_ 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::bip32::{ChildNumber, ExtendedPrivKey, ExtendedPubKey};
  16 use bitcoin::blockdata::locktime::absolute::LockTime;
  17 use bitcoin::blockdata::opcodes;
  18 use bitcoin::blockdata::script::{Builder, Script, ScriptBuf};
  19 use bitcoin::blockdata::transaction::{Transaction, TxIn, TxOut};
  20 use bitcoin::ecdsa::Signature as EcdsaSignature;
  21 use bitcoin::network::constants::Network;
  22 use bitcoin::psbt::PartiallySignedTransaction;
  23 use bitcoin::sighash;
  24 use bitcoin::sighash::EcdsaSighashType;
  25
  26 use bitcoin::bech32::u5;
  27 use bitcoin::hash_types::WPubkeyHash;
  28 use bitcoin::hashes::sha256::Hash as Sha256;
  29 use bitcoin::hashes::sha256d::Hash as Sha256dHash;
  30 use bitcoin::hashes::{Hash, HashEngine};
  31
  32 use bitcoin::secp256k1::ecdh::SharedSecret;
  33 use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature};
  34 use bitcoin::secp256k1::schnorr;
  35 #[cfg(taproot)]
  36 use bitcoin::secp256k1::All;
  37 use bitcoin::secp256k1::{KeyPair, PublicKey, Scalar, Secp256k1, SecretKey, Signing};
  38 use bitcoin::{secp256k1, Sequence, Txid, Witness};
  39
  40 use crate::chain::transaction::OutPoint;
  41 use crate::crypto::utils::{hkdf_extract_expand_twice, sign, sign_with_aux_rand};
  42 use crate::ln::chan_utils::{
  43         get_revokeable_redeemscript, make_funding_redeemscript, ChannelPublicKeys,
  44         ChannelTransactionParameters, ClosingTransaction, CommitmentTransaction,
  45         HTLCOutputInCommitment, HolderCommitmentTransaction,
  46 };
  47 use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
  48 use crate::ln::channel_keys::{
  49         add_public_key_tweak, DelayedPaymentBasepoint, DelayedPaymentKey, HtlcBasepoint, HtlcKey,
  50         RevocationBasepoint, RevocationKey,
  51 };
  52 #[cfg(taproot)]
  53 use crate::ln::msgs::PartialSignatureWithNonce;
  54 use crate::ln::msgs::{UnsignedChannelAnnouncement, UnsignedGossipMessage};
  55 use crate::ln::script::ShutdownScript;
  56 use crate::ln::{chan_utils, PaymentPreimage};
  57 use crate::offers::invoice::UnsignedBolt12Invoice;
  58 use crate::offers::invoice_request::UnsignedInvoiceRequest;
  59 use crate::util::ser::{Readable, ReadableArgs, Writeable, Writer};
  60 use crate::util::transaction_utils;
  61
  62 use crate::crypto::chacha20::ChaCha20;
  63 use crate::io::{self, Error};
  64 use crate::ln::features::ChannelTypeFeatures;
  65 use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
  66 use crate::prelude::*;
  67 use crate::sign::ecdsa::{EcdsaChannelSigner, WriteableEcdsaChannelSigner};
  68 #[cfg(taproot)]
  69 use crate::sign::taproot::TaprootChannelSigner;
  70 use crate::util::atomic_counter::AtomicCounter;
  71 use crate::util::invoice::construct_invoice_preimage;
  72 use core::convert::TryInto;
  73 use core::ops::Deref;
  74 use core::sync::atomic::{AtomicUsize, Ordering};
  75 #[cfg(taproot)]
  76 use musig2::types::{PartialSignature, PublicNonce};
  77
  78 pub(crate) mod type_resolver;
  79
  80 pub mod ecdsa;
  81 #[cfg(taproot)]
  82 pub mod taproot;
  83
  84 /// Used as initial key material, to be expanded into multiple secret keys (but not to be used
  85 /// directly). This is used within LDK to encrypt/decrypt inbound payment data.
  86 ///
  87 /// This is not exported to bindings users as we just use `[u8; 32]` directly
  88 #[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
  89 pub struct KeyMaterial(pub [u8; 32]);
  90
  91 /// Information about a spendable output to a P2WSH script.
  92 ///
  93 /// See [`SpendableOutputDescriptor::DelayedPaymentOutput`] for more details on how to spend this.
  94 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
  95 pub struct DelayedPaymentOutputDescriptor {
  96         /// The outpoint which is spendable.
  97         pub outpoint: OutPoint,
  98         /// Per commitment point to derive the delayed payment key by key holder.
  99         pub per_commitment_point: PublicKey,
 100         /// The `nSequence` value which must be set in the spending input to satisfy the `OP_CSV` in
 101         /// the witness_script.
 102         pub to_self_delay: u16,
 103         /// The output which is referenced by the given outpoint.
 104         pub output: TxOut,
 105         /// The revocation point specific to the commitment transaction which was broadcast. Used to
 106         /// derive the witnessScript for this output.
 107         pub revocation_pubkey: RevocationKey,
 108         /// Arbitrary identification information returned by a call to [`ChannelSigner::channel_keys_id`].
 109         /// This may be useful in re-deriving keys used in the channel to spend the output.
 110         pub channel_keys_id: [u8; 32],
 111         /// The value of the channel which this output originated from, possibly indirectly.
 112         pub channel_value_satoshis: u64,
 113         /// The channel public keys and other parameters needed to generate a spending transaction or to provide to a re-derived signer through
 114         /// [`ChannelSigner::provide_channel_parameters`].
 115         ///
 116         /// Added as optional, but always `Some` if the descriptor was produced in v0.0.123 or later.
 117         pub channel_transaction_parameters: Option<ChannelTransactionParameters>,
 118 }
 119
 120 impl DelayedPaymentOutputDescriptor {
 121         /// The maximum length a well-formed witness spending one of these should have.
 122         /// Note: If you have the grind_signatures feature enabled, this will be at least 1 byte
 123         /// shorter.
 124         // Calculated as 1 byte length + 73 byte signature, 1 byte empty vec push, 1 byte length plus
 125         // redeemscript push length.
 126         pub const MAX_WITNESS_LENGTH: u64 =
 127                 1 + 73 + 1 + chan_utils::REVOKEABLE_REDEEMSCRIPT_MAX_LENGTH as u64 + 1;
 128 }
 129
 130 impl_writeable_tlv_based!(DelayedPaymentOutputDescriptor, {
 131         (0, outpoint, required),
 132         (2, per_commitment_point, required),
 133         (4, to_self_delay, required),
 134         (6, output, required),
 135         (8, revocation_pubkey, required),
 136         (10, channel_keys_id, required),
 137         (12, channel_value_satoshis, required),
 138         (13, channel_transaction_parameters, option),
 139 });
 140
 141 pub(crate) const P2WPKH_WITNESS_WEIGHT: u64 = 1 /* num stack items */ +
 142         1 /* sig length */ +
 143         73 /* sig including sighash flag */ +
 144         1 /* pubkey length */ +
 145         33 /* pubkey */;
 146
 147 /// Witness weight for satisying a P2TR key-path spend.
 148 pub(crate) const P2TR_KEY_PATH_WITNESS_WEIGHT: u64 = 1 /* witness items */
 149         + 1 /* schnorr sig len */ + 64 /* schnorr sig */;
 150
 151 /// Information about a spendable output to our "payment key".
 152 ///
 153 /// See [`SpendableOutputDescriptor::StaticPaymentOutput`] for more details on how to spend this.
 154 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 155 pub struct StaticPaymentOutputDescriptor {
 156         /// The outpoint which is spendable.
 157         pub outpoint: OutPoint,
 158         /// The output which is referenced by the given outpoint.
 159         pub output: TxOut,
 160         /// Arbitrary identification information returned by a call to [`ChannelSigner::channel_keys_id`].
 161         /// This may be useful in re-deriving keys used in the channel to spend the output.
 162         pub channel_keys_id: [u8; 32],
 163         /// The value of the channel which this transactions spends.
 164         pub channel_value_satoshis: u64,
 165         /// The necessary channel parameters that need to be provided to the re-derived signer through
 166         /// [`ChannelSigner::provide_channel_parameters`].
 167         ///
 168         /// Added as optional, but always `Some` if the descriptor was produced in v0.0.117 or later.
 169         pub channel_transaction_parameters: Option<ChannelTransactionParameters>,
 170 }
 171
 172 impl StaticPaymentOutputDescriptor {
 173         /// Returns the `witness_script` of the spendable output.
 174         ///
 175         /// Note that this will only return `Some` for [`StaticPaymentOutputDescriptor`]s that
 176         /// originated from an anchor outputs channel, as they take the form of a P2WSH script.
 177         pub fn witness_script(&self) -> Option<ScriptBuf> {
 178                 self.channel_transaction_parameters.as_ref().and_then(|channel_params| {
 179                         if channel_params.supports_anchors() {
 180                                 let payment_point = channel_params.holder_pubkeys.payment_point;
 181                                 Some(chan_utils::get_to_countersignatory_with_anchors_redeemscript(&payment_point))
 182                         } else {
 183                                 None
 184                         }
 185                 })
 186         }
 187
 188         /// The maximum length a well-formed witness spending one of these should have.
 189         /// Note: If you have the grind_signatures feature enabled, this will be at least 1 byte
 190         /// shorter.
 191         pub fn max_witness_length(&self) -> u64 {
 192                 if self.channel_transaction_parameters.as_ref().map_or(false, |p| p.supports_anchors()) {
 193                         let witness_script_weight = 1 /* pubkey push */ + 33 /* pubkey */ +
 194                                 1 /* OP_CHECKSIGVERIFY */ + 1 /* OP_1 */ + 1 /* OP_CHECKSEQUENCEVERIFY */;
 195                         1 /* num witness items */ + 1 /* sig push */ + 73 /* sig including sighash flag */ +
 196                                 1 /* witness script push */ + witness_script_weight
 197                 } else {
 198                         P2WPKH_WITNESS_WEIGHT
 199                 }
 200         }
 201 }
 202 impl_writeable_tlv_based!(StaticPaymentOutputDescriptor, {
 203         (0, outpoint, required),
 204         (2, output, required),
 205         (4, channel_keys_id, required),
 206         (6, channel_value_satoshis, required),
 207         (7, channel_transaction_parameters, option),
 208 });
 209
 210 /// Describes the necessary information to spend a spendable output.
 211 ///
 212 /// When on-chain outputs are created by LDK (which our counterparty is not able to claim at any
 213 /// point in the future) a [`SpendableOutputs`] event is generated which you must track and be able
 214 /// to spend on-chain. The information needed to do this is provided in this enum, including the
 215 /// outpoint describing which `txid` and output `index` is available, the full output which exists
 216 /// at that `txid`/`index`, and any keys or other information required to sign.
 217 ///
 218 /// [`SpendableOutputs`]: crate::events::Event::SpendableOutputs
 219 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 220 pub enum SpendableOutputDescriptor {
 221         /// An output to a script which was provided via [`SignerProvider`] directly, either from
 222         /// [`get_destination_script`] or [`get_shutdown_scriptpubkey`], thus you should already
 223         /// know how to spend it. No secret keys are provided as LDK was never given any key.
 224         /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
 225         /// on-chain using the payment preimage or after it has timed out.
 226         ///
 227         /// [`get_shutdown_scriptpubkey`]: SignerProvider::get_shutdown_scriptpubkey
 228         /// [`get_destination_script`]: SignerProvider::get_shutdown_scriptpubkey
 229         StaticOutput {
 230                 /// The outpoint which is spendable.
 231                 outpoint: OutPoint,
 232                 /// The output which is referenced by the given outpoint.
 233                 output: TxOut,
 234                 /// The `channel_keys_id` for the channel which this output came from.
 235                 ///
 236                 /// For channels which were generated on LDK 0.0.119 or later, this is the value which was
 237                 /// passed to the [`SignerProvider::get_destination_script`] call which provided this
 238                 /// output script.
 239                 ///
 240                 /// For channels which were generated prior to LDK 0.0.119, no such argument existed,
 241                 /// however this field may still be filled in if such data is available.
 242                 channel_keys_id: Option<[u8; 32]>,
 243         },
 244         /// An output to a P2WSH script which can be spent with a single signature after an `OP_CSV`
 245         /// delay.
 246         ///
 247         /// The witness in the spending input should be:
 248         /// ```bitcoin
 249         /// <BIP 143 signature> <empty vector> (MINIMALIF standard rule) <provided witnessScript>
 250         /// ```
 251         ///
 252         /// Note that the `nSequence` field in the spending input must be set to
 253         /// [`DelayedPaymentOutputDescriptor::to_self_delay`] (which means the transaction is not
 254         /// broadcastable until at least [`DelayedPaymentOutputDescriptor::to_self_delay`] blocks after
 255         /// the outpoint confirms, see [BIP
 256         /// 68](https://github.com/bitcoin/bips/blob/master/bip-0068.mediawiki)). Also note that LDK
 257         /// won't generate a [`SpendableOutputDescriptor`] until the corresponding block height
 258         /// is reached.
 259         ///
 260         /// These are generally the result of a "revocable" output to us, spendable only by us unless
 261         /// it is an output from an old state which we broadcast (which should never happen).
 262         ///
 263         /// To derive the delayed payment key which is used to sign this input, you must pass the
 264         /// holder [`InMemorySigner::delayed_payment_base_key`] (i.e., the private key which corresponds to the
 265         /// [`ChannelPublicKeys::delayed_payment_basepoint`] in [`ChannelSigner::pubkeys`]) and the provided
 266         /// [`DelayedPaymentOutputDescriptor::per_commitment_point`] to [`chan_utils::derive_private_key`]. The DelayedPaymentKey can be
 267         /// generated without the secret key using [`DelayedPaymentKey::from_basepoint`] and only the
 268         /// [`ChannelPublicKeys::delayed_payment_basepoint`] which appears in [`ChannelSigner::pubkeys`].
 269         ///
 270         /// To derive the [`DelayedPaymentOutputDescriptor::revocation_pubkey`] provided here (which is
 271         /// used in the witness script generation), you must pass the counterparty
 272         /// [`ChannelPublicKeys::revocation_basepoint`] (which appears in the call to
 273         /// [`ChannelSigner::provide_channel_parameters`]) and the provided
 274         /// [`DelayedPaymentOutputDescriptor::per_commitment_point`] to
 275         /// [`RevocationKey`].
