_ Git - rust-lightning/blob - lightning/src/sign/mod.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! Provides keys to LDK and defines some useful objects describing spendable on-chain outputs.
  11 //!
  12 //! The provided output descriptors follow a custom LDK data format and are currently not fully
  13 //! compatible with Bitcoin Core output descriptors.
  14
  15 use bitcoin::blockdata::locktime::absolute::LockTime;
  16 use bitcoin::blockdata::transaction::{Transaction, TxOut, TxIn};
  17 use bitcoin::blockdata::script::{Script, ScriptBuf, Builder};
  18 use bitcoin::blockdata::opcodes;
  19 use bitcoin::ecdsa::Signature as EcdsaSignature;
  20 use bitcoin::network::constants::Network;
  21 use bitcoin::psbt::PartiallySignedTransaction;
  22 use bitcoin::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber};
  23 use bitcoin::sighash;
  24 use bitcoin::sighash::EcdsaSighashType;
  25
  26 use bitcoin::bech32::u5;
  27 use bitcoin::hashes::{Hash, HashEngine};
  28 use bitcoin::hashes::sha256::Hash as Sha256;
  29 use bitcoin::hashes::sha256d::Hash as Sha256dHash;
  30 use bitcoin::hash_types::WPubkeyHash;
  31
  32 #[cfg(taproot)]
  33 use bitcoin::secp256k1::All;
  34 use bitcoin::secp256k1::{KeyPair, PublicKey, Scalar, Secp256k1, SecretKey, Signing};
  35 use bitcoin::secp256k1::ecdh::SharedSecret;
  36 use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature};
  37 use bitcoin::secp256k1::schnorr;
  38 use bitcoin::{secp256k1, Sequence, Witness, Txid};
  39
  40 use crate::util::transaction_utils;
  41 use crate::crypto::utils::{hkdf_extract_expand_twice, sign, sign_with_aux_rand};
  42 use crate::util::ser::{Writeable, Writer, Readable, ReadableArgs};
  43 use crate::chain::transaction::OutPoint;
  44 use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
  45 use crate::ln::{chan_utils, PaymentPreimage};
  46 use crate::ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction, ClosingTransaction};
  47 use crate::ln::channel_keys::{DelayedPaymentBasepoint, DelayedPaymentKey, HtlcKey, HtlcBasepoint, RevocationKey, RevocationBasepoint};
  48 use crate::ln::msgs::{UnsignedChannelAnnouncement, UnsignedGossipMessage};
  49 #[cfg(taproot)]
  50 use crate::ln::msgs::PartialSignatureWithNonce;
  51 use crate::ln::script::ShutdownScript;
  52 use crate::offers::invoice::UnsignedBolt12Invoice;
  53 use crate::offers::invoice_request::UnsignedInvoiceRequest;
  54
  55 use crate::prelude::*;
  56 use core::ops::Deref;
  57 use core::sync::atomic::{AtomicUsize, Ordering};
  58 #[cfg(taproot)]
  59 use musig2::types::{PartialSignature, PublicNonce};
  60 use crate::io::{self, Error};
  61 use crate::ln::features::ChannelTypeFeatures;
  62 use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
  63 use crate::sign::ecdsa::{EcdsaChannelSigner, WriteableEcdsaChannelSigner};
  64 #[cfg(taproot)]
  65 use crate::sign::taproot::TaprootChannelSigner;
  66 use crate::util::atomic_counter::AtomicCounter;
  67 use crate::crypto::chacha20::ChaCha20;
  68 use crate::util::invoice::construct_invoice_preimage;
  69
  70 pub(crate) mod type_resolver;
  71
  72 pub mod ecdsa;
  73 #[cfg(taproot)]
  74 pub mod taproot;
  75
  76 /// Used as initial key material, to be expanded into multiple secret keys (but not to be used
  77 /// directly). This is used within LDK to encrypt/decrypt inbound payment data.
  78 ///
  79 /// This is not exported to bindings users as we just use `[u8; 32]` directly
  80 #[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
  81 pub struct KeyMaterial(pub [u8; 32]);
  82
  83 /// Information about a spendable output to a P2WSH script.
  84 ///
  85 /// See [`SpendableOutputDescriptor::DelayedPaymentOutput`] for more details on how to spend this.
  86 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
  87 pub struct DelayedPaymentOutputDescriptor {
  88         /// The outpoint which is spendable.
  89         pub outpoint: OutPoint,
  90         /// Per commitment point to derive the delayed payment key by key holder.
  91         pub per_commitment_point: PublicKey,
  92         /// The `nSequence` value which must be set in the spending input to satisfy the `OP_CSV` in
  93         /// the witness_script.
  94         pub to_self_delay: u16,
  95         /// The output which is referenced by the given outpoint.
  96         pub output: TxOut,
  97         /// The revocation point specific to the commitment transaction which was broadcast. Used to
  98         /// derive the witnessScript for this output.
  99         pub revocation_pubkey: RevocationKey,
 100         /// Arbitrary identification information returned by a call to [`ChannelSigner::channel_keys_id`].
 101         /// This may be useful in re-deriving keys used in the channel to spend the output.
 102         pub channel_keys_id: [u8; 32],
 103         /// The value of the channel which this output originated from, possibly indirectly.
 104         pub channel_value_satoshis: u64,
 105 }
 106 impl DelayedPaymentOutputDescriptor {
 107         /// The maximum length a well-formed witness spending one of these should have.
 108         /// Note: If you have the grind_signatures feature enabled, this will be at least 1 byte
 109         /// shorter.
 110         // Calculated as 1 byte length + 73 byte signature, 1 byte empty vec push, 1 byte length plus
 111         // redeemscript push length.
 112         pub const MAX_WITNESS_LENGTH: u64 = 1 + 73 + 1 + chan_utils::REVOKEABLE_REDEEMSCRIPT_MAX_LENGTH as u64 + 1;
 113 }
 114
 115 impl_writeable_tlv_based!(DelayedPaymentOutputDescriptor, {
 116         (0, outpoint, required),
 117         (2, per_commitment_point, required),
 118         (4, to_self_delay, required),
 119         (6, output, required),
 120         (8, revocation_pubkey, required),
 121         (10, channel_keys_id, required),
 122         (12, channel_value_satoshis, required),
 123 });
 124
 125 pub(crate) const P2WPKH_WITNESS_WEIGHT: u64 = 1 /* num stack items */ +
 126         1 /* sig length */ +
 127         73 /* sig including sighash flag */ +
 128         1 /* pubkey length */ +
 129         33 /* pubkey */;
 130
 131 /// Information about a spendable output to our "payment key".
 132 ///
 133 /// See [`SpendableOutputDescriptor::StaticPaymentOutput`] for more details on how to spend this.
 134 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 135 pub struct StaticPaymentOutputDescriptor {
 136         /// The outpoint which is spendable.
 137         pub outpoint: OutPoint,
 138         /// The output which is referenced by the given outpoint.
 139         pub output: TxOut,
 140         /// Arbitrary identification information returned by a call to [`ChannelSigner::channel_keys_id`].
 141         /// This may be useful in re-deriving keys used in the channel to spend the output.
 142         pub channel_keys_id: [u8; 32],
 143         /// The value of the channel which this transactions spends.
 144         pub channel_value_satoshis: u64,
 145         /// The necessary channel parameters that need to be provided to the re-derived signer through
 146         /// [`ChannelSigner::provide_channel_parameters`].
 147         ///
 148         /// Added as optional, but always `Some` if the descriptor was produced in v0.0.117 or later.
 149         pub channel_transaction_parameters: Option<ChannelTransactionParameters>,
 150 }
 151 impl StaticPaymentOutputDescriptor {
 152         /// Returns the `witness_script` of the spendable output.
 153         ///
 154         /// Note that this will only return `Some` for [`StaticPaymentOutputDescriptor`]s that
 155         /// originated from an anchor outputs channel, as they take the form of a P2WSH script.
 156         pub fn witness_script(&self) -> Option<ScriptBuf> {
 157                 self.channel_transaction_parameters.as_ref()
 158                         .and_then(|channel_params|
 159                                  if channel_params.supports_anchors() {
 160                                         let payment_point = channel_params.holder_pubkeys.payment_point;
 161                                         Some(chan_utils::get_to_countersignatory_with_anchors_redeemscript(&payment_point))
 162                                  } else {
 163                                          None
 164                                  }
 165                         )
 166         }
 167
 168         /// The maximum length a well-formed witness spending one of these should have.
 169         /// Note: If you have the grind_signatures feature enabled, this will be at least 1 byte
 170         /// shorter.
 171         pub fn max_witness_length(&self) -> u64 {
 172                 if self.channel_transaction_parameters.as_ref().map_or(false, |p| p.supports_anchors())
 173                 {
 174                         let witness_script_weight = 1 /* pubkey push */ + 33 /* pubkey */ +
 175                                 1 /* OP_CHECKSIGVERIFY */ + 1 /* OP_1 */ + 1 /* OP_CHECKSEQUENCEVERIFY */;
 176                         1 /* num witness items */ + 1 /* sig push */ + 73 /* sig including sighash flag */ +
 177                                 1 /* witness script push */ + witness_script_weight
 178                 } else {
 179                         P2WPKH_WITNESS_WEIGHT
 180                 }
 181         }
 182 }
 183 impl_writeable_tlv_based!(StaticPaymentOutputDescriptor, {
 184         (0, outpoint, required),
 185         (2, output, required),
 186         (4, channel_keys_id, required),
 187         (6, channel_value_satoshis, required),
 188         (7, channel_transaction_parameters, option),
 189 });
 190
 191 /// Describes the necessary information to spend a spendable output.
 192 ///
 193 /// When on-chain outputs are created by LDK (which our counterparty is not able to claim at any
 194 /// point in the future) a [`SpendableOutputs`] event is generated which you must track and be able
 195 /// to spend on-chain. The information needed to do this is provided in this enum, including the
 196 /// outpoint describing which `txid` and output `index` is available, the full output which exists
 197 /// at that `txid`/`index`, and any keys or other information required to sign.
 198 ///
 199 /// [`SpendableOutputs`]: crate::events::Event::SpendableOutputs
 200 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 201 pub enum SpendableOutputDescriptor {
 202         /// An output to a script which was provided via [`SignerProvider`] directly, either from
 203         /// [`get_destination_script`] or [`get_shutdown_scriptpubkey`], thus you should already
 204         /// know how to spend it. No secret keys are provided as LDK was never given any key.
 205         /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
 206         /// on-chain using the payment preimage or after it has timed out.
 207         ///
 208         /// [`get_shutdown_scriptpubkey`]: SignerProvider::get_shutdown_scriptpubkey
 209         /// [`get_destination_script`]: SignerProvider::get_shutdown_scriptpubkey
 210         StaticOutput {
 211                 /// The outpoint which is spendable.
 212                 outpoint: OutPoint,
 213                 /// The output which is referenced by the given outpoint.
 214                 output: TxOut,
 215                 /// The `channel_keys_id` for the channel which this output came from.
 216                 ///
 217                 /// For channels which were generated on LDK 0.0.119 or later, this is the value which was
 218                 /// passed to the [`SignerProvider::get_destination_script`] call which provided this
 219                 /// output script.
 220                 ///
 221                 /// For channels which were generated prior to LDK 0.0.119, no such argument existed,
 222                 /// however this field may still be filled in if such data is available.
 223                 channel_keys_id: Option<[u8; 32]>
 224         },
 225         /// An output to a P2WSH script which can be spent with a single signature after an `OP_CSV`
 226         /// delay.
 227         ///
 228         /// The witness in the spending input should be:
 229         /// ```bitcoin
 230         /// <BIP 143 signature> <empty vector> (MINIMALIF standard rule) <provided witnessScript>
 231         /// ```
 232         ///
 233         /// Note that the `nSequence` field in the spending input must be set to
 234         /// [`DelayedPaymentOutputDescriptor::to_self_delay`] (which means the transaction is not
 235         /// broadcastable until at least [`DelayedPaymentOutputDescriptor::to_self_delay`] blocks after
 236         /// the outpoint confirms, see [BIP
 237         /// 68](https://github.com/bitcoin/bips/blob/master/bip-0068.mediawiki)). Also note that LDK
 238         /// won't generate a [`SpendableOutputDescriptor`] until the corresponding block height
 239         /// is reached.
