_ Git - rust-lightning/blob - lightning/src/chain/keysinterface.rs

   1 //! keysinterface provides keys into rust-lightning and defines some useful enums which describe
   2 //! spendable on-chain outputs which the user owns and is responsible for using just as any other
   3 //! on-chain output which is theirs.
   4
   5 use bitcoin::blockdata::transaction::{OutPoint, TxOut};
   6 use bitcoin::blockdata::script::{Script, Builder};
   7 use bitcoin::blockdata::opcodes;
   8 use bitcoin::network::constants::Network;
   9 use bitcoin::util::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber};
  10
  11 use bitcoin_hashes::{Hash, HashEngine};
  12 use bitcoin_hashes::sha256::HashEngine as Sha256State;
  13 use bitcoin_hashes::sha256::Hash as Sha256;
  14 use bitcoin_hashes::hash160::Hash as Hash160;
  15
  16 use secp256k1::key::{SecretKey, PublicKey};
  17 use secp256k1::Secp256k1;
  18 use secp256k1;
  19
  20 use util::byte_utils;
  21 use util::logger::Logger;
  22
  23 use std::sync::Arc;
  24 use std::sync::atomic::{AtomicUsize, Ordering};
  25
  26 /// When on-chain outputs are created by rust-lightning an event is generated which informs the
  27 /// user thereof. This enum describes the format of the output and provides the OutPoint.
  28 pub enum SpendableOutputDescriptor {
  29         /// Outpoint with an output to a script which was provided via KeysInterface, thus you should
  30         /// have stored somewhere how to spend script_pubkey!
  31         /// Outputs from a justice tx, claim tx or preimage tx
  32         StaticOutput {
  33                 /// The outpoint spendable by user wallet
  34                 outpoint: OutPoint,
  35                 /// The output which is referenced by the given outpoint
  36                 output: TxOut,
  37         },
  38         /// Outpoint commits to a P2WSH
  39         /// P2WSH should be spend by the following witness :
  40         /// <local_delayedsig> 0 <witnessScript>
  41         /// With input nSequence set to_self_delay.
  42         /// Outputs from a HTLC-Success/Timeout tx/commitment tx
  43         DynamicOutputP2WSH {
  44                 /// Outpoint spendable by user wallet
  45                 outpoint: OutPoint,
  46                 /// local_delayedkey = delayed_payment_basepoint_secret + SHA256(per_commitment_point || delayed_payment_basepoint) OR
  47                 key: SecretKey,
  48                 /// witness redeemScript encumbering output.
  49                 witness_script: Script,
  50                 /// nSequence input must commit to self_delay to satisfy script's OP_CSV
  51                 to_self_delay: u16,
  52                 /// The output which is referenced by the given outpoint
  53                 output: TxOut,
  54         },
  55         /// Outpoint commits to a P2WPKH
  56         /// P2WPKH should be spend by the following witness :
  57         /// <local_sig> <local_pubkey>
  58         /// Outputs to_remote from a commitment tx
  59         DynamicOutputP2WPKH {
  60                 /// Outpoint spendable by user wallet
  61                 outpoint: OutPoint,
  62                 /// localkey = payment_basepoint_secret + SHA256(per_commitment_point || payment_basepoint
  63                 key: SecretKey,
  64                 /// The output which is reference by the given outpoint
  65                 output: TxOut,
  66         }
  67 }
  68
  69 /// A trait to describe an object which can get user secrets and key material.
  70 pub trait KeysInterface: Send + Sync {
  71         /// Get node secret key (aka node_id or network_key)
  72         fn get_node_secret(&self) -> SecretKey;
  73         /// Get destination redeemScript to encumber static protocol exit points.
  74         fn get_destination_script(&self) -> Script;
  75         /// Get shutdown_pubkey to use as PublicKey at channel closure
  76         fn get_shutdown_pubkey(&self) -> PublicKey;
  77         /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
  78         /// restarted with some stale data!
  79         fn get_channel_keys(&self, inbound: bool) -> ChannelKeys;
  80         /// Get a secret for construting an onion packet
  81         fn get_session_key(&self) -> SecretKey;
  82         /// Get a unique temporary channel id. Channels will be referred to by this until the funding
  83         /// transaction is created, at which point they will use the outpoint in the funding
  84         /// transaction.
  85         fn get_channel_id(&self) -> [u8; 32];
  86 }
  87
  88 /// Set of lightning keys needed to operate a channel as described in BOLT 3
  89 #[derive(Clone)]
  90 pub struct ChannelKeys {
  91         /// Private key of anchor tx
  92         pub funding_key: SecretKey,
  93         /// Local secret key for blinded revocation pubkey
  94         pub revocation_base_key: SecretKey,
  95         /// Local secret key used in commitment tx htlc outputs
  96         pub payment_base_key: SecretKey,
  97         /// Local secret key used in HTLC tx
  98         pub delayed_payment_base_key: SecretKey,
  99         /// Local htlc secret key used in commitment tx htlc outputs
 100         pub htlc_base_key: SecretKey,
 101         /// Commitment seed
 102         pub commitment_seed: [u8; 32],
 103 }
 104
 105 impl_writeable!(ChannelKeys, 0, {
 106         funding_key,
 107         revocation_base_key,
 108         payment_base_key,
 109         delayed_payment_base_key,
 110         htlc_base_key,
 111         commitment_seed
 112 });
 113
 114 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
 115 /// and derives keys from that.
 116 ///
 117 /// Your node_id is seed/0'
 118 /// ChannelMonitor closes may use seed/1'
 119 /// Cooperative closes may use seed/2'
 120 /// The two close keys may be needed to claim on-chain funds!
