 			&self.onchain_tx_handler.secp_ctx, &their_per_commitment_point,
 			&self.holder_revocation_basepoint);
-		let delayed_key = chan_utils::derive_public_key(&self.onchain_tx_handler.secp_ctx,
-			&their_per_commitment_point,
-			&self.counterparty_commitment_params.counterparty_delayed_payment_base_key);
+		let delayed_payment_basepoint = DelayedPaymentBasepoint::from(self.counterparty_commitment_params.counterparty_delayed_payment_base_key);
+		let delayed_key = DelayedPaymentKey::from_basepoint(&self.onchain_tx_handler.secp_ctx,
+			&delayed_payment_basepoint,
+			&their_per_commitment_point);
 		let revokeable_redeemscript = chan_utils::get_revokeable_redeemscript(&revocation_pubkey,
 			self.counterparty_commitment_params.on_counterparty_tx_csv, &delayed_key);
 
@@ -2989,7 +2990,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 			let per_commitment_key = ignore_error!(SecretKey::from_slice(&secret));
 			let per_commitment_point = PublicKey::from_secret_key(&self.onchain_tx_handler.secp_ctx, &per_commitment_key);
 			let revocation_pubkey = chan_utils::derive_public_revocation_key(&self.onchain_tx_handler.secp_ctx, &per_commitment_point, &self.holder_revocation_basepoint);
-			let delayed_key = chan_utils::derive_public_key(&self.onchain_tx_handler.secp_ctx, &PublicKey::from_secret_key(&self.onchain_tx_handler.secp_ctx, &per_commitment_key), &self.counterparty_commitment_params.counterparty_delayed_payment_base_key);
+			let delayed_key = DelayedPaymentKey::from_basepoint(&self.onchain_tx_handler.secp_ctx, &self.counterparty_commitment_params.counterparty_delayed_payment_base_key, &PublicKey::from_secret_key(&self.onchain_tx_handler.secp_ctx, &per_commitment_key));
 
 			let revokeable_redeemscript = chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.counterparty_commitment_params.on_counterparty_tx_csv, &delayed_key);
 			let revokeable_p2wsh = revokeable_redeemscript.to_v0_p2wsh();
@@ -3103,9 +3104,9 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 		if let Some(transaction) = tx {
 			let revocation_pubkey = chan_utils::derive_public_revocation_key(
 				&self.onchain_tx_handler.secp_ctx, &per_commitment_point, &self.holder_revocation_basepoint);
-			let delayed_key = chan_utils::derive_public_key(&self.onchain_tx_handler.secp_ctx,
-				&per_commitment_point,
-				&self.counterparty_commitment_params.counterparty_delayed_payment_base_key);
+			
+			let delayed_key = DelayedPaymentKey::from_basepoint(&self.onchain_tx_handler.secp_ctx, &self.counterparty_commitment_params.counterparty_delayed_payment_base_key, &per_commitment_point);
+
 			let revokeable_p2wsh = chan_utils::get_revokeable_redeemscript(&revocation_pubkey,
 				self.counterparty_commitment_params.on_counterparty_tx_csv,
 				&delayed_key).to_v0_p2wsh();
@@ -4501,7 +4502,7 @@ mod tests {
 	use crate::chain::transaction::OutPoint;
 	use crate::sign::InMemorySigner;
 	use crate::ln::{PaymentPreimage, PaymentHash};
-	use crate::ln::chan_utils;
+	use crate::ln::chan_utils::{self, DelayedPaymentBasepoint, DelayedPaymentKey};
 	use crate::ln::chan_utils::{HTLCOutputInCommitment, ChannelPublicKeys, ChannelTransactionParameters, HolderCommitmentTransaction, CounterpartyChannelTransactionParameters};
 	use crate::ln::channelmanager::{PaymentSendFailure, PaymentId, RecipientOnionFields};
 	use crate::ln::functional_test_utils::*;
@@ -4670,7 +4671,7 @@ mod tests {
 			funding_pubkey: PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[44; 32]).unwrap()),
 			revocation_basepoint: PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()),
 			payment_point: PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[46; 32]).unwrap()),
-			delayed_payment_basepoint: PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[47; 32]).unwrap()),
+			delayed_payment_basepoint: DelayedPaymentBasepoint::from(PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[47; 32]).unwrap())),
 			htlc_basepoint: PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[48; 32]).unwrap())
 		};
 		let funding_outpoint = OutPoint { txid: Txid::all_zeros(), index: u16::max_value() };
@@ -4770,7 +4771,7 @@ mod tests {
 					payment_hash: PaymentHash([1; 32]),
 					transaction_output_index: Some($idx as u32),
 				};
-				let redeem_script = if *$weight == WEIGHT_REVOKED_OUTPUT { chan_utils::get_revokeable_redeemscript(&pubkey, 256, &pubkey) } else { chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, $opt_anchors, &pubkey, &pubkey, &pubkey) };
+				let redeem_script = if *$weight == WEIGHT_REVOKED_OUTPUT { chan_utils::get_revokeable_redeemscript(&pubkey, 256, &DelayedPaymentKey::from_basepoint(&secp_ctx, &DelayedPaymentBasepoint::from(pubkey), &pubkey)) } else { chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, $opt_anchors, &pubkey, &pubkey, &pubkey) };
 				let sighash = hash_to_message!(&$sighash_parts.segwit_signature_hash($idx, &redeem_script, $amount, EcdsaSighashType::All).unwrap()[..]);
 				let sig = secp_ctx.sign_ecdsa(&sighash, &privkey);
 				let mut ser_sig = sig.serialize_der().to_vec();

