1 // This file is Copyright its original authors, visible in version control
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
10 //! Provides keys to LDK and defines some useful objects describing spendable on-chain outputs.
12 //! The provided output descriptors follow a custom LDK data format and are currently not fully
13 //! compatible with Bitcoin Core output descriptors.
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;
24 use bitcoin::sighash::EcdsaSighashType;
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};
32 use bitcoin::secp256k1::ecdh::SharedSecret;
33 use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature};
34 use bitcoin::secp256k1::schnorr;
36 use bitcoin::secp256k1::All;
37 use bitcoin::secp256k1::{KeyPair, PublicKey, Scalar, Secp256k1, SecretKey, Signing};
38 use bitcoin::{secp256k1, Sequence, Txid, Witness};
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 make_funding_redeemscript, ChannelPublicKeys, ChannelTransactionParameters, ClosingTransaction,
44 CommitmentTransaction, HTLCOutputInCommitment, HolderCommitmentTransaction,
46 use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
47 use crate::ln::channel_keys::{
48 DelayedPaymentBasepoint, DelayedPaymentKey, HtlcBasepoint, HtlcKey, RevocationBasepoint,
52 use crate::ln::msgs::PartialSignatureWithNonce;
53 use crate::ln::msgs::{UnsignedChannelAnnouncement, UnsignedGossipMessage};
54 use crate::ln::script::ShutdownScript;
55 use crate::ln::{chan_utils, PaymentPreimage};
56 use crate::offers::invoice::UnsignedBolt12Invoice;
57 use crate::offers::invoice_request::UnsignedInvoiceRequest;
58 use crate::util::ser::{Readable, ReadableArgs, Writeable, Writer};
59 use crate::util::transaction_utils;
61 use crate::crypto::chacha20::ChaCha20;
62 use crate::io::{self, Error};
63 use crate::ln::features::ChannelTypeFeatures;
64 use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
65 use crate::prelude::*;
66 use crate::sign::ecdsa::{EcdsaChannelSigner, WriteableEcdsaChannelSigner};
68 use crate::sign::taproot::TaprootChannelSigner;
69 use crate::util::atomic_counter::AtomicCounter;
70 use crate::util::invoice::construct_invoice_preimage;
72 use core::sync::atomic::{AtomicUsize, Ordering};
74 use musig2::types::{PartialSignature, PublicNonce};
76 pub(crate) mod type_resolver;
82 /// Used as initial key material, to be expanded into multiple secret keys (but not to be used
83 /// directly). This is used within LDK to encrypt/decrypt inbound payment data.
85 /// This is not exported to bindings users as we just use `[u8; 32]` directly
86 #[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
87 pub struct KeyMaterial(pub [u8; 32]);
89 /// Information about a spendable output to a P2WSH script.
91 /// See [`SpendableOutputDescriptor::DelayedPaymentOutput`] for more details on how to spend this.
92 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
93 pub struct DelayedPaymentOutputDescriptor {
94 /// The outpoint which is spendable.
95 pub outpoint: OutPoint,
96 /// Per commitment point to derive the delayed payment key by key holder.
97 pub per_commitment_point: PublicKey,
98 /// The `nSequence` value which must be set in the spending input to satisfy the `OP_CSV` in
99 /// the witness_script.
100 pub to_self_delay: u16,
101 /// The output which is referenced by the given outpoint.
103 /// The revocation point specific to the commitment transaction which was broadcast. Used to
104 /// derive the witnessScript for this output.
105 pub revocation_pubkey: RevocationKey,
106 /// Arbitrary identification information returned by a call to [`ChannelSigner::channel_keys_id`].
107 /// This may be useful in re-deriving keys used in the channel to spend the output.
108 pub channel_keys_id: [u8; 32],
109 /// The value of the channel which this output originated from, possibly indirectly.
110 pub channel_value_satoshis: u64,
112 impl DelayedPaymentOutputDescriptor {
113 /// The maximum length a well-formed witness spending one of these should have.