 240         ///
 241         /// These are generally the result of a "revocable" output to us, spendable only by us unless
 242         /// it is an output from an old state which we broadcast (which should never happen).
 243         ///
 244         /// To derive the delayed payment key which is used to sign this input, you must pass the
 245         /// holder [`InMemorySigner::delayed_payment_base_key`] (i.e., the private key which corresponds to the
 246         /// [`ChannelPublicKeys::delayed_payment_basepoint`] in [`ChannelSigner::pubkeys`]) and the provided
 247         /// [`DelayedPaymentOutputDescriptor::per_commitment_point`] to [`chan_utils::derive_private_key`]. The DelayedPaymentKey can be
 248         /// generated without the secret key using [`DelayedPaymentKey::from_basepoint`] and only the
 249         /// [`ChannelPublicKeys::delayed_payment_basepoint`] which appears in [`ChannelSigner::pubkeys`].
 250         ///
 251         /// To derive the [`DelayedPaymentOutputDescriptor::revocation_pubkey`] provided here (which is
 252         /// used in the witness script generation), you must pass the counterparty
 253         /// [`ChannelPublicKeys::revocation_basepoint`] (which appears in the call to
 254         /// [`ChannelSigner::provide_channel_parameters`]) and the provided
 255         /// [`DelayedPaymentOutputDescriptor::per_commitment_point`] to
 256         /// [`RevocationKey`].
 257         ///
 258         /// The witness script which is hashed and included in the output `script_pubkey` may be
 259         /// regenerated by passing the [`DelayedPaymentOutputDescriptor::revocation_pubkey`] (derived
 260         /// as explained above), our delayed payment pubkey (derived as explained above), and the
 261         /// [`DelayedPaymentOutputDescriptor::to_self_delay`] contained here to
 262         /// [`chan_utils::get_revokeable_redeemscript`].
 263         DelayedPaymentOutput(DelayedPaymentOutputDescriptor),
 264         /// An output spendable exclusively by our payment key (i.e., the private key that corresponds
 265         /// to the `payment_point` in [`ChannelSigner::pubkeys`]). The output type depends on the
 266         /// channel type negotiated.
 267         ///
 268         /// On an anchor outputs channel, the witness in the spending input is:
 269         /// ```bitcoin
 270         /// <BIP 143 signature> <witness script>
 271         /// ```
 272         ///
 273         /// Otherwise, it is:
 274         /// ```bitcoin
 275         /// <BIP 143 signature> <payment key>
 276         /// ```
 277         ///
 278         /// These are generally the result of our counterparty having broadcast the current state,
 279         /// allowing us to claim the non-HTLC-encumbered outputs immediately, or after one confirmation
 280         /// in the case of anchor outputs channels.
 281         StaticPaymentOutput(StaticPaymentOutputDescriptor),
 282 }
 283
 284 impl_writeable_tlv_based_enum!(SpendableOutputDescriptor,
 285         (0, StaticOutput) => {
 286                 (0, outpoint, required),
 287                 (1, channel_keys_id, option),
 288                 (2, output, required),
 289         },
 290 ;
 291         (1, DelayedPaymentOutput),
 292         (2, StaticPaymentOutput),
 293 );
 294
 295 impl SpendableOutputDescriptor {
 296         /// Turns this into a [`bitcoin::psbt::Input`] which can be used to create a
 297         /// [`PartiallySignedTransaction`] which spends the given descriptor.
 298         ///
 299         /// Note that this does not include any signatures, just the information required to
 300         /// construct the transaction and sign it.
 301         ///
 302         /// This is not exported to bindings users as there is no standard serialization for an input.
 303         /// See [`Self::create_spendable_outputs_psbt`] instead.
 304         pub fn to_psbt_input(&self) -> bitcoin::psbt::Input {
 305                 match self {
 306                         SpendableOutputDescriptor::StaticOutput { output, .. } => {
 307                                 // Is a standard P2WPKH, no need for witness script
 308                                 bitcoin::psbt::Input {
 309                                         witness_utxo: Some(output.clone()),
 310                                         ..Default::default()
 311                                 }
 312                         },
 313                         SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
 314                                 // TODO we could add the witness script as well
 315                                 bitcoin::psbt::Input {
 316                                         witness_utxo: Some(descriptor.output.clone()),
 317                                         ..Default::default()
 318                                 }
 319                         },
 320                         SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
 321                                 // TODO we could add the witness script as well
 322                                 bitcoin::psbt::Input {
 323                                         witness_utxo: Some(descriptor.output.clone()),
 324                                         ..Default::default()
 325                                 }
 326                         },
 327                 }
 328         }
 329
 330         /// Creates an unsigned [`PartiallySignedTransaction`] which spends the given descriptors to
 331         /// the given outputs, plus an output to the given change destination (if sufficient
 332         /// change value remains). The PSBT will have a feerate, at least, of the given value.
 333         ///
 334         /// The `locktime` argument is used to set the transaction's locktime. If `None`, the
 335         /// transaction will have a locktime of 0. It it recommended to set this to the current block
 336         /// height to avoid fee sniping, unless you have some specific reason to use a different
 337         /// locktime.
 338         ///
 339         /// Returns the PSBT and expected max transaction weight.
 340         ///
 341         /// Returns `Err(())` if the output value is greater than the input value minus required fee,
 342         /// if a descriptor was duplicated, or if an output descriptor `script_pubkey`
 343         /// does not match the one we can spend.
 344         ///
 345         /// We do not enforce that outputs meet the dust limit or that any output scripts are standard.
 346         pub fn create_spendable_outputs_psbt(descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>, change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32, locktime: Option<LockTime>) -> Result<(PartiallySignedTransaction, u64), ()> {
 347                 let mut input = Vec::with_capacity(descriptors.len());
 348                 let mut input_value = 0;
 349                 let mut witness_weight = 0;
 350                 let mut output_set = hash_set_with_capacity(descriptors.len());
 351                 for outp in descriptors {
 352                         match outp {
 353                                 SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
 354                                         if !output_set.insert(descriptor.outpoint) { return Err(()); }
 355                                         let sequence =
 356                                                 if descriptor.channel_transaction_parameters.as_ref()
 357                                                         .map_or(false, |p| p.supports_anchors())
 358                                                 {
 359                                                         Sequence::from_consensus(1)
 360                                                 } else {
 361                                                         Sequence::ZERO
 362                                                 };
 363                                         input.push(TxIn {
 364                                                 previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
 365                                                 script_sig: ScriptBuf::new(),
 366                                                 sequence,
 367                                                 witness: Witness::new(),
 368                                         });
 369                                         witness_weight += descriptor.max_witness_length();
 370                                         #[cfg(feature = "grind_signatures")]
 371                                         { witness_weight -= 1; } // Guarantees a low R signature
 372                                         input_value += descriptor.output.value;
 373                                 },
 374                                 SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
 375                                         if !output_set.insert(descriptor.outpoint) { return Err(()); }
 376                                         input.push(TxIn {
 377                                                 previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
 378                                                 script_sig: ScriptBuf::new(),
 379                                                 sequence: Sequence(descriptor.to_self_delay as u32),
 380                                                 witness: Witness::new(),
 381                                         });
 382                                         witness_weight += DelayedPaymentOutputDescriptor::MAX_WITNESS_LENGTH;
 383                                         #[cfg(feature = "grind_signatures")]
 384                                         { witness_weight -= 1; } // Guarantees a low R signature
 385                                         input_value += descriptor.output.value;
 386                                 },
 387                                 SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output, .. } => {
 388                                         if !output_set.insert(*outpoint) { return Err(()); }
 389                                         input.push(TxIn {
 390                                                 previous_output: outpoint.into_bitcoin_outpoint(),
 391                                                 script_sig: ScriptBuf::new(),
 392                                                 sequence: Sequence::ZERO,
 393                                                 witness: Witness::new(),
 394                                         });
 395                                         witness_weight += 1 + 73 + 34;
 396                                         #[cfg(feature = "grind_signatures")]
 397                                         { witness_weight -= 1; } // Guarantees a low R signature
 398                                         input_value += output.value;
 399                                 }
 400                         }
 401                         if input_value > MAX_VALUE_MSAT / 1000 { return Err(()); }
 402                 }
 403                 let mut tx = Transaction {
 404                         version: 2,
 405                         lock_time: locktime.unwrap_or(LockTime::ZERO),
 406                         input,
 407                         output: outputs,
 408                 };
 409                 let expected_max_weight =
 410                         transaction_utils::maybe_add_change_output(&mut tx, input_value, witness_weight, feerate_sat_per_1000_weight, change_destination_script)?;
 411
 412                 let psbt_inputs = descriptors.iter().map(|d| d.to_psbt_input()).collect::<Vec<_>>();
 413                 let psbt = PartiallySignedTransaction {
 414                         inputs: psbt_inputs,
 415                         outputs: vec![Default::default(); tx.output.len()],
 416                         unsigned_tx: tx,
 417                         xpub: Default::default(),
 418                         version: 0,
 419                         proprietary: Default::default(),
 420                         unknown: Default::default(),
 421                 };
 422                 Ok((psbt, expected_max_weight))
 423         }
 424 }
 425
 426 /// The parameters required to derive a channel signer via [`SignerProvider`].
 427 #[derive(Clone, Debug, PartialEq, Eq)]
 428 pub struct ChannelDerivationParameters {
 429         /// The value in satoshis of the channel we're attempting to spend the anchor output of.
 430         pub value_satoshis: u64,
 431         /// The unique identifier to re-derive the signer for the associated channel.
 432         pub keys_id: [u8; 32],
 433         /// The necessary channel parameters that need to be provided to the re-derived signer through
 434         /// [`ChannelSigner::provide_channel_parameters`].
 435         pub transaction_parameters: ChannelTransactionParameters,
 436 }
 437
 438 impl_writeable_tlv_based!(ChannelDerivationParameters, {
 439     (0, value_satoshis, required),
 440     (2, keys_id, required),
 441     (4, transaction_parameters, required),
 442 });
 443
 444 /// A descriptor used to sign for a commitment transaction's HTLC output.
 445 #[derive(Clone, Debug, PartialEq, Eq)]
 446 pub struct HTLCDescriptor {
 447         /// The parameters required to derive the signer for the HTLC input.
 448         pub channel_derivation_parameters: ChannelDerivationParameters,
 449         /// The txid of the commitment transaction in which the HTLC output lives.
 450         pub commitment_txid: Txid,
 451         /// The number of the commitment transaction in which the HTLC output lives.
 452         pub per_commitment_number: u64,
 453         /// The key tweak corresponding to the number of the commitment transaction in which the HTLC
 454         /// output lives. This tweak is applied to all the basepoints for both parties in the channel to
 455         /// arrive at unique keys per commitment.
 456         ///
 457         /// See <https://github.com/lightning/bolts/blob/master/03-transactions.md#keys> for more info.
 458         pub per_commitment_point: PublicKey,
 459         /// The feerate to use on the HTLC claiming transaction. This is always `0` for HTLCs
 460         /// originating from a channel supporting anchor outputs, otherwise it is the channel's
 461         /// negotiated feerate at the time the commitment transaction was built.
 462         pub feerate_per_kw: u32,
 463         /// The details of the HTLC as it appears in the commitment transaction.
 464         pub htlc: HTLCOutputInCommitment,
 465         /// The preimage, if `Some`, to claim the HTLC output with. If `None`, the timeout path must be
 466         /// taken.
 467         pub preimage: Option<PaymentPreimage>,
 468         /// The counterparty's signature required to spend the HTLC output.
 469         pub counterparty_sig: Signature
 470 }
 471
 472 impl_writeable_tlv_based!(HTLCDescriptor, {
 473         (0, channel_derivation_parameters, required),
 474         (1, feerate_per_kw, (default_value, 0)),
 475         (2, commitment_txid, required),
 476         (4, per_commitment_number, required),
 477         (6, per_commitment_point, required),
 478         (8, htlc, required),
 479         (10, preimage, option),
 480         (12, counterparty_sig, required),
 481 });
 482
 483 impl HTLCDescriptor {
 484         /// Returns the outpoint of the HTLC output in the commitment transaction. This is the outpoint
 485         /// being spent by the HTLC input in the HTLC transaction.
