_ 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::{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 use bitcoin::util::bip143;
  11
  12 use bitcoin_hashes::{Hash, HashEngine};
  13 use bitcoin_hashes::sha256::HashEngine as Sha256State;
  14 use bitcoin_hashes::sha256::Hash as Sha256;
  15 use bitcoin_hashes::sha256d::Hash as Sha256dHash;
  16 use bitcoin_hashes::hash160::Hash as Hash160;
  17
  18 use secp256k1::key::{SecretKey, PublicKey};
  19 use secp256k1::{Secp256k1, Signature, Signing};
  20 use secp256k1;
  21
  22 use util::byte_utils;
  23 use util::logger::Logger;
  24 use util::ser::{Writeable, Writer, Readable};
  25
  26 use ln::chan_utils;
  27 use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys};
  28 use ln::msgs;
  29
  30 use std::sync::Arc;
  31 use std::sync::atomic::{AtomicUsize, Ordering};
  32 use std::io::Error;
  33 use ln::msgs::DecodeError;
  34
  35 /// When on-chain outputs are created by rust-lightning (which our counterparty is not able to
  36 /// claim at any point in the future) an event is generated which you must track and be able to
  37 /// spend on-chain. The information needed to do this is provided in this enum, including the
  38 /// outpoint describing which txid and output index is available, the full output which exists at
  39 /// that txid/index, and any keys or other information required to sign.
  40 pub enum SpendableOutputDescriptor {
  41         /// An output to a script which was provided via KeysInterface, thus you should already know
  42         /// how to spend it. No keys are provided as rust-lightning was never given any keys - only the
  43         /// script_pubkey as it appears in the output.
  44         /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
  45         /// on-chain using the payment preimage or after it has timed out.
  46         StaticOutput {
  47                 /// The outpoint which is spendable
  48                 outpoint: OutPoint,
  49                 /// The output which is referenced by the given outpoint.
  50                 output: TxOut,
  51         },
  52         /// An output to a P2WSH script which can be spent with a single signature after a CSV delay.
  53         /// The private key which should be used to sign the transaction is provided, as well as the
  54         /// full witness redeemScript which is hashed in the output script_pubkey.
  55         /// The witness in the spending input should be:
  56         /// <BIP 143 signature generated with the given key> <one zero byte aka OP_0>
  57         /// <witness_script as provided>
  58         /// Note that the nSequence field in the input must be set to_self_delay (which corresponds to
  59         /// the transaction not being broadcastable until at least to_self_delay blocks after the input
  60         /// confirms).
  61         /// These are generally the result of a "revocable" output to us, spendable only by us unless
  62         /// it is an output from us having broadcast an old state (which should never happen).
  63         DynamicOutputP2WSH {
  64                 /// The outpoint which is spendable
  65                 outpoint: OutPoint,
  66                 /// The secret key which must be used to sign the spending transaction
  67                 key: SecretKey,
  68                 /// The witness redeemScript which is hashed to create the script_pubkey in the given output
  69                 witness_script: Script,
  70                 /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in
  71                 /// the witness_script.
  72                 to_self_delay: u16,
  73                 /// The output which is referenced by the given outpoint
  74                 output: TxOut,
  75         },
  76         /// An output to a P2WPKH, spendable exclusively by the given private key.
  77         /// The witness in the spending input, is, thus, simply:
  78         /// <BIP 143 signature generated with the given key> <public key derived from the given key>
  79         /// These are generally the result of our counterparty having broadcast the current state,
  80         /// allowing us to claim the non-HTLC-encumbered outputs immediately.
  81         DynamicOutputP2WPKH {
  82                 /// The outpoint which is spendable
  83                 outpoint: OutPoint,
  84                 /// The secret key which must be used to sign the spending transaction
  85                 key: SecretKey,
  86                 /// The output which is reference by the given outpoint
  87                 output: TxOut,
  88         }
  89 }
  90
  91 /// A trait to describe an object which can get user secrets and key material.
  92 pub trait KeysInterface: Send + Sync {
  93         /// A type which implements ChannelKeys which will be returned by get_channel_keys.
  94         type ChanKeySigner : ChannelKeys;
  95
  96         /// Get node secret key (aka node_id or network_key)
  97         fn get_node_secret(&self) -> SecretKey;
  98         /// Get destination redeemScript to encumber static protocol exit points.