114 /// Note: If you have the grind_signatures feature enabled, this will be at least 1 byte
116 // Calculated as 1 byte length + 73 byte signature, 1 byte empty vec push, 1 byte length plus
117 // redeemscript push length.
118 pub const MAX_WITNESS_LENGTH: u64 =
119 1 + 73 + 1 + chan_utils::REVOKEABLE_REDEEMSCRIPT_MAX_LENGTH as u64 + 1;
122 impl_writeable_tlv_based!(DelayedPaymentOutputDescriptor, {
123 (0, outpoint, required),
124 (2, per_commitment_point, required),
125 (4, to_self_delay, required),
126 (6, output, required),
127 (8, revocation_pubkey, required),
128 (10, channel_keys_id, required),
129 (12, channel_value_satoshis, required),
132 pub(crate) const P2WPKH_WITNESS_WEIGHT: u64 = 1 /* num stack items */ +
134 73 /* sig including sighash flag */ +
135 1 /* pubkey length */ +
138 /// Information about a spendable output to our "payment key".
140 /// See [`SpendableOutputDescriptor::StaticPaymentOutput`] for more details on how to spend this.
141 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
142 pub struct StaticPaymentOutputDescriptor {
143 /// The outpoint which is spendable.
144 pub outpoint: OutPoint,
145 /// The output which is referenced by the given outpoint.
147 /// Arbitrary identification information returned by a call to [`ChannelSigner::channel_keys_id`].
148 /// This may be useful in re-deriving keys used in the channel to spend the output.
149 pub channel_keys_id: [u8; 32],
150 /// The value of the channel which this transactions spends.
151 pub channel_value_satoshis: u64,
152 /// The necessary channel parameters that need to be provided to the re-derived signer through
153 /// [`ChannelSigner::provide_channel_parameters`].
155 /// Added as optional, but always `Some` if the descriptor was produced in v0.0.117 or later.
156 pub channel_transaction_parameters: Option<ChannelTransactionParameters>,
158 impl StaticPaymentOutputDescriptor {
159 /// Returns the `witness_script` of the spendable output.
161 /// Note that this will only return `Some` for [`StaticPaymentOutputDescriptor`]s that
162 /// originated from an anchor outputs channel, as they take the form of a P2WSH script.
163 pub fn witness_script(&self) -> Option<ScriptBuf> {
164 self.channel_transaction_parameters.as_ref().and_then(|channel_params| {
165 if channel_params.supports_anchors() {
166 let payment_point = channel_params.holder_pubkeys.payment_point;
167 Some(chan_utils::get_to_countersignatory_with_anchors_redeemscript(&payment_point))
174 /// The maximum length a well-formed witness spending one of these should have.
175 /// Note: If you have the grind_signatures feature enabled, this will be at least 1 byte
177 pub fn max_witness_length(&self) -> u64 {
178 if self.channel_transaction_parameters.as_ref().map_or(false, |p| p.supports_anchors()) {
179 let witness_script_weight = 1 /* pubkey push */ + 33 /* pubkey */ +
180 1 /* OP_CHECKSIGVERIFY */ + 1 /* OP_1 */ + 1 /* OP_CHECKSEQUENCEVERIFY */;
181 1 /* num witness items */ + 1 /* sig push */ + 73 /* sig including sighash flag */ +
182 1 /* witness script push */ + witness_script_weight
184 P2WPKH_WITNESS_WEIGHT
188 impl_writeable_tlv_based!(StaticPaymentOutputDescriptor, {
189 (0, outpoint, required),
190 (2, output, required),
191 (4, channel_keys_id, required),
192 (6, channel_value_satoshis, required),
193 (7, channel_transaction_parameters, option),
196 /// Describes the necessary information to spend a spendable output.
198 /// When on-chain outputs are created by LDK (which our counterparty is not able to claim at any
199 /// point in the future) a [`SpendableOutputs`] event is generated which you must track and be able
200 /// to spend on-chain. The information needed to do this is provided in this enum, including the
201 /// outpoint describing which `txid` and output `index` is available, the full output which exists
202 /// at that `txid`/`index`, and any keys or other information required to sign.