 486         pub fn outpoint(&self) -> bitcoin::OutPoint {
 487                 bitcoin::OutPoint {
 488                         txid: self.commitment_txid,
 489                         vout: self.htlc.transaction_output_index.unwrap(),
 490                 }
 491         }
 492
 493         /// Returns the UTXO to be spent by the HTLC input, which can be obtained via
 494         /// [`Self::unsigned_tx_input`].
 495         pub fn previous_utxo<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> TxOut {
 496                 TxOut {
 497                         script_pubkey: self.witness_script(secp).to_v0_p2wsh(),
 498                         value: self.htlc.amount_msat / 1000,
 499                 }
 500         }
 501
 502         /// Returns the unsigned transaction input spending the HTLC output in the commitment
 503         /// transaction.
 504         pub fn unsigned_tx_input(&self) -> TxIn {
 505                 chan_utils::build_htlc_input(
 506                         &self.commitment_txid, &self.htlc, &self.channel_derivation_parameters.transaction_parameters.channel_type_features
 507                 )
 508         }
 509
 510         /// Returns the delayed output created as a result of spending the HTLC output in the commitment
 511         /// transaction.
 512         pub fn tx_output<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> TxOut {
 513                 let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
 514                 let broadcaster_keys = channel_params.broadcaster_pubkeys();
 515                 let counterparty_keys = channel_params.countersignatory_pubkeys();
 516                 let broadcaster_delayed_key = DelayedPaymentKey::from_basepoint(
 517                         secp, &broadcaster_keys.delayed_payment_basepoint, &self.per_commitment_point
 518                 );
 519                 let counterparty_revocation_key = &RevocationKey::from_basepoint(&secp, &counterparty_keys.revocation_basepoint, &self.per_commitment_point);
 520                 chan_utils::build_htlc_output(
 521                         self.feerate_per_kw, channel_params.contest_delay(), &self.htlc,
 522                         channel_params.channel_type_features(), &broadcaster_delayed_key, &counterparty_revocation_key
 523                 )
 524         }
 525
 526         /// Returns the witness script of the HTLC output in the commitment transaction.
 527         pub fn witness_script<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> ScriptBuf {
 528                 let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
 529                 let broadcaster_keys = channel_params.broadcaster_pubkeys();
 530                 let counterparty_keys = channel_params.countersignatory_pubkeys();
 531                 let broadcaster_htlc_key = HtlcKey::from_basepoint(
 532                         secp, &broadcaster_keys.htlc_basepoint, &self.per_commitment_point
 533                 );
 534                 let counterparty_htlc_key = HtlcKey::from_basepoint(
 535                         secp, &counterparty_keys.htlc_basepoint, &self.per_commitment_point,
 536                 );
 537                 let counterparty_revocation_key = &RevocationKey::from_basepoint(&secp, &counterparty_keys.revocation_basepoint, &self.per_commitment_point);
 538                 chan_utils::get_htlc_redeemscript_with_explicit_keys(
 539                         &self.htlc, channel_params.channel_type_features(), &broadcaster_htlc_key, &counterparty_htlc_key,
 540                         &counterparty_revocation_key,
 541                 )
 542         }
 543
 544         /// Returns the fully signed witness required to spend the HTLC output in the commitment
 545         /// transaction.
 546         pub fn tx_input_witness(&self, signature: &Signature, witness_script: &Script) -> Witness {
 547                 chan_utils::build_htlc_input_witness(
 548                         signature, &self.counterparty_sig, &self.preimage, witness_script,
 549                         &self.channel_derivation_parameters.transaction_parameters.channel_type_features
 550                 )
 551         }
 552
 553         /// Derives the channel signer required to sign the HTLC input.
 554         pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
 555         where
 556                 SP::Target: SignerProvider<EcdsaSigner= S>
 557         {
 558                 let mut signer = signer_provider.derive_channel_signer(
 559                         self.channel_derivation_parameters.value_satoshis,
 560                         self.channel_derivation_parameters.keys_id,
 561                 );
 562                 signer.provide_channel_parameters(&self.channel_derivation_parameters.transaction_parameters);
 563                 signer
 564         }
 565 }
 566
 567 /// A trait to handle Lightning channel key material without concretizing the channel type or
 568 /// the signature mechanism.
 569 pub trait ChannelSigner {
 570         /// Gets the per-commitment point for a specific commitment number
 571         ///
 572         /// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
 573         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey;
 574
 575         /// Gets the commitment secret for a specific commitment number as part of the revocation process
 576         ///
 577         /// An external signer implementation should error here if the commitment was already signed
 578         /// and should refuse to sign it in the future.
 579         ///
 580         /// May be called more than once for the same index.
 581         ///
 582         /// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
 583         // TODO: return a Result so we can signal a validation error
 584         fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
 585
 586         /// Validate the counterparty's signatures on the holder commitment transaction and HTLCs.
 587         ///
 588         /// This is required in order for the signer to make sure that releasing a commitment
 589         /// secret won't leave us without a broadcastable holder transaction.
 590         /// Policy checks should be implemented in this function, including checking the amount
 591         /// sent to us and checking the HTLCs.
 592         ///
 593         /// The preimages of outbound HTLCs that were fulfilled since the last commitment are provided.
 594         /// A validating signer should ensure that an HTLC output is removed only when the matching
 595         /// preimage is provided, or when the value to holder is restored.
 596         ///
 597         /// Note that all the relevant preimages will be provided, but there may also be additional
 598         /// irrelevant or duplicate preimages.
 599         fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction,
 600                 outbound_htlc_preimages: Vec<PaymentPreimage>) -> Result<(), ()>;
 601
 602         /// Validate the counterparty's revocation.
 603         ///
 604         /// This is required in order for the signer to make sure that the state has moved
 605         /// forward and it is safe to sign the next counterparty commitment.
 606         fn validate_counterparty_revocation(&self, idx: u64, secret: &SecretKey) -> Result<(), ()>;
 607
 608         /// Returns the holder's channel public keys and basepoints.
 609         fn pubkeys(&self) -> &ChannelPublicKeys;
 610
 611         /// Returns an arbitrary identifier describing the set of keys which are provided back to you in
 612         /// some [`SpendableOutputDescriptor`] types. This should be sufficient to identify this
 613         /// [`EcdsaChannelSigner`] object uniquely and lookup or re-derive its keys.
 614         fn channel_keys_id(&self) -> [u8; 32];
 615
 616         /// Set the counterparty static channel data, including basepoints,
 617         /// `counterparty_selected`/`holder_selected_contest_delay` and funding outpoint.
 618         ///
 619         /// This data is static, and will never change for a channel once set. For a given [`ChannelSigner`]
 620         /// instance, LDK will call this method exactly once - either immediately after construction
 621         /// (not including if done via [`SignerProvider::read_chan_signer`]) or when the funding
 622         /// information has been generated.
 623         ///
 624         /// channel_parameters.is_populated() MUST be true.
 625         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters);
 626 }
 627
 628 /// Specifies the recipient of an invoice.
 629 ///
 630 /// This indicates to [`NodeSigner::sign_invoice`] what node secret key should be used to sign
 631 /// the invoice.
 632 pub enum Recipient {
 633         /// The invoice should be signed with the local node secret key.
 634         Node,
 635         /// The invoice should be signed with the phantom node secret key. This secret key must be the
 636         /// same for all nodes participating in the [phantom node payment].
 637         ///
 638         /// [phantom node payment]: PhantomKeysManager
 639         PhantomNode,
 640 }
 641
 642 /// A trait that describes a source of entropy.
 643 pub trait EntropySource {
 644         /// Gets a unique, cryptographically-secure, random 32-byte value. This method must return a
 645         /// different value each time it is called.
 646         fn get_secure_random_bytes(&self) -> [u8; 32];
 647 }
 648
 649 /// A trait that can handle cryptographic operations at the scope level of a node.
 650 pub trait NodeSigner {
 651         /// Get secret key material as bytes for use in encrypting and decrypting inbound payment data.
 652         ///
 653         /// If the implementor of this trait supports [phantom node payments], then every node that is
 654         /// intended to be included in the phantom invoice route hints must return the same value from
 655         /// this method.
 656         // This is because LDK avoids storing inbound payment data by encrypting payment data in the
 657         // payment hash and/or payment secret, therefore for a payment to be receivable by multiple
 658         // nodes, they must share the key that encrypts this payment data.
 659         ///
 660         /// This method must return the same value each time it is called.
 661         ///
 662         /// [phantom node payments]: PhantomKeysManager
 663         fn get_inbound_payment_key_material(&self) -> KeyMaterial;
 664
 665         /// Get node id based on the provided [`Recipient`].
 666         ///
 667         /// This method must return the same value each time it is called with a given [`Recipient`]
 668         /// parameter.
 669         ///
 670         /// Errors if the [`Recipient`] variant is not supported by the implementation.
 671         fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()>;
 672
 673         /// Gets the ECDH shared secret of our node secret and `other_key`, multiplying by `tweak` if
 674         /// one is provided. Note that this tweak can be applied to `other_key` instead of our node
 675         /// secret, though this is less efficient.
 676         ///
 677         /// Note that if this fails while attempting to forward an HTLC, LDK will panic. The error
 678         /// should be resolved to allow LDK to resume forwarding HTLCs.
 679         ///
 680         /// Errors if the [`Recipient`] variant is not supported by the implementation.
 681         fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result<SharedSecret, ()>;
 682
 683         /// Sign an invoice.
 684         ///
 685         /// By parameterizing by the raw invoice bytes instead of the hash, we allow implementors of
 686         /// this trait to parse the invoice and make sure they're signing what they expect, rather than
 687         /// blindly signing the hash.
 688         ///
 689         /// The `hrp_bytes` are ASCII bytes, while the `invoice_data` is base32.
 690         ///
 691         /// The secret key used to sign the invoice is dependent on the [`Recipient`].
 692         ///
 693         /// Errors if the [`Recipient`] variant is not supported by the implementation.
 694         fn sign_invoice(&self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient) -> Result<RecoverableSignature, ()>;
 695
 696         /// Signs the [`TaggedHash`] of a BOLT 12 invoice request.
 697         ///
 698         /// May be called by a function passed to [`UnsignedInvoiceRequest::sign`] where
 699         /// `invoice_request` is the callee.
 700         ///
 701         /// Implementors may check that the `invoice_request` is expected rather than blindly signing
 702         /// the tagged hash. An `Ok` result should sign `invoice_request.tagged_hash().as_digest()` with
 703         /// the node's signing key or an ephemeral key to preserve privacy, whichever is associated with
 704         /// [`UnsignedInvoiceRequest::payer_id`].
 705         ///
 706         /// [`TaggedHash`]: crate::offers::merkle::TaggedHash
 707         fn sign_bolt12_invoice_request(
 708                 &self, invoice_request: &UnsignedInvoiceRequest
 709         ) -> Result<schnorr::Signature, ()>;
 710
 711         /// Signs the [`TaggedHash`] of a BOLT 12 invoice.
 712         ///
 713         /// May be called by a function passed to [`UnsignedBolt12Invoice::sign`] where `invoice` is the
 714         /// callee.
 715         ///
 716         /// Implementors may check that the `invoice` is expected rather than blindly signing the tagged
 717         /// hash. An `Ok` result should sign `invoice.tagged_hash().as_digest()` with the node's signing
 718         /// key or an ephemeral key to preserve privacy, whichever is associated with
 719         /// [`UnsignedBolt12Invoice::signing_pubkey`].
 720         ///
 721         /// [`TaggedHash`]: crate::offers::merkle::TaggedHash
 722         fn sign_bolt12_invoice(
 723                 &self, invoice: &UnsignedBolt12Invoice
 724         ) -> Result<schnorr::Signature, ()>;
 725
 726         /// Sign a gossip message.
 727         ///
 728         /// Note that if this fails, LDK may panic and the message will not be broadcast to the network
 729         /// or a possible channel counterparty. If LDK panics, the error should be resolved to allow the
 730         /// message to be broadcast, as otherwise it may prevent one from receiving funds over the
 731         /// corresponding channel.