  99         fn get_destination_script(&self) -> Script;
 100         /// Get shutdown_pubkey to use as PublicKey at channel closure
 101         fn get_shutdown_pubkey(&self) -> PublicKey;
 102         /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
 103         /// restarted with some stale data!
 104         fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
 105         /// Get a secret and PRNG seed for construting an onion packet
 106         fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
 107         /// Get a unique temporary channel id. Channels will be referred to by this until the funding
 108         /// transaction is created, at which point they will use the outpoint in the funding
 109         /// transaction.
 110         fn get_channel_id(&self) -> [u8; 32];
 111 }
 112
 113 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
 114 ///
 115 /// Signing services could be implemented on a hardware wallet. In this case,
 116 /// the current ChannelKeys would be a front-end on top of a communication
 117 /// channel connected to your secure device and lightning key material wouldn't
 118 /// reside on a hot server. Nevertheless, a this deployment would still need
 119 /// to trust the ChannelManager to avoid loss of funds as this latest component
 120 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
 121 ///
 122 /// A more secure iteration would be to use hashlock (or payment points) to pair
 123 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
 124 /// at the price of more state and computation on the hardware wallet side. In the future,
 125 /// we are looking forward to design such interface.
 126 ///
 127 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
 128 /// to act, as liveness and breach reply correctness are always going to be hard requirements
 129 /// of LN security model, orthogonal of key management issues.
 130 ///
 131 /// If you're implementing a custom signer, you almost certainly want to implement
 132 /// Readable/Writable to serialize out a unique reference to this set of keys so
 133 /// that you can serialize the full ChannelManager object.
 134 ///
 135 /// (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
 136 /// to the possibility of reentrancy issues by calling the user's code during our deserialization
 137 /// routine).
 138 /// TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
 139 /// ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
 140 pub trait ChannelKeys : Send+Clone {
 141         /// Gets the private key for the anchor tx
 142         fn funding_key<'a>(&'a self) -> &'a SecretKey;
 143         /// Gets the local secret key for blinded revocation pubkey
 144         fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
 145         /// Gets the local secret key used in to_remote output of remote commitment tx
 146         /// (and also as part of obscured commitment number)
 147         fn payment_base_key<'a>(&'a self) -> &'a SecretKey;
 148         /// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output
 149         fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
 150         /// Gets the local htlc secret key used in commitment tx htlc outputs
 151         fn htlc_base_key<'a>(&'a self) -> &'a SecretKey;
 152         /// Gets the commitment seed
 153         fn commitment_seed<'a>(&'a self) -> &'a [u8; 32];
 154         /// Gets the local channel public keys and basepoints
 155         fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys;
 156
 157         /// Create a signature for a remote commitment transaction and associated HTLC transactions.
 158         ///
 159         /// Note that if signing fails or is rejected, the channel will be force-closed.
 160         ///
 161         /// TODO: Document the things someone using this interface should enforce before signing.
 162         /// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
 163         /// making the callee generate it via some util function we expose)!
 164         fn sign_remote_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
 165
 166         /// Create a signature for a (proposed) closing transaction.
 167         ///
 168         /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
 169         /// chosen to forgo their output as dust.
 170         fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
 171
 172         /// Signs a channel announcement message with our funding key, proving it comes from one
 173         /// of the channel participants.
 174         ///
 175         /// Note that if this fails or is rejected, the channel will not be publicly announced and
 176         /// our counterparty may (though likely will not) close the channel on us for violating the
 177         /// protocol.
 178         fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
 179
 180         /// Set the remote channel basepoints.  This is done immediately on incoming channels
 181         /// and as soon as the channel is accepted on outgoing channels.
 182         ///
 183         /// Will be called before any signatures are applied.
