f move bytes -> int to callsite

Author: TheBlueMatt

lightning/src/sign/mod.rs

@@ -2072,10 +2072,8 @@ impl KeysManager {
 		self.node_secret
 	}
 
-	fn derive_payment_key_v2(&self, params: &[u8; 32]) -> SecretKey {
-		let mut eight_bytes = [0; 8];
-		eight_bytes.copy_from_slice(&params[0..8]);
-		let idx = u64::from_le_bytes(eight_bytes) % u64::from(STATIC_PAYMENT_KEY_COUNT);
+	fn derive_payment_key_v2(&self, key_idx: u64) -> SecretKey {
+		let idx = key_idx % u64::from(STATIC_PAYMENT_KEY_COUNT);
 		self.static_payment_key
 			.derive_priv(
 				&self.secp_ctx,
@@ -2130,11 +2128,14 @@ impl KeysManager {
 		let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
 		let prng_seed = self.get_secure_random_bytes();
 
+		let payment_key_v2_idx =
+			u64::from_le_bytes(commitment_seed[..8].try_into().expect("8 bytes"));
+
 		InMemorySigner::new(
 			funding_key,
 			revocation_base_key,
 			payment_key_v1,
-			self.derive_payment_key_v2(&commitment_seed),
+			self.derive_payment_key_v2(payment_key_v2_idx),
 			self.v2_remote_key_derivation,
 			delayed_payment_base_key,
 			htlc_base_key,