_ 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::hkdf::{hkdf_extract,hkdf_expand};
  17
  18 use util::sha2::Sha256;
  19 use util::logger::Logger;
  20
  21 use std::sync::Arc;
  22
  23 /// When on-chain outputs are created by rust-lightning an event is generated which informs the
  24 /// user thereof. This enum describes the format of the output and provides the OutPoint.
  25 pub enum SpendableOutputDescriptor {
  26         /// Outpoint with an output to a script which was provided via KeysInterface, thus you should
  27         /// have stored somewhere how to spend script_pubkey!
  28         /// Outputs from a justice tx, claim tx or preimage tx
  29         StaticOutput {
  30                 /// The outpoint spendable by user wallet
  31                 outpoint: OutPoint,
  32                 /// The output which is referenced by the given outpoint
  33                 output: TxOut,
  34         },
  35         /// Outpoint commits to a P2WSH, should be spend by the following witness :
  36         /// <local_delayedsig> 0 <witnessScript>
  37         /// With input nSequence set to_self_delay.
  38         /// Outputs from a HTLC-Success/Timeout tx
  39         DynamicOutput {
  40                 /// Outpoint spendable by user wallet
  41                 outpoint: OutPoint,
  42                 /// local_delayedkey = delayed_payment_basepoint_secret + SHA256(per_commitment_point || delayed_payment_basepoint
  43                 local_delayedkey: SecretKey,
  44                 /// witness redeemScript encumbering output
  45                 witness_script: Script,
  46                 /// nSequence input must commit to self_delay to satisfy script's OP_CSV
  47                 to_self_delay: u16,
  48         }
  49 }
  50
  51 /// A trait to describe an object which can get user secrets and key material.
  52 pub trait KeysInterface: Send + Sync {
  53         /// Get node secret key (aka node_id or network_key)
  54         fn get_node_secret(&self) -> SecretKey;
  55         /// Get destination redeemScript to encumber static protocol exit points.
  56         fn get_destination_script(&self) -> Script;
  57         /// Get shutdown_pubkey to use as PublicKey at channel closure
  58         fn get_shutdown_pubkey(&self) -> PublicKey;
  59         /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
  60         /// restarted with some stale data!
  61         fn get_channel_keys(&self, inbound: bool) -> ChannelKeys;
  62 }
  63
  64 /// Set of lightning keys needed to operate a channel as described in BOLT 3
  65 #[derive(Clone)]
  66 pub struct ChannelKeys {
  67         /// Private key of anchor tx
  68         pub funding_key: SecretKey,
  69         /// Local secret key for blinded revocation pubkey
  70         pub revocation_base_key: SecretKey,
  71         /// Local secret key used in commitment tx htlc outputs
  72         pub payment_base_key: SecretKey,
  73         /// Local secret key used in HTLC tx
  74         pub delayed_payment_base_key: SecretKey,
  75         /// Local htlc secret key used in commitment tx htlc outputs
  76         pub htlc_base_key: SecretKey,
  77         /// Commitment seed
  78         pub commitment_seed: [u8; 32],
  79 }
  80
  81 impl ChannelKeys {
  82         /// Generate a set of lightning keys needed to operate a channel by HKDF-expanding a given
  83         /// random 32-byte seed
  84         pub fn new_from_seed(seed: &[u8; 32]) -> ChannelKeys {
  85                 let mut prk = [0; 32];
  86                 hkdf_extract(Sha256::new(), b"rust-lightning key gen salt", seed, &mut prk);
  87                 let secp_ctx = Secp256k1::without_caps();
  88
  89                 let mut okm = [0; 32];
  90                 hkdf_expand(Sha256::new(), &prk, b"rust-lightning funding key info", &mut okm);
  91                 let funding_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
  92
  93                 hkdf_expand(Sha256::new(), &prk, b"rust-lightning revocation base key info", &mut okm);
  94                 let revocation_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
  95
  96                 hkdf_expand(Sha256::new(), &prk, b"rust-lightning payment base key info", &mut okm);
  97                 let payment_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
  98
  99                 hkdf_expand(Sha256::new(), &prk, b"rust-lightning delayed payment base key info", &mut okm);
 100                 let delayed_payment_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
 101
 102                 hkdf_expand(Sha256::new(), &prk, b"rust-lightning htlc base key info", &mut okm);
 103                 let htlc_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
 104
 105                 hkdf_expand(Sha256::new(), &prk, b"rust-lightning local commitment seed info", &mut okm);
 106
 107                 ChannelKeys {
 108                         funding_key: funding_key,
 109                         revocation_base_key: revocation_base_key,
 110                         payment_base_key: payment_base_key,
 111                         delayed_payment_base_key: delayed_payment_base_key,
 112                         htlc_base_key: htlc_base_key,
 113                         commitment_seed: okm
 114                 }
 115         }
 116 }
 117
 118 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
 119 /// and derives keys from that.
 120 ///
 121 /// Your node_id is seed/0'
 122 /// ChannelMonitor closes may use seed/1'
 123 /// Cooperative closes may use seed/2'
 124 /// The two close keys may be needed to claim on-chain funds!
 125 pub struct KeysManager {
 126         secp_ctx: Secp256k1<secp256k1::All>,
 127         node_secret: SecretKey,
 128         destination_script: Script,
 129         shutdown_pubkey: PublicKey,
 130         channel_master_key: ExtendedPrivKey,
 131
 132         logger: Arc<Logger>,
 133 }
 134
 135 impl KeysManager {
 136         /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
 137         /// RNG is busted) this may panic.
 138         pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>) -> KeysManager {
 139                 let secp_ctx = Secp256k1::new();
 140                 match ExtendedPrivKey::new_master(&secp_ctx, network.clone(), seed) {
 141                         Ok(master_key) => {
 142                                 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0)).expect("Your RNG is busted").secret_key;
 143                                 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1)) {
 144                                         Ok(destination_key) => {
 145                                                 let pubkey_hash160 = Hash160::from_data(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.serialize()[..]);
 146                                                 Builder::new().push_opcode(opcodes::All::OP_PUSHBYTES_0)
 147                                                               .push_slice(pubkey_hash160.as_bytes())
 148                                                               .into_script()
 149                                         },
 150                                         Err(_) => panic!("Your RNG is busted"),
 151                                 };
 152                                 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2)) {
 153                                         Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key,
 154                                         Err(_) => panic!("Your RNG is busted"),
 155                                 };
 156                                 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3)).expect("Your RNG is busted");
 157                                 KeysManager {
 158                                         secp_ctx,
 159                                         node_secret,
 160                                         destination_script,
 161                                         shutdown_pubkey,
 162                                         channel_master_key,
 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                 let channel_pubkey = ExtendedPubKey::from_private(&self.secp_ctx, &self. channel_master_key);
 187                 let mut seed = [0; 32];
 188                 for (arr, slice) in seed.iter_mut().zip((&channel_pubkey.public_key.serialize()[0..32]).iter()) {
 189                         *arr = *slice;
 190                 }
 191                 ChannelKeys::new_from_seed(&seed)
 192         }
 193 }