 184         fn set_remote_channel_pubkeys(&mut self, channel_points: &ChannelPublicKeys);
 185 }
 186
 187 #[derive(Clone)]
 188 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
 189 pub struct InMemoryChannelKeys {
 190         /// Private key of anchor tx
 191         funding_key: SecretKey,
 192         /// Local secret key for blinded revocation pubkey
 193         revocation_base_key: SecretKey,
 194         /// Local secret key used in commitment tx htlc outputs
 195         payment_base_key: SecretKey,
 196         /// Local secret key used in HTLC tx
 197         delayed_payment_base_key: SecretKey,
 198         /// Local htlc secret key used in commitment tx htlc outputs
 199         htlc_base_key: SecretKey,
 200         /// Commitment seed
 201         commitment_seed: [u8; 32],
 202         /// Local public keys and basepoints
 203         pub(crate) local_channel_pubkeys: ChannelPublicKeys,
 204         /// Remote public keys and base points
 205         pub(crate) remote_channel_pubkeys: Option<ChannelPublicKeys>,
 206         /// The total value of this channel
 207         channel_value_satoshis: u64,
 208 }
 209
 210 impl InMemoryChannelKeys {
 211         /// Create a new InMemoryChannelKeys
 212         pub fn new<C: Signing>(
 213                 secp_ctx: &Secp256k1<C>,
 214                 funding_key: SecretKey,
 215                 revocation_base_key: SecretKey,
 216                 payment_base_key: SecretKey,
 217                 delayed_payment_base_key: SecretKey,
 218                 htlc_base_key: SecretKey,
 219                 commitment_seed: [u8; 32],
 220                 channel_value_satoshis: u64) -> InMemoryChannelKeys {
 221                 let local_channel_pubkeys =
 222                         InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key,
 223                                                              &payment_base_key, &delayed_payment_base_key,
 224                                                              &htlc_base_key);
 225                 InMemoryChannelKeys {
 226                         funding_key,
 227                         revocation_base_key,
 228                         payment_base_key,
 229                         delayed_payment_base_key,
 230                         htlc_base_key,
 231                         commitment_seed,
 232                         channel_value_satoshis,
 233                         local_channel_pubkeys,
 234                         remote_channel_pubkeys: None,
 235                 }
 236         }
 237
 238         fn make_local_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
 239                                        funding_key: &SecretKey,
 240                                        revocation_base_key: &SecretKey,
 241                                        payment_base_key: &SecretKey,
 242                                        delayed_payment_base_key: &SecretKey,
 243                                        htlc_base_key: &SecretKey) -> ChannelPublicKeys {
 244                 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
 245                 ChannelPublicKeys {
 246                         funding_pubkey: from_secret(&funding_key),
 247                         revocation_basepoint: from_secret(&revocation_base_key),
 248                         payment_basepoint: from_secret(&payment_base_key),
 249                         delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
 250                         htlc_basepoint: from_secret(&htlc_base_key),
 251                 }
 252         }
 253 }
 254
 255 impl ChannelKeys for InMemoryChannelKeys {
 256         fn funding_key(&self) -> &SecretKey { &self.funding_key }
 257         fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
 258         fn payment_base_key(&self) -> &SecretKey { &self.payment_base_key }
 259         fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
 260         fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
 261         fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
 262         fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { &self.local_channel_pubkeys }
 263
 264         fn sign_remote_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
 265                 if commitment_tx.input.len() != 1 { return Err(()); }
 266
 267                 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
 268                 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
 269                 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
 270
 271                 let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
 272                 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
 273
 274                 let commitment_txid = commitment_tx.txid();
 275
 276                 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
 277                 for ref htlc in htlcs {
 278                         if let Some(_) = htlc.transaction_output_index {
 279                                 let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, feerate_per_kw, to_self_delay, htlc, &keys.a_delayed_payment_key, &keys.revocation_key);
 280                                 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
 281                                 let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
 282                                 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
 283                                         Ok(s) => s,
 284                                         Err(_) => return Err(()),
 285                                 };
 286                                 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
 287                         }
 288                 }
 289
 290                 Ok((commitment_sig, htlc_sigs))
 291         }
 292