 732         fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()>;
 733 }
 734
 735 // Primarily needed in doctests because of https://github.com/rust-lang/rust/issues/67295
 736 /// A dynamic [`SignerProvider`] temporarily needed for doc tests.
 737 #[cfg(taproot)]
 738 #[doc(hidden)]
 739 #[deprecated(note = "Remove once taproot cfg is removed")]
 740 pub type DynSignerProvider = dyn SignerProvider<EcdsaSigner = InMemorySigner, TaprootSigner = InMemorySigner>;
 741
 742 /// A dynamic [`SignerProvider`] temporarily needed for doc tests.
 743 #[cfg(not(taproot))]
 744 #[doc(hidden)]
 745 #[deprecated(note = "Remove once taproot cfg is removed")]
 746 pub type DynSignerProvider = dyn SignerProvider<EcdsaSigner = InMemorySigner>;
 747
 748 /// A trait that can return signer instances for individual channels.
 749 pub trait SignerProvider {
 750         /// A type which implements [`WriteableEcdsaChannelSigner`] which will be returned by [`Self::derive_channel_signer`].
 751         type EcdsaSigner: WriteableEcdsaChannelSigner;
 752         #[cfg(taproot)]
 753         /// A type which implements [`TaprootChannelSigner`]
 754         type TaprootSigner: TaprootChannelSigner;
 755
 756         /// Generates a unique `channel_keys_id` that can be used to obtain a [`Self::EcdsaSigner`] through
 757         /// [`SignerProvider::derive_channel_signer`]. The `user_channel_id` is provided to allow
 758         /// implementations of [`SignerProvider`] to maintain a mapping between itself and the generated
 759         /// `channel_keys_id`.
 760         ///
 761         /// This method must return a different value each time it is called.
 762         fn generate_channel_keys_id(&self, inbound: bool, channel_value_satoshis: u64, user_channel_id: u128) -> [u8; 32];
 763
 764         /// Derives the private key material backing a `Signer`.
 765         ///
 766         /// To derive a new `Signer`, a fresh `channel_keys_id` should be obtained through
 767         /// [`SignerProvider::generate_channel_keys_id`]. Otherwise, an existing `Signer` can be
 768         /// re-derived from its `channel_keys_id`, which can be obtained through its trait method
 769         /// [`ChannelSigner::channel_keys_id`].
 770         fn derive_channel_signer(&self, channel_value_satoshis: u64, channel_keys_id: [u8; 32]) -> Self::EcdsaSigner;
 771
 772         /// Reads a [`Signer`] for this [`SignerProvider`] from the given input stream.
 773         /// This is only called during deserialization of other objects which contain
 774         /// [`WriteableEcdsaChannelSigner`]-implementing objects (i.e., [`ChannelMonitor`]s and [`ChannelManager`]s).
 775         /// The bytes are exactly those which `<Self::Signer as Writeable>::write()` writes, and
 776         /// contain no versioning scheme. You may wish to include your own version prefix and ensure
 777         /// you've read all of the provided bytes to ensure no corruption occurred.
 778         ///
 779         /// This method is slowly being phased out -- it will only be called when reading objects
 780         /// written by LDK versions prior to 0.0.113.
 781         ///
 782         /// [`Signer`]: Self::EcdsaSigner
 783         /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
 784         /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
 785         fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::EcdsaSigner, DecodeError>;
 786
 787         /// Get a script pubkey which we send funds to when claiming on-chain contestable outputs.
 788         ///
 789         /// If this function returns an error, this will result in a channel failing to open.
 790         ///
 791         /// This method should return a different value each time it is called, to avoid linking
 792         /// on-chain funds across channels as controlled to the same user. `channel_keys_id` may be
 793         /// used to derive a unique value for each channel.
 794         fn get_destination_script(&self, channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()>;
 795
 796         /// Get a script pubkey which we will send funds to when closing a channel.
 797         ///
 798         /// If this function returns an error, this will result in a channel failing to open or close.
 799         /// In the event of a failure when the counterparty is initiating a close, this can result in a
 800         /// channel force close.
 801         ///
 802         /// This method should return a different value each time it is called, to avoid linking
 803         /// on-chain funds across channels as controlled to the same user.
 804         fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()>;
 805 }
 806
 807 /// A simple implementation of [`WriteableEcdsaChannelSigner`] that just keeps the private keys in memory.
 808 ///
 809 /// This implementation performs no policy checks and is insufficient by itself as
 810 /// a secure external signer.
 811 #[derive(Debug)]
 812 pub struct InMemorySigner {
 813         /// Holder secret key in the 2-of-2 multisig script of a channel. This key also backs the
 814         /// holder's anchor output in a commitment transaction, if one is present.
 815         pub funding_key: SecretKey,
 816         /// Holder secret key for blinded revocation pubkey.
 817         pub revocation_base_key: SecretKey,
 818         /// Holder secret key used for our balance in counterparty-broadcasted commitment transactions.
 819         pub payment_key: SecretKey,
 820         /// Holder secret key used in an HTLC transaction.
 821         pub delayed_payment_base_key: SecretKey,
 822         /// Holder HTLC secret key used in commitment transaction HTLC outputs.
 823         pub htlc_base_key: SecretKey,
 824         /// Commitment seed.
 825         pub commitment_seed: [u8; 32],
 826         /// Holder public keys and basepoints.
 827         pub(crate) holder_channel_pubkeys: ChannelPublicKeys,
 828         /// Counterparty public keys and counterparty/holder `selected_contest_delay`, populated on channel acceptance.
 829         channel_parameters: Option<ChannelTransactionParameters>,
 830         /// The total value of this channel.
 831         channel_value_satoshis: u64,
 832         /// Key derivation parameters.
 833         channel_keys_id: [u8; 32],
 834         /// A source of random bytes.
 835         entropy_source: RandomBytes,
 836 }
 837
 838 impl PartialEq for InMemorySigner {
 839         fn eq(&self, other: &Self) -> bool {
 840                 self.funding_key == other.funding_key &&
 841                         self.revocation_base_key == other.revocation_base_key &&
 842                         self.payment_key == other.payment_key &&
 843                         self.delayed_payment_base_key == other.delayed_payment_base_key &&
 844                         self.htlc_base_key == other.htlc_base_key &&
 845                         self.commitment_seed == other.commitment_seed &&
 846                         self.holder_channel_pubkeys == other.holder_channel_pubkeys &&
 847                         self.channel_parameters == other.channel_parameters &&
 848                         self.channel_value_satoshis == other.channel_value_satoshis &&
 849                         self.channel_keys_id == other.channel_keys_id
 850         }
 851 }
 852
 853 impl Clone for InMemorySigner {
 854         fn clone(&self) -> Self {
 855                 Self {
 856                         funding_key: self.funding_key.clone(),
 857                         revocation_base_key: self.revocation_base_key.clone(),
 858                         payment_key: self.payment_key.clone(),
 859                         delayed_payment_base_key: self.delayed_payment_base_key.clone(),
 860                         htlc_base_key: self.htlc_base_key.clone(),
 861                         commitment_seed: self.commitment_seed.clone(),
 862                         holder_channel_pubkeys: self.holder_channel_pubkeys.clone(),
 863                         channel_parameters: self.channel_parameters.clone(),
 864                         channel_value_satoshis: self.channel_value_satoshis,
 865                         channel_keys_id: self.channel_keys_id,
 866                         entropy_source: RandomBytes::new(self.get_secure_random_bytes()),
 867                 }
 868         }
 869 }
 870
 871 impl InMemorySigner {
 872         /// Creates a new [`InMemorySigner`].
 873         pub fn new<C: Signing>(
 874                 secp_ctx: &Secp256k1<C>,
 875                 funding_key: SecretKey,
 876                 revocation_base_key: SecretKey,
 877                 payment_key: SecretKey,
 878                 delayed_payment_base_key: SecretKey,
 879                 htlc_base_key: SecretKey,
 880                 commitment_seed: [u8; 32],
 881                 channel_value_satoshis: u64,
 882                 channel_keys_id: [u8; 32],
 883                 rand_bytes_unique_start: [u8; 32],
 884         ) -> InMemorySigner {
 885                 let holder_channel_pubkeys =
 886                         InMemorySigner::make_holder_keys(secp_ctx, &funding_key, &revocation_base_key,
 887                                 &payment_key, &delayed_payment_base_key,
 888                                 &htlc_base_key);
 889                 InMemorySigner {
 890                         funding_key,
 891                         revocation_base_key,
 892                         payment_key,
 893                         delayed_payment_base_key,
 894                         htlc_base_key,
 895                         commitment_seed,
 896                         channel_value_satoshis,
 897                         holder_channel_pubkeys,
 898                         channel_parameters: None,
 899                         channel_keys_id,
 900                         entropy_source: RandomBytes::new(rand_bytes_unique_start),
 901                 }
 902         }
 903
 904         fn make_holder_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
 905                         funding_key: &SecretKey,
 906                         revocation_base_key: &SecretKey,
 907                         payment_key: &SecretKey,
 908                         delayed_payment_base_key: &SecretKey,
 909                         htlc_base_key: &SecretKey) -> ChannelPublicKeys {
 910                 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
 911                 ChannelPublicKeys {
 912                         funding_pubkey: from_secret(&funding_key),
 913                         revocation_basepoint: RevocationBasepoint::from(from_secret(&revocation_base_key)),
 914                         payment_point: from_secret(&payment_key),
 915                         delayed_payment_basepoint: DelayedPaymentBasepoint::from(from_secret(&delayed_payment_base_key)),
 916                         htlc_basepoint: HtlcBasepoint::from(from_secret(&htlc_base_key)),
 917                 }
 918         }
 919
 920         /// Returns the counterparty's pubkeys.
 921         ///
 922         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
 923         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
 924         pub fn counterparty_pubkeys(&self) -> Option<&ChannelPublicKeys> {
 925                 self.get_channel_parameters()
 926                         .and_then(|params| params.counterparty_parameters.as_ref().map(|params| &params.pubkeys))
 927         }
 928
 929         /// Returns the `contest_delay` value specified by our counterparty and applied on holder-broadcastable
 930         /// transactions, i.e., the amount of time that we have to wait to recover our funds if we
 931         /// broadcast a transaction.
 932         ///
 933         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
 934         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
 935         pub fn counterparty_selected_contest_delay(&self) -> Option<u16> {
 936                 self.get_channel_parameters()
 937                         .and_then(|params| params.counterparty_parameters.as_ref().map(|params| params.selected_contest_delay))
 938         }
 939
 940         /// Returns the `contest_delay` value specified by us and applied on transactions broadcastable
 941         /// by our counterparty, i.e., the amount of time that they have to wait to recover their funds
 942         /// if they broadcast a transaction.
 943         ///
 944         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
 945         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
 946         pub fn holder_selected_contest_delay(&self) -> Option<u16> {
 947                 self.get_channel_parameters().map(|params| params.holder_selected_contest_delay)
 948         }
 949
 950         /// Returns whether the holder is the initiator.
 951         ///
 952         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
 953         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
 954         pub fn is_outbound(&self) -> Option<bool> {
 955                 self.get_channel_parameters().map(|params| params.is_outbound_from_holder)
 956         }
 957
 958         /// Funding outpoint
 959         ///
 960         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
 961         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
 962         pub fn funding_outpoint(&self) -> Option<&OutPoint> {
 963                 self.get_channel_parameters().map(|params| params.funding_outpoint.as_ref()).flatten()
 964         }
 965
 966         /// Returns a [`ChannelTransactionParameters`] for this channel, to be used when verifying or
 967         /// building transactions.
 968         ///
 969         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
 970         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
 971         pub fn get_channel_parameters(&self) -> Option<&ChannelTransactionParameters> {
 972                 self.channel_parameters.as_ref()
 973         }
 974
 975         /// Returns the channel type features of the channel parameters. Should be helpful for
 976         /// determining a channel's category, i. e. legacy/anchors/taproot/etc.
 977         ///
 978         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
 979         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
 980         pub fn channel_type_features(&self) -> Option<&ChannelTypeFeatures> {
 981                 self.get_channel_parameters().map(|params| &params.channel_type_features)
 982         }
 983
 984         /// Sign the single input of `spend_tx` at index `input_idx`, which spends the output described
 985         /// by `descriptor`, returning the witness stack for the input.