 276         ///
 277         /// The witness script which is hashed and included in the output `script_pubkey` may be
 278         /// regenerated by passing the [`DelayedPaymentOutputDescriptor::revocation_pubkey`] (derived
 279         /// as explained above), our delayed payment pubkey (derived as explained above), and the
 280         /// [`DelayedPaymentOutputDescriptor::to_self_delay`] contained here to
 281         /// [`chan_utils::get_revokeable_redeemscript`].
 282         DelayedPaymentOutput(DelayedPaymentOutputDescriptor),
 283         /// An output spendable exclusively by our payment key (i.e., the private key that corresponds
 284         /// to the `payment_point` in [`ChannelSigner::pubkeys`]). The output type depends on the
 285         /// channel type negotiated.
 286         ///
 287         /// On an anchor outputs channel, the witness in the spending input is:
 288         /// ```bitcoin
 289         /// <BIP 143 signature> <witness script>
 290         /// ```
 291         ///
 292         /// Otherwise, it is:
 293         /// ```bitcoin
 294         /// <BIP 143 signature> <payment key>
 295         /// ```
 296         ///
 297         /// These are generally the result of our counterparty having broadcast the current state,
 298         /// allowing us to claim the non-HTLC-encumbered outputs immediately, or after one confirmation
 299         /// in the case of anchor outputs channels.
 300         StaticPaymentOutput(StaticPaymentOutputDescriptor),
 301 }
 302
 303 impl_writeable_tlv_based_enum!(SpendableOutputDescriptor,
 304         (0, StaticOutput) => {
 305                 (0, outpoint, required),
 306                 (1, channel_keys_id, option),
 307                 (2, output, required),
 308         },
 309 ;
 310         (1, DelayedPaymentOutput),
 311         (2, StaticPaymentOutput),
 312 );
 313
 314 impl SpendableOutputDescriptor {
 315         /// Turns this into a [`bitcoin::psbt::Input`] which can be used to create a
 316         /// [`PartiallySignedTransaction`] which spends the given descriptor.
 317         ///
 318         /// Note that this does not include any signatures, just the information required to
 319         /// construct the transaction and sign it.
 320         ///
 321         /// This is not exported to bindings users as there is no standard serialization for an input.
 322         /// See [`Self::create_spendable_outputs_psbt`] instead.
 323         ///
 324         /// The proprietary field is used to store add tweak for the signing key of this transaction.
 325         /// See the [`DelayedPaymentBasepoint::derive_add_tweak`] docs for more info on add tweak and how to use it.
 326         ///
 327         /// To get the proprietary field use:
 328         /// ```
 329         /// use bitcoin::psbt::{PartiallySignedTransaction};
 330         /// use bitcoin::hashes::hex::FromHex;
 331         ///
 332         /// # let s = "70736274ff0100520200000001dee978529ab3e61a2987bea5183713d0e6d5ceb5ac81100fdb54a1a2\
 333         ///     #                69cef505000000000090000000011f26000000000000160014abb3ab63280d4ccc5c11d6b50fd427a8\
 334         ///     #                e19d6470000000000001012b10270000000000002200200afe4736760d814a2651bae63b572d935d9a\
 335         /// #            b74a1a16c01774e341a32afa763601054d63210394a27a700617f5b7aee72bd4f8076b5770a582b7fb\
 336         ///     #                d1d4ee2ea3802cd3cfbe2067029000b27521034629b1c8fdebfaeb58a74cd181f485e2c462e594cb30\
 337         ///     #                34dee655875f69f6c7c968ac20fc144c444b5f7370656e6461626c655f6f7574707574006164645f74\
 338         ///     #                7765616b20a86534f38ad61dc580ef41c3886204adf0911b81619c1ad7a2f5b5de39a2ba600000";
 339         /// # let psbt = PartiallySignedTransaction::deserialize(<Vec<u8> as FromHex>::from_hex(s).unwrap().as_slice()).unwrap();
 340         /// let key = bitcoin::psbt::raw::ProprietaryKey {
 341         ///     prefix: "LDK_spendable_output".as_bytes().to_vec(),
 342         ///     subtype: 0,
 343         ///     key: "add_tweak".as_bytes().to_vec(),
 344         /// };
 345         /// let value = psbt
 346         ///     .inputs
 347         ///     .first()
 348         ///     .expect("Unable to get add tweak as there are no inputs")
 349         ///     .proprietary
 350         ///     .get(&key)
 351         ///     .map(|x| x.to_owned());
 352         /// ```
 353         pub fn to_psbt_input<T: secp256k1::Signing>(
 354                 &self, secp_ctx: &Secp256k1<T>,
 355         ) -> bitcoin::psbt::Input {
 356                 match self {
 357                         SpendableOutputDescriptor::StaticOutput { output, .. } => {
 358                                 // Is a standard P2WPKH, no need for witness script
 359                                 bitcoin::psbt::Input { witness_utxo: Some(output.clone()), ..Default::default() }
 360                         },
 361                         SpendableOutputDescriptor::DelayedPaymentOutput(DelayedPaymentOutputDescriptor {
 362                                 channel_transaction_parameters,
 363                                 per_commitment_point,
 364                                 revocation_pubkey,
 365                                 to_self_delay,
 366                                 output,
 367                                 ..
 368                         }) => {
 369                                 let delayed_payment_basepoint = channel_transaction_parameters
 370                                         .as_ref()
 371                                         .map(|params| params.holder_pubkeys.delayed_payment_basepoint);
 372
 373                                 let (witness_script, add_tweak) =
 374                                         if let Some(basepoint) = delayed_payment_basepoint.as_ref() {
 375                                                 // Required to derive signing key: privkey = basepoint_secret + SHA256(per_commitment_point || basepoint)
 376                                                 let add_tweak = basepoint.derive_add_tweak(&per_commitment_point);
 377                                                 let payment_key = DelayedPaymentKey(add_public_key_tweak(
 378                                                         secp_ctx,
 379                                                         &basepoint.to_public_key(),
 380                                                         &add_tweak,
 381                                                 ));
 382
 383                                                 (
 384                                                         Some(get_revokeable_redeemscript(
 385                                                                 &revocation_pubkey,
 386                                                                 *to_self_delay,
 387                                                                 &payment_key,
 388                                                         )),
 389                                                         Some(add_tweak),
 390                                                 )
 391                                         } else {
 392                                                 (None, None)
 393                                         };
 394
 395                                 bitcoin::psbt::Input {
 396                                         witness_utxo: Some(output.clone()),
 397                                         witness_script,
 398                                         proprietary: add_tweak
 399                                                 .map(|add_tweak| {
 400                                                         [(
 401                                                                 bitcoin::psbt::raw::ProprietaryKey {
 402                                                                         // A non standard namespace for spendable outputs, used to store the tweak needed
 403                                                                         // to derive the private key
 404                                                                         prefix: "LDK_spendable_output".as_bytes().to_vec(),
 405                                                                         subtype: 0,
 406                                                                         key: "add_tweak".as_bytes().to_vec(),
 407                                                                 },
 408                                                                 add_tweak.to_vec(),
 409                                                         )]
 410                                                         .into_iter()
 411                                                         .collect()
 412                                                 })
 413                                                 .unwrap_or_default(),
 414                                         ..Default::default()
 415                                 }
 416                         },
 417                         SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => bitcoin::psbt::Input {
 418                                 witness_utxo: Some(descriptor.output.clone()),
 419                                 witness_script: descriptor.witness_script(),
 420                                 ..Default::default()
 421                         },
 422                 }
 423         }
 424
 425         /// Creates an unsigned [`PartiallySignedTransaction`] which spends the given descriptors to
 426         /// the given outputs, plus an output to the given change destination (if sufficient
 427         /// change value remains). The PSBT will have a feerate, at least, of the given value.
 428         ///
 429         /// The `locktime` argument is used to set the transaction's locktime. If `None`, the
 430         /// transaction will have a locktime of 0. It it recommended to set this to the current block
 431         /// height to avoid fee sniping, unless you have some specific reason to use a different
 432         /// locktime.
 433         ///
 434         /// Returns the PSBT and expected max transaction weight.
 435         ///
 436         /// Returns `Err(())` if the output value is greater than the input value minus required fee,
 437         /// if a descriptor was duplicated, or if an output descriptor `script_pubkey`
 438         /// does not match the one we can spend.
 439         ///
 440         /// We do not enforce that outputs meet the dust limit or that any output scripts are standard.
 441         pub fn create_spendable_outputs_psbt<T: secp256k1::Signing>(
 442                 secp_ctx: &Secp256k1<T>, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
 443                 change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
 444                 locktime: Option<LockTime>,
 445         ) -> Result<(PartiallySignedTransaction, u64), ()> {
 446                 let mut input = Vec::with_capacity(descriptors.len());
 447                 let mut input_value = 0;
 448                 let mut witness_weight = 0;
 449                 let mut output_set = hash_set_with_capacity(descriptors.len());
 450                 for outp in descriptors {
 451                         match outp {
 452                                 SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
 453                                         if !output_set.insert(descriptor.outpoint) {
 454                                                 return Err(());
 455                                         }
 456                                         let sequence = if descriptor
 457                                                 .channel_transaction_parameters
 458                                                 .as_ref()
 459                                                 .map_or(false, |p| p.supports_anchors())
 460                                         {
 461                                                 Sequence::from_consensus(1)
 462                                         } else {
 463                                                 Sequence::ZERO
 464                                         };
 465                                         input.push(TxIn {
 466                                                 previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
 467                                                 script_sig: ScriptBuf::new(),
 468                                                 sequence,
 469                                                 witness: Witness::new(),
 470                                         });
 471                                         witness_weight += descriptor.max_witness_length();
 472                                         #[cfg(feature = "grind_signatures")]
 473                                         {
 474                                                 // Guarantees a low R signature
 475                                                 witness_weight -= 1;
 476                                         }
 477                                         input_value += descriptor.output.value;
 478                                 },
 479                                 SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
 480                                         if !output_set.insert(descriptor.outpoint) {
 481                                                 return Err(());
 482                                         }
 483                                         input.push(TxIn {
 484                                                 previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
 485                                                 script_sig: ScriptBuf::new(),
 486                                                 sequence: Sequence(descriptor.to_self_delay as u32),
 487                                                 witness: Witness::new(),
 488                                         });
 489                                         witness_weight += DelayedPaymentOutputDescriptor::MAX_WITNESS_LENGTH;
 490                                         #[cfg(feature = "grind_signatures")]
 491                                         {
 492                                                 // Guarantees a low R signature
 493                                                 witness_weight -= 1;
 494                                         }
 495                                         input_value += descriptor.output.value;
 496                                 },
 497                                 SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output, .. } => {
 498                                         if !output_set.insert(*outpoint) {
 499                                                 return Err(());
 500                                         }
 501                                         input.push(TxIn {
 502                                                 previous_output: outpoint.into_bitcoin_outpoint(),
 503                                                 script_sig: ScriptBuf::new(),
 504                                                 sequence: Sequence::ZERO,
 505                                                 witness: Witness::new(),
 506                                         });
 507                                         witness_weight += 1 + 73 + 34;
 508                                         #[cfg(feature = "grind_signatures")]
 509                                         {
 510                                                 // Guarantees a low R signature
 511                                                 witness_weight -= 1;
 512                                         }
 513                                         input_value += output.value;
 514                                 },
 515                         }
 516                         if input_value > MAX_VALUE_MSAT / 1000 {
 517                                 return Err(());
 518                         }
 519                 }
 520                 let mut tx = Transaction {
 521                         version: 2,
 522                         lock_time: locktime.unwrap_or(LockTime::ZERO),
 523                         input,
 524                         output: outputs,
 525                 };
 526                 let expected_max_weight = transaction_utils::maybe_add_change_output(
 527                         &mut tx,
 528                         input_value,
 529                         witness_weight,
 530                         feerate_sat_per_1000_weight,
 531                         change_destination_script,
 532                 )?;
 533
 534                 let psbt_inputs =
 535                         descriptors.iter().map(|d| d.to_psbt_input(&secp_ctx)).collect::<Vec<_>>();
 536                 let psbt = PartiallySignedTransaction {
 537                         inputs: psbt_inputs,
 538                         outputs: vec![Default::default(); tx.output.len()],
 539                         unsigned_tx: tx,
 540                         xpub: Default::default(),
 541                         version: 0,
 542                         proprietary: Default::default(),
 543                         unknown: Default::default(),
 544                 };
 545                 Ok((psbt, expected_max_weight))
 546         }
 547 }
 548
 549 /// The parameters required to derive a channel signer via [`SignerProvider`].
 550 #[derive(Clone, Debug, PartialEq, Eq)]
 551 pub struct ChannelDerivationParameters {
 552         /// The value in satoshis of the channel we're attempting to spend the anchor output of.
 553         pub value_satoshis: u64,
 554         /// The unique identifier to re-derive the signer for the associated channel.
 555         pub keys_id: [u8; 32],
 556         /// The necessary channel parameters that need to be provided to the re-derived signer through
 557         /// [`ChannelSigner::provide_channel_parameters`].
 558         pub transaction_parameters: ChannelTransactionParameters,
 559 }
 560
 561 impl_writeable_tlv_based!(ChannelDerivationParameters, {
 562         (0, value_satoshis, required),
 563         (2, keys_id, required),
 564         (4, transaction_parameters, required),
 565 });
 566
 567 /// A descriptor used to sign for a commitment transaction's HTLC output.
 568 #[derive(Clone, Debug, PartialEq, Eq)]
 569 pub struct HTLCDescriptor {
 570         /// The parameters required to derive the signer for the HTLC input.
 571         pub channel_derivation_parameters: ChannelDerivationParameters,
 572         /// The txid of the commitment transaction in which the HTLC output lives.
 573         pub commitment_txid: Txid,
 574         /// The number of the commitment transaction in which the HTLC output lives.
 575         pub per_commitment_number: u64,
 576         /// The key tweak corresponding to the number of the commitment transaction in which the HTLC
 577         /// output lives. This tweak is applied to all the basepoints for both parties in the channel to
 578         /// arrive at unique keys per commitment.
 579         ///
 580         /// See <https://github.com/lightning/bolts/blob/master/03-transactions.md#keys> for more info.