204 /// [`SpendableOutputs`]: crate::events::Event::SpendableOutputs
205 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
206 pub enum SpendableOutputDescriptor {
207 /// An output to a script which was provided via [`SignerProvider`] directly, either from
208 /// [`get_destination_script`] or [`get_shutdown_scriptpubkey`], thus you should already
209 /// know how to spend it. No secret keys are provided as LDK was never given any key.
210 /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
211 /// on-chain using the payment preimage or after it has timed out.
213 /// [`get_shutdown_scriptpubkey`]: SignerProvider::get_shutdown_scriptpubkey
214 /// [`get_destination_script`]: SignerProvider::get_shutdown_scriptpubkey
216 /// The outpoint which is spendable.
218 /// The output which is referenced by the given outpoint.
220 /// The `channel_keys_id` for the channel which this output came from.
222 /// For channels which were generated on LDK 0.0.119 or later, this is the value which was
223 /// passed to the [`SignerProvider::get_destination_script`] call which provided this
226 /// For channels which were generated prior to LDK 0.0.119, no such argument existed,
227 /// however this field may still be filled in if such data is available.
228 channel_keys_id: Option<[u8; 32]>,
230 /// An output to a P2WSH script which can be spent with a single signature after an `OP_CSV`
233 /// The witness in the spending input should be:
235 /// <BIP 143 signature> <empty vector> (MINIMALIF standard rule) <provided witnessScript>
238 /// Note that the `nSequence` field in the spending input must be set to
239 /// [`DelayedPaymentOutputDescriptor::to_self_delay`] (which means the transaction is not
240 /// broadcastable until at least [`DelayedPaymentOutputDescriptor::to_self_delay`] blocks after
241 /// the outpoint confirms, see [BIP
242 /// 68](https://github.com/bitcoin/bips/blob/master/bip-0068.mediawiki)). Also note that LDK
243 /// won't generate a [`SpendableOutputDescriptor`] until the corresponding block height
246 /// These are generally the result of a "revocable" output to us, spendable only by us unless
247 /// it is an output from an old state which we broadcast (which should never happen).
249 /// To derive the delayed payment key which is used to sign this input, you must pass the
250 /// holder [`InMemorySigner::delayed_payment_base_key`] (i.e., the private key which corresponds to the
251 /// [`ChannelPublicKeys::delayed_payment_basepoint`] in [`ChannelSigner::pubkeys`]) and the provided
252 /// [`DelayedPaymentOutputDescriptor::per_commitment_point`] to [`chan_utils::derive_private_key`]. The DelayedPaymentKey can be
253 /// generated without the secret key using [`DelayedPaymentKey::from_basepoint`] and only the
254 /// [`ChannelPublicKeys::delayed_payment_basepoint`] which appears in [`ChannelSigner::pubkeys`].
256 /// To derive the [`DelayedPaymentOutputDescriptor::revocation_pubkey`] provided here (which is
257 /// used in the witness script generation), you must pass the counterparty
258 /// [`ChannelPublicKeys::revocation_basepoint`] (which appears in the call to
259 /// [`ChannelSigner::provide_channel_parameters`]) and the provided
260 /// [`DelayedPaymentOutputDescriptor::per_commitment_point`] to
261 /// [`RevocationKey`].
263 /// The witness script which is hashed and included in the output `script_pubkey` may be
264 /// regenerated by passing the [`DelayedPaymentOutputDescriptor::revocation_pubkey`] (derived
265 /// as explained above), our delayed payment pubkey (derived as explained above), and the
266 /// [`DelayedPaymentOutputDescriptor::to_self_delay`] contained here to
267 /// [`chan_utils::get_revokeable_redeemscript`].
268 DelayedPaymentOutput(DelayedPaymentOutputDescriptor),
269 /// An output spendable exclusively by our payment key (i.e., the private key that corresponds
270 /// to the `payment_point` in [`ChannelSigner::pubkeys`]). The output type depends on the
271 /// channel type negotiated.