 986         ///
 987         /// Returns an error if the input at `input_idx` does not exist, has a non-empty `script_sig`,
 988         /// is not spending the outpoint described by [`descriptor.outpoint`],
 989         /// or if an output descriptor `script_pubkey` does not match the one we can spend.
 990         ///
 991         /// [`descriptor.outpoint`]: StaticPaymentOutputDescriptor::outpoint
 992         pub fn sign_counterparty_payment_input<C: Signing>(&self, spend_tx: &Transaction, input_idx: usize, descriptor: &StaticPaymentOutputDescriptor, secp_ctx: &Secp256k1<C>) -> Result<Witness, ()> {
 993                 // TODO: We really should be taking the SigHashCache as a parameter here instead of
 994                 // spend_tx, but ideally the SigHashCache would expose the transaction's inputs read-only
 995                 // so that we can check them. This requires upstream rust-bitcoin changes (as well as
 996                 // bindings updates to support SigHashCache objects).
 997                 if spend_tx.input.len() <= input_idx { return Err(()); }
 998                 if !spend_tx.input[input_idx].script_sig.is_empty() { return Err(()); }
 999                 if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint() { return Err(()); }
1000
1001                 let remotepubkey = bitcoin::PublicKey::new(self.pubkeys().payment_point);
1002                 // We cannot always assume that `channel_parameters` is set, so can't just call
1003                 // `self.channel_parameters()` or anything that relies on it
1004                 let supports_anchors_zero_fee_htlc_tx = self.channel_type_features()
1005                         .map(|features| features.supports_anchors_zero_fee_htlc_tx())
1006                         .unwrap_or(false);
1007
1008                 let witness_script = if supports_anchors_zero_fee_htlc_tx {
1009                         chan_utils::get_to_countersignatory_with_anchors_redeemscript(&remotepubkey.inner)
1010                 } else {
1011                         ScriptBuf::new_p2pkh(&remotepubkey.pubkey_hash())
1012                 };
1013                 let sighash = hash_to_message!(&sighash::SighashCache::new(spend_tx).segwit_signature_hash(input_idx, &witness_script, descriptor.output.value, EcdsaSighashType::All).unwrap()[..]);
1014                 let remotesig = sign_with_aux_rand(secp_ctx, &sighash, &self.payment_key, &self);
1015                 let payment_script = if supports_anchors_zero_fee_htlc_tx {
1016                         witness_script.to_v0_p2wsh()
1017                 } else {
1018                         ScriptBuf::new_v0_p2wpkh(&remotepubkey.wpubkey_hash().unwrap())
1019                 };
1020
1021                 if payment_script != descriptor.output.script_pubkey { return Err(()); }
1022
1023                 let mut witness = Vec::with_capacity(2);
1024                 witness.push(remotesig.serialize_der().to_vec());
1025                 witness[0].push(EcdsaSighashType::All as u8);
1026                 if supports_anchors_zero_fee_htlc_tx {
1027                         witness.push(witness_script.to_bytes());
1028                 } else {
1029                         witness.push(remotepubkey.to_bytes());
1030                 }
1031                 Ok(witness.into())
1032         }
1033
1034         /// Sign the single input of `spend_tx` at index `input_idx` which spends the output
1035         /// described by `descriptor`, returning the witness stack for the input.
1036         ///
1037         /// Returns an error if the input at `input_idx` does not exist, has a non-empty `script_sig`,
1038         /// is not spending the outpoint described by [`descriptor.outpoint`], does not have a
1039         /// sequence set to [`descriptor.to_self_delay`], or if an output descriptor
1040         /// `script_pubkey` does not match the one we can spend.
1041         ///
1042         /// [`descriptor.outpoint`]: DelayedPaymentOutputDescriptor::outpoint
1043         /// [`descriptor.to_self_delay`]: DelayedPaymentOutputDescriptor::to_self_delay
1044         pub fn sign_dynamic_p2wsh_input<C: Signing>(&self, spend_tx: &Transaction, input_idx: usize, descriptor: &DelayedPaymentOutputDescriptor, secp_ctx: &Secp256k1<C>) -> Result<Witness, ()> {
1045                 // TODO: We really should be taking the SigHashCache as a parameter here instead of
1046                 // spend_tx, but ideally the SigHashCache would expose the transaction's inputs read-only
1047                 // so that we can check them. This requires upstream rust-bitcoin changes (as well as
1048                 // bindings updates to support SigHashCache objects).
1049                 if spend_tx.input.len() <= input_idx { return Err(()); }
1050                 if !spend_tx.input[input_idx].script_sig.is_empty() { return Err(()); }
1051                 if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint() { return Err(()); }
1052                 if spend_tx.input[input_idx].sequence.0 != descriptor.to_self_delay as u32 { return Err(()); }
1053
1054                 let delayed_payment_key = chan_utils::derive_private_key(&secp_ctx, &descriptor.per_commitment_point, &self.delayed_payment_base_key);
1055                 let delayed_payment_pubkey = DelayedPaymentKey::from_secret_key(&secp_ctx, &delayed_payment_key);
1056                 let witness_script = chan_utils::get_revokeable_redeemscript(&descriptor.revocation_pubkey, descriptor.to_self_delay, &delayed_payment_pubkey);
1057                 let sighash = hash_to_message!(&sighash::SighashCache::new(spend_tx).segwit_signature_hash(input_idx, &witness_script, descriptor.output.value, EcdsaSighashType::All).unwrap()[..]);
1058                 let local_delayedsig = EcdsaSignature {
1059                         sig: sign_with_aux_rand(secp_ctx, &sighash, &delayed_payment_key, &self),
1060                         hash_ty: EcdsaSighashType::All,
1061                 };
1062                 let payment_script = bitcoin::Address::p2wsh(&witness_script, Network::Bitcoin).script_pubkey();
1063
1064                 if descriptor.output.script_pubkey != payment_script { return Err(()); }
1065
1066                 Ok(Witness::from_slice(&[
1067                         &local_delayedsig.serialize()[..],
1068                         &[], // MINIMALIF
1069                         witness_script.as_bytes(),
1070                 ]))
1071         }
1072 }
1073
1074 impl EntropySource for InMemorySigner {
1075         fn get_secure_random_bytes(&self) -> [u8; 32] {
1076                 self.entropy_source.get_secure_random_bytes()
1077         }
1078 }
1079
1080 impl ChannelSigner for InMemorySigner {
1081         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
1082                 let commitment_secret = SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx)).unwrap();
1083                 PublicKey::from_secret_key(secp_ctx, &commitment_secret)
1084         }
1085
1086         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
1087                 chan_utils::build_commitment_secret(&self.commitment_seed, idx)
1088         }
1089
1090         fn validate_holder_commitment(&self, _holder_tx: &HolderCommitmentTransaction, _outbound_htlc_preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
1091                 Ok(())
1092         }
1093
1094         fn validate_counterparty_revocation(&self, _idx: u64, _secret: &SecretKey) -> Result<(), ()> {
1095                 Ok(())
1096         }
1097
1098         fn pubkeys(&self) -> &ChannelPublicKeys { &self.holder_channel_pubkeys }
1099
1100         fn channel_keys_id(&self) -> [u8; 32] { self.channel_keys_id }
1101
1102         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
1103                 assert!(self.channel_parameters.is_none() || self.channel_parameters.as_ref().unwrap() == channel_parameters);
1104                 if self.channel_parameters.is_some() {
1105                         // The channel parameters were already set and they match, return early.
1106                         return;
1107                 }
1108                 assert!(channel_parameters.is_populated(), "Channel parameters must be fully populated");
1109                 self.channel_parameters = Some(channel_parameters.clone());
1110         }
1111 }
1112
1113 const MISSING_PARAMS_ERR: &'static str = "ChannelSigner::provide_channel_parameters must be called before signing operations";
1114
1115 impl EcdsaChannelSigner for InMemorySigner {
1116         fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, _inbound_htlc_preimages: Vec<PaymentPreimage>, _outbound_htlc_preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
1117                 let trusted_tx = commitment_tx.trust();
1118                 let keys = trusted_tx.keys();
1119
1120                 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1121                 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1122                 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1123
1124                 let built_tx = trusted_tx.built_transaction();
1125                 let commitment_sig = built_tx.sign_counterparty_commitment(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx);
1126                 let commitment_txid = built_tx.txid;
1127
1128                 let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len());
1129                 for htlc in commitment_tx.htlcs() {
1130                         let channel_parameters = self.get_channel_parameters().expect(MISSING_PARAMS_ERR);
1131                         let holder_selected_contest_delay =
1132                                 self.holder_selected_contest_delay().expect(MISSING_PARAMS_ERR);
1133                         let chan_type = &channel_parameters.channel_type_features;
1134                         let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), holder_selected_contest_delay, htlc, chan_type, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
1135                         let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, chan_type, &keys);
1136                         let htlc_sighashtype = if chan_type.supports_anchors_zero_fee_htlc_tx() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
1137                         let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).segwit_signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, htlc_sighashtype).unwrap()[..]);
1138                         let holder_htlc_key = chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key);
1139                         htlc_sigs.push(sign(secp_ctx, &htlc_sighash, &holder_htlc_key));
1140                 }
1141
1142                 Ok((commitment_sig, htlc_sigs))
1143         }
1144
1145         fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
1146                 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1147                 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1148                 let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1149                 let trusted_tx = commitment_tx.trust();
1150                 Ok(trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx))
1151         }
1152
1153         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
1154         fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
1155                 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1156                 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1157                 let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1158                 let trusted_tx = commitment_tx.trust();
1159                 Ok(trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx))
1160         }
1161
1162         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
1163                 let revocation_key = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key);
1164                 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
1165                 let revocation_pubkey = RevocationKey::from_basepoint(
1166                         &secp_ctx,  &self.pubkeys().revocation_basepoint, &per_commitment_point,
1167                 );
1168                 let witness_script = {
1169                         let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1170                         let holder_selected_contest_delay =
1171                                 self.holder_selected_contest_delay().expect(MISSING_PARAMS_ERR);
1172                         let counterparty_delayedpubkey = DelayedPaymentKey::from_basepoint(&secp_ctx, &counterparty_keys.delayed_payment_basepoint, &per_commitment_point);
1173                         chan_utils::get_revokeable_redeemscript(&revocation_pubkey, holder_selected_contest_delay, &counterparty_delayedpubkey)
1174                 };
1175                 let mut sighash_parts = sighash::SighashCache::new(justice_tx);
1176                 let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
1177                 return Ok(sign_with_aux_rand(secp_ctx, &sighash, &revocation_key, &self))
1178         }
1179
1180         fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
1181                 let revocation_key = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key);
1182                 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
1183                 let revocation_pubkey = RevocationKey::from_basepoint(
1184                         &secp_ctx,  &self.pubkeys().revocation_basepoint, &per_commitment_point,
1185                 );
1186                 let witness_script = {
1187                         let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1188                         let counterparty_htlcpubkey = HtlcKey::from_basepoint(
1189                                 &secp_ctx, &counterparty_keys.htlc_basepoint, &per_commitment_point,
1190                         );
1191                         let holder_htlcpubkey = HtlcKey::from_basepoint(
1192                                 &secp_ctx, &self.pubkeys().htlc_basepoint, &per_commitment_point,
1193                         );
1194                         let chan_type = self.channel_type_features().expect(MISSING_PARAMS_ERR);
1195                         chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, chan_type, &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
1196                 };
1197                 let mut sighash_parts = sighash::SighashCache::new(justice_tx);
1198                 let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
1199                 return Ok(sign_with_aux_rand(secp_ctx, &sighash, &revocation_key, &self))
1200         }
1201
1202         fn sign_holder_htlc_transaction(
1203                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
1204                 secp_ctx: &Secp256k1<secp256k1::All>
1205         ) -> Result<Signature, ()> {
1206                 let witness_script = htlc_descriptor.witness_script(secp_ctx);
1207                 let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
1208                         input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, EcdsaSighashType::All
1209                 ).map_err(|_| ())?;
1210                 let our_htlc_private_key = chan_utils::derive_private_key(
1211                         &secp_ctx, &htlc_descriptor.per_commitment_point, &self.htlc_base_key