lightning/src/chain/package.rs

@@ -21,7 +21,7 @@ use bitcoin::hash_types::Txid;
 use bitcoin::secp256k1::{SecretKey,PublicKey};
 
 use crate::ln::PaymentPreimage;
-use crate::ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment};
+use crate::ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, DelayedPaymentBasepoint};
 use crate::ln::chan_utils;
 use crate::ln::msgs::DecodeError;
 use crate::chain::chaininterface::{FeeEstimator, ConfirmationTarget, MIN_RELAY_FEE_SAT_PER_1000_WEIGHT};
@@ -114,7 +114,7 @@ const HIGH_FREQUENCY_BUMP_INTERVAL: u32 = 1;
 #[derive(Clone, PartialEq, Eq)]
 pub(crate) struct RevokedOutput {
 	per_commitment_point: PublicKey,
-	counterparty_delayed_payment_base_key: PublicKey,
+	counterparty_delayed_payment_base_key: DelayedPaymentBasepoint,
 	counterparty_htlc_base_key: PublicKey,
 	per_commitment_key: SecretKey,
 	weight: u64,
@@ -124,7 +124,7 @@ pub(crate) struct RevokedOutput {
 }
 
 impl RevokedOutput {
-	pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, per_commitment_key: SecretKey, amount: u64, on_counterparty_tx_csv: u16, is_counterparty_balance_on_anchors: bool) -> Self {
+	pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: DelayedPaymentBasepoint, counterparty_htlc_base_key: PublicKey, per_commitment_key: SecretKey, amount: u64, on_counterparty_tx_csv: u16, is_counterparty_balance_on_anchors: bool) -> Self {
 		RevokedOutput {
 			per_commitment_point,
 			counterparty_delayed_payment_base_key,
@@ -160,7 +160,7 @@ impl_writeable_tlv_based!(RevokedOutput, {
 #[derive(Clone, PartialEq, Eq)]
 pub(crate) struct RevokedHTLCOutput {
 	per_commitment_point: PublicKey,
-	counterparty_delayed_payment_base_key: PublicKey,
+	counterparty_delayed_payment_base_key: DelayedPaymentBasepoint,
 	counterparty_htlc_base_key: PublicKey,
 	per_commitment_key: SecretKey,
 	weight: u64,
@@ -169,7 +169,7 @@ pub(crate) struct RevokedHTLCOutput {
 }
 
 impl RevokedHTLCOutput {
-	pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, per_commitment_key: SecretKey, amount: u64, htlc: HTLCOutputInCommitment, channel_type_features: &ChannelTypeFeatures) -> Self {
+	pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: DelayedPaymentBasepoint, counterparty_htlc_base_key: PublicKey, per_commitment_key: SecretKey, amount: u64, htlc: HTLCOutputInCommitment, channel_type_features: &ChannelTypeFeatures) -> Self {
 		let weight = if htlc.offered { weight_revoked_offered_htlc(channel_type_features) } else { weight_revoked_received_htlc(channel_type_features) };
 		RevokedHTLCOutput {
 			per_commitment_point,
@@ -204,15 +204,15 @@ impl_writeable_tlv_based!(RevokedHTLCOutput, {
 #[derive(Clone, PartialEq, Eq)]
 pub(crate) struct CounterpartyOfferedHTLCOutput {
 	per_commitment_point: PublicKey,
-	counterparty_delayed_payment_base_key: PublicKey,
+	counterparty_delayed_payment_base_key: DelayedPaymentBasepoint,
 	counterparty_htlc_base_key: PublicKey,
 	preimage: PaymentPreimage,
 	htlc: HTLCOutputInCommitment,
 	channel_type_features: ChannelTypeFeatures,
 }
 