 581         pub per_commitment_point: PublicKey,
 582         /// The feerate to use on the HTLC claiming transaction. This is always `0` for HTLCs
 583         /// originating from a channel supporting anchor outputs, otherwise it is the channel's
 584         /// negotiated feerate at the time the commitment transaction was built.
 585         pub feerate_per_kw: u32,
 586         /// The details of the HTLC as it appears in the commitment transaction.
 587         pub htlc: HTLCOutputInCommitment,
 588         /// The preimage, if `Some`, to claim the HTLC output with. If `None`, the timeout path must be
 589         /// taken.
 590         pub preimage: Option<PaymentPreimage>,
 591         /// The counterparty's signature required to spend the HTLC output.
 592         pub counterparty_sig: Signature,
 593 }
 594
 595 impl_writeable_tlv_based!(HTLCDescriptor, {
 596         (0, channel_derivation_parameters, required),
 597         (1, feerate_per_kw, (default_value, 0)),
 598         (2, commitment_txid, required),
 599         (4, per_commitment_number, required),
 600         (6, per_commitment_point, required),
 601         (8, htlc, required),
 602         (10, preimage, option),
 603         (12, counterparty_sig, required),
 604 });
 605
 606 impl HTLCDescriptor {
 607         /// Returns the outpoint of the HTLC output in the commitment transaction. This is the outpoint
 608         /// being spent by the HTLC input in the HTLC transaction.
 609         pub fn outpoint(&self) -> bitcoin::OutPoint {
 610                 bitcoin::OutPoint {
 611                         txid: self.commitment_txid,
 612                         vout: self.htlc.transaction_output_index.unwrap(),
 613                 }
 614         }
 615
 616         /// Returns the UTXO to be spent by the HTLC input, which can be obtained via
 617         /// [`Self::unsigned_tx_input`].
 618         pub fn previous_utxo<C: secp256k1::Signing + secp256k1::Verification>(
 619                 &self, secp: &Secp256k1<C>,
 620         ) -> TxOut {
 621                 TxOut {
 622                         script_pubkey: self.witness_script(secp).to_v0_p2wsh(),
 623                         value: self.htlc.amount_msat / 1000,
 624                 }
 625         }
 626
 627         /// Returns the unsigned transaction input spending the HTLC output in the commitment
 628         /// transaction.
 629         pub fn unsigned_tx_input(&self) -> TxIn {
 630                 chan_utils::build_htlc_input(
 631                         &self.commitment_txid,
 632                         &self.htlc,
 633                         &self.channel_derivation_parameters.transaction_parameters.channel_type_features,
 634                 )
 635         }
 636
 637         /// Returns the delayed output created as a result of spending the HTLC output in the commitment
 638         /// transaction.
 639         pub fn tx_output<C: secp256k1::Signing + secp256k1::Verification>(
 640                 &self, secp: &Secp256k1<C>,
 641         ) -> TxOut {
 642                 let channel_params =
 643                         self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
 644                 let broadcaster_keys = channel_params.broadcaster_pubkeys();
 645                 let counterparty_keys = channel_params.countersignatory_pubkeys();
 646                 let broadcaster_delayed_key = DelayedPaymentKey::from_basepoint(
 647                         secp,
 648                         &broadcaster_keys.delayed_payment_basepoint,
 649                         &self.per_commitment_point,
 650                 );
 651                 let counterparty_revocation_key = &RevocationKey::from_basepoint(
 652                         &secp,
 653                         &counterparty_keys.revocation_basepoint,
 654                         &self.per_commitment_point,
 655                 );
 656                 chan_utils::build_htlc_output(
 657                         self.feerate_per_kw,
 658                         channel_params.contest_delay(),
 659                         &self.htlc,
 660                         channel_params.channel_type_features(),
 661                         &broadcaster_delayed_key,
 662                         &counterparty_revocation_key,
 663                 )
 664         }
 665
 666         /// Returns the witness script of the HTLC output in the commitment transaction.
 667         pub fn witness_script<C: secp256k1::Signing + secp256k1::Verification>(
 668                 &self, secp: &Secp256k1<C>,
 669         ) -> ScriptBuf {
 670                 let channel_params =
 671                         self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
 672                 let broadcaster_keys = channel_params.broadcaster_pubkeys();
 673                 let counterparty_keys = channel_params.countersignatory_pubkeys();
 674                 let broadcaster_htlc_key = HtlcKey::from_basepoint(
 675                         secp,
 676                         &broadcaster_keys.htlc_basepoint,
 677                         &self.per_commitment_point,
 678                 );
 679                 let counterparty_htlc_key = HtlcKey::from_basepoint(
 680                         secp,
 681                         &counterparty_keys.htlc_basepoint,
 682                         &self.per_commitment_point,
 683                 );
 684                 let counterparty_revocation_key = &RevocationKey::from_basepoint(
 685                         &secp,
 686                         &counterparty_keys.revocation_basepoint,
 687                         &self.per_commitment_point,
 688                 );
 689                 chan_utils::get_htlc_redeemscript_with_explicit_keys(
 690                         &self.htlc,
 691                         channel_params.channel_type_features(),
 692                         &broadcaster_htlc_key,
 693                         &counterparty_htlc_key,
 694                         &counterparty_revocation_key,
 695                 )
 696         }
 697
 698         /// Returns the fully signed witness required to spend the HTLC output in the commitment
 699         /// transaction.
 700         pub fn tx_input_witness(&self, signature: &Signature, witness_script: &Script) -> Witness {
 701                 chan_utils::build_htlc_input_witness(
 702                         signature,
 703                         &self.counterparty_sig,
 704                         &self.preimage,
 705                         witness_script,
 706                         &self.channel_derivation_parameters.transaction_parameters.channel_type_features,
 707                 )
 708         }
 709
 710         /// Derives the channel signer required to sign the HTLC input.
 711         pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(
 712                 &self, signer_provider: &SP,
 713         ) -> S
 714         where
 715                 SP::Target: SignerProvider<EcdsaSigner = S>,
 716         {
 717                 let mut signer = signer_provider.derive_channel_signer(
 718                         self.channel_derivation_parameters.value_satoshis,
 719                         self.channel_derivation_parameters.keys_id,
 720                 );
 721                 signer
 722                         .provide_channel_parameters(&self.channel_derivation_parameters.transaction_parameters);
 723                 signer
 724         }
 725 }
 726
 727 /// A trait to handle Lightning channel key material without concretizing the channel type or
 728 /// the signature mechanism.
 729 pub trait ChannelSigner {
 730         /// Gets the per-commitment point for a specific commitment number
 731         ///
 732         /// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
 733         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>)
 734                 -> PublicKey;
 735
 736         /// Gets the commitment secret for a specific commitment number as part of the revocation process
 737         ///
 738         /// An external signer implementation should error here if the commitment was already signed
 739         /// and should refuse to sign it in the future.
 740         ///
 741         /// May be called more than once for the same index.
 742         ///
 743         /// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
 744         // TODO: return a Result so we can signal a validation error
 745         fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
 746
 747         /// Validate the counterparty's signatures on the holder commitment transaction and HTLCs.
 748         ///
 749         /// This is required in order for the signer to make sure that releasing a commitment
 750         /// secret won't leave us without a broadcastable holder transaction.
 751         /// Policy checks should be implemented in this function, including checking the amount
 752         /// sent to us and checking the HTLCs.
 753         ///
 754         /// The preimages of outbound HTLCs that were fulfilled since the last commitment are provided.
 755         /// A validating signer should ensure that an HTLC output is removed only when the matching
 756         /// preimage is provided, or when the value to holder is restored.
 757         ///
 758         /// Note that all the relevant preimages will be provided, but there may also be additional
 759         /// irrelevant or duplicate preimages.
 760         fn validate_holder_commitment(
 761                 &self, holder_tx: &HolderCommitmentTransaction,
 762                 outbound_htlc_preimages: Vec<PaymentPreimage>,
 763         ) -> Result<(), ()>;
 764
 765         /// Validate the counterparty's revocation.
 766         ///
 767         /// This is required in order for the signer to make sure that the state has moved
 768         /// forward and it is safe to sign the next counterparty commitment.
 769         fn validate_counterparty_revocation(&self, idx: u64, secret: &SecretKey) -> Result<(), ()>;
 770
 771         /// Returns the holder's channel public keys and basepoints.
 772         fn pubkeys(&self) -> &ChannelPublicKeys;
 773
 774         /// Returns an arbitrary identifier describing the set of keys which are provided back to you in
 775         /// some [`SpendableOutputDescriptor`] types. This should be sufficient to identify this
 776         /// [`EcdsaChannelSigner`] object uniquely and lookup or re-derive its keys.
 777         fn channel_keys_id(&self) -> [u8; 32];
 778
 779         /// Set the counterparty static channel data, including basepoints,
 780         /// `counterparty_selected`/`holder_selected_contest_delay` and funding outpoint.
 781         ///
 782         /// This data is static, and will never change for a channel once set. For a given [`ChannelSigner`]
 783         /// instance, LDK will call this method exactly once - either immediately after construction
 784         /// (not including if done via [`SignerProvider::read_chan_signer`]) or when the funding
 785         /// information has been generated.
 786         ///
 787         /// channel_parameters.is_populated() MUST be true.
 788         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters);
 789 }
 790
 791 /// Specifies the recipient of an invoice.
 792 ///
 793 /// This indicates to [`NodeSigner::sign_invoice`] what node secret key should be used to sign
 794 /// the invoice.
 795 pub enum Recipient {
 796         /// The invoice should be signed with the local node secret key.
 797         Node,
 798         /// The invoice should be signed with the phantom node secret key. This secret key must be the
 799         /// same for all nodes participating in the [phantom node payment].
 800         ///
 801         /// [phantom node payment]: PhantomKeysManager
 802         PhantomNode,
 803 }
 804
 805 /// A trait that describes a source of entropy.
 806 pub trait EntropySource {
 807         /// Gets a unique, cryptographically-secure, random 32-byte value. This method must return a
 808         /// different value each time it is called.
 809         fn get_secure_random_bytes(&self) -> [u8; 32];
 810 }
 811
 812 /// A trait that can handle cryptographic operations at the scope level of a node.
 813 pub trait NodeSigner {
 814         /// Get secret key material as bytes for use in encrypting and decrypting inbound payment data.
 815         ///
 816         /// If the implementor of this trait supports [phantom node payments], then every node that is
 817         /// intended to be included in the phantom invoice route hints must return the same value from
 818         /// this method.
 819         // This is because LDK avoids storing inbound payment data by encrypting payment data in the
 820         // payment hash and/or payment secret, therefore for a payment to be receivable by multiple
 821         // nodes, they must share the key that encrypts this payment data.
 822         ///
 823         /// This method must return the same value each time it is called.
 824         ///
 825         /// [phantom node payments]: PhantomKeysManager
 826         fn get_inbound_payment_key_material(&self) -> KeyMaterial;
 827
 828         /// Get node id based on the provided [`Recipient`].
 829         ///
 830         /// This method must return the same value each time it is called with a given [`Recipient`]
 831         /// parameter.
 832         ///
 833         /// Errors if the [`Recipient`] variant is not supported by the implementation.
 834         fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()>;
 835
 836         /// Gets the ECDH shared secret of our node secret and `other_key`, multiplying by `tweak` if
 837         /// one is provided. Note that this tweak can be applied to `other_key` instead of our node
 838         /// secret, though this is less efficient.
 839         ///
 840         /// Note that if this fails while attempting to forward an HTLC, LDK will panic. The error
 841         /// should be resolved to allow LDK to resume forwarding HTLCs.
 842         ///
 843         /// Errors if the [`Recipient`] variant is not supported by the implementation.
 844         fn ecdh(
 845                 &self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>,
 846         ) -> Result<SharedSecret, ()>;
 847
 848         /// Sign an invoice.
 849         ///
 850         /// By parameterizing by the raw invoice bytes instead of the hash, we allow implementors of
 851         /// this trait to parse the invoice and make sure they're signing what they expect, rather than
 852         /// blindly signing the hash.
 853         ///
 854         /// The `hrp_bytes` are ASCII bytes, while the `invoice_data` is base32.
 855         ///
 856         /// The secret key used to sign the invoice is dependent on the [`Recipient`].
 857         ///
 858         /// Errors if the [`Recipient`] variant is not supported by the implementation.
 859         fn sign_invoice(
 860                 &self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient,
 861         ) -> Result<RecoverableSignature, ()>;
 862
 863         /// Signs the [`TaggedHash`] of a BOLT 12 invoice request.
 864         ///
 865         /// May be called by a function passed to [`UnsignedInvoiceRequest::sign`] where
 866         /// `invoice_request` is the callee.
 867         ///
 868         /// Implementors may check that the `invoice_request` is expected rather than blindly signing
 869         /// the tagged hash. An `Ok` result should sign `invoice_request.tagged_hash().as_digest()` with
 870         /// the node's signing key or an ephemeral key to preserve privacy, whichever is associated with
 871         /// [`UnsignedInvoiceRequest::payer_id`].
 872         ///
 873         /// [`TaggedHash`]: crate::offers::merkle::TaggedHash
 874         fn sign_bolt12_invoice_request(
 875                 &self, invoice_request: &UnsignedInvoiceRequest,
 876         ) -> Result<schnorr::Signature, ()>;
 877
 878         /// Signs the [`TaggedHash`] of a BOLT 12 invoice.
 879         ///
 880         /// May be called by a function passed to [`UnsignedBolt12Invoice::sign`] where `invoice` is the
 881         /// callee.
 882         ///
 883         /// Implementors may check that the `invoice` is expected rather than blindly signing the tagged
 884         /// hash. An `Ok` result should sign `invoice.tagged_hash().as_digest()` with the node's signing
 885         /// key or an ephemeral key to preserve privacy, whichever is associated with
 886         /// [`UnsignedBolt12Invoice::signing_pubkey`].
 887         ///
 888         /// [`TaggedHash`]: crate::offers::merkle::TaggedHash
 889         fn sign_bolt12_invoice(
 890                 &self, invoice: &UnsignedBolt12Invoice,
 891         ) -> Result<schnorr::Signature, ()>;
 892
 893         /// Sign a gossip message.