1212                 );
1213                 Ok(sign_with_aux_rand(&secp_ctx, &hash_to_message!(sighash.as_byte_array()), &our_htlc_private_key, &self))
1214         }
1215
1216         fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
1217                 let htlc_key = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key);
1218                 let revocation_pubkey = RevocationKey::from_basepoint(
1219                         &secp_ctx,  &self.pubkeys().revocation_basepoint, &per_commitment_point,
1220                 );
1221                 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1222                 let counterparty_htlcpubkey = HtlcKey::from_basepoint(
1223                         &secp_ctx, &counterparty_keys.htlc_basepoint, &per_commitment_point,
1224                 );
1225                 let htlcpubkey = HtlcKey::from_basepoint(&secp_ctx, &self.pubkeys().htlc_basepoint, &per_commitment_point);
1226                 let chan_type = self.channel_type_features().expect(MISSING_PARAMS_ERR);
1227                 let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, chan_type, &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey);
1228                 let mut sighash_parts = sighash::SighashCache::new(htlc_tx);
1229                 let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
1230                 Ok(sign_with_aux_rand(secp_ctx, &sighash, &htlc_key, &self))
1231         }
1232
1233         fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
1234                 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1235                 let counterparty_funding_key = &self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR).funding_pubkey;
1236                 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, counterparty_funding_key);
1237                 Ok(closing_tx.trust().sign(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
1238         }
1239
1240         fn sign_holder_anchor_input(
1241                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
1242         ) -> Result<Signature, ()> {
1243                 let witness_script = chan_utils::get_anchor_redeemscript(&self.holder_channel_pubkeys.funding_pubkey);
1244                 let sighash = sighash::SighashCache::new(&*anchor_tx).segwit_signature_hash(
1245                         input, &witness_script, ANCHOR_OUTPUT_VALUE_SATOSHI, EcdsaSighashType::All,
1246                 ).unwrap();
1247                 Ok(sign_with_aux_rand(secp_ctx, &hash_to_message!(&sighash[..]), &self.funding_key, &self))
1248         }
1249
1250         fn sign_channel_announcement_with_funding_key(
1251                 &self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
1252         ) -> Result<Signature, ()> {
1253                 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
1254                 Ok(secp_ctx.sign_ecdsa(&msghash, &self.funding_key))
1255         }
1256 }
1257
1258 #[cfg(taproot)]
1259 impl TaprootChannelSigner for InMemorySigner {
1260         fn generate_local_nonce_pair(&self, commitment_number: u64, secp_ctx: &Secp256k1<All>) -> PublicNonce {
1261                 todo!()
1262         }
1263
1264         fn partially_sign_counterparty_commitment(&self, counterparty_nonce: PublicNonce, commitment_tx: &CommitmentTransaction, inbound_htlc_preimages: Vec<PaymentPreimage>, outbound_htlc_preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<All>) -> Result<(PartialSignatureWithNonce, Vec<schnorr::Signature>), ()> {
1265                 todo!()
1266         }
1267
1268         fn finalize_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
1269                 todo!()
1270         }
1271
1272         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<All>) -> Result<schnorr::Signature, ()> {
1273                 todo!()
1274         }
1275
1276         fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<All>) -> Result<schnorr::Signature, ()> {
1277                 todo!()
1278         }
1279
1280         fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<All>) -> Result<schnorr::Signature, ()> {
1281                 todo!()
1282         }
1283
1284         fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<All>) -> Result<schnorr::Signature, ()> {
1285                 todo!()
1286         }
1287
1288         fn partially_sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>) -> Result<PartialSignature, ()> {
1289                 todo!()
1290         }
1291
1292         fn sign_holder_anchor_input(&self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>) -> Result<schnorr::Signature, ()> {
1293                 todo!()
1294         }
1295 }
1296
1297 const SERIALIZATION_VERSION: u8 = 1;
1298
1299 const MIN_SERIALIZATION_VERSION: u8 = 1;
1300
1301 impl WriteableEcdsaChannelSigner for InMemorySigner {}
1302
1303 impl Writeable for InMemorySigner {
1304         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
1305                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
1306
1307                 self.funding_key.write(writer)?;
1308                 self.revocation_base_key.write(writer)?;
1309                 self.payment_key.write(writer)?;
1310                 self.delayed_payment_base_key.write(writer)?;
1311                 self.htlc_base_key.write(writer)?;
1312                 self.commitment_seed.write(writer)?;
1313                 self.channel_parameters.write(writer)?;
1314                 self.channel_value_satoshis.write(writer)?;
1315                 self.channel_keys_id.write(writer)?;
1316
1317                 write_tlv_fields!(writer, {});
1318
1319                 Ok(())
1320         }
1321 }
1322
1323 impl<ES: Deref> ReadableArgs<ES> for InMemorySigner where ES::Target: EntropySource {
1324         fn read<R: io::Read>(reader: &mut R, entropy_source: ES) -> Result<Self, DecodeError> {
1325                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
1326
1327                 let funding_key = Readable::read(reader)?;
1328                 let revocation_base_key = Readable::read(reader)?;
1329                 let payment_key = Readable::read(reader)?;
1330                 let delayed_payment_base_key = Readable::read(reader)?;
1331                 let htlc_base_key = Readable::read(reader)?;
1332                 let commitment_seed = Readable::read(reader)?;
1333                 let counterparty_channel_data = Readable::read(reader)?;
1334                 let channel_value_satoshis = Readable::read(reader)?;
1335                 let secp_ctx = Secp256k1::signing_only();
1336                 let holder_channel_pubkeys =
1337                         InMemorySigner::make_holder_keys(&secp_ctx, &funding_key, &revocation_base_key,
1338                                  &payment_key, &delayed_payment_base_key, &htlc_base_key);
1339                 let keys_id = Readable::read(reader)?;
1340
1341                 read_tlv_fields!(reader, {});
1342
1343                 Ok(InMemorySigner {
1344                         funding_key,
1345                         revocation_base_key,
1346                         payment_key,
1347                         delayed_payment_base_key,
1348                         htlc_base_key,
1349                         commitment_seed,
1350                         channel_value_satoshis,
1351                         holder_channel_pubkeys,
1352                         channel_parameters: counterparty_channel_data,
1353                         channel_keys_id: keys_id,
1354                         entropy_source: RandomBytes::new(entropy_source.get_secure_random_bytes()),
1355                 })
1356         }
1357 }
1358
1359 /// Simple implementation of [`EntropySource`], [`NodeSigner`], and [`SignerProvider`] that takes a
1360 /// 32-byte seed for use as a BIP 32 extended key and derives keys from that.
1361 ///
1362 /// Your `node_id` is seed/0'.
1363 /// Unilateral closes may use seed/1'.
1364 /// Cooperative closes may use seed/2'.
1365 /// The two close keys may be needed to claim on-chain funds!
1366 ///
1367 /// This struct cannot be used for nodes that wish to support receiving phantom payments;
1368 /// [`PhantomKeysManager`] must be used instead.
1369 ///
1370 /// Note that switching between this struct and [`PhantomKeysManager`] will invalidate any
1371 /// previously issued invoices and attempts to pay previous invoices will fail.
1372 pub struct KeysManager {
1373         secp_ctx: Secp256k1<secp256k1::All>,
1374         node_secret: SecretKey,
1375         node_id: PublicKey,
1376         inbound_payment_key: KeyMaterial,
1377         destination_script: ScriptBuf,
1378         shutdown_pubkey: PublicKey,
1379         channel_master_key: ExtendedPrivKey,
1380         channel_child_index: AtomicUsize,
1381
1382         entropy_source: RandomBytes,
1383
1384         seed: [u8; 32],
1385         starting_time_secs: u64,
1386         starting_time_nanos: u32,
1387 }
1388
1389 impl KeysManager {
1390         /// Constructs a [`KeysManager`] from a 32-byte seed. If the seed is in some way biased (e.g.,
1391         /// your CSRNG is busted) this may panic (but more importantly, you will possibly lose funds).
1392         /// `starting_time` isn't strictly required to actually be a time, but it must absolutely,
1393         /// without a doubt, be unique to this instance. ie if you start multiple times with the same
1394         /// `seed`, `starting_time` must be unique to each run. Thus, the easiest way to achieve this
1395         /// is to simply use the current time (with very high precision).
1396         ///
1397         /// The `seed` MUST be backed up safely prior to use so that the keys can be re-created, however,
1398         /// obviously, `starting_time` should be unique every time you reload the library - it is only
1399         /// used to generate new ephemeral key data (which will be stored by the individual channel if
1400         /// necessary).
1401         ///
1402         /// Note that the seed is required to recover certain on-chain funds independent of
1403         /// [`ChannelMonitor`] data, though a current copy of [`ChannelMonitor`] data is also required
1404         /// for any channel, and some on-chain during-closing funds.
1405         ///
1406         /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
1407         pub fn new(seed: &[u8; 32], starting_time_secs: u64, starting_time_nanos: u32) -> Self {
1408                 let secp_ctx = Secp256k1::new();
1409                 // Note that when we aren't serializing the key, network doesn't matter
1410                 match ExtendedPrivKey::new_master(Network::Testnet, seed) {
1411                         Ok(master_key) => {
1412                                 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key;
1413                                 let node_id = PublicKey::from_secret_key(&secp_ctx, &node_secret);
1414                                 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
1415                                         Ok(destination_key) => {
1416                                                 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_priv(&secp_ctx, &destination_key).to_pub().to_bytes());
1417                                                 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
1418                                                         .push_slice(&wpubkey_hash.to_byte_array())
1419                                                         .into_script()
1420                                         },
1421                                         Err(_) => panic!("Your RNG is busted"),
1422                                 };
1423                                 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
1424                                         Ok(shutdown_key) => ExtendedPubKey::from_priv(&secp_ctx, &shutdown_key).public_key,
1425                                         Err(_) => panic!("Your RNG is busted"),
1426                                 };
1427                                 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
1428                                 let inbound_payment_key: SecretKey = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted").private_key;
1429                                 let mut inbound_pmt_key_bytes = [0; 32];
1430                                 inbound_pmt_key_bytes.copy_from_slice(&inbound_payment_key[..]);
1431
1432                                 let mut rand_bytes_engine = Sha256::engine();
1433                                 rand_bytes_engine.input(&starting_time_secs.to_be_bytes());
1434                                 rand_bytes_engine.input(&starting_time_nanos.to_be_bytes());
1435                                 rand_bytes_engine.input(seed);
1436                                 rand_bytes_engine.input(b"LDK PRNG Seed");
1437                                 let rand_bytes_unique_start = Sha256::from_engine(rand_bytes_engine).to_byte_array();
1438
1439                                 let mut res = KeysManager {
1440                                         secp_ctx,
1441                                         node_secret,
1442                                         node_id,
1443                                         inbound_payment_key: KeyMaterial(inbound_pmt_key_bytes),
1444
1445                                         destination_script,
1446                                         shutdown_pubkey,
1447
1448                                         channel_master_key,
1449                                         channel_child_index: AtomicUsize::new(0),
1450
1451                                         entropy_source: RandomBytes::new(rand_bytes_unique_start),
1452
1453                                         seed: *seed,
1454                                         starting_time_secs,
1455                                         starting_time_nanos,
1456                                 };
1457                                 let secp_seed = res.get_secure_random_bytes();
1458                                 res.secp_ctx.seeded_randomize(&secp_seed);
1459                                 res
1460                         },
1461                         Err(_) => panic!("Your rng is busted"),
1462                 }
1463         }
1464
1465         /// Gets the "node_id" secret key used to sign gossip announcements, decode onion data, etc.
1466         pub fn get_node_secret_key(&self) -> SecretKey {
1467                 self.node_secret
1468         }
1469
1470         /// Derive an old [`WriteableEcdsaChannelSigner`] containing per-channel secrets based on a key derivation parameters.
1471         pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params: &[u8; 32]) -> InMemorySigner {
1472                 let chan_id = u64::from_be_bytes(params[0..8].try_into().unwrap());
1473                 let mut unique_start = Sha256::engine();
1474                 unique_start.input(params);
1475                 unique_start.input(&self.seed);
1476
1477                 // We only seriously intend to rely on the channel_master_key for true secure
1478                 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
1479                 // starting_time provided in the constructor) to be unique.
