Use 72 WU instead of 73 WU for signature weight

diff --git a/lightning/src/ln/chan_utils.rs b/lightning/src/ln/chan_utils.rs
index ff40050..242f560 100644
--- a/lightning/src/ln/chan_utils.rs
+++ b/lightning/src/ln/chan_utils.rs
@@ -116,19 +116,24 @@ pub const HTLC_SUCCESS_INPUT_P2A_ANCHOR_WITNESS_WEIGHT: u64 = 324;
 /// The size of the 2-of-2 multisig script
 const MULTISIG_SCRIPT_SIZE: u64 = 1 + // OP_2
 	1 + // data len
-	33 + // pubkey1
+	crate::sign::COMPRESSED_PUBLIC_KEY_SIZE as u64 + // pubkey1
 	1 + // data len
-	33 + // pubkey2
+	crate::sign::COMPRESSED_PUBLIC_KEY_SIZE as u64 + // pubkey2
 	1 + // OP_2
 	1; // OP_CHECKMULTISIG
-/// The weight of a funding transaction input (2-of-2 P2WSH)
-/// See https://github.com/lightning/bolts/blob/master/03-transactions.md#expected-weight-of-the-commitment-transaction
+
+/// The weight of a funding transaction input (2-of-2 P2WSH).
+///
+/// Unlike in the [spec], 72 WU is used for the max signature size since 73 WU signatures are
+/// non-standard.
+///
+/// [spec]: https://github.com/lightning/bolts/blob/master/03-transactions.md#expected-weight-of-the-commitment-transaction
 pub const FUNDING_TRANSACTION_WITNESS_WEIGHT: u64 = 1 + // number_of_witness_elements
 	1 + // nil_len
 	1 + // sig len
-	73 + // sig1
+	crate::sign::MAX_STANDARD_SIGNATURE_SIZE as u64 + // sig1
 	1 + // sig len
-	73 + // sig2
+	crate::sign::MAX_STANDARD_SIGNATURE_SIZE as u64 + // sig2
 	1 + // witness_script_length
 	MULTISIG_SCRIPT_SIZE;
 
diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index 75905db..234168e 100644
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -17397,19 +17397,19 @@ mod tests {
 		// 2 inputs, initiator, 2000 sat/kw feerate
 		assert_eq!(
 			estimate_v2_funding_transaction_fee(&two_inputs, &[], true, false, 2000),
-			1520,
+			1516,
 		);
 
 		// higher feerate
 		assert_eq!(
 			estimate_v2_funding_transaction_fee(&two_inputs, &[], true, false, 3000),
-			2280,
+			2274,
 		);
 
 		// only 1 input
 		assert_eq!(
 			estimate_v2_funding_transaction_fee(&one_input, &[], true, false, 2000),
-			974,
+			972,
 		);
 
 		// 0 inputs
@@ -17427,13 +17427,13 @@ mod tests {
 		// splice initiator
 		assert_eq!(
 			estimate_v2_funding_transaction_fee(&one_input, &[], true, true, 2000),
-			1746,
+			1740,
 		);
 
 		// splice acceptor
 		assert_eq!(
 			estimate_v2_funding_transaction_fee(&one_input, &[], false, true, 2000),
-			546,
+			544,
 		);
 	}
 
@@ -17468,7 +17468,7 @@ mod tests {
 				true,
 				2000,
 			).unwrap(),
-			2292,
+			2284,
 		);
 
 		// negative case, inputs clearly insufficient
@@ -17484,13 +17484,13 @@ mod tests {
 			);
 			assert_eq!(
 				res.err().unwrap(),
-				"Total input amount 100000 is lower than needed for contribution 220000, considering fees of 1746. Need more inputs.",
+				"Total input amount 100000 is lower than needed for contribution 220000, considering fees of 1740. Need more inputs.",
 			);
 		}
 
 		// barely covers
 		{
-			let expected_fee: u64 = 2292;
+			let expected_fee: u64 = 2284;
 			assert_eq!(
 				check_v2_funding_inputs_sufficient(
 					(300_000 - expected_fee - 20) as i64,
@@ -17520,13 +17520,13 @@ mod tests {
 			);
 			assert_eq!(
 				res.err().unwrap(),
-				"Total input amount 300000 is lower than needed for contribution 298032, considering fees of 2522. Need more inputs.",
+				"Total input amount 300000 is lower than needed for contribution 298032, considering fees of 2513. Need more inputs.",
 			);
 		}
 
