Add a KeysInterface to bridge between user wallet and others lightning

componenents, responsible to get seed from the former and derive
appropriate keyring materials

Author: Antoine Riard

src/ln/keysinterface.rs

@@ -11,6 +11,7 @@ use bitcoin::blockdata::script::Script;
 
 use secp256k1::key::SecretKey;
 
+use ln::channel::ChannelKeys;
 use util::events;
 
 /// A trait to describe a wallet which sould receive data to be able to spend onchain outputs
@@ -68,3 +69,21 @@ impl CustomOutputScriptDescriptor {
 		}
 	}
 }
+
+/// A trait to describe an object which should get secrets from user wallet and apply derivation
+/// to provide keys materials downstream
+pub trait KeysInterface: Send + Sync {
+	/// User wallet has to provide this KeysInterface with a master seed used to derive 
+	/// node_id as /0' and destination_script as /N'
+	fn provide_master_seed(&mut self, seed : &[u8; 32]);
+	/// Get node secret key to derive node_id
+	fn get_node_secret(&self) -> Option<SecretKey>;
+	/// Get destination redeemScript to encumber static protocol exit points. For now
+	/// redeemScript is a pay-2-public-key-hash.
+	fn get_destination_script(&self) -> Option<Script>;
+	/// Get shutdown_pubkey to use as PublicKey at channel closure
+	fn get_shutdown_pubkey(&self) -> Option<PublicKey>;
+	/// Get a new set of ChannelKeys from per-channel random key /3/N'
+	/// For Channel N, keys correspond to ChannelKeys::new_from_seed(/3/N')
+	fn get_channel_keys(&mut self) -> Option<ChannelKeys>;
+}