273 /// On an anchor outputs channel, the witness in the spending input is:
275 /// <BIP 143 signature> <witness script>
278 /// Otherwise, it is:
280 /// <BIP 143 signature> <payment key>
283 /// These are generally the result of our counterparty having broadcast the current state,
284 /// allowing us to claim the non-HTLC-encumbered outputs immediately, or after one confirmation
285 /// in the case of anchor outputs channels.
286 StaticPaymentOutput(StaticPaymentOutputDescriptor),
289 impl_writeable_tlv_based_enum!(SpendableOutputDescriptor,
290 (0, StaticOutput) => {
291 (0, outpoint, required),
292 (1, channel_keys_id, option),
293 (2, output, required),
296 (1, DelayedPaymentOutput),
297 (2, StaticPaymentOutput),
300 impl SpendableOutputDescriptor {
301 /// Turns this into a [`bitcoin::psbt::Input`] which can be used to create a
302 /// [`PartiallySignedTransaction`] which spends the given descriptor.
304 /// Note that this does not include any signatures, just the information required to
305 /// construct the transaction and sign it.
307 /// This is not exported to bindings users as there is no standard serialization for an input.
308 /// See [`Self::create_spendable_outputs_psbt`] instead.
309 pub fn to_psbt_input(&self) -> bitcoin::psbt::Input {
311 SpendableOutputDescriptor::StaticOutput { output, .. } => {
312 // Is a standard P2WPKH, no need for witness script
313 bitcoin::psbt::Input { witness_utxo: Some(output.clone()), ..Default::default() }
315 SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
316 // TODO we could add the witness script as well
317 bitcoin::psbt::Input {
318 witness_utxo: Some(descriptor.output.clone()),
322 SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
323 // TODO we could add the witness script as well
324 bitcoin::psbt::Input {
325 witness_utxo: Some(descriptor.output.clone()),
332 /// Creates an unsigned [`PartiallySignedTransaction`] which spends the given descriptors to
333 /// the given outputs, plus an output to the given change destination (if sufficient
334 /// change value remains). The PSBT will have a feerate, at least, of the given value.
336 /// The `locktime` argument is used to set the transaction's locktime. If `None`, the
337 /// transaction will have a locktime of 0. It it recommended to set this to the current block
338 /// height to avoid fee sniping, unless you have some specific reason to use a different
341 /// Returns the PSBT and expected max transaction weight.
343 /// Returns `Err(())` if the output value is greater than the input value minus required fee,
344 /// if a descriptor was duplicated, or if an output descriptor `script_pubkey`
345 /// does not match the one we can spend.
347 /// We do not enforce that outputs meet the dust limit or that any output scripts are standard.
348 pub fn create_spendable_outputs_psbt(
349 descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
350 change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
351 locktime: Option<LockTime>,
352 ) -> Result<(PartiallySignedTransaction, u64), ()> {
353 let mut input = Vec::with_capacity(descriptors.len());
354 let mut input_value = 0;
355 let mut witness_weight = 0;
356 let mut output_set = hash_set_with_capacity(descriptors.len());
357 for outp in descriptors {
359 SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
360 if !output_set.insert(descriptor.outpoint) {
363 let sequence = if descriptor
364 .channel_transaction_parameters
366 .map_or(false, |p| p.supports_anchors())
368 Sequence::from_consensus(1)
373 previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
374 script_sig: ScriptBuf::new(),
376 witness: Witness::new(),
378 witness_weight += descriptor.max_witness_length();
379 #[cfg(feature = "grind_signatures")]
381 // Guarantees a low R signature
384 input_value += descriptor.output.value;
386 SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
387 if !output_set.insert(descriptor.outpoint) {
391 previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
392 script_sig: ScriptBuf::new(),
393 sequence: Sequence(descriptor.to_self_delay as u32),