 894         ///
 895         /// Note that if this fails, LDK may panic and the message will not be broadcast to the network
 896         /// or a possible channel counterparty. If LDK panics, the error should be resolved to allow the
 897         /// message to be broadcast, as otherwise it may prevent one from receiving funds over the
 898         /// corresponding channel.
 899         fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()>;
 900 }
 901
 902 /// A trait that describes a wallet capable of creating a spending [`Transaction`] from a set of
 903 /// [`SpendableOutputDescriptor`]s.
 904 pub trait OutputSpender {
 905         /// Creates a [`Transaction`] which spends the given descriptors to the given outputs, plus an
 906         /// output to the given change destination (if sufficient change value remains). The
 907         /// transaction will have a feerate, at least, of the given value.
 908         ///
 909         /// The `locktime` argument is used to set the transaction's locktime. If `None`, the
 910         /// transaction will have a locktime of 0. It it recommended to set this to the current block
 911         /// height to avoid fee sniping, unless you have some specific reason to use a different
 912         /// locktime.
 913         ///
 914         /// Returns `Err(())` if the output value is greater than the input value minus required fee,
 915         /// if a descriptor was duplicated, or if an output descriptor `script_pubkey`
 916         /// does not match the one we can spend.
 917         fn spend_spendable_outputs<C: Signing>(
 918                 &self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
 919                 change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
 920                 locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>,
 921         ) -> Result<Transaction, ()>;
 922 }
 923
 924 // Primarily needed in doctests because of https://github.com/rust-lang/rust/issues/67295
 925 /// A dynamic [`SignerProvider`] temporarily needed for doc tests.
 926 #[cfg(taproot)]
 927 #[doc(hidden)]
 928 #[deprecated(note = "Remove once taproot cfg is removed")]
 929 pub type DynSignerProvider =
 930         dyn SignerProvider<EcdsaSigner = InMemorySigner, TaprootSigner = InMemorySigner>;
 931
 932 /// A dynamic [`SignerProvider`] temporarily needed for doc tests.
 933 #[cfg(not(taproot))]
 934 #[doc(hidden)]
 935 #[deprecated(note = "Remove once taproot cfg is removed")]
 936 pub type DynSignerProvider = dyn SignerProvider<EcdsaSigner = InMemorySigner>;
 937
 938 /// A trait that can return signer instances for individual channels.
 939 pub trait SignerProvider {
 940         /// A type which implements [`WriteableEcdsaChannelSigner`] which will be returned by [`Self::derive_channel_signer`].
 941         type EcdsaSigner: WriteableEcdsaChannelSigner;
 942         #[cfg(taproot)]
 943         /// A type which implements [`TaprootChannelSigner`]
 944         type TaprootSigner: TaprootChannelSigner;
 945
 946         /// Generates a unique `channel_keys_id` that can be used to obtain a [`Self::EcdsaSigner`] through
 947         /// [`SignerProvider::derive_channel_signer`]. The `user_channel_id` is provided to allow
 948         /// implementations of [`SignerProvider`] to maintain a mapping between itself and the generated
 949         /// `channel_keys_id`.
 950         ///
 951         /// This method must return a different value each time it is called.
 952         fn generate_channel_keys_id(
 953                 &self, inbound: bool, channel_value_satoshis: u64, user_channel_id: u128,
 954         ) -> [u8; 32];
 955
 956         /// Derives the private key material backing a `Signer`.
 957         ///
 958         /// To derive a new `Signer`, a fresh `channel_keys_id` should be obtained through
 959         /// [`SignerProvider::generate_channel_keys_id`]. Otherwise, an existing `Signer` can be
 960         /// re-derived from its `channel_keys_id`, which can be obtained through its trait method
 961         /// [`ChannelSigner::channel_keys_id`].
 962         fn derive_channel_signer(
 963                 &self, channel_value_satoshis: u64, channel_keys_id: [u8; 32],
 964         ) -> Self::EcdsaSigner;
 965
 966         /// Reads a [`Signer`] for this [`SignerProvider`] from the given input stream.
 967         /// This is only called during deserialization of other objects which contain
 968         /// [`WriteableEcdsaChannelSigner`]-implementing objects (i.e., [`ChannelMonitor`]s and [`ChannelManager`]s).
 969         /// The bytes are exactly those which `<Self::Signer as Writeable>::write()` writes, and
 970         /// contain no versioning scheme. You may wish to include your own version prefix and ensure
 971         /// you've read all of the provided bytes to ensure no corruption occurred.
 972         ///
 973         /// This method is slowly being phased out -- it will only be called when reading objects
 974         /// written by LDK versions prior to 0.0.113.
 975         ///
 976         /// [`Signer`]: Self::EcdsaSigner
 977         /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
 978         /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
 979         fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::EcdsaSigner, DecodeError>;
 980
 981         /// Get a script pubkey which we send funds to when claiming on-chain contestable outputs.
 982         ///
 983         /// If this function returns an error, this will result in a channel failing to open.
 984         ///
 985         /// This method should return a different value each time it is called, to avoid linking
 986         /// on-chain funds across channels as controlled to the same user. `channel_keys_id` may be
 987         /// used to derive a unique value for each channel.
 988         fn get_destination_script(&self, channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()>;
 989
 990         /// Get a script pubkey which we will send funds to when closing a channel.
 991         ///
 992         /// If this function returns an error, this will result in a channel failing to open or close.
 993         /// In the event of a failure when the counterparty is initiating a close, this can result in a
 994         /// channel force close.
 995         ///
 996         /// This method should return a different value each time it is called, to avoid linking
 997         /// on-chain funds across channels as controlled to the same user.
 998         fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()>;
 999 }
1000
1001 /// A helper trait that describes an on-chain wallet capable of returning a (change) destination
1002 /// script.
1003 pub trait ChangeDestinationSource {
1004         /// Returns a script pubkey which can be used as a change destination for
1005         /// [`OutputSpender::spend_spendable_outputs`].
1006         ///
1007         /// This method should return a different value each time it is called, to avoid linking
1008         /// on-chain funds controlled to the same user.
1009         fn get_change_destination_script(&self) -> Result<ScriptBuf, ()>;
1010 }
1011
1012 /// A simple implementation of [`WriteableEcdsaChannelSigner`] that just keeps the private keys in memory.
1013 ///
1014 /// This implementation performs no policy checks and is insufficient by itself as
1015 /// a secure external signer.
1016 #[derive(Debug)]
1017 pub struct InMemorySigner {
1018         /// Holder secret key in the 2-of-2 multisig script of a channel. This key also backs the
1019         /// holder's anchor output in a commitment transaction, if one is present.
1020         pub funding_key: SecretKey,
1021         /// Holder secret key for blinded revocation pubkey.
1022         pub revocation_base_key: SecretKey,
1023         /// Holder secret key used for our balance in counterparty-broadcasted commitment transactions.
1024         pub payment_key: SecretKey,
1025         /// Holder secret key used in an HTLC transaction.
1026         pub delayed_payment_base_key: SecretKey,
1027         /// Holder HTLC secret key used in commitment transaction HTLC outputs.
1028         pub htlc_base_key: SecretKey,
1029         /// Commitment seed.
1030         pub commitment_seed: [u8; 32],
1031         /// Holder public keys and basepoints.
1032         pub(crate) holder_channel_pubkeys: ChannelPublicKeys,
1033         /// Counterparty public keys and counterparty/holder `selected_contest_delay`, populated on channel acceptance.
1034         channel_parameters: Option<ChannelTransactionParameters>,
1035         /// The total value of this channel.
1036         channel_value_satoshis: u64,
1037         /// Key derivation parameters.
1038         channel_keys_id: [u8; 32],
1039         /// A source of random bytes.
1040         entropy_source: RandomBytes,
1041 }
1042
1043 impl PartialEq for InMemorySigner {
1044         fn eq(&self, other: &Self) -> bool {
1045                 self.funding_key == other.funding_key
1046                         && self.revocation_base_key == other.revocation_base_key
1047                         && self.payment_key == other.payment_key
1048                         && self.delayed_payment_base_key == other.delayed_payment_base_key
1049                         && self.htlc_base_key == other.htlc_base_key
1050                         && self.commitment_seed == other.commitment_seed
1051                         && self.holder_channel_pubkeys == other.holder_channel_pubkeys
1052                         && self.channel_parameters == other.channel_parameters
1053                         && self.channel_value_satoshis == other.channel_value_satoshis
1054                         && self.channel_keys_id == other.channel_keys_id
1055         }
1056 }
1057
1058 impl Clone for InMemorySigner {
1059         fn clone(&self) -> Self {
1060                 Self {
1061                         funding_key: self.funding_key.clone(),
1062                         revocation_base_key: self.revocation_base_key.clone(),
1063                         payment_key: self.payment_key.clone(),
1064                         delayed_payment_base_key: self.delayed_payment_base_key.clone(),
1065                         htlc_base_key: self.htlc_base_key.clone(),
1066                         commitment_seed: self.commitment_seed.clone(),
1067                         holder_channel_pubkeys: self.holder_channel_pubkeys.clone(),
1068                         channel_parameters: self.channel_parameters.clone(),
1069                         channel_value_satoshis: self.channel_value_satoshis,
1070                         channel_keys_id: self.channel_keys_id,
1071                         entropy_source: RandomBytes::new(self.get_secure_random_bytes()),
1072                 }
1073         }
1074 }
1075
1076 impl InMemorySigner {
1077         /// Creates a new [`InMemorySigner`].
1078         pub fn new<C: Signing>(
1079                 secp_ctx: &Secp256k1<C>, funding_key: SecretKey, revocation_base_key: SecretKey,
1080                 payment_key: SecretKey, delayed_payment_base_key: SecretKey, htlc_base_key: SecretKey,
1081                 commitment_seed: [u8; 32], channel_value_satoshis: u64, channel_keys_id: [u8; 32],
1082                 rand_bytes_unique_start: [u8; 32],
1083         ) -> InMemorySigner {
1084                 let holder_channel_pubkeys = InMemorySigner::make_holder_keys(
1085                         secp_ctx,
1086                         &funding_key,
1087                         &revocation_base_key,
1088                         &payment_key,
1089                         &delayed_payment_base_key,
1090                         &htlc_base_key,
1091                 );
1092                 InMemorySigner {
1093                         funding_key,
1094                         revocation_base_key,
1095                         payment_key,
1096                         delayed_payment_base_key,
1097                         htlc_base_key,
1098                         commitment_seed,
1099                         channel_value_satoshis,
1100                         holder_channel_pubkeys,
1101                         channel_parameters: None,
1102                         channel_keys_id,
1103                         entropy_source: RandomBytes::new(rand_bytes_unique_start),
1104                 }
1105         }
1106
1107         fn make_holder_keys<C: Signing>(
1108                 secp_ctx: &Secp256k1<C>, funding_key: &SecretKey, revocation_base_key: &SecretKey,
1109                 payment_key: &SecretKey, delayed_payment_base_key: &SecretKey, htlc_base_key: &SecretKey,
1110         ) -> ChannelPublicKeys {
1111                 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
1112                 ChannelPublicKeys {
1113                         funding_pubkey: from_secret(&funding_key),
1114                         revocation_basepoint: RevocationBasepoint::from(from_secret(&revocation_base_key)),
1115                         payment_point: from_secret(&payment_key),
1116                         delayed_payment_basepoint: DelayedPaymentBasepoint::from(from_secret(
1117                                 &delayed_payment_base_key,
1118                         )),
1119                         htlc_basepoint: HtlcBasepoint::from(from_secret(&htlc_base_key)),
1120                 }
1121         }
1122
1123         /// Returns the counterparty's pubkeys.
1124         ///
1125         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1126         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1127         pub fn counterparty_pubkeys(&self) -> Option<&ChannelPublicKeys> {
1128                 self.get_channel_parameters().and_then(|params| {
1129                         params.counterparty_parameters.as_ref().map(|params| &params.pubkeys)
1130                 })
1131         }
1132
1133         /// Returns the `contest_delay` value specified by our counterparty and applied on holder-broadcastable
1134         /// transactions, i.e., the amount of time that we have to wait to recover our funds if we
1135         /// broadcast a transaction.
1136         ///
1137         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1138         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1139         pub fn counterparty_selected_contest_delay(&self) -> Option<u16> {
1140                 self.get_channel_parameters().and_then(|params| {
1141                         params.counterparty_parameters.as_ref().map(|params| params.selected_contest_delay)
1142                 })
1143         }
1144
1145         /// Returns the `contest_delay` value specified by us and applied on transactions broadcastable
1146         /// by our counterparty, i.e., the amount of time that they have to wait to recover their funds
1147         /// if they broadcast a transaction.
1148         ///
1149         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1150         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1151         pub fn holder_selected_contest_delay(&self) -> Option<u16> {
1152                 self.get_channel_parameters().map(|params| params.holder_selected_contest_delay)
1153         }
1154
1155         /// Returns whether the holder is the initiator.
1156         ///
1157         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1158         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1159         pub fn is_outbound(&self) -> Option<bool> {
1160                 self.get_channel_parameters().map(|params| params.is_outbound_from_holder)
1161         }
1162
1163         /// Funding outpoint
1164         ///
1165         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1166         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1167         pub fn funding_outpoint(&self) -> Option<&OutPoint> {
1168                 self.get_channel_parameters().map(|params| params.funding_outpoint.as_ref()).flatten()
1169         }
1170
1171         /// Returns a [`ChannelTransactionParameters`] for this channel, to be used when verifying or
1172         /// building transactions.
1173         ///
1174         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1175         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1176         pub fn get_channel_parameters(&self) -> Option<&ChannelTransactionParameters> {
1177                 self.channel_parameters.as_ref()
1178         }
1179
1180         /// Returns the channel type features of the channel parameters. Should be helpful for
1181         /// determining a channel's category, i. e. legacy/anchors/taproot/etc.
1182         ///
1183         /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1184         /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1185         pub fn channel_type_features(&self) -> Option<&ChannelTypeFeatures> {
1186                 self.get_channel_parameters().map(|params| &params.channel_type_features)
1187         }
1188
1189         /// Sign the single input of `spend_tx` at index `input_idx`, which spends the output described
1190         /// by `descriptor`, returning the witness stack for the input.
1191         ///
1192         /// Returns an error if the input at `input_idx` does not exist, has a non-empty `script_sig`,
1193         /// is not spending the outpoint described by [`descriptor.outpoint`],
1194         /// or if an output descriptor `script_pubkey` does not match the one we can spend.
