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