394 witness: Witness::new(),
396 witness_weight += DelayedPaymentOutputDescriptor::MAX_WITNESS_LENGTH;
397 #[cfg(feature = "grind_signatures")]
399 // Guarantees a low R signature
402 input_value += descriptor.output.value;
404 SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output, .. } => {
405 if !output_set.insert(*outpoint) {
409 previous_output: outpoint.into_bitcoin_outpoint(),
410 script_sig: ScriptBuf::new(),
411 sequence: Sequence::ZERO,
412 witness: Witness::new(),
414 witness_weight += 1 + 73 + 34;
415 #[cfg(feature = "grind_signatures")]
417 // Guarantees a low R signature
420 input_value += output.value;
423 if input_value > MAX_VALUE_MSAT / 1000 {
427 let mut tx = Transaction {
429 lock_time: locktime.unwrap_or(LockTime::ZERO),
433 let expected_max_weight = transaction_utils::maybe_add_change_output(
437 feerate_sat_per_1000_weight,
438 change_destination_script,
441 let psbt_inputs = descriptors.iter().map(|d| d.to_psbt_input()).collect::<Vec<_>>();
442 let psbt = PartiallySignedTransaction {
444 outputs: vec![Default::default(); tx.output.len()],
446 xpub: Default::default(),
448 proprietary: Default::default(),
449 unknown: Default::default(),
451 Ok((psbt, expected_max_weight))
455 /// The parameters required to derive a channel signer via [`SignerProvider`].
456 #[derive(Clone, Debug, PartialEq, Eq)]
457 pub struct ChannelDerivationParameters {
458 /// The value in satoshis of the channel we're attempting to spend the anchor output of.
459 pub value_satoshis: u64,
460 /// The unique identifier to re-derive the signer for the associated channel.
461 pub keys_id: [u8; 32],
462 /// The necessary channel parameters that need to be provided to the re-derived signer through
463 /// [`ChannelSigner::provide_channel_parameters`].
464 pub transaction_parameters: ChannelTransactionParameters,
467 impl_writeable_tlv_based!(ChannelDerivationParameters, {
468 (0, value_satoshis, required),
469 (2, keys_id, required),
470 (4, transaction_parameters, required),
473 /// A descriptor used to sign for a commitment transaction's HTLC output.
474 #[derive(Clone, Debug, PartialEq, Eq)]
475 pub struct HTLCDescriptor {
476 /// The parameters required to derive the signer for the HTLC input.
477 pub channel_derivation_parameters: ChannelDerivationParameters,
478 /// The txid of the commitment transaction in which the HTLC output lives.
479 pub commitment_txid: Txid,
480 /// The number of the commitment transaction in which the HTLC output lives.
481 pub per_commitment_number: u64,
482 /// The key tweak corresponding to the number of the commitment transaction in which the HTLC
483 /// output lives. This tweak is applied to all the basepoints for both parties in the channel to
484 /// arrive at unique keys per commitment.
486 /// See <https://github.com/lightning/bolts/blob/master/03-transactions.md#keys> for more info.
487 pub per_commitment_point: PublicKey,
488 /// The feerate to use on the HTLC claiming transaction. This is always `0` for HTLCs
489 /// originating from a channel supporting anchor outputs, otherwise it is the channel's
490 /// negotiated feerate at the time the commitment transaction was built.
491 pub feerate_per_kw: u32,
492 /// The details of the HTLC as it appears in the commitment transaction.
493 pub htlc: HTLCOutputInCommitment,
494 /// The preimage, if `Some`, to claim the HTLC output with. If `None`, the timeout path must be
496 pub preimage: Option<PaymentPreimage>,
497 /// The counterparty's signature required to spend the HTLC output.
498 pub counterparty_sig: Signature,
501 impl_writeable_tlv_based!(HTLCDescriptor, {
502 (0, channel_derivation_parameters, required),
503 (1, feerate_per_kw, (default_value, 0)),
504 (2, commitment_txid, required),
505 (4, per_commitment_number, required),
506 (6, per_commitment_point, required),
508 (10, preimage, option),
509 (12, counterparty_sig, required),
512 impl HTLCDescriptor {
513 /// Returns the outpoint of the HTLC output in the commitment transaction. This is the outpoint
514 /// being spent by the HTLC input in the HTLC transaction.