1480                 let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx,
1481                                 ChildNumber::from_hardened_idx((chan_id as u32) % (1 << 31)).expect("key space exhausted")
1482                         ).expect("Your RNG is busted");
1483                 unique_start.input(&child_privkey.private_key[..]);
1484
1485                 let seed = Sha256::from_engine(unique_start).to_byte_array();
1486
1487                 let commitment_seed = {
1488                         let mut sha = Sha256::engine();
1489                         sha.input(&seed);
1490                         sha.input(&b"commitment seed"[..]);
1491                         Sha256::from_engine(sha).to_byte_array()
1492                 };
1493                 macro_rules! key_step {
1494                         ($info: expr, $prev_key: expr) => {{
1495                                 let mut sha = Sha256::engine();
1496                                 sha.input(&seed);
1497                                 sha.input(&$prev_key[..]);
1498                                 sha.input(&$info[..]);
1499                                 SecretKey::from_slice(&Sha256::from_engine(sha).to_byte_array()).expect("SHA-256 is busted")
1500                         }}
1501                 }
1502                 let funding_key = key_step!(b"funding key", commitment_seed);
1503                 let revocation_base_key = key_step!(b"revocation base key", funding_key);
1504                 let payment_key = key_step!(b"payment key", revocation_base_key);
1505                 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
1506                 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
1507                 let prng_seed = self.get_secure_random_bytes();
1508
1509                 InMemorySigner::new(
1510                         &self.secp_ctx,
1511                         funding_key,
1512                         revocation_base_key,
1513                         payment_key,
1514                         delayed_payment_base_key,
1515                         htlc_base_key,
1516                         commitment_seed,
1517                         channel_value_satoshis,
1518                         params.clone(),
1519                         prng_seed,
1520                 )
1521         }
1522
1523         /// Signs the given [`PartiallySignedTransaction`] which spends the given [`SpendableOutputDescriptor`]s.
1524         /// The resulting inputs will be finalized and the PSBT will be ready for broadcast if there
1525         /// are no other inputs that need signing.
1526         ///
1527         /// Returns `Err(())` if the PSBT is missing a descriptor or if we fail to sign.
1528         ///
1529         /// May panic if the [`SpendableOutputDescriptor`]s were not generated by channels which used
1530         /// this [`KeysManager`] or one of the [`InMemorySigner`] created by this [`KeysManager`].
1531         pub fn sign_spendable_outputs_psbt<C: Signing>(&self, descriptors: &[&SpendableOutputDescriptor], mut psbt: PartiallySignedTransaction, secp_ctx: &Secp256k1<C>) -> Result<PartiallySignedTransaction, ()> {
1532                 let mut keys_cache: Option<(InMemorySigner, [u8; 32])> = None;
1533                 for outp in descriptors {
1534                         match outp {
1535                                 SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
1536                                         let input_idx = psbt.unsigned_tx.input.iter().position(|i| i.previous_output == descriptor.outpoint.into_bitcoin_outpoint()).ok_or(())?;
1537                                         if keys_cache.is_none() || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id {
1538                                                 let mut signer = self.derive_channel_keys(descriptor.channel_value_satoshis, &descriptor.channel_keys_id);
1539                                                 if let Some(channel_params) = descriptor.channel_transaction_parameters.as_ref() {
1540                                                         signer.provide_channel_parameters(channel_params);
1541                                                 }
1542                                                 keys_cache = Some((signer, descriptor.channel_keys_id));
1543                                         }
1544                                         let witness = keys_cache.as_ref().unwrap().0.sign_counterparty_payment_input(&psbt.unsigned_tx, input_idx, &descriptor, &secp_ctx)?;
1545                                         psbt.inputs[input_idx].final_script_witness = Some(witness);
1546                                 },
1547                                 SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
1548                                         let input_idx = psbt.unsigned_tx.input.iter().position(|i| i.previous_output == descriptor.outpoint.into_bitcoin_outpoint()).ok_or(())?;
1549                                         if keys_cache.is_none() || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id {
1550                                                 keys_cache = Some((
1551                                                         self.derive_channel_keys(descriptor.channel_value_satoshis, &descriptor.channel_keys_id),
1552                                                         descriptor.channel_keys_id));
1553                                         }
1554                                         let witness = keys_cache.as_ref().unwrap().0.sign_dynamic_p2wsh_input(&psbt.unsigned_tx, input_idx, &descriptor, &secp_ctx)?;
1555                                         psbt.inputs[input_idx].final_script_witness = Some(witness);
1556                                 },
1557                                 SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output, .. } => {
1558                                         let input_idx = psbt.unsigned_tx.input.iter().position(|i| i.previous_output == outpoint.into_bitcoin_outpoint()).ok_or(())?;
1559                                         let derivation_idx = if output.script_pubkey == self.destination_script {
1560                                                 1
1561                                         } else {
1562                                                 2
1563                                         };
1564                                         let secret = {
1565                                                 // Note that when we aren't serializing the key, network doesn't matter
1566                                                 match ExtendedPrivKey::new_master(Network::Testnet, &self.seed) {
1567                                                         Ok(master_key) => {
1568                                                                 match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(derivation_idx).expect("key space exhausted")) {
1569                                                                         Ok(key) => key,
1570                                                                         Err(_) => panic!("Your RNG is busted"),
1571                                                                 }
1572                                                         }
1573                                                         Err(_) => panic!("Your rng is busted"),
1574                                                 }
1575                                         };
1576                                         let pubkey = ExtendedPubKey::from_priv(&secp_ctx, &secret).to_pub();
1577                                         if derivation_idx == 2 {
1578                                                 assert_eq!(pubkey.inner, self.shutdown_pubkey);
1579                                         }
1580                                         let witness_script = bitcoin::Address::p2pkh(&pubkey, Network::Testnet).script_pubkey();
1581                                         let payment_script = bitcoin::Address::p2wpkh(&pubkey, Network::Testnet).expect("uncompressed key found").script_pubkey();
1582
1583                                         if payment_script != output.script_pubkey { return Err(()); };
1584
1585                                         let sighash = hash_to_message!(&sighash::SighashCache::new(&psbt.unsigned_tx).segwit_signature_hash(input_idx, &witness_script, output.value, EcdsaSighashType::All).unwrap()[..]);
1586                                         let sig = sign_with_aux_rand(secp_ctx, &sighash, &secret.private_key, &self);
1587                                         let mut sig_ser = sig.serialize_der().to_vec();
1588                                         sig_ser.push(EcdsaSighashType::All as u8);
1589                                         let witness = Witness::from_slice(&[&sig_ser, &pubkey.inner.serialize().to_vec()]);
1590                                         psbt.inputs[input_idx].final_script_witness = Some(witness);
1591                                 },
1592                         }
1593                 }
1594
1595                 Ok(psbt)
1596         }
1597
1598         /// Creates a [`Transaction`] which spends the given descriptors to the given outputs, plus an
1599         /// output to the given change destination (if sufficient change value remains). The
1600         /// transaction will have a feerate, at least, of the given value.
1601         ///
1602         /// The `locktime` argument is used to set the transaction's locktime. If `None`, the
1603         /// transaction will have a locktime of 0. It it recommended to set this to the current block
1604         /// height to avoid fee sniping, unless you have some specific reason to use a different
1605         /// locktime.
1606         ///
1607         /// Returns `Err(())` if the output value is greater than the input value minus required fee,
1608         /// if a descriptor was duplicated, or if an output descriptor `script_pubkey`
1609         /// does not match the one we can spend.
1610         ///
1611         /// We do not enforce that outputs meet the dust limit or that any output scripts are standard.
1612         ///
1613         /// May panic if the [`SpendableOutputDescriptor`]s were not generated by channels which used
1614         /// this [`KeysManager`] or one of the [`InMemorySigner`] created by this [`KeysManager`].
1615         pub fn spend_spendable_outputs<C: Signing>(&self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>, change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32, locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>) -> Result<Transaction, ()> {
1616                 let (mut psbt, expected_max_weight) = SpendableOutputDescriptor::create_spendable_outputs_psbt(descriptors, outputs, change_destination_script, feerate_sat_per_1000_weight, locktime)?;
1617                 psbt = self.sign_spendable_outputs_psbt(descriptors, psbt, secp_ctx)?;
1618
1619                 let spend_tx = psbt.extract_tx();
1620
1621                 debug_assert!(expected_max_weight >= spend_tx.weight().to_wu());
1622                 // Note that witnesses with a signature vary somewhat in size, so allow
1623                 // `expected_max_weight` to overshoot by up to 3 bytes per input.
1624                 debug_assert!(expected_max_weight <= spend_tx.weight().to_wu() + descriptors.len() as u64 * 3);
1625
1626                 Ok(spend_tx)
1627         }
1628 }
1629
1630 impl EntropySource for KeysManager {
1631         fn get_secure_random_bytes(&self) -> [u8; 32] {
1632                 self.entropy_source.get_secure_random_bytes()
1633         }
1634 }
1635
1636 impl NodeSigner for KeysManager {
1637         fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()> {
1638                 match recipient {
1639                         Recipient::Node => Ok(self.node_id.clone()),
1640                         Recipient::PhantomNode => Err(())
1641                 }
1642         }
1643
1644         fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result<SharedSecret, ()> {
1645                 let mut node_secret = match recipient {
1646                         Recipient::Node => Ok(self.node_secret.clone()),
1647                         Recipient::PhantomNode => Err(())
1648                 }?;
1649                 if let Some(tweak) = tweak {
1650                         node_secret = node_secret.mul_tweak(tweak).map_err(|_| ())?;
1651                 }
1652                 Ok(SharedSecret::new(other_key, &node_secret))
1653         }
1654
1655         fn get_inbound_payment_key_material(&self) -> KeyMaterial {
1656                 self.inbound_payment_key.clone()
1657         }
1658
1659         fn sign_invoice(&self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient) -> Result<RecoverableSignature, ()> {
1660                 let preimage = construct_invoice_preimage(&hrp_bytes, &invoice_data);
1661                 let secret = match recipient {
1662                         Recipient::Node => Ok(&self.node_secret),
1663                         Recipient::PhantomNode => Err(())
1664                 }?;
1665                 Ok(self.secp_ctx.sign_ecdsa_recoverable(&hash_to_message!(&Sha256::hash(&preimage).to_byte_array()), secret))
1666         }
1667
1668         fn sign_bolt12_invoice_request(
1669                 &self, invoice_request: &UnsignedInvoiceRequest
1670         ) -> Result<schnorr::Signature, ()> {
1671                 let message = invoice_request.tagged_hash().as_digest();
1672                 let keys = KeyPair::from_secret_key(&self.secp_ctx, &self.node_secret);
1673                 let aux_rand = self.get_secure_random_bytes();
1674                 Ok(self.secp_ctx.sign_schnorr_with_aux_rand(message, &keys, &aux_rand))
1675         }
1676
1677         fn sign_bolt12_invoice(
1678                 &self, invoice: &UnsignedBolt12Invoice
1679         ) -> Result<schnorr::Signature, ()> {
1680                 let message = invoice.tagged_hash().as_digest();
1681                 let keys = KeyPair::from_secret_key(&self.secp_ctx, &self.node_secret);
1682                 let aux_rand = self.get_secure_random_bytes();
1683                 Ok(self.secp_ctx.sign_schnorr_with_aux_rand(message, &keys, &aux_rand))
1684         }
1685
1686         fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()> {
1687                 let msg_hash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
1688                 Ok(self.secp_ctx.sign_ecdsa(&msg_hash, &self.node_secret))
1689         }
1690 }
1691
1692 impl SignerProvider for KeysManager {
1693         type EcdsaSigner = InMemorySigner;
1694         #[cfg(taproot)]
1695         type TaprootSigner = InMemorySigner;
1696
1697         fn generate_channel_keys_id(&self, _inbound: bool, _channel_value_satoshis: u64, user_channel_id: u128) -> [u8; 32] {
1698                 let child_idx = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
1699                 // `child_idx` is the only thing guaranteed to make each channel unique without a restart
1700                 // (though `user_channel_id` should help, depending on user behavior). If it manages to
1701                 // roll over, we may generate duplicate keys for two different channels, which could result
1702                 // in loss of funds. Because we only support 32-bit+ systems, assert that our `AtomicUsize`
1703                 // doesn't reach `u32::MAX`.
