common: Add derive_node_pk convenience fn

Author: MaxFangX

common/Cargo.toml

@@ -72,7 +72,7 @@ rustls = { version = "0.20", default-features = false, features = [
 rustls-pemfile = "1"
 # A wrapper type for carefully handling secrets
 secrecy = "0.8"
-# Serializing/deserializing types
+# Serialization / deserialization framework
 serde = { version = "1", features = ["derive"] }
 serde_qs = "0"
 serde_json = "1"

common/src/root_seed.rs

@@ -2,7 +2,7 @@ use std::fmt;
 use std::str::FromStr;
 
 use anyhow::format_err;
-use bitcoin::secp256k1::Secp256k1;
+use bitcoin::secp256k1::{PublicKey, Secp256k1};
 use bitcoin::util::bip32::{ChildNumber, ExtendedPrivKey};
 use bitcoin::{KeyPair, Network};
 use rand_core::{CryptoRng, RngCore};
@@ -118,6 +118,11 @@ impl RootSeed {
         KeyPair::from_secret_key(&secp_ctx, node_sk)
     }
 
+    /// Derive the Lightning node pubkey.
+    pub fn derive_node_pk<R: Crng>(&self, rng: &mut R) -> PublicKey {
+        PublicKey::from(self.derive_node_key_pair(rng))
+    }
+
     #[cfg(test)]
     fn as_bytes(&self) -> &[u8] {
         self.0.expose_secret().as_slice()