Implement KeysInterface for KeysManager util

diff --git a/src/chain/keysinterface.rs b/src/chain/keysinterface.rs
index 568b91e82b52410605c83a55b1cc59fafc323cd7..3e4ff0e36991320fb67f4be28f4fa460f05408c1 100644 (file)
--- a/src/chain/keysinterface.rs
+++ b/src/chain/keysinterface.rs
@@ -3,14 +3,22 @@
 //! on-chain output which is theirs.
 
 use bitcoin::blockdata::transaction::{OutPoint, TxOut};
-use bitcoin::blockdata::script::Script;
+use bitcoin::blockdata::script::{Script, Builder};
+use bitcoin::blockdata::opcodes;
+use bitcoin::network::constants::Network;
+use bitcoin::util::hash::Hash160;
+use bitcoin::util::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber};
 
 use secp256k1::key::{SecretKey, PublicKey};
 use secp256k1::Secp256k1;
+use secp256k1;
 
 use crypto::hkdf::{hkdf_extract,hkdf_expand};
 
 use util::sha2::Sha256;
+use util::logger::Logger;
+
+use std::sync::Arc;
 
 /// When on-chain outputs are created by rust-lightning an event is generated which informs the
 /// user thereof. This enum describes the format of the output and provides the OutPoint.
@@ -117,3 +125,80 @@ impl ChannelKeys {
                }
        }
 }
+
+/// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
+/// and derives keys from that.
+///
+/// Your node_id is seed/0'
+/// ChannelMonitor closes may use seed/1'
+/// Cooperative closes may use seed/2'
+/// The two close keys may be needed to claim on-chain funds!
+pub struct KeysManager {
+       secp_ctx: Secp256k1<secp256k1::All>,
+       node_secret: SecretKey,
+       destination_script: Script,
+       shutdown_pubkey: PublicKey,
+       channel_master_key: ExtendedPrivKey,
+
+       logger: Arc<Logger>,
+}
+
+impl KeysManager {
+       /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
+       /// RNG is busted) this may panic.
+       pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>) -> KeysManager {
+               let secp_ctx = Secp256k1::new();
+               match ExtendedPrivKey::new_master(&secp_ctx, network.clone(), seed) {
+                       Ok(master_key) => {
+                               let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0)).expect("Your RNG is busted").secret_key;
+                               let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1)) {
+                                       Ok(destination_key) => {
+                                               let pubkey_hash160 = Hash160::from_data(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.serialize()[..]);
+                                               Builder::new().push_opcode(opcodes::All::OP_PUSHBYTES_0)
+                                                             .push_slice(pubkey_hash160.as_bytes())
+                                                             .into_script()
+                                       },
+                                       Err(_) => panic!("Your RNG is busted"),
+                               };
+                               let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2)) {
+                                       Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key,
+                                       Err(_) => panic!("Your RNG is busted"),
+                               };
+                               let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3)).expect("Your RNG is busted");
+                               KeysManager {
+                                       secp_ctx,
+                                       node_secret,
+                                       destination_script,
+                                       shutdown_pubkey,
+                                       channel_master_key,
+
+                                       logger,
+                               }
+                       },
+                       Err(_) => panic!("Your rng is busted"),
+               }
+       }
+}
+
+impl KeysInterface for KeysManager {
+       fn get_node_secret(&self) -> SecretKey {
+               self.node_secret.clone()
+       }
+
+       fn get_destination_script(&self) -> Script {
+               self.destination_script.clone()
+       }
+
+       fn get_shutdown_pubkey(&self) -> PublicKey {
+               self.shutdown_pubkey.clone()
+       }
+
+       fn get_channel_keys(&self, _inbound: bool) -> ChannelKeys {
+               let channel_pubkey = ExtendedPubKey::from_private(&self.secp_ctx, &self. channel_master_key);
+               let mut seed = [0; 32];
+               for (arr, slice) in seed.iter_mut().zip((&channel_pubkey.public_key.serialize()[0..32]).iter()) {
+                       *arr = *slice;
+               }
+               ChannelKeys::new_from_seed(&seed)
+       }
+}