1195         ///
1196         /// [`descriptor.outpoint`]: StaticPaymentOutputDescriptor::outpoint
1197         pub fn sign_counterparty_payment_input<C: Signing>(
1198                 &self, spend_tx: &Transaction, input_idx: usize,
1199                 descriptor: &StaticPaymentOutputDescriptor, secp_ctx: &Secp256k1<C>,
1200         ) -> Result<Witness, ()> {
1201                 // TODO: We really should be taking the SigHashCache as a parameter here instead of
1202                 // spend_tx, but ideally the SigHashCache would expose the transaction's inputs read-only
1203                 // so that we can check them. This requires upstream rust-bitcoin changes (as well as
1204                 // bindings updates to support SigHashCache objects).
1205                 if spend_tx.input.len() <= input_idx {
1206                         return Err(());
1207                 }
1208                 if !spend_tx.input[input_idx].script_sig.is_empty() {
1209                         return Err(());
1210                 }
1211                 if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint()
1212                 {
1213                         return Err(());
1214                 }
1215
1216                 let remotepubkey = bitcoin::PublicKey::new(self.pubkeys().payment_point);
1217                 // We cannot always assume that `channel_parameters` is set, so can't just call
1218                 // `self.channel_parameters()` or anything that relies on it
1219                 let supports_anchors_zero_fee_htlc_tx = self
1220                         .channel_type_features()
1221                         .map(|features| features.supports_anchors_zero_fee_htlc_tx())
1222                         .unwrap_or(false);
1223
1224                 let witness_script = if supports_anchors_zero_fee_htlc_tx {
1225                         chan_utils::get_to_countersignatory_with_anchors_redeemscript(&remotepubkey.inner)
1226                 } else {
1227                         ScriptBuf::new_p2pkh(&remotepubkey.pubkey_hash())
1228                 };
1229                 let sighash = hash_to_message!(
1230                         &sighash::SighashCache::new(spend_tx)
1231                                 .segwit_signature_hash(
1232                                         input_idx,
1233                                         &witness_script,
1234                                         descriptor.output.value,
1235                                         EcdsaSighashType::All
1236                                 )
1237                                 .unwrap()[..]
1238                 );
1239                 let remotesig = sign_with_aux_rand(secp_ctx, &sighash, &self.payment_key, &self);
1240                 let payment_script = if supports_anchors_zero_fee_htlc_tx {
1241                         witness_script.to_v0_p2wsh()
1242                 } else {
1243                         ScriptBuf::new_v0_p2wpkh(&remotepubkey.wpubkey_hash().unwrap())
1244                 };
1245
1246                 if payment_script != descriptor.output.script_pubkey {
1247                         return Err(());
1248                 }
1249
1250                 let mut witness = Vec::with_capacity(2);
1251                 witness.push(remotesig.serialize_der().to_vec());
1252                 witness[0].push(EcdsaSighashType::All as u8);
1253                 if supports_anchors_zero_fee_htlc_tx {
1254                         witness.push(witness_script.to_bytes());
1255                 } else {
1256                         witness.push(remotepubkey.to_bytes());
1257                 }
1258                 Ok(witness.into())
1259         }
1260
1261         /// Sign the single input of `spend_tx` at index `input_idx` which spends the output
1262         /// described by `descriptor`, returning the witness stack for the input.
1263         ///
1264         /// Returns an error if the input at `input_idx` does not exist, has a non-empty `script_sig`,
1265         /// is not spending the outpoint described by [`descriptor.outpoint`], does not have a
1266         /// sequence set to [`descriptor.to_self_delay`], or if an output descriptor
1267         /// `script_pubkey` does not match the one we can spend.
1268         ///
1269         /// [`descriptor.outpoint`]: DelayedPaymentOutputDescriptor::outpoint
1270         /// [`descriptor.to_self_delay`]: DelayedPaymentOutputDescriptor::to_self_delay
1271         pub fn sign_dynamic_p2wsh_input<C: Signing>(
1272                 &self, spend_tx: &Transaction, input_idx: usize,
1273                 descriptor: &DelayedPaymentOutputDescriptor, secp_ctx: &Secp256k1<C>,
1274         ) -> Result<Witness, ()> {
1275                 // TODO: We really should be taking the SigHashCache as a parameter here instead of
1276                 // spend_tx, but ideally the SigHashCache would expose the transaction's inputs read-only
1277                 // so that we can check them. This requires upstream rust-bitcoin changes (as well as
1278                 // bindings updates to support SigHashCache objects).
1279                 if spend_tx.input.len() <= input_idx {
1280                         return Err(());
1281                 }
1282                 if !spend_tx.input[input_idx].script_sig.is_empty() {
1283                         return Err(());
1284                 }
1285                 if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint()
1286                 {
1287                         return Err(());
1288                 }
1289                 if spend_tx.input[input_idx].sequence.0 != descriptor.to_self_delay as u32 {
1290                         return Err(());
1291                 }
1292
1293                 let delayed_payment_key = chan_utils::derive_private_key(
1294                         &secp_ctx,
1295                         &descriptor.per_commitment_point,
1296                         &self.delayed_payment_base_key,
1297                 );
1298                 let delayed_payment_pubkey =
1299                         DelayedPaymentKey::from_secret_key(&secp_ctx, &delayed_payment_key);
1300                 let witness_script = chan_utils::get_revokeable_redeemscript(
1301                         &descriptor.revocation_pubkey,
1302                         descriptor.to_self_delay,
1303                         &delayed_payment_pubkey,
1304                 );
1305                 let sighash = hash_to_message!(
1306                         &sighash::SighashCache::new(spend_tx)
1307                                 .segwit_signature_hash(
1308                                         input_idx,
1309                                         &witness_script,
1310                                         descriptor.output.value,
1311                                         EcdsaSighashType::All
1312                                 )
1313                                 .unwrap()[..]
1314                 );
1315                 let local_delayedsig = EcdsaSignature {
1316                         sig: sign_with_aux_rand(secp_ctx, &sighash, &delayed_payment_key, &self),
1317                         hash_ty: EcdsaSighashType::All,
1318                 };
1319                 let payment_script =
1320                         bitcoin::Address::p2wsh(&witness_script, Network::Bitcoin).script_pubkey();
1321
1322                 if descriptor.output.script_pubkey != payment_script {
1323                         return Err(());
1324                 }
1325
1326                 Ok(Witness::from_slice(&[
1327                         &local_delayedsig.serialize()[..],
1328                         &[], // MINIMALIF
1329                         witness_script.as_bytes(),
1330                 ]))
1331         }
1332 }
1333
1334 impl EntropySource for InMemorySigner {
1335         fn get_secure_random_bytes(&self) -> [u8; 32] {
1336                 self.entropy_source.get_secure_random_bytes()
1337         }
1338 }
1339
1340 impl ChannelSigner for InMemorySigner {
1341         fn get_per_commitment_point(
1342                 &self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>,
1343         ) -> PublicKey {
1344                 let commitment_secret =
1345                         SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx))
1346                                 .unwrap();
1347                 PublicKey::from_secret_key(secp_ctx, &commitment_secret)
1348         }
1349
1350         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
1351                 chan_utils::build_commitment_secret(&self.commitment_seed, idx)
1352         }
1353
1354         fn validate_holder_commitment(
1355                 &self, _holder_tx: &HolderCommitmentTransaction,
1356                 _outbound_htlc_preimages: Vec<PaymentPreimage>,
1357         ) -> Result<(), ()> {
1358                 Ok(())
1359         }
1360
1361         fn validate_counterparty_revocation(&self, _idx: u64, _secret: &SecretKey) -> Result<(), ()> {
1362                 Ok(())
1363         }
1364
1365         fn pubkeys(&self) -> &ChannelPublicKeys {
1366                 &self.holder_channel_pubkeys
1367         }
1368
1369         fn channel_keys_id(&self) -> [u8; 32] {
1370                 self.channel_keys_id
1371         }
1372
1373         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
1374                 assert!(
1375                         self.channel_parameters.is_none()
1376                                 || self.channel_parameters.as_ref().unwrap() == channel_parameters
1377                 );
1378                 if self.channel_parameters.is_some() {
1379                         // The channel parameters were already set and they match, return early.
1380                         return;
1381                 }
1382                 assert!(channel_parameters.is_populated(), "Channel parameters must be fully populated");
1383                 self.channel_parameters = Some(channel_parameters.clone());
1384         }
1385 }
1386
1387 const MISSING_PARAMS_ERR: &'static str =
1388         "ChannelSigner::provide_channel_parameters must be called before signing operations";
1389
1390 impl EcdsaChannelSigner for InMemorySigner {
1391         fn sign_counterparty_commitment(
1392                 &self, commitment_tx: &CommitmentTransaction,
1393                 _inbound_htlc_preimages: Vec<PaymentPreimage>,
1394                 _outbound_htlc_preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>,
1395         ) -> Result<(Signature, Vec<Signature>), ()> {
1396                 let trusted_tx = commitment_tx.trust();
1397                 let keys = trusted_tx.keys();
1398
1399                 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1400                 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1401                 let channel_funding_redeemscript =
1402                         make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1403
1404                 let built_tx = trusted_tx.built_transaction();
1405                 let commitment_sig = built_tx.sign_counterparty_commitment(
1406                         &self.funding_key,
1407                         &channel_funding_redeemscript,
1408                         self.channel_value_satoshis,
1409                         secp_ctx,
1410                 );
1411                 let commitment_txid = built_tx.txid;
1412
1413                 let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len());
1414                 for htlc in commitment_tx.htlcs() {
1415                         let channel_parameters = self.get_channel_parameters().expect(MISSING_PARAMS_ERR);
1416                         let holder_selected_contest_delay =
1417                                 self.holder_selected_contest_delay().expect(MISSING_PARAMS_ERR);
1418                         let chan_type = &channel_parameters.channel_type_features;
1419                         let htlc_tx = chan_utils::build_htlc_transaction(
1420                                 &commitment_txid,
1421                                 commitment_tx.feerate_per_kw(),
1422                                 holder_selected_contest_delay,
1423                                 htlc,
1424                                 chan_type,
1425                                 &keys.broadcaster_delayed_payment_key,
1426                                 &keys.revocation_key,
1427                         );
1428                         let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, chan_type, &keys);
1429                         let htlc_sighashtype = if chan_type.supports_anchors_zero_fee_htlc_tx() {
1430                                 EcdsaSighashType::SinglePlusAnyoneCanPay
1431                         } else {
1432                                 EcdsaSighashType::All
1433                         };
1434                         let htlc_sighash = hash_to_message!(
1435                                 &sighash::SighashCache::new(&htlc_tx)
1436                                         .segwit_signature_hash(
1437                                                 0,
1438                                                 &htlc_redeemscript,
1439                                                 htlc.amount_msat / 1000,
1440                                                 htlc_sighashtype
1441                                         )
1442                                         .unwrap()[..]
1443                         );
1444                         let holder_htlc_key = chan_utils::derive_private_key(
1445                                 &secp_ctx,
1446                                 &keys.per_commitment_point,
1447                                 &self.htlc_base_key,
1448                         );
1449                         htlc_sigs.push(sign(secp_ctx, &htlc_sighash, &holder_htlc_key));
1450                 }
1451
1452                 Ok((commitment_sig, htlc_sigs))
1453         }
1454
1455         fn sign_holder_commitment(
1456                 &self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>,
1457         ) -> Result<Signature, ()> {
1458                 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1459                 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1460                 let funding_redeemscript =
1461                         make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1462                 let trusted_tx = commitment_tx.trust();
1463                 Ok(trusted_tx.built_transaction().sign_holder_commitment(
1464                         &self.funding_key,
1465                         &funding_redeemscript,
1466                         self.channel_value_satoshis,
1467                         &self,
1468                         secp_ctx,
1469                 ))
1470         }
1471
1472         #[cfg(any(test, feature = "unsafe_revoked_tx_signing"))]
1473         fn unsafe_sign_holder_commitment(
1474                 &self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>,
1475         ) -> Result<Signature, ()> {
1476                 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1477                 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1478                 let funding_redeemscript =
1479                         make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1480                 let trusted_tx = commitment_tx.trust();
1481                 Ok(trusted_tx.built_transaction().sign_holder_commitment(
1482                         &self.funding_key,
1483                         &funding_redeemscript,
1484                         self.channel_value_satoshis,
1485                         &self,
1486                         secp_ctx,
1487                 ))
1488         }
1489
1490         fn sign_justice_revoked_output(
1491                 &self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
1492                 secp_ctx: &Secp256k1<secp256k1::All>,
1493         ) -> Result<Signature, ()> {
1494                 let revocation_key = chan_utils::derive_private_revocation_key(
1495                         &secp_ctx,
1496                         &per_commitment_key,
1497                         &self.revocation_base_key,
1498                 );
1499                 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
1500                 let revocation_pubkey = RevocationKey::from_basepoint(
1501                         &secp_ctx,
1502                         &self.pubkeys().revocation_basepoint,
1503                         &per_commitment_point,
1504                 );
1505                 let witness_script = {
1506                         let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1507                         let holder_selected_contest_delay =
1508                                 self.holder_selected_contest_delay().expect(MISSING_PARAMS_ERR);
1509                         let counterparty_delayedpubkey = DelayedPaymentKey::from_basepoint(
1510                                 &secp_ctx,
1511                                 &counterparty_keys.delayed_payment_basepoint,
1512                                 &per_commitment_point,
1513                         );
1514                         chan_utils::get_revokeable_redeemscript(
1515                                 &revocation_pubkey,
1516                                 holder_selected_contest_delay,
1517                                 &counterparty_delayedpubkey,
1518                         )
1519                 };
1520                 let mut sighash_parts = sighash::SighashCache::new(justice_tx);
1521                 let sighash = hash_to_message!(
1522                         &sighash_parts
1523                                 .segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All)
1524                                 .unwrap()[..]