1704                 assert!(child_idx < core::u32::MAX as usize, "2^32 channels opened without restart");
1705                 let mut id = [0; 32];
1706                 id[0..4].copy_from_slice(&(child_idx as u32).to_be_bytes());
1707                 id[4..8].copy_from_slice(&self.starting_time_nanos.to_be_bytes());
1708                 id[8..16].copy_from_slice(&self.starting_time_secs.to_be_bytes());
1709                 id[16..32].copy_from_slice(&user_channel_id.to_be_bytes());
1710                 id
1711         }
1712
1713         fn derive_channel_signer(&self, channel_value_satoshis: u64, channel_keys_id: [u8; 32]) -> Self::EcdsaSigner {
1714                 self.derive_channel_keys(channel_value_satoshis, &channel_keys_id)
1715         }
1716
1717         fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::EcdsaSigner, DecodeError> {
1718                 InMemorySigner::read(&mut io::Cursor::new(reader), self)
1719         }
1720
1721         fn get_destination_script(&self, _channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()> {
1722                 Ok(self.destination_script.clone())
1723         }
1724
1725         fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
1726                 Ok(ShutdownScript::new_p2wpkh_from_pubkey(self.shutdown_pubkey.clone()))
1727         }
1728 }
1729
1730 /// Similar to [`KeysManager`], but allows the node using this struct to receive phantom node
1731 /// payments.
1732 ///
1733 /// A phantom node payment is a payment made to a phantom invoice, which is an invoice that can be
1734 /// paid to one of multiple nodes. This works because we encode the invoice route hints such that
1735 /// LDK will recognize an incoming payment as destined for a phantom node, and collect the payment
1736 /// itself without ever needing to forward to this fake node.
1737 ///
1738 /// Phantom node payments are useful for load balancing between multiple LDK nodes. They also
1739 /// provide some fault tolerance, because payers will automatically retry paying other provided
1740 /// nodes in the case that one node goes down.
1741 ///
1742 /// Note that multi-path payments are not supported in phantom invoices for security reasons.
1743 // In the hypothetical case that we did support MPP phantom payments, there would be no way for
1744 // nodes to know when the full payment has been received (and the preimage can be released) without
1745 // significantly compromising on our safety guarantees. I.e., if we expose the ability for the user
1746 // to tell LDK when the preimage can be released, we open ourselves to attacks where the preimage
1747 // is released too early.
1748 //
1749 /// Switching between this struct and [`KeysManager`] will invalidate any previously issued
1750 /// invoices and attempts to pay previous invoices will fail.
1751 pub struct PhantomKeysManager {
1752         inner: KeysManager,
1753         inbound_payment_key: KeyMaterial,
1754         phantom_secret: SecretKey,
1755         phantom_node_id: PublicKey,
1756 }
1757
1758 impl EntropySource for PhantomKeysManager {
1759         fn get_secure_random_bytes(&self) -> [u8; 32] {
1760                 self.inner.get_secure_random_bytes()
1761         }
1762 }
1763
1764 impl NodeSigner for PhantomKeysManager {
1765         fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()> {
1766                 match recipient {
1767                         Recipient::Node => self.inner.get_node_id(Recipient::Node),
1768                         Recipient::PhantomNode => Ok(self.phantom_node_id.clone()),
1769                 }
1770         }
1771
1772         fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result<SharedSecret, ()> {
1773                 let mut node_secret = match recipient {
1774                         Recipient::Node => self.inner.node_secret.clone(),
1775                         Recipient::PhantomNode => self.phantom_secret.clone(),
1776                 };
1777                 if let Some(tweak) = tweak {
1778                         node_secret = node_secret.mul_tweak(tweak).map_err(|_| ())?;
1779                 }
1780                 Ok(SharedSecret::new(other_key, &node_secret))
1781         }
1782
1783         fn get_inbound_payment_key_material(&self) -> KeyMaterial {
1784                 self.inbound_payment_key.clone()
1785         }
1786
1787         fn sign_invoice(&self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient) -> Result<RecoverableSignature, ()> {
1788                 let preimage = construct_invoice_preimage(&hrp_bytes, &invoice_data);
1789                 let secret = match recipient {
1790                         Recipient::Node => &self.inner.node_secret,
1791                         Recipient::PhantomNode => &self.phantom_secret,
1792                 };
1793                 Ok(self.inner.secp_ctx.sign_ecdsa_recoverable(&hash_to_message!(&Sha256::hash(&preimage).to_byte_array()), secret))
1794         }
1795
1796         fn sign_bolt12_invoice_request(
1797                 &self, invoice_request: &UnsignedInvoiceRequest
1798         ) -> Result<schnorr::Signature, ()> {
1799                 self.inner.sign_bolt12_invoice_request(invoice_request)
1800         }
1801
1802         fn sign_bolt12_invoice(
1803                 &self, invoice: &UnsignedBolt12Invoice
1804         ) -> Result<schnorr::Signature, ()> {
1805                 self.inner.sign_bolt12_invoice(invoice)
1806         }
1807
1808         fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()> {
1809                 self.inner.sign_gossip_message(msg)
1810         }
1811 }
1812
1813 impl SignerProvider for PhantomKeysManager {
1814         type EcdsaSigner = InMemorySigner;
1815         #[cfg(taproot)]
1816         type TaprootSigner = InMemorySigner;
1817
1818         fn generate_channel_keys_id(&self, inbound: bool, channel_value_satoshis: u64, user_channel_id: u128) -> [u8; 32] {
1819                 self.inner.generate_channel_keys_id(inbound, channel_value_satoshis, user_channel_id)
1820         }
1821
1822         fn derive_channel_signer(&self, channel_value_satoshis: u64, channel_keys_id: [u8; 32]) -> Self::EcdsaSigner {
1823                 self.inner.derive_channel_signer(channel_value_satoshis, channel_keys_id)
1824         }
1825
1826         fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::EcdsaSigner, DecodeError> {
1827                 self.inner.read_chan_signer(reader)
1828         }
1829
1830         fn get_destination_script(&self, channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()> {
1831                 self.inner.get_destination_script(channel_keys_id)
1832         }
1833
1834         fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
1835                 self.inner.get_shutdown_scriptpubkey()
1836         }
1837 }
1838
1839 impl PhantomKeysManager {
1840         /// Constructs a [`PhantomKeysManager`] given a 32-byte seed and an additional `cross_node_seed`
1841         /// that is shared across all nodes that intend to participate in [phantom node payments]
1842         /// together.
1843         ///
1844         /// See [`KeysManager::new`] for more information on `seed`, `starting_time_secs`, and
1845         /// `starting_time_nanos`.
1846         ///
1847         /// `cross_node_seed` must be the same across all phantom payment-receiving nodes and also the
1848         /// same across restarts, or else inbound payments may fail.
1849         ///
1850         /// [phantom node payments]: PhantomKeysManager
1851         pub fn new(seed: &[u8; 32], starting_time_secs: u64, starting_time_nanos: u32, cross_node_seed: &[u8; 32]) -> Self {
1852                 let inner = KeysManager::new(seed, starting_time_secs, starting_time_nanos);
1853                 let (inbound_key, phantom_key) = hkdf_extract_expand_twice(b"LDK Inbound and Phantom Payment Key Expansion", cross_node_seed);
1854                 let phantom_secret = SecretKey::from_slice(&phantom_key).unwrap();
1855                 let phantom_node_id = PublicKey::from_secret_key(&inner.secp_ctx, &phantom_secret);
1856                 Self {
1857                         inner,
1858                         inbound_payment_key: KeyMaterial(inbound_key),
1859                         phantom_secret,
1860                         phantom_node_id,
1861                 }
1862         }
1863
1864         /// See [`KeysManager::spend_spendable_outputs`] for documentation on this method.
1865         pub fn spend_spendable_outputs<C: Signing>(&self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>, change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32, locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>) -> Result<Transaction, ()> {
1866                 self.inner.spend_spendable_outputs(descriptors, outputs, change_destination_script, feerate_sat_per_1000_weight, locktime, secp_ctx)
1867         }
1868
1869         /// See [`KeysManager::derive_channel_keys`] for documentation on this method.
1870         pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params: &[u8; 32]) -> InMemorySigner {
1871                 self.inner.derive_channel_keys(channel_value_satoshis, params)
1872         }
1873
1874         /// Gets the "node_id" secret key used to sign gossip announcements, decode onion data, etc.
1875         pub fn get_node_secret_key(&self) -> SecretKey {
1876                 self.inner.get_node_secret_key()
1877         }
1878
1879         /// Gets the "node_id" secret key of the phantom node used to sign invoices, decode the
1880         /// last-hop onion data, etc.
1881         pub fn get_phantom_node_secret_key(&self) -> SecretKey {
1882                 self.phantom_secret
1883         }
1884 }
1885
1886 /// An implementation of [`EntropySource`] using ChaCha20.
1887 #[derive(Debug)]
1888 pub struct RandomBytes {
1889         /// Seed from which all randomness produced is derived from.
1890         seed: [u8; 32],
1891         /// Tracks the number of times we've produced randomness to ensure we don't return the same
1892         /// bytes twice.
1893         index: AtomicCounter,
1894 }
1895
1896 impl RandomBytes {
1897         /// Creates a new instance using the given seed.
1898         pub fn new(seed: [u8; 32]) -> Self {
1899                 Self {
1900                         seed,
1901                         index: AtomicCounter::new(),
1902                 }
1903         }
1904 }
1905
1906 impl EntropySource for RandomBytes {
1907         fn get_secure_random_bytes(&self) -> [u8; 32] {
1908                 let index = self.index.get_increment();
1909                 let mut nonce = [0u8; 16];
1910                 nonce[..8].copy_from_slice(&index.to_be_bytes());
1911                 ChaCha20::get_single_block(&self.seed, &nonce)
1912         }
1913 }
1914
1915 // Ensure that EcdsaChannelSigner can have a vtable
1916 #[test]
1917 pub fn dyn_sign() {
1918         let _signer: Box<dyn EcdsaChannelSigner>;
1919 }
1920
1921 #[cfg(ldk_bench)]
1922 pub mod benches {
1923         use std::sync::{Arc, mpsc};
1924         use std::sync::mpsc::TryRecvError;
1925         use std::thread;
1926         use std::time::Duration;
1927         use bitcoin::blockdata::constants::genesis_block;
1928         use bitcoin::Network;
1929         use crate::sign::{EntropySource, KeysManager};
1930
1931         use criterion::Criterion;
1932
1933         pub fn bench_get_secure_random_bytes(bench: &mut Criterion) {
1934                 let seed = [0u8; 32];
1935                 let now = Duration::from_secs(genesis_block(Network::Testnet).header.time as u64);
1936                 let keys_manager = Arc::new(KeysManager::new(&seed, now.as_secs(), now.subsec_micros()));
1937
1938                 let mut handles = Vec::new();
1939                 let mut stops = Vec::new();
1940                 for _ in 1..5 {
1941                         let keys_manager_clone = Arc::clone(&keys_manager);
1942                         let (stop_sender, stop_receiver) = mpsc::channel();
1943                         let handle = thread::spawn(move || {
1944                                 loop {
1945                                         keys_manager_clone.get_secure_random_bytes();
1946                                         match stop_receiver.try_recv() {
1947                                                 Ok(_) | Err(TryRecvError::Disconnected) => {
1948                                                         println!("Terminating.");
1949                                                         break;
1950                                                 }
1951                                                 Err(TryRecvError::Empty) => {}
1952                                         }
1953                                 }
1954                         });
1955                         handles.push(handle);
1956                         stops.push(stop_sender);
1957                 }
1958
1959                 bench.bench_function("get_secure_random_bytes", |b| b.iter(||
1960                         keys_manager.get_secure_random_bytes()));
1961
1962                 for stop in stops {
1963                         let _ = stop.send(());
1964                 }
1965                 for handle in handles {
1966                         handle.join().unwrap();
1967                 }
1968         }
1969 }