From f8ea748268a7700c33b6e0905f9f33844469fc83 Mon Sep 17 00:00:00 2001 From: Antoine Riard Date: Mon, 11 May 2020 20:29:39 -0400 Subject: [PATCH] Add KeysManager::derive_unique_start In next commit, we add derive_channel_keys, a helper to rederive keys from a SpendableOuptutDescriptor. We still need to ensure that user rederive same set of keys even if KeyManager is started at a later time. For doing so we need to pass starting time as part of the re-derived sha_state, therefore we need to make it accessible and part of channel state key material. Seed is already required to be conserved between KeysManager serializations. --- lightning/src/chain/keysinterface.rs | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs index e6255da9e..7b71784ca 100644 --- a/lightning/src/chain/keysinterface.rs +++ b/lightning/src/chain/keysinterface.rs @@ -542,7 +542,9 @@ pub struct KeysManager { channel_id_master_key: ExtendedPrivKey, channel_id_child_index: AtomicUsize, - unique_start: Sha256State, + seed: [u8; 32], + starting_time_secs: u64, + starting_time_nanos: u32, } impl KeysManager { @@ -587,11 +589,6 @@ impl KeysManager { let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted"); let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted"); - let mut unique_start = Sha256::engine(); - unique_start.input(&byte_utils::be64_to_array(starting_time_secs)); - unique_start.input(&byte_utils::be32_to_array(starting_time_nanos)); - unique_start.input(seed); - KeysManager { secp_ctx, node_secret, @@ -604,12 +601,21 @@ impl KeysManager { channel_id_master_key, channel_id_child_index: AtomicUsize::new(0), - unique_start, + seed: *seed, + starting_time_secs, + starting_time_nanos, } }, Err(_) => panic!("Your rng is busted"), } } + fn derive_unique_start(&self) -> Sha256State { + let mut unique_start = Sha256::engine(); + unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs)); + unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos)); + unique_start.input(&self.seed); + unique_start + } } impl KeysInterface for KeysManager { @@ -631,7 +637,7 @@ impl KeysInterface for KeysManager { // We only seriously intend to rely on the channel_master_key for true secure // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie // starting_time provided in the constructor) to be unique. - let mut sha = self.unique_start.clone(); + let mut sha = self.derive_unique_start(); let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel); let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted"); @@ -673,7 +679,7 @@ impl KeysInterface for KeysManager { } fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) { - let mut sha = self.unique_start.clone(); + let mut sha = self.derive_unique_start(); let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel); let child_privkey = self.session_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted"); @@ -689,7 +695,7 @@ impl KeysInterface for KeysManager { } fn get_channel_id(&self) -> [u8; 32] { - let mut sha = self.unique_start.clone(); + let mut sha = self.derive_unique_start(); let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel); let child_privkey = self.channel_id_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted"); -- 2.39.5