1525                 );
1526                 return Ok(sign_with_aux_rand(secp_ctx, &sighash, &revocation_key, &self));
1527         }
1528
1529         fn sign_justice_revoked_htlc(
1530                 &self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
1531                 htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>,
1532         ) -> Result<Signature, ()> {
1533                 let revocation_key = chan_utils::derive_private_revocation_key(
1534                         &secp_ctx,
1535                         &per_commitment_key,
1536                         &self.revocation_base_key,
1537                 );
1538                 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
1539                 let revocation_pubkey = RevocationKey::from_basepoint(
1540                         &secp_ctx,
1541                         &self.pubkeys().revocation_basepoint,
1542                         &per_commitment_point,
1543                 );
1544                 let witness_script = {
1545                         let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1546                         let counterparty_htlcpubkey = HtlcKey::from_basepoint(
1547                                 &secp_ctx,
1548                                 &counterparty_keys.htlc_basepoint,
1549                                 &per_commitment_point,
1550                         );
1551                         let holder_htlcpubkey = HtlcKey::from_basepoint(
1552                                 &secp_ctx,
1553                                 &self.pubkeys().htlc_basepoint,
1554                                 &per_commitment_point,
1555                         );
1556                         let chan_type = self.channel_type_features().expect(MISSING_PARAMS_ERR);
1557                         chan_utils::get_htlc_redeemscript_with_explicit_keys(
1558                                 &htlc,
1559                                 chan_type,
1560                                 &counterparty_htlcpubkey,
1561                                 &holder_htlcpubkey,
1562                                 &revocation_pubkey,
1563                         )
1564                 };
1565                 let mut sighash_parts = sighash::SighashCache::new(justice_tx);
1566                 let sighash = hash_to_message!(
1567                         &sighash_parts
1568                                 .segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All)
1569                                 .unwrap()[..]
1570                 );
1571                 return Ok(sign_with_aux_rand(secp_ctx, &sighash, &revocation_key, &self));
1572         }
1573
1574         fn sign_holder_htlc_transaction(
1575                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
1576                 secp_ctx: &Secp256k1<secp256k1::All>,
1577         ) -> Result<Signature, ()> {
1578                 let witness_script = htlc_descriptor.witness_script(secp_ctx);
1579                 let sighash = &sighash::SighashCache::new(&*htlc_tx)
1580                         .segwit_signature_hash(
1581                                 input,
1582                                 &witness_script,
1583                                 htlc_descriptor.htlc.amount_msat / 1000,
1584                                 EcdsaSighashType::All,
1585                         )
1586                         .map_err(|_| ())?;
1587                 let our_htlc_private_key = chan_utils::derive_private_key(
1588                         &secp_ctx,
1589                         &htlc_descriptor.per_commitment_point,
1590                         &self.htlc_base_key,
1591                 );
1592                 let sighash = hash_to_message!(sighash.as_byte_array());
1593                 Ok(sign_with_aux_rand(&secp_ctx, &sighash, &our_htlc_private_key, &self))
1594         }
1595
1596         fn sign_counterparty_htlc_transaction(
1597                 &self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey,
1598                 htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>,
1599         ) -> Result<Signature, ()> {
1600                 let htlc_key =
1601                         chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key);
1602                 let revocation_pubkey = RevocationKey::from_basepoint(
1603                         &secp_ctx,
1604                         &self.pubkeys().revocation_basepoint,
1605                         &per_commitment_point,
1606                 );
1607                 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1608                 let counterparty_htlcpubkey = HtlcKey::from_basepoint(
1609                         &secp_ctx,
1610                         &counterparty_keys.htlc_basepoint,
1611                         &per_commitment_point,
1612                 );
1613                 let htlc_basepoint = self.pubkeys().htlc_basepoint;
1614                 let htlcpubkey = HtlcKey::from_basepoint(&secp_ctx, &htlc_basepoint, &per_commitment_point);
1615                 let chan_type = self.channel_type_features().expect(MISSING_PARAMS_ERR);
1616                 let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(
1617                         &htlc,
1618                         chan_type,
1619                         &counterparty_htlcpubkey,
1620                         &htlcpubkey,
1621                         &revocation_pubkey,
1622                 );
1623                 let mut sighash_parts = sighash::SighashCache::new(htlc_tx);
1624                 let sighash = hash_to_message!(
1625                         &sighash_parts
1626                                 .segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All)
1627                                 .unwrap()[..]
1628                 );
1629                 Ok(sign_with_aux_rand(secp_ctx, &sighash, &htlc_key, &self))
1630         }
1631
1632         fn sign_closing_transaction(
1633                 &self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>,
1634         ) -> Result<Signature, ()> {
1635                 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1636                 let counterparty_funding_key =
1637                         &self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR).funding_pubkey;
1638                 let channel_funding_redeemscript =
1639                         make_funding_redeemscript(&funding_pubkey, counterparty_funding_key);
1640                 Ok(closing_tx.trust().sign(
1641                         &self.funding_key,
1642                         &channel_funding_redeemscript,
1643                         self.channel_value_satoshis,
1644                         secp_ctx,
1645                 ))
1646         }
1647
1648         fn sign_holder_anchor_input(
1649                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
1650         ) -> Result<Signature, ()> {
1651                 let witness_script =
1652                         chan_utils::get_anchor_redeemscript(&self.holder_channel_pubkeys.funding_pubkey);
1653                 let sighash = sighash::SighashCache::new(&*anchor_tx)
1654                         .segwit_signature_hash(
1655                                 input,
1656                                 &witness_script,
1657                                 ANCHOR_OUTPUT_VALUE_SATOSHI,
1658                                 EcdsaSighashType::All,
1659                         )
1660                         .unwrap();
1661                 Ok(sign_with_aux_rand(secp_ctx, &hash_to_message!(&sighash[..]), &self.funding_key, &self))
1662         }
1663
1664         fn sign_channel_announcement_with_funding_key(
1665                 &self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>,
1666         ) -> Result<Signature, ()> {
1667                 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
1668                 Ok(secp_ctx.sign_ecdsa(&msghash, &self.funding_key))
1669         }
1670 }
1671
1672 #[cfg(taproot)]
1673 impl TaprootChannelSigner for InMemorySigner {
1674         fn generate_local_nonce_pair(
1675                 &self, commitment_number: u64, secp_ctx: &Secp256k1<All>,
1676         ) -> PublicNonce {
1677                 todo!()
1678         }
1679
1680         fn partially_sign_counterparty_commitment(
1681                 &self, counterparty_nonce: PublicNonce, commitment_tx: &CommitmentTransaction,
1682                 inbound_htlc_preimages: Vec<PaymentPreimage>,
1683                 outbound_htlc_preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<All>,
1684         ) -> Result<(PartialSignatureWithNonce, Vec<schnorr::Signature>), ()> {
1685                 todo!()
1686         }
1687
1688         fn finalize_holder_commitment(
1689                 &self, commitment_tx: &HolderCommitmentTransaction,
1690                 counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>,
1691         ) -> Result<PartialSignature, ()> {
1692                 todo!()
1693         }
1694
1695         fn sign_justice_revoked_output(
1696                 &self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
1697                 secp_ctx: &Secp256k1<All>,
1698         ) -> Result<schnorr::Signature, ()> {
1699                 todo!()
1700         }
1701
1702         fn sign_justice_revoked_htlc(
1703                 &self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
1704                 htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<All>,
1705         ) -> Result<schnorr::Signature, ()> {
1706                 todo!()
1707         }
1708
1709         fn sign_holder_htlc_transaction(
1710                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
1711                 secp_ctx: &Secp256k1<All>,
1712         ) -> Result<schnorr::Signature, ()> {
1713                 todo!()
1714         }
1715
1716         fn sign_counterparty_htlc_transaction(
1717                 &self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey,
1718                 htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<All>,
1719         ) -> Result<schnorr::Signature, ()> {
1720                 todo!()
1721         }
1722
1723         fn partially_sign_closing_transaction(
1724                 &self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>,
1725         ) -> Result<PartialSignature, ()> {
1726                 todo!()
1727         }
1728
1729         fn sign_holder_anchor_input(
1730                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>,
1731         ) -> Result<schnorr::Signature, ()> {
1732                 todo!()
1733         }
1734 }
1735
1736 const SERIALIZATION_VERSION: u8 = 1;
1737
1738 const MIN_SERIALIZATION_VERSION: u8 = 1;
1739
1740 impl WriteableEcdsaChannelSigner for InMemorySigner {}
1741
1742 impl Writeable for InMemorySigner {
1743         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
1744                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
1745
1746                 self.funding_key.write(writer)?;
1747                 self.revocation_base_key.write(writer)?;
1748                 self.payment_key.write(writer)?;
1749                 self.delayed_payment_base_key.write(writer)?;
1750                 self.htlc_base_key.write(writer)?;
1751                 self.commitment_seed.write(writer)?;
1752                 self.channel_parameters.write(writer)?;
1753                 self.channel_value_satoshis.write(writer)?;
1754                 self.channel_keys_id.write(writer)?;
1755
1756                 write_tlv_fields!(writer, {});
1757
1758                 Ok(())
1759         }
1760 }
1761
1762 impl<ES: Deref> ReadableArgs<ES> for InMemorySigner
1763 where
1764         ES::Target: EntropySource,
1765 {
1766         fn read<R: io::Read>(reader: &mut R, entropy_source: ES) -> Result<Self, DecodeError> {
1767                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
1768
1769                 let funding_key = Readable::read(reader)?;
1770                 let revocation_base_key = Readable::read(reader)?;
1771                 let payment_key = Readable::read(reader)?;
1772                 let delayed_payment_base_key = Readable::read(reader)?;
1773                 let htlc_base_key = Readable::read(reader)?;
1774                 let commitment_seed = Readable::read(reader)?;
1775                 let counterparty_channel_data = Readable::read(reader)?;
1776                 let channel_value_satoshis = Readable::read(reader)?;
1777                 let secp_ctx = Secp256k1::signing_only();
1778                 let holder_channel_pubkeys = InMemorySigner::make_holder_keys(
1779                         &secp_ctx,
1780                         &funding_key,
1781                         &revocation_base_key,
1782                         &payment_key,
1783                         &delayed_payment_base_key,
1784                         &htlc_base_key,
1785                 );
1786                 let keys_id = Readable::read(reader)?;
1787
1788                 read_tlv_fields!(reader, {});
1789
1790                 Ok(InMemorySigner {
1791                         funding_key,
1792                         revocation_base_key,
1793                         payment_key,
1794                         delayed_payment_base_key,
1795                         htlc_base_key,
1796                         commitment_seed,
1797                         channel_value_satoshis,
1798                         holder_channel_pubkeys,
1799                         channel_parameters: counterparty_channel_data,
1800                         channel_keys_id: keys_id,
1801                         entropy_source: RandomBytes::new(entropy_source.get_secure_random_bytes()),
1802                 })
1803         }
1804 }
1805
1806 /// Simple implementation of [`EntropySource`], [`NodeSigner`], and [`SignerProvider`] that takes a
1807 /// 32-byte seed for use as a BIP 32 extended key and derives keys from that.
1808 ///
1809 /// Your `node_id` is seed/0'.
1810 /// Unilateral closes may use seed/1'.
1811 /// Cooperative closes may use seed/2'.
1812 /// The two close keys may be needed to claim on-chain funds!
1813 ///
1814 /// This struct cannot be used for nodes that wish to support receiving phantom payments;
1815 /// [`PhantomKeysManager`] must be used instead.
1816 ///
1817 /// Note that switching between this struct and [`PhantomKeysManager`] will invalidate any
1818 /// previously issued invoices and attempts to pay previous invoices will fail.
1819 pub struct KeysManager {
1820         secp_ctx: Secp256k1<secp256k1::All>,
1821         node_secret: SecretKey,
1822         node_id: PublicKey,
1823         inbound_payment_key: KeyMaterial,
1824         destination_script: ScriptBuf,
1825         shutdown_pubkey: PublicKey,
1826         channel_master_key: ExtendedPrivKey,
1827         channel_child_index: AtomicUsize,
1828
1829         entropy_source: RandomBytes,
1830
1831         seed: [u8; 32],
1832         starting_time_secs: u64,
1833         starting_time_nanos: u32,
1834 }
1835
1836 impl KeysManager {
1837         /// Constructs a [`KeysManager`] from a 32-byte seed. If the seed is in some way biased (e.g.,
1838         /// your CSRNG is busted) this may panic (but more importantly, you will possibly lose funds).
1839         /// `starting_time` isn't strictly required to actually be a time, but it must absolutely,
1840         /// without a doubt, be unique to this instance. ie if you start multiple times with the same
1841         /// `seed`, `starting_time` must be unique to each run. Thus, the easiest way to achieve this
1842         /// is to simply use the current time (with very high precision).
1843         ///
1844         /// The `seed` MUST be backed up safely prior to use so that the keys can be re-created, however,
1845         /// obviously, `starting_time` should be unique every time you reload the library - it is only
1846         /// used to generate new ephemeral key data (which will be stored by the individual channel if
1847         /// necessary).
1848         ///
1849         /// Note that the seed is required to recover certain on-chain funds independent of
1850         /// [`ChannelMonitor`] data, though a current copy of [`ChannelMonitor`] data is also required
1851         /// for any channel, and some on-chain during-closing funds.