 		// barely covers, less fees (no extra weight, no init)
 		{
-			let expected_fee: u64 = 1092;
+			let expected_fee: u64 = 1088;
 			assert_eq!(
 				check_v2_funding_inputs_sufficient(
 					(300_000 - expected_fee - 20) as i64,
diff --git a/lightning/src/ln/interactivetxs.rs b/lightning/src/ln/interactivetxs.rs
index 97047eb..b223fa3 100644
--- a/lightning/src/ln/interactivetxs.rs
+++ b/lightning/src/ln/interactivetxs.rs
@@ -3353,21 +3353,19 @@ mod tests {
 				FundingTxInput::new_p2wpkh(prevtx, 0).unwrap()
 			})
 			.collect();
-		let our_contributed = 110_000;
 		let txout = TxOut { value: Amount::from_sat(10_000), script_pubkey: ScriptBuf::new() };
 		let outputs = vec![txout];
 		let funding_feerate_sat_per_1000_weight = 3000;
 
-		let total_inputs: u64 = input_prevouts.iter().map(|o| o.value.to_sat()).sum();
-		let total_outputs: u64 = outputs.iter().map(|o| o.value.to_sat()).sum();
-		let gross_change = total_inputs - total_outputs - our_contributed;
-		let fees = 1746;
-		let common_fees = 234;
+		let total_inputs: Amount = input_prevouts.iter().map(|o| o.value).sum();
+		let total_outputs: Amount = outputs.iter().map(|o| o.value).sum();
+		let fees = Amount::from_sat(1740);
+		let common_fees = Amount::from_sat(234);
 
 		// There is leftover for change
 		let context = FundingNegotiationContext {
 			is_initiator: true,
-			our_funding_contribution: SignedAmount::from_sat(our_contributed as i64),
+			our_funding_contribution: SignedAmount::from_sat(110_000),
 			funding_tx_locktime: AbsoluteLockTime::ZERO,
 			funding_feerate_sat_per_1000_weight,
 			shared_funding_input: None,
@@ -3375,16 +3373,18 @@ mod tests {
 			our_funding_outputs: outputs,
 			change_script: None,
 		};
+		let gross_change =
+			total_inputs - total_outputs - context.our_funding_contribution.to_unsigned().unwrap();
 		assert_eq!(
 			calculate_change_output_value(&context, false, &ScriptBuf::new(), 300),
-			Ok(Some(gross_change - fees - common_fees)),
+			Ok(Some((gross_change - fees - common_fees).to_sat())),
 		);
 
 		// There is leftover for change, without common fees
 		let context = FundingNegotiationContext { is_initiator: false, ..context };
 		assert_eq!(
 			calculate_change_output_value(&context, false, &ScriptBuf::new(), 300),
-			Ok(Some(gross_change - fees)),
+			Ok(Some((gross_change - fees).to_sat())),
 		);
 
 		// Insufficient inputs, no leftover
@@ -3415,21 +3415,25 @@ mod tests {
 			our_funding_contribution: SignedAmount::from_sat(117_992),
 			..context
 		};
+		let gross_change =
+			total_inputs - total_outputs - context.our_funding_contribution.to_unsigned().unwrap();
 		assert_eq!(
 			calculate_change_output_value(&context, false, &ScriptBuf::new(), 100),
-			Ok(Some(262)),
+			Ok(Some((gross_change - fees).to_sat())),
 		);
 
 		// Larger fee, smaller change
 		let context = FundingNegotiationContext {
 			is_initiator: true,
-			our_funding_contribution: SignedAmount::from_sat(our_contributed as i64),
+			our_funding_contribution: SignedAmount::from_sat(110_000),
 			funding_feerate_sat_per_1000_weight: funding_feerate_sat_per_1000_weight * 3,
 			..context
 		};
+		let gross_change =
+			total_inputs - total_outputs - context.our_funding_contribution.to_unsigned().unwrap();
 		assert_eq!(
 			calculate_change_output_value(&context, false, &ScriptBuf::new(), 300),
-			Ok(Some(4060)),
+			Ok(Some((gross_change - fees * 3 - common_fees * 3).to_sat())),
 		);
 	}
 
diff --git a/lightning/src/sign/mod.rs b/lightning/src/sign/mod.rs
index 1d771d2..ca80338 100644
--- a/lightning/src/sign/mod.rs
+++ b/lightning/src/sign/mod.rs
@@ -81,6 +81,11 @@ pub mod ecdsa;
 pub mod taproot;
 pub mod tx_builder;
 
