revert extra byte in weight calc

Author: joostjager

lightning/src/sign/mod.rs

@@ -75,6 +75,8 @@ pub mod tx_builder;
 
 pub(crate) const COMPRESSED_PUBLIC_KEY_SIZE: usize = bitcoin::secp256k1::constants::PUBLIC_KEY_SIZE;
 
+// Standard low-S ECDSA signatures fit in the secp256k1 DER bound; the appended sighash byte
+// replaces the extra DER padding byte that a high-S signature could require.
 pub(crate) const MAX_STANDARD_SIGNATURE_SIZE: usize =
 	bitcoin::secp256k1::constants::MAX_SIGNATURE_SIZE;
 
@@ -135,7 +137,6 @@ impl_writeable_tlv_based!(DelayedPaymentOutputDescriptor, {
 pub(crate) const P2WPKH_WITNESS_WEIGHT: u64 = (1 /* witness items */
 	+ 1 /* sig push */
 	+ MAX_STANDARD_SIGNATURE_SIZE
-	+ 1 /* sighash flag */
 	+ 1 /* pubkey push */
 	+ COMPRESSED_PUBLIC_KEY_SIZE) as u64;
 
@@ -2714,15 +2715,6 @@ pub fn dyn_sign() {
 	let _signer: Box<dyn EcdsaChannelSigner>;
 }
 
-#[test]
-pub fn p2wpkh_witness_weight_matches_serialized_witness() {
-	let witness = Witness::from_slice(&[
-		vec![0; MAX_STANDARD_SIGNATURE_SIZE + 1],
-		vec![0; COMPRESSED_PUBLIC_KEY_SIZE],
-	]);
-	assert_eq!(witness.size() as u64, P2WPKH_WITNESS_WEIGHT);
-}
-
 #[cfg(ldk_bench)]
 pub mod benches {
 	use crate::sign::{EntropySource, KeysManager};