 293         fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
 294                 if closing_tx.input.len() != 1 { return Err(()); }
 295                 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
 296                 if closing_tx.output.len() > 2 { return Err(()); }
 297
 298                 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
 299                 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
 300                 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
 301
 302                 let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
 303                         .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
 304                 Ok(secp_ctx.sign(&sighash, &self.funding_key))
 305         }
 306
 307         fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
 308                 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
 309                 Ok(secp_ctx.sign(&msghash, &self.funding_key))
 310         }
 311
 312         fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) {
 313                 assert!(self.remote_channel_pubkeys.is_none(), "Already set remote channel pubkeys");
 314                 self.remote_channel_pubkeys = Some(channel_pubkeys.clone());
 315         }
 316 }
 317
 318 impl Writeable for InMemoryChannelKeys {
 319         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 320                 self.funding_key.write(writer)?;
 321                 self.revocation_base_key.write(writer)?;
 322                 self.payment_base_key.write(writer)?;
 323                 self.delayed_payment_base_key.write(writer)?;
 324                 self.htlc_base_key.write(writer)?;
 325                 self.commitment_seed.write(writer)?;
 326                 self.remote_channel_pubkeys.write(writer)?;
 327                 self.channel_value_satoshis.write(writer)?;
 328
 329                 Ok(())
 330         }
 331 }
 332
 333 impl<R: ::std::io::Read> Readable<R> for InMemoryChannelKeys {
 334         fn read(reader: &mut R) -> Result<Self, DecodeError> {
 335                 let funding_key = Readable::read(reader)?;
 336                 let revocation_base_key = Readable::read(reader)?;
 337                 let payment_base_key = Readable::read(reader)?;
 338                 let delayed_payment_base_key = Readable::read(reader)?;
 339                 let htlc_base_key = Readable::read(reader)?;
 340                 let commitment_seed = Readable::read(reader)?;
 341                 let remote_channel_pubkeys = Readable::read(reader)?;
 342                 let channel_value_satoshis = Readable::read(reader)?;
 343                 let secp_ctx = Secp256k1::signing_only();
 344                 let local_channel_pubkeys =
 345                         InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key,
 346                                                              &payment_base_key, &delayed_payment_base_key,
 347                                                              &htlc_base_key);
 348
 349                 Ok(InMemoryChannelKeys {
 350                         funding_key,
 351                         revocation_base_key,
 352                         payment_base_key,
 353                         delayed_payment_base_key,
 354                         htlc_base_key,
 355                         commitment_seed,
 356                         channel_value_satoshis,
 357                         local_channel_pubkeys,
 358                         remote_channel_pubkeys
 359                 })
 360         }
 361 }
 362
 363 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
 364 /// and derives keys from that.
 365 ///
 366 /// Your node_id is seed/0'
 367 /// ChannelMonitor closes may use seed/1'
 368 /// Cooperative closes may use seed/2'
 369 /// The two close keys may be needed to claim on-chain funds!
 370 pub struct KeysManager {
 371         secp_ctx: Secp256k1<secp256k1::SignOnly>,
 372         node_secret: SecretKey,
 373         destination_script: Script,
 374         shutdown_pubkey: PublicKey,
 375         channel_master_key: ExtendedPrivKey,
 376         channel_child_index: AtomicUsize,
 377         session_master_key: ExtendedPrivKey,
 378         session_child_index: AtomicUsize,
 379         channel_id_master_key: ExtendedPrivKey,
 380         channel_id_child_index: AtomicUsize,
 381
 382         unique_start: Sha256State,
 383         logger: Arc<Logger>,
 384 }
 385
 386 impl KeysManager {
 387         /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
 388         /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
 389         /// starting_time isn't strictly required to actually be a time, but it must absolutely,
 390         /// without a doubt, be unique to this instance. ie if you start multiple times with the same
 391         /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
 392         /// simply use the current time (with very high precision).
 393         ///
 394         /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
 395         /// obviously, starting_time should be unique every time you reload the library - it is only
 396         /// used to generate new ephemeral key data (which will be stored by the individual channel if
 397         /// necessary).
 398         ///
 399         /// Note that the seed is required to recover certain on-chain funds independent of
 400         /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
 401         /// channel, and some on-chain during-closing funds.
 402         ///
 403         /// Note that until the 0.1 release there is no guarantee of backward compatibility between
 404         /// versions. Once the library is more fully supported, the docs will be updated to include a
 405         /// detailed description of the guarantee.