1852         ///
1853         /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
1854         pub fn new(seed: &[u8; 32], starting_time_secs: u64, starting_time_nanos: u32) -> Self {
1855                 let secp_ctx = Secp256k1::new();
1856                 // Note that when we aren't serializing the key, network doesn't matter
1857                 match ExtendedPrivKey::new_master(Network::Testnet, seed) {
1858                         Ok(master_key) => {
1859                                 let node_secret = master_key
1860                                         .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap())
1861                                         .expect("Your RNG is busted")
1862                                         .private_key;
1863                                 let node_id = PublicKey::from_secret_key(&secp_ctx, &node_secret);
1864                                 let destination_script = match master_key
1865                                         .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap())
1866                                 {
1867                                         Ok(destination_key) => {
1868                                                 let wpubkey_hash = WPubkeyHash::hash(
1869                                                         &ExtendedPubKey::from_priv(&secp_ctx, &destination_key)
1870                                                                 .to_pub()
1871                                                                 .to_bytes(),
1872                                                 );
1873                                                 Builder::new()
1874                                                         .push_opcode(opcodes::all::OP_PUSHBYTES_0)
1875                                                         .push_slice(&wpubkey_hash.to_byte_array())
1876                                                         .into_script()
1877                                         },
1878                                         Err(_) => panic!("Your RNG is busted"),
1879                                 };
1880                                 let shutdown_pubkey = match master_key
1881                                         .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap())
1882                                 {
1883                                         Ok(shutdown_key) => {
1884                                                 ExtendedPubKey::from_priv(&secp_ctx, &shutdown_key).public_key
1885                                         },
1886                                         Err(_) => panic!("Your RNG is busted"),
1887                                 };
1888                                 let channel_master_key = master_key
1889                                         .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap())
1890                                         .expect("Your RNG is busted");
1891                                 let inbound_payment_key: SecretKey = master_key
1892                                         .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap())
1893                                         .expect("Your RNG is busted")
1894                                         .private_key;
1895                                 let mut inbound_pmt_key_bytes = [0; 32];
1896                                 inbound_pmt_key_bytes.copy_from_slice(&inbound_payment_key[..]);
1897
1898                                 let mut rand_bytes_engine = Sha256::engine();
1899                                 rand_bytes_engine.input(&starting_time_secs.to_be_bytes());
1900                                 rand_bytes_engine.input(&starting_time_nanos.to_be_bytes());
1901                                 rand_bytes_engine.input(seed);
1902                                 rand_bytes_engine.input(b"LDK PRNG Seed");
1903                                 let rand_bytes_unique_start =
1904                                         Sha256::from_engine(rand_bytes_engine).to_byte_array();
1905
1906                                 let mut res = KeysManager {
1907                                         secp_ctx,
1908                                         node_secret,
1909                                         node_id,
1910                                         inbound_payment_key: KeyMaterial(inbound_pmt_key_bytes),
1911
1912                                         destination_script,
1913                                         shutdown_pubkey,
1914
1915                                         channel_master_key,
1916                                         channel_child_index: AtomicUsize::new(0),
1917
1918                                         entropy_source: RandomBytes::new(rand_bytes_unique_start),
1919
1920                                         seed: *seed,
1921                                         starting_time_secs,
1922                                         starting_time_nanos,
1923                                 };
1924                                 let secp_seed = res.get_secure_random_bytes();
1925                                 res.secp_ctx.seeded_randomize(&secp_seed);
1926                                 res
1927                         },
1928                         Err(_) => panic!("Your rng is busted"),
1929                 }
1930         }
1931
1932         /// Gets the "node_id" secret key used to sign gossip announcements, decode onion data, etc.
1933         pub fn get_node_secret_key(&self) -> SecretKey {
1934                 self.node_secret
1935         }
1936
1937         /// Derive an old [`WriteableEcdsaChannelSigner`] containing per-channel secrets based on a key derivation parameters.
1938         pub fn derive_channel_keys(
1939                 &self, channel_value_satoshis: u64, params: &[u8; 32],
1940         ) -> InMemorySigner {
1941                 let chan_id = u64::from_be_bytes(params[0..8].try_into().unwrap());
1942                 let mut unique_start = Sha256::engine();
1943                 unique_start.input(params);
1944                 unique_start.input(&self.seed);
1945
1946                 // We only seriously intend to rely on the channel_master_key for true secure
1947                 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
1948                 // starting_time provided in the constructor) to be unique.
1949                 let child_privkey = self
1950                         .channel_master_key
1951                         .ckd_priv(
1952                                 &self.secp_ctx,
1953                                 ChildNumber::from_hardened_idx((chan_id as u32) % (1 << 31))
1954                                         .expect("key space exhausted"),
1955                         )
1956                         .expect("Your RNG is busted");
1957                 unique_start.input(&child_privkey.private_key[..]);
1958
1959                 let seed = Sha256::from_engine(unique_start).to_byte_array();
1960
1961                 let commitment_seed = {
1962                         let mut sha = Sha256::engine();
1963                         sha.input(&seed);
1964                         sha.input(&b"commitment seed"[..]);
1965                         Sha256::from_engine(sha).to_byte_array()
1966                 };
1967                 macro_rules! key_step {
1968                         ($info: expr, $prev_key: expr) => {{
1969                                 let mut sha = Sha256::engine();
1970                                 sha.input(&seed);
1971                                 sha.input(&$prev_key[..]);
1972                                 sha.input(&$info[..]);
1973                                 SecretKey::from_slice(&Sha256::from_engine(sha).to_byte_array())
1974                                         .expect("SHA-256 is busted")
1975                         }};
1976                 }
1977                 let funding_key = key_step!(b"funding key", commitment_seed);
1978                 let revocation_base_key = key_step!(b"revocation base key", funding_key);
1979                 let payment_key = key_step!(b"payment key", revocation_base_key);
1980                 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
1981                 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
1982                 let prng_seed = self.get_secure_random_bytes();
1983
1984                 InMemorySigner::new(
1985                         &self.secp_ctx,
1986                         funding_key,
1987                         revocation_base_key,
1988                         payment_key,
1989                         delayed_payment_base_key,
1990                         htlc_base_key,
1991                         commitment_seed,
1992                         channel_value_satoshis,
1993                         params.clone(),
1994                         prng_seed,
1995                 )
1996         }
1997
1998         /// Signs the given [`PartiallySignedTransaction`] which spends the given [`SpendableOutputDescriptor`]s.
1999         /// The resulting inputs will be finalized and the PSBT will be ready for broadcast if there
2000         /// are no other inputs that need signing.
2001         ///
2002         /// Returns `Err(())` if the PSBT is missing a descriptor or if we fail to sign.
2003         ///
2004         /// May panic if the [`SpendableOutputDescriptor`]s were not generated by channels which used
2005         /// this [`KeysManager`] or one of the [`InMemorySigner`] created by this [`KeysManager`].
2006         pub fn sign_spendable_outputs_psbt<C: Signing>(
2007                 &self, descriptors: &[&SpendableOutputDescriptor], mut psbt: PartiallySignedTransaction,
2008                 secp_ctx: &Secp256k1<C>,
2009         ) -> Result<PartiallySignedTransaction, ()> {
2010                 let mut keys_cache: Option<(InMemorySigner, [u8; 32])> = None;
2011                 for outp in descriptors {
2012                         let get_input_idx = |outpoint: &OutPoint| {
2013                                 psbt.unsigned_tx
2014                                         .input
2015                                         .iter()
2016                                         .position(|i| i.previous_output == outpoint.into_bitcoin_outpoint())
2017                                         .ok_or(())
2018                         };
2019                         match outp {
2020                                 SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
2021                                         let input_idx = get_input_idx(&descriptor.outpoint)?;
2022                                         if keys_cache.is_none()
2023                                                 || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id
2024                                         {
2025                                                 let mut signer = self.derive_channel_keys(
2026                                                         descriptor.channel_value_satoshis,
2027                                                         &descriptor.channel_keys_id,
2028                                                 );
2029                                                 if let Some(channel_params) =
2030                                                         descriptor.channel_transaction_parameters.as_ref()
2031                                                 {
2032                                                         signer.provide_channel_parameters(channel_params);
2033                                                 }
2034                                                 keys_cache = Some((signer, descriptor.channel_keys_id));
2035                                         }
2036                                         let witness = keys_cache.as_ref().unwrap().0.sign_counterparty_payment_input(
2037                                                 &psbt.unsigned_tx,
2038                                                 input_idx,
2039                                                 &descriptor,
2040                                                 &secp_ctx,
2041                                         )?;
2042                                         psbt.inputs[input_idx].final_script_witness = Some(witness);
2043                                 },
2044                                 SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
2045                                         let input_idx = get_input_idx(&descriptor.outpoint)?;
2046                                         if keys_cache.is_none()
2047                                                 || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id
2048                                         {
2049                                                 keys_cache = Some((
2050                                                         self.derive_channel_keys(
2051                                                                 descriptor.channel_value_satoshis,
2052                                                                 &descriptor.channel_keys_id,
2053                                                         ),
2054                                                         descriptor.channel_keys_id,
2055                                                 ));
2056                                         }
2057                                         let witness = keys_cache.as_ref().unwrap().0.sign_dynamic_p2wsh_input(
2058                                                 &psbt.unsigned_tx,
2059                                                 input_idx,
2060                                                 &descriptor,
2061                                                 &secp_ctx,
2062                                         )?;
2063                                         psbt.inputs[input_idx].final_script_witness = Some(witness);
2064                                 },
2065                                 SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output, .. } => {
2066                                         let input_idx = get_input_idx(outpoint)?;
2067                                         let derivation_idx =
2068                                                 if output.script_pubkey == self.destination_script { 1 } else { 2 };
2069                                         let secret = {
2070                                                 // Note that when we aren't serializing the key, network doesn't matter
2071                                                 match ExtendedPrivKey::new_master(Network::Testnet, &self.seed) {
2072                                                         Ok(master_key) => {
2073                                                                 match master_key.ckd_priv(
2074                                                                         &secp_ctx,
2075                                                                         ChildNumber::from_hardened_idx(derivation_idx)
2076                                                                                 .expect("key space exhausted"),
2077                                                                 ) {
2078                                                                         Ok(key) => key,
2079                                                                         Err(_) => panic!("Your RNG is busted"),
2080                                                                 }
2081                                                         },
2082                                                         Err(_) => panic!("Your rng is busted"),
2083                                                 }
2084                                         };
2085                                         let pubkey = ExtendedPubKey::from_priv(&secp_ctx, &secret).to_pub();
2086                                         if derivation_idx == 2 {
2087                                                 assert_eq!(pubkey.inner, self.shutdown_pubkey);
2088                                         }
2089                                         let witness_script =
2090                                                 bitcoin::Address::p2pkh(&pubkey, Network::Testnet).script_pubkey();
2091                                         let payment_script = bitcoin::Address::p2wpkh(&pubkey, Network::Testnet)
2092                                                 .expect("uncompressed key found")
2093                                                 .script_pubkey();
2094
2095                                         if payment_script != output.script_pubkey {
2096                                                 return Err(());
2097                                         };
2098
2099                                         let sighash = hash_to_message!(
2100                                                 &sighash::SighashCache::new(&psbt.unsigned_tx)
2101                                                         .segwit_signature_hash(
2102                                                                 input_idx,
2103                                                                 &witness_script,
2104                                                                 output.value,
2105                                                                 EcdsaSighashType::All
2106                                                         )
2107                                                         .unwrap()[..]
2108                                         );
2109                                         let sig = sign_with_aux_rand(secp_ctx, &sighash, &secret.private_key, &self);
2110                                         let mut sig_ser = sig.serialize_der().to_vec();
2111                                         sig_ser.push(EcdsaSighashType::All as u8);
2112                                         let witness =
2113                                                 Witness::from_slice(&[&sig_ser, &pubkey.inner.serialize().to_vec()]);
2114                                         psbt.inputs[input_idx].final_script_witness = Some(witness);
2115                                 },
2116                         }
2117                 }
2118
2119                 Ok(psbt)
2120         }
2121 }
2122
2123 impl EntropySource for KeysManager {
2124         fn get_secure_random_bytes(&self) -> [u8; 32] {
2125                 self.entropy_source.get_secure_random_bytes()
2126         }
2127 }
2128
2129 impl NodeSigner for KeysManager {
2130         fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()> {
2131                 match recipient {
2132                         Recipient::Node => Ok(self.node_id.clone()),
2133                         Recipient::PhantomNode => Err(()),
2134                 }
2135         }
2136
2137         fn ecdh(
2138                 &self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>,
2139         ) -> Result<SharedSecret, ()> {
2140                 let mut node_secret = match recipient {
2141                         Recipient::Node => Ok(self.node_secret.clone()),
2142                         Recipient::PhantomNode => Err(()),
2143                 }?;
2144                 if let Some(tweak) = tweak {
2145                         node_secret = node_secret.mul_tweak(tweak).map_err(|_| ())?;
2146                 }
2147                 Ok(SharedSecret::new(other_key, &node_secret))
2148         }
2149
2150         fn get_inbound_payment_key_material(&self) -> KeyMaterial {
2151                 self.inbound_payment_key.clone()
2152         }
2153
2154         fn sign_invoice(
2155                 &self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient,
2156         ) -> Result<RecoverableSignature, ()> {
2157                 let preimage = construct_invoice_preimage(&hrp_bytes, &invoice_data);
2158                 let secret = match recipient {
2159                         Recipient::Node => Ok(&self.node_secret),
2160                         Recipient::PhantomNode => Err(()),
2161                 }?;
2162                 Ok(self.secp_ctx.sign_ecdsa_recoverable(
2163                         &hash_to_message!(&Sha256::hash(&preimage).to_byte_array()),
2164                         secret,
2165                 ))
2166         }
2167
2168         fn sign_bolt12_invoice_request(
2169                 &self, invoice_request: &UnsignedInvoiceRequest,
2170         ) -> Result<schnorr::Signature, ()> {
2171                 let message = invoice_request.tagged_hash().as_digest();
2172                 let keys = KeyPair::from_secret_key(&self.secp_ctx, &self.node_secret);
2173                 let aux_rand = self.get_secure_random_bytes();
2174                 Ok(self.secp_ctx.sign_schnorr_with_aux_rand(message, &keys, &aux_rand))
2175         }
2176
2177         fn sign_bolt12_invoice(
2178                 &self, invoice: &UnsignedBolt12Invoice,
2179         ) -> Result<schnorr::Signature, ()> {
2180                 let message = invoice.tagged_hash().as_digest();
2181                 let keys = KeyPair::from_secret_key(&self.secp_ctx, &self.node_secret);
2182                 let aux_rand = self.get_secure_random_bytes();
2183                 Ok(self.secp_ctx.sign_schnorr_with_aux_rand(message, &keys, &aux_rand))
2184         }
2185
2186         fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()> {
2187                 let msg_hash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
2188                 Ok(self.secp_ctx.sign_ecdsa(&msg_hash, &self.node_secret))
2189         }
2190 }
2191
2192 impl OutputSpender for KeysManager {
2193         /// Creates a [`Transaction`] which spends the given descriptors to the given outputs, plus an
2194         /// output to the given change destination (if sufficient change value remains).
2195         ///
2196         /// See [`OutputSpender::spend_spendable_outputs`] documentation for more information.
2197         ///
2198         /// We do not enforce that outputs meet the dust limit or that any output scripts are standard.
2199         ///
2200         /// May panic if the [`SpendableOutputDescriptor`]s were not generated by channels which used
2201         /// this [`KeysManager`] or one of the [`InMemorySigner`] created by this [`KeysManager`].