 121 pub struct KeysManager {
 122         secp_ctx: Secp256k1<secp256k1::SignOnly>,
 123         node_secret: SecretKey,
 124         destination_script: Script,
 125         shutdown_pubkey: PublicKey,
 126         channel_master_key: ExtendedPrivKey,
 127         channel_child_index: AtomicUsize,
 128         session_master_key: ExtendedPrivKey,
 129         session_child_index: AtomicUsize,
 130         channel_id_master_key: ExtendedPrivKey,
 131         channel_id_child_index: AtomicUsize,
 132
 133         unique_start: Sha256State,
 134         logger: Arc<Logger>,
 135 }
 136
 137 impl KeysManager {
 138         /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
 139         /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
 140         /// starting_time isn't strictly required to actually be a time, but it must absolutely,
 141         /// without a doubt, be unique to this instance. ie if you start multiple times with the same
 142         /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
 143         /// simply use the current time (with very high precision).
 144         ///
 145         /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
 146         /// obviously, starting_time should be unique every time you reload the library - it is only
 147         /// used to generate new ephemeral key data (which will be stored by the individual channel if
 148         /// necessary).
 149         ///
 150         /// Note that the seed is required to recover certain on-chain funds independent of
 151         /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
 152         /// channel, and some on-chain during-closing funds.
 153         ///
 154         /// Note that until the 0.1 release there is no guarantee of backward compatibility between
 155         /// versions. Once the library is more fully supported, the docs will be updated to include a
 156         /// detailed description of the guarantee.
 157         pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager {
 158                 let secp_ctx = Secp256k1::signing_only();
 159                 match ExtendedPrivKey::new_master(network.clone(), seed) {
 160                         Ok(master_key) => {
 161                                 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
 162                                 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
 163                                         Ok(destination_key) => {
 164                                                 let pubkey_hash160 = Hash160::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.key.serialize()[..]);
 165                                                 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
 166                                                               .push_slice(&pubkey_hash160.into_inner())
 167                                                               .into_script()
 168                                         },
 169                                         Err(_) => panic!("Your RNG is busted"),
 170                                 };
 171                                 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
 172                                         Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
 173                                         Err(_) => panic!("Your RNG is busted"),
 174                                 };
 175                                 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
 176                                 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
 177                                 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
 178
 179                                 let mut unique_start = Sha256::engine();
 180                                 unique_start.input(&byte_utils::be64_to_array(starting_time_secs));
 181                                 unique_start.input(&byte_utils::be32_to_array(starting_time_nanos));
 182                                 unique_start.input(seed);
 183
 184                                 KeysManager {
 185                                         secp_ctx,
 186                                         node_secret,
 187                                         destination_script,
 188                                         shutdown_pubkey,
 189                                         channel_master_key,
 190                                         channel_child_index: AtomicUsize::new(0),
 191                                         session_master_key,
 192                                         session_child_index: AtomicUsize::new(0),
 193                                         channel_id_master_key,
 194                                         channel_id_child_index: AtomicUsize::new(0),
 195
 196                                         unique_start,
 197                                         logger,
 198                                 }
 199                         },
 200                         Err(_) => panic!("Your rng is busted"),
 201                 }
 202         }
 203 }
 204
 205 impl KeysInterface for KeysManager {
 206         fn get_node_secret(&self) -> SecretKey {
 207                 self.node_secret.clone()
 208         }
 209
 210         fn get_destination_script(&self) -> Script {
 211                 self.destination_script.clone()
 212         }
 213
 214         fn get_shutdown_pubkey(&self) -> PublicKey {
 215                 self.shutdown_pubkey.clone()
 216         }
 217
 218         fn get_channel_keys(&self, _inbound: bool) -> ChannelKeys {
 219                 // We only seriously intend to rely on the channel_master_key for true secure
 220                 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
 221                 // starting_time provided in the constructor) to be unique.
 222                 let mut sha = self.unique_start.clone();
 223
 224                 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
 225                 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");
 226                 sha.input(&child_privkey.private_key.key[..]);
 227
 228                 let seed = Sha256::from_engine(sha).into_inner();
 229
 230                 let commitment_seed = {
 231                         let mut sha = Sha256::engine();
 232                         sha.input(&seed);
 233                         sha.input(&b"commitment seed"[..]);
 234                         Sha256::from_engine(sha).into_inner()
 235                 };
 236                 macro_rules! key_step {
 237                         ($info: expr, $prev_key: expr) => {{
 238                                 let mut sha = Sha256::engine();
 239                                 sha.input(&seed);
 240                                 sha.input(&$prev_key[..]);
 241                                 sha.input(&$info[..]);
 242                                 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
 243                         }}
 244                 }
 245                 let funding_key = key_step!(b"funding key", commitment_seed);
 246                 let revocation_base_key = key_step!(b"revocation base key", funding_key);
 247                 let payment_base_key = key_step!(b"payment base key", revocation_base_key);
 248                 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key);
 249                 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
 250
 251                 ChannelKeys {
 252                         funding_key,
 253                         revocation_base_key,
 254                         payment_base_key,
 255                         delayed_payment_base_key,
 256                         htlc_base_key,
 257                         commitment_seed,
 258                 }
 259         }
 260
 261         fn get_session_key(&self) -> SecretKey {
 262                 let mut sha = self.unique_start.clone();
 263
 264                 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
 265                 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");
 266                 sha.input(&child_privkey.private_key.key[..]);
 267                 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted")
 268         }
 269
 270         fn get_channel_id(&self) -> [u8; 32] {
 271                 let mut sha = self.unique_start.clone();
 272
 273                 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
 274                 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");
 275                 sha.input(&child_privkey.private_key.key[..]);
 276
 277                 (Sha256::from_engine(sha).into_inner())
 278         }
 279 }