 406         pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager {
 407                 let secp_ctx = Secp256k1::signing_only();
 408                 match ExtendedPrivKey::new_master(network.clone(), seed) {
 409                         Ok(master_key) => {
 410                                 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
 411                                 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
 412                                         Ok(destination_key) => {
 413                                                 let pubkey_hash160 = Hash160::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.key.serialize()[..]);
 414                                                 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
 415                                                               .push_slice(&pubkey_hash160.into_inner())
 416                                                               .into_script()
 417                                         },
 418                                         Err(_) => panic!("Your RNG is busted"),
 419                                 };
 420                                 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
 421                                         Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
 422                                         Err(_) => panic!("Your RNG is busted"),
 423                                 };
 424                                 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
 425                                 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
 426                                 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
 427
 428                                 let mut unique_start = Sha256::engine();
 429                                 unique_start.input(&byte_utils::be64_to_array(starting_time_secs));
 430                                 unique_start.input(&byte_utils::be32_to_array(starting_time_nanos));
 431                                 unique_start.input(seed);
 432
 433                                 KeysManager {
 434                                         secp_ctx,
 435                                         node_secret,
 436                                         destination_script,
 437                                         shutdown_pubkey,
 438                                         channel_master_key,
 439                                         channel_child_index: AtomicUsize::new(0),
 440                                         session_master_key,
 441                                         session_child_index: AtomicUsize::new(0),
 442                                         channel_id_master_key,
 443                                         channel_id_child_index: AtomicUsize::new(0),
 444
 445                                         unique_start,
 446                                         logger,
 447                                 }
 448                         },
 449                         Err(_) => panic!("Your rng is busted"),
 450                 }
 451         }
 452 }
 453
 454 impl KeysInterface for KeysManager {
 455         type ChanKeySigner = InMemoryChannelKeys;
 456
 457         fn get_node_secret(&self) -> SecretKey {
 458                 self.node_secret.clone()
 459         }
 460
 461         fn get_destination_script(&self) -> Script {
 462                 self.destination_script.clone()
 463         }
 464
 465         fn get_shutdown_pubkey(&self) -> PublicKey {
 466                 self.shutdown_pubkey.clone()
 467         }
 468
 469         fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys {
 470                 // We only seriously intend to rely on the channel_master_key for true secure
 471                 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
 472                 // starting_time provided in the constructor) to be unique.
 473                 let mut sha = self.unique_start.clone();
 474
 475                 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
 476                 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");
 477                 sha.input(&child_privkey.private_key.key[..]);
 478
 479                 let seed = Sha256::from_engine(sha).into_inner();
 480
 481                 let commitment_seed = {
 482                         let mut sha = Sha256::engine();
 483                         sha.input(&seed);
 484                         sha.input(&b"commitment seed"[..]);
 485                         Sha256::from_engine(sha).into_inner()
 486                 };
 487                 macro_rules! key_step {
 488                         ($info: expr, $prev_key: expr) => {{
 489                                 let mut sha = Sha256::engine();
 490                                 sha.input(&seed);
 491                                 sha.input(&$prev_key[..]);
 492                                 sha.input(&$info[..]);
 493                                 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
 494                         }}
 495                 }
 496                 let funding_key = key_step!(b"funding key", commitment_seed);
 497                 let revocation_base_key = key_step!(b"revocation base key", funding_key);
 498                 let payment_base_key = key_step!(b"payment base key", revocation_base_key);
 499                 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key);
 500                 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
 501
 502                 InMemoryChannelKeys::new(
 503                         &self.secp_ctx,
 504                         funding_key,
 505                         revocation_base_key,
 506                         payment_base_key,
 507                         delayed_payment_base_key,
 508                         htlc_base_key,
 509                         commitment_seed,
 510                         channel_value_satoshis
 511                 )
 512         }
 513
 514         fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
 515                 let mut sha = self.unique_start.clone();
 516
 517                 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
 518                 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");
 519                 sha.input(&child_privkey.private_key.key[..]);
 520
 521                 let mut rng_seed = sha.clone();
 522                 // Not exactly the most ideal construction, but the second value will get fed into
 523                 // ChaCha so it is another step harder to break.
 524                 rng_seed.input(b"RNG Seed Salt");
 525                 sha.input(b"Session Key Salt");
 526                 (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
 527                 Sha256::from_engine(rng_seed).into_inner())
 528         }
 529
 530         fn get_channel_id(&self) -> [u8; 32] {
 531                 let mut sha = self.unique_start.clone();
 532
 533                 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
 534                 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");
 535                 sha.input(&child_privkey.private_key.key[..]);
 536
 537                 (Sha256::from_engine(sha).into_inner())
 538         }
 539 }