 impl CounterpartyOfferedHTLCOutput {
-	pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, preimage: PaymentPreimage, htlc: HTLCOutputInCommitment, channel_type_features: ChannelTypeFeatures) -> Self {
+	pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: DelayedPaymentBasepoint, counterparty_htlc_base_key: PublicKey, preimage: PaymentPreimage, htlc: HTLCOutputInCommitment, channel_type_features: ChannelTypeFeatures) -> Self {
 		CounterpartyOfferedHTLCOutput {
 			per_commitment_point,
 			counterparty_delayed_payment_base_key,
@@ -282,14 +282,14 @@ impl Readable for CounterpartyOfferedHTLCOutput {
 #[derive(Clone, PartialEq, Eq)]
 pub(crate) struct CounterpartyReceivedHTLCOutput {
 	per_commitment_point: PublicKey,
-	counterparty_delayed_payment_base_key: PublicKey,
+	counterparty_delayed_payment_base_key: DelayedPaymentBasepoint,
 	counterparty_htlc_base_key: PublicKey,
 	htlc: HTLCOutputInCommitment,
 	channel_type_features: ChannelTypeFeatures,
 }
 
 impl CounterpartyReceivedHTLCOutput {
-	pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, htlc: HTLCOutputInCommitment, channel_type_features: ChannelTypeFeatures) -> Self {
+	pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: DelayedPaymentBasepoint, counterparty_htlc_base_key: PublicKey, htlc: HTLCOutputInCommitment, channel_type_features: ChannelTypeFeatures) -> Self {
 		CounterpartyReceivedHTLCOutput {
 			per_commitment_point,
 			counterparty_delayed_payment_base_key,
@@ -1200,6 +1200,7 @@ mod tests {
 	use crate::chain::Txid;
 	use crate::ln::chan_utils::HTLCOutputInCommitment;
 	use crate::ln::{PaymentPreimage, PaymentHash};
+	use crate::ln::chan_utils::DelayedPaymentBasepoint;
 
 	use bitcoin::blockdata::constants::WITNESS_SCALE_FACTOR;
 	use bitcoin::blockdata::script::Script;
@@ -1216,7 +1217,7 @@ mod tests {
 			{
 				let dumb_scalar = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
 				let dumb_point = PublicKey::from_secret_key(&$secp_ctx, &dumb_scalar);
-				PackageSolvingData::RevokedOutput(RevokedOutput::build(dumb_point, dumb_point, dumb_point, dumb_scalar, 0, 0, $is_counterparty_balance_on_anchors))
+				PackageSolvingData::RevokedOutput(RevokedOutput::build(dumb_point, DelayedPaymentBasepoint::from(dumb_point), dumb_point, dumb_scalar, 0, 0, $is_counterparty_balance_on_anchors))
 			}
 		}
 	}
@@ -1228,7 +1229,7 @@ mod tests {
 				let dumb_point = PublicKey::from_secret_key(&$secp_ctx, &dumb_scalar);
 				let hash = PaymentHash([1; 32]);
 				let htlc = HTLCOutputInCommitment { offered: true, amount_msat: $amt, cltv_expiry: 0, payment_hash: hash, transaction_output_index: None };
-				PackageSolvingData::CounterpartyReceivedHTLCOutput(CounterpartyReceivedHTLCOutput::build(dumb_point, dumb_point, dumb_point, htlc, $opt_anchors))
+				PackageSolvingData::CounterpartyReceivedHTLCOutput(CounterpartyReceivedHTLCOutput::build(dumb_point, DelayedPaymentBasepoint::from(dumb_point), dumb_point, htlc, $opt_anchors))
 			}
 		}
 	}
@@ -1241,7 +1242,7 @@ mod tests {
 				let hash = PaymentHash([1; 32]);
 				let preimage = PaymentPreimage([2;32]);
 				let htlc = HTLCOutputInCommitment { offered: false, amount_msat: $amt, cltv_expiry: 1000, payment_hash: hash, transaction_output_index: None };
-				PackageSolvingData::CounterpartyOfferedHTLCOutput(CounterpartyOfferedHTLCOutput::build(dumb_point, dumb_point, dumb_point, preimage, htlc, $opt_anchors))
+				PackageSolvingData::CounterpartyOfferedHTLCOutput(CounterpartyOfferedHTLCOutput::build(dumb_point, DelayedPaymentBasepoint::from(dumb_point), dumb_point, preimage, htlc, $opt_anchors))
 			}
 		}
 	}

lightning/src/events/bump_transaction.rs

@@ -18,7 +18,7 @@ use crate::chain::chaininterface::{BroadcasterInterface, fee_for_weight};
 use crate::chain::ClaimId;
 use crate::io_extras::sink;
 use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
-use crate::ln::chan_utils;
+use crate::ln::chan_utils::{self, DelayedPaymentKey};
 use crate::ln::chan_utils::{
 	ANCHOR_INPUT_WITNESS_WEIGHT, HTLC_SUCCESS_INPUT_ANCHOR_WITNESS_WEIGHT,
 	HTLC_TIMEOUT_INPUT_ANCHOR_WITNESS_WEIGHT, ChannelTransactionParameters, HTLCOutputInCommitment
@@ -186,9 +186,7 @@ impl HTLCDescriptor {
 		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 broadcaster_delayed_key = DelayedPaymentKey::from_basepoint(&secp, &broadcaster_keys.delayed_payment_basepoint, &self.per_commitment_point);
 		let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
 			secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint
 		);