2202         fn spend_spendable_outputs<C: Signing>(
2203                 &self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
2204                 change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
2205                 locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>,
2206         ) -> Result<Transaction, ()> {
2207                 let (mut psbt, expected_max_weight) =
2208                         SpendableOutputDescriptor::create_spendable_outputs_psbt(
2209                                 secp_ctx,
2210                                 descriptors,
2211                                 outputs,
2212                                 change_destination_script,
2213                                 feerate_sat_per_1000_weight,
2214                                 locktime,
2215                         )?;
2216                 psbt = self.sign_spendable_outputs_psbt(descriptors, psbt, secp_ctx)?;
2217
2218                 let spend_tx = psbt.extract_tx();
2219
2220                 debug_assert!(expected_max_weight >= spend_tx.weight().to_wu());
2221                 // Note that witnesses with a signature vary somewhat in size, so allow
2222                 // `expected_max_weight` to overshoot by up to 3 bytes per input.
2223                 debug_assert!(
2224                         expected_max_weight <= spend_tx.weight().to_wu() + descriptors.len() as u64 * 3
2225                 );
2226
2227                 Ok(spend_tx)
2228         }
2229 }
2230
2231 impl SignerProvider for KeysManager {
2232         type EcdsaSigner = InMemorySigner;
2233         #[cfg(taproot)]
2234         type TaprootSigner = InMemorySigner;
2235
2236         fn generate_channel_keys_id(
2237                 &self, _inbound: bool, _channel_value_satoshis: u64, user_channel_id: u128,
2238         ) -> [u8; 32] {
2239                 let child_idx = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
2240                 // `child_idx` is the only thing guaranteed to make each channel unique without a restart
2241                 // (though `user_channel_id` should help, depending on user behavior). If it manages to
2242                 // roll over, we may generate duplicate keys for two different channels, which could result
2243                 // in loss of funds. Because we only support 32-bit+ systems, assert that our `AtomicUsize`
2244                 // doesn't reach `u32::MAX`.
2245                 assert!(child_idx < core::u32::MAX as usize, "2^32 channels opened without restart");
2246                 let mut id = [0; 32];
2247                 id[0..4].copy_from_slice(&(child_idx as u32).to_be_bytes());
2248                 id[4..8].copy_from_slice(&self.starting_time_nanos.to_be_bytes());
2249                 id[8..16].copy_from_slice(&self.starting_time_secs.to_be_bytes());
2250                 id[16..32].copy_from_slice(&user_channel_id.to_be_bytes());
2251                 id
2252         }
2253
2254         fn derive_channel_signer(
2255                 &self, channel_value_satoshis: u64, channel_keys_id: [u8; 32],
2256         ) -> Self::EcdsaSigner {
2257                 self.derive_channel_keys(channel_value_satoshis, &channel_keys_id)
2258         }
2259
2260         fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::EcdsaSigner, DecodeError> {
2261                 InMemorySigner::read(&mut io::Cursor::new(reader), self)
2262         }
2263
2264         fn get_destination_script(&self, _channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()> {
2265                 Ok(self.destination_script.clone())
2266         }
2267
2268         fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
2269                 Ok(ShutdownScript::new_p2wpkh_from_pubkey(self.shutdown_pubkey.clone()))
2270         }
2271 }
2272
2273 /// Similar to [`KeysManager`], but allows the node using this struct to receive phantom node
2274 /// payments.
2275 ///
2276 /// A phantom node payment is a payment made to a phantom invoice, which is an invoice that can be
2277 /// paid to one of multiple nodes. This works because we encode the invoice route hints such that
2278 /// LDK will recognize an incoming payment as destined for a phantom node, and collect the payment
2279 /// itself without ever needing to forward to this fake node.
2280 ///
2281 /// Phantom node payments are useful for load balancing between multiple LDK nodes. They also
2282 /// provide some fault tolerance, because payers will automatically retry paying other provided
2283 /// nodes in the case that one node goes down.
2284 ///
2285 /// Note that multi-path payments are not supported in phantom invoices for security reasons.
2286 // In the hypothetical case that we did support MPP phantom payments, there would be no way for
2287 // nodes to know when the full payment has been received (and the preimage can be released) without
2288 // significantly compromising on our safety guarantees. I.e., if we expose the ability for the user
2289 // to tell LDK when the preimage can be released, we open ourselves to attacks where the preimage
2290 // is released too early.
2291 //
2292 /// Switching between this struct and [`KeysManager`] will invalidate any previously issued
2293 /// invoices and attempts to pay previous invoices will fail.
2294 pub struct PhantomKeysManager {
2295         inner: KeysManager,
2296         inbound_payment_key: KeyMaterial,
2297         phantom_secret: SecretKey,
2298         phantom_node_id: PublicKey,
2299 }
2300
2301 impl EntropySource for PhantomKeysManager {
2302         fn get_secure_random_bytes(&self) -> [u8; 32] {
2303                 self.inner.get_secure_random_bytes()
2304         }
2305 }
2306
2307 impl NodeSigner for PhantomKeysManager {
2308         fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()> {
2309                 match recipient {
2310                         Recipient::Node => self.inner.get_node_id(Recipient::Node),
2311                         Recipient::PhantomNode => Ok(self.phantom_node_id.clone()),
2312                 }
2313         }
2314
2315         fn ecdh(
2316                 &self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>,
2317         ) -> Result<SharedSecret, ()> {
2318                 let mut node_secret = match recipient {
2319                         Recipient::Node => self.inner.node_secret.clone(),
2320                         Recipient::PhantomNode => self.phantom_secret.clone(),
2321                 };
2322                 if let Some(tweak) = tweak {
2323                         node_secret = node_secret.mul_tweak(tweak).map_err(|_| ())?;
2324                 }
2325                 Ok(SharedSecret::new(other_key, &node_secret))
2326         }
2327
2328         fn get_inbound_payment_key_material(&self) -> KeyMaterial {
2329                 self.inbound_payment_key.clone()
2330         }
2331
2332         fn sign_invoice(
2333                 &self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient,
2334         ) -> Result<RecoverableSignature, ()> {
2335                 let preimage = construct_invoice_preimage(&hrp_bytes, &invoice_data);
2336                 let secret = match recipient {
2337                         Recipient::Node => &self.inner.node_secret,
2338                         Recipient::PhantomNode => &self.phantom_secret,
2339                 };
2340                 Ok(self.inner.secp_ctx.sign_ecdsa_recoverable(
2341                         &hash_to_message!(&Sha256::hash(&preimage).to_byte_array()),
2342                         secret,
2343                 ))
2344         }
2345
2346         fn sign_bolt12_invoice_request(
2347                 &self, invoice_request: &UnsignedInvoiceRequest,
2348         ) -> Result<schnorr::Signature, ()> {
2349                 self.inner.sign_bolt12_invoice_request(invoice_request)
2350         }
2351
2352         fn sign_bolt12_invoice(
2353                 &self, invoice: &UnsignedBolt12Invoice,
2354         ) -> Result<schnorr::Signature, ()> {
2355                 self.inner.sign_bolt12_invoice(invoice)
2356         }
2357
2358         fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()> {
2359                 self.inner.sign_gossip_message(msg)
2360         }
2361 }
2362
2363 impl OutputSpender for PhantomKeysManager {
2364         /// See [`OutputSpender::spend_spendable_outputs`] and [`KeysManager::spend_spendable_outputs`]
2365         /// for documentation on this method.
2366         fn spend_spendable_outputs<C: Signing>(
2367                 &self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
2368                 change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
2369                 locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>,
2370         ) -> Result<Transaction, ()> {
2371                 self.inner.spend_spendable_outputs(
2372                         descriptors,
2373                         outputs,
2374                         change_destination_script,
2375                         feerate_sat_per_1000_weight,
2376                         locktime,
2377                         secp_ctx,
2378                 )
2379         }
2380 }
2381
2382 impl SignerProvider for PhantomKeysManager {
2383         type EcdsaSigner = InMemorySigner;
2384         #[cfg(taproot)]
2385         type TaprootSigner = InMemorySigner;
2386
2387         fn generate_channel_keys_id(
2388                 &self, inbound: bool, channel_value_satoshis: u64, user_channel_id: u128,
2389         ) -> [u8; 32] {
2390                 self.inner.generate_channel_keys_id(inbound, channel_value_satoshis, user_channel_id)
2391         }
2392
2393         fn derive_channel_signer(
2394                 &self, channel_value_satoshis: u64, channel_keys_id: [u8; 32],
2395         ) -> Self::EcdsaSigner {
2396                 self.inner.derive_channel_signer(channel_value_satoshis, channel_keys_id)
2397         }
2398
2399         fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::EcdsaSigner, DecodeError> {
2400                 self.inner.read_chan_signer(reader)
2401         }
2402
2403         fn get_destination_script(&self, channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()> {
2404                 self.inner.get_destination_script(channel_keys_id)
2405         }
2406
2407         fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
2408                 self.inner.get_shutdown_scriptpubkey()
2409         }
2410 }
2411
2412 impl PhantomKeysManager {
2413         /// Constructs a [`PhantomKeysManager`] given a 32-byte seed and an additional `cross_node_seed`
2414         /// that is shared across all nodes that intend to participate in [phantom node payments]
2415         /// together.
2416         ///
2417         /// See [`KeysManager::new`] for more information on `seed`, `starting_time_secs`, and
2418         /// `starting_time_nanos`.
2419         ///
2420         /// `cross_node_seed` must be the same across all phantom payment-receiving nodes and also the
2421         /// same across restarts, or else inbound payments may fail.
2422         ///
2423         /// [phantom node payments]: PhantomKeysManager
2424         pub fn new(
2425                 seed: &[u8; 32], starting_time_secs: u64, starting_time_nanos: u32,
2426                 cross_node_seed: &[u8; 32],
2427         ) -> Self {
2428                 let inner = KeysManager::new(seed, starting_time_secs, starting_time_nanos);
2429                 let (inbound_key, phantom_key) = hkdf_extract_expand_twice(
2430                         b"LDK Inbound and Phantom Payment Key Expansion",
2431                         cross_node_seed,
2432                 );
2433                 let phantom_secret = SecretKey::from_slice(&phantom_key).unwrap();
2434                 let phantom_node_id = PublicKey::from_secret_key(&inner.secp_ctx, &phantom_secret);
2435                 Self {
2436                         inner,
2437                         inbound_payment_key: KeyMaterial(inbound_key),
2438                         phantom_secret,
2439                         phantom_node_id,
2440                 }
2441         }
2442
2443         /// See [`KeysManager::derive_channel_keys`] for documentation on this method.
2444         pub fn derive_channel_keys(
2445                 &self, channel_value_satoshis: u64, params: &[u8; 32],
2446         ) -> InMemorySigner {
2447                 self.inner.derive_channel_keys(channel_value_satoshis, params)
2448         }
2449
2450         /// Gets the "node_id" secret key used to sign gossip announcements, decode onion data, etc.
2451         pub fn get_node_secret_key(&self) -> SecretKey {
2452                 self.inner.get_node_secret_key()
2453         }
2454
2455         /// Gets the "node_id" secret key of the phantom node used to sign invoices, decode the
2456         /// last-hop onion data, etc.
2457         pub fn get_phantom_node_secret_key(&self) -> SecretKey {
2458                 self.phantom_secret
2459         }
2460 }
2461
2462 /// An implementation of [`EntropySource`] using ChaCha20.
2463 #[derive(Debug)]
2464 pub struct RandomBytes {
2465         /// Seed from which all randomness produced is derived from.
2466         seed: [u8; 32],
2467         /// Tracks the number of times we've produced randomness to ensure we don't return the same
2468         /// bytes twice.
2469         index: AtomicCounter,
2470 }
2471
2472 impl RandomBytes {
2473         /// Creates a new instance using the given seed.
2474         pub fn new(seed: [u8; 32]) -> Self {
2475                 Self { seed, index: AtomicCounter::new() }
2476         }
2477 }
2478
2479 impl EntropySource for RandomBytes {
2480         fn get_secure_random_bytes(&self) -> [u8; 32] {
2481                 let index = self.index.get_increment();
2482                 let mut nonce = [0u8; 16];
2483                 nonce[..8].copy_from_slice(&index.to_be_bytes());
2484                 ChaCha20::get_single_block(&self.seed, &nonce)
2485         }
2486 }
2487
2488 // Ensure that EcdsaChannelSigner can have a vtable
2489 #[test]
2490 pub fn dyn_sign() {
2491         let _signer: Box<dyn EcdsaChannelSigner>;
2492 }
2493
2494 #[cfg(ldk_bench)]
2495 pub mod benches {
2496         use crate::sign::{EntropySource, KeysManager};
2497         use bitcoin::blockdata::constants::genesis_block;
2498         use bitcoin::Network;
2499         use std::sync::mpsc::TryRecvError;
2500         use std::sync::{mpsc, Arc};
2501         use std::thread;
2502         use std::time::Duration;
2503
2504         use criterion::Criterion;
2505
2506         pub fn bench_get_secure_random_bytes(bench: &mut Criterion) {
2507                 let seed = [0u8; 32];
2508                 let now = Duration::from_secs(genesis_block(Network::Testnet).header.time as u64);
2509                 let keys_manager = Arc::new(KeysManager::new(&seed, now.as_secs(), now.subsec_micros()));
2510
2511                 let mut handles = Vec::new();
2512                 let mut stops = Vec::new();
2513                 for _ in 1..5 {
2514                         let keys_manager_clone = Arc::clone(&keys_manager);
2515                         let (stop_sender, stop_receiver) = mpsc::channel();
2516                         let handle = thread::spawn(move || loop {
2517                                 keys_manager_clone.get_secure_random_bytes();
2518                                 match stop_receiver.try_recv() {
2519                                         Ok(_) | Err(TryRecvError::Disconnected) => {
2520                                                 println!("Terminating.");
2521                                                 break;
2522                                         },
2523                                         Err(TryRecvError::Empty) => {},
2524                                 }
2525                         });
2526                         handles.push(handle);
2527                         stops.push(stop_sender);
2528                 }
2529
2530                 bench.bench_function("get_secure_random_bytes", |b| {
2531                         b.iter(|| keys_manager.get_secure_random_bytes())
2532                 });
2533
2534                 for stop in stops {
2535                         let _ = stop.send(());
2536                 }
2537                 for handle in handles {
2538                         handle.join().unwrap();
2539                 }
2540         }
2541 }