+pub(crate) const COMPRESSED_PUBLIC_KEY_SIZE: usize = bitcoin::secp256k1::constants::PUBLIC_KEY_SIZE;
+
+pub(crate) const MAX_STANDARD_SIGNATURE_SIZE: usize =
+	bitcoin::secp256k1::constants::MAX_SIGNATURE_SIZE;
+
 /// Information about a spendable output to a P2WSH script.
 ///
 /// See [`SpendableOutputDescriptor::DelayedPaymentOutput`] for more details on how to spend this.
@@ -114,10 +119,12 @@ impl DelayedPaymentOutputDescriptor {
 	/// 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 length + 73 byte signature, 1 byte empty vec push, 1 byte length plus
-	// redeemscript push length.
-	pub const MAX_WITNESS_LENGTH: u64 =
-		1 + 73 + 1 + chan_utils::REVOKEABLE_REDEEMSCRIPT_MAX_LENGTH as u64 + 1;
+	pub const MAX_WITNESS_LENGTH: u64 = (1 /* witness items */
+		+ 1 /* sig push */
+		+ MAX_STANDARD_SIGNATURE_SIZE
+		+ 1 /* empty vec push */
+		+ 1 /* redeemscript push */
+		+ chan_utils::REVOKEABLE_REDEEMSCRIPT_MAX_LENGTH) as u64;
 }
 
 impl_writeable_tlv_based!(DelayedPaymentOutputDescriptor, {
@@ -131,15 +138,18 @@ impl_writeable_tlv_based!(DelayedPaymentOutputDescriptor, {
 	(13, channel_transaction_parameters, (option: ReadableArgs, Some(channel_value_satoshis.0.unwrap()))),
 });
 
-pub(crate) const P2WPKH_WITNESS_WEIGHT: u64 = 1 /* num stack items */ +
-	1 /* sig length */ +
-	73 /* sig including sighash flag */ +
-	1 /* pubkey length */ +
-	33 /* pubkey */;
+/// Witness weight for satisfying a P2WPKH spend.
+pub(crate) const P2WPKH_WITNESS_WEIGHT: u64 = (1 /* witness items */
+	+ 1 /* sig push */
+	+ MAX_STANDARD_SIGNATURE_SIZE
+	+ 1 /* pubkey push */
+	+ COMPRESSED_PUBLIC_KEY_SIZE) as u64;
 
-/// Witness weight for satisying a P2TR key-path spend.
-pub(crate) const P2TR_KEY_PATH_WITNESS_WEIGHT: u64 = 1 /* witness items */
-	+ 1 /* schnorr sig len */ + 64 /* schnorr sig */;
+/// Witness weight for satisfying a P2TR key-path spend.
+pub(crate) const P2TR_KEY_PATH_WITNESS_WEIGHT: u64 = (1 /* witness items */
+	+ 1 /* sig push */
+	+ bitcoin::secp256k1::constants::SCHNORR_SIGNATURE_SIZE)
+	as u64;
 
 /// If a [`KeysManager`] is built with [`KeysManager::new`] with `v2_remote_key_derivation` set
 /// (and for all channels after they've been spliced), the script which we receive funds to on-chain
@@ -192,10 +202,16 @@ impl StaticPaymentOutputDescriptor {
 	/// shorter.
 	pub fn max_witness_length(&self) -> u64 {
 		if self.needs_csv_1_for_spend() {
-			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
+			let witness_script_weight = 1 /* pubkey push */
+				+ COMPRESSED_PUBLIC_KEY_SIZE
+				+ 1 /* OP_CHECKSIGVERIFY */
+				+ 1 /* OP_1 */
+				+ 1 /* OP_CHECKSEQUENCEVERIFY */;
+			(1 /* num witness items */
+				+ 1 /* sig push */
+				+ MAX_STANDARD_SIGNATURE_SIZE
+				+ 1 /* witness script push */
+				+ witness_script_weight) as u64
 		} else {
 			P2WPKH_WITNESS_WEIGHT
 		}
@@ -511,7 +527,7 @@ impl SpendableOutputDescriptor {
 						sequence: Sequence::ZERO,
 						witness: Witness::new(),
 					});
-					witness_weight += 1 + 73 + 34;
+					witness_weight += P2WPKH_WITNESS_WEIGHT;
 					#[cfg(feature = "grind_signatures")]
 					{
 						// Guarantees a low R signature