_ 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::hash::Hash160;
  10 use bitcoin::util::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber};
  11
  12 use secp256k1::key::{SecretKey, PublicKey};
  13 use secp256k1::Secp256k1;
  14 use secp256k1;
  15
  16 use crypto::digest::Digest;
  17
  18 use util::sha2::Sha256;
  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 }
  84
  85 /// Set of lightning keys needed to operate a channel as described in BOLT 3
  86 #[derive(Clone)]
  87 pub struct ChannelKeys {
  88         /// Private key of anchor tx
  89         pub funding_key: SecretKey,
  90         /// Local secret key for blinded revocation pubkey
  91         pub revocation_base_key: SecretKey,
  92         /// Local secret key used in commitment tx htlc outputs
  93         pub payment_base_key: SecretKey,
  94         /// Local secret key used in HTLC tx
  95         pub delayed_payment_base_key: SecretKey,
  96         /// Local htlc secret key used in commitment tx htlc outputs
  97         pub htlc_base_key: SecretKey,
  98         /// Commitment seed
  99         pub commitment_seed: [u8; 32],
 100 }
 101
 102 impl_writeable!(ChannelKeys, 0, {
 103         funding_key,
 104         revocation_base_key,
 105         payment_base_key,
 106         delayed_payment_base_key,
 107         htlc_base_key,
 108         commitment_seed
 109 });
 110
 111 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
 112 /// and derives keys from that.
 113 ///
 114 /// Your node_id is seed/0'
 115 /// ChannelMonitor closes may use seed/1'
 116 /// Cooperative closes may use seed/2'
 117 /// The two close keys may be needed to claim on-chain funds!
 118 pub struct KeysManager {
 119         secp_ctx: Secp256k1<secp256k1::All>,
 120         node_secret: SecretKey,
 121         destination_script: Script,
 122         shutdown_pubkey: PublicKey,
 123         channel_master_key: ExtendedPrivKey,
 124         channel_child_index: AtomicUsize,
 125         session_master_key: ExtendedPrivKey,
 126         session_child_index: AtomicUsize,
 127
 128         logger: Arc<Logger>,
 129 }
 130
 131 impl KeysManager {
 132         /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
 133         /// RNG is busted) this may panic.
 134         pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>) -> KeysManager {
 135                 let secp_ctx = Secp256k1::new();
 136                 match ExtendedPrivKey::new_master(&secp_ctx, network.clone(), seed) {
 137                         Ok(master_key) => {
 138                                 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0)).expect("Your RNG is busted").secret_key;
 139                                 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1)) {
 140                                         Ok(destination_key) => {
 141                                                 let pubkey_hash160 = Hash160::from_data(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.serialize()[..]);
 142                                                 Builder::new().push_opcode(opcodes::All::OP_PUSHBYTES_0)
 143                                                               .push_slice(pubkey_hash160.as_bytes())
 144                                                               .into_script()
 145                                         },
 146                                         Err(_) => panic!("Your RNG is busted"),
 147                                 };
 148                                 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2)) {
 149                                         Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key,
 150                                         Err(_) => panic!("Your RNG is busted"),
 151                                 };
 152                                 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3)).expect("Your RNG is busted");
 153                                 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4)).expect("Your RNG is busted");
 154                                 KeysManager {
 155                                         secp_ctx,
 156                                         node_secret,
 157                                         destination_script,
 158                                         shutdown_pubkey,
 159                                         channel_master_key,
 160                                         channel_child_index: AtomicUsize::new(0),
 161                                         session_master_key,
 162                                         session_child_index: AtomicUsize::new(0),
 163
 164                                         logger,
 165                                 }
 166                         },
 167                         Err(_) => panic!("Your rng is busted"),
 168                 }
 169         }
 170 }
 171
 172 impl KeysInterface for KeysManager {
 173         fn get_node_secret(&self) -> SecretKey {
 174                 self.node_secret.clone()
 175         }
 176
 177         fn get_destination_script(&self) -> Script {
 178                 self.destination_script.clone()
 179         }
 180
 181         fn get_shutdown_pubkey(&self) -> PublicKey {
 182                 self.shutdown_pubkey.clone()
 183         }
 184
 185         fn get_channel_keys(&self, _inbound: bool) -> ChannelKeys {
 186                 // We only seriously intend to rely on the channel_master_key for true secure
 187                 // entropy, everything else just ensures uniqueness. We generally don't expect
 188                 // all clients to have non-broken RNGs here, so we also include the current
 189                 // time as a fallback to get uniqueness.
 190                 let mut sha = Sha256::new();
 191
 192                 let mut seed = [0u8; 32];
 193                 rng::fill_bytes(&mut seed[..]);
 194                 sha.input(&seed);
 195
 196                 let now = SystemTime::now().duration_since(UNIX_EPOCH).expect("Time went backwards");
 197                 sha.input(&byte_utils::be32_to_array(now.subsec_nanos()));
 198                 sha.input(&byte_utils::be64_to_array(now.as_secs()));
 199
 200                 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
 201                 let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32)).expect("Your RNG is busted");
 202                 sha.input(&child_privkey.secret_key[..]);
 203
 204                 sha.result(&mut seed);
 205
 206                 let commitment_seed = {
 207                         let mut sha = Sha256::new();
 208                         sha.input(&seed);
 209                         sha.input(&b"commitment seed"[..]);
 210                         let mut res = [0; 32];
 211                         sha.result(&mut res);
 212                         res
 213                 };
 214                 macro_rules! key_step {
 215                         ($info: expr, $prev_key: expr) => {{
 216                                 let mut sha = Sha256::new();
 217                                 sha.input(&seed);
 218                                 sha.input(&$prev_key[..]);
 219                                 sha.input(&$info[..]);
 220                                 let mut res = [0; 32];
 221                                 sha.result(&mut res);
 222                                 SecretKey::from_slice(&self.secp_ctx, &res).expect("SHA-256 is busted")
 223                         }}
 224                 }
 225                 let funding_key = key_step!(b"funding key", commitment_seed);
 226                 let revocation_base_key = key_step!(b"revocation base key", funding_key);
 227                 let payment_base_key = key_step!(b"payment base key", revocation_base_key);
 228                 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key);
 229                 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
 230
 231                 ChannelKeys {
 232                         funding_key,
 233                         revocation_base_key,
 234                         payment_base_key,
 235                         delayed_payment_base_key,
 236                         htlc_base_key,
 237                         commitment_seed,
 238                 }
 239         }
 240
 241         fn get_session_key(&self) -> SecretKey {
 242                 let mut sha = Sha256::new();
 243                 let mut res = [0u8; 32];
 244
 245                 let now = SystemTime::now().duration_since(UNIX_EPOCH).expect("Time went backwards");
 246                 sha.input(&byte_utils::be32_to_array(now.subsec_nanos()));
 247                 sha.input(&byte_utils::be64_to_array(now.as_secs()));
 248
 249                 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
 250                 let child_privkey = self.session_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32)).expect("Your RNG is busted");
 251                 sha.input(&child_privkey.secret_key[..]);
 252                 sha.result(&mut res);
 253                 SecretKey::from_slice(&self.secp_ctx, &res).expect("Your RNG is busted")
 254         }
 255 }