515 pub fn outpoint(&self) -> bitcoin::OutPoint {
517 txid: self.commitment_txid,
518 vout: self.htlc.transaction_output_index.unwrap(),
522 /// Returns the UTXO to be spent by the HTLC input, which can be obtained via
523 /// [`Self::unsigned_tx_input`].
524 pub fn previous_utxo<C: secp256k1::Signing + secp256k1::Verification>(
525 &self, secp: &Secp256k1<C>,
528 script_pubkey: self.witness_script(secp).to_v0_p2wsh(),
529 value: self.htlc.amount_msat / 1000,
533 /// Returns the unsigned transaction input spending the HTLC output in the commitment
535 pub fn unsigned_tx_input(&self) -> TxIn {
536 chan_utils::build_htlc_input(
537 &self.commitment_txid,
539 &self.channel_derivation_parameters.transaction_parameters.channel_type_features,
543 /// Returns the delayed output created as a result of spending the HTLC output in the commitment
545 pub fn tx_output<C: secp256k1::Signing + secp256k1::Verification>(
546 &self, secp: &Secp256k1<C>,
549 self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
550 let broadcaster_keys = channel_params.broadcaster_pubkeys();
551 let counterparty_keys = channel_params.countersignatory_pubkeys();
552 let broadcaster_delayed_key = DelayedPaymentKey::from_basepoint(
554 &broadcaster_keys.delayed_payment_basepoint,
555 &self.per_commitment_point,
557 let counterparty_revocation_key = &RevocationKey::from_basepoint(
559 &counterparty_keys.revocation_basepoint,
560 &self.per_commitment_point,
562 chan_utils::build_htlc_output(
564 channel_params.contest_delay(),
566 channel_params.channel_type_features(),
567 &broadcaster_delayed_key,
568 &counterparty_revocation_key,
572 /// Returns the witness script of the HTLC output in the commitment transaction.
573 pub fn witness_script<C: secp256k1::Signing + secp256k1::Verification>(
574 &self, secp: &Secp256k1<C>,
577 self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
578 let broadcaster_keys = channel_params.broadcaster_pubkeys();
579 let counterparty_keys = channel_params.countersignatory_pubkeys();
580 let broadcaster_htlc_key = HtlcKey::from_basepoint(
582 &broadcaster_keys.htlc_basepoint,
583 &self.per_commitment_point,
585 let counterparty_htlc_key = HtlcKey::from_basepoint(
587 &counterparty_keys.htlc_basepoint,
588 &self.per_commitment_point,
590 let counterparty_revocation_key = &RevocationKey::from_basepoint(
592 &counterparty_keys.revocation_basepoint,
593 &self.per_commitment_point,
595 chan_utils::get_htlc_redeemscript_with_explicit_keys(
597 channel_params.channel_type_features(),
598 &broadcaster_htlc_key,
599 &counterparty_htlc_key,
600 &counterparty_revocation_key,
604 /// Returns the fully signed witness required to spend the HTLC output in the commitment
606 pub fn tx_input_witness(&self, signature: &Signature, witness_script: &Script) -> Witness {
607 chan_utils::build_htlc_input_witness(
609 &self.counterparty_sig,
612 &self.channel_derivation_parameters.transaction_parameters.channel_type_features,
616 /// Derives the channel signer required to sign the HTLC input.
617 pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(
618 &self, signer_provider: &SP,
621 SP::Target: SignerProvider<EcdsaSigner = S>,
623 let mut signer = signer_provider.derive_channel_signer(
624 self.channel_derivation_parameters.value_satoshis,
625 self.channel_derivation_parameters.keys_id,
628 .provide_channel_parameters(&self.channel_derivation_parameters.transaction_parameters);
633 /// A trait to handle Lightning channel key material without concretizing the channel type or
634 /// the signature mechanism.
635 pub trait ChannelSigner {
636 /// Gets the per-commitment point for a specific commitment number
638 /// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
639 fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>)
642 /// Gets the commitment secret for a specific commitment number as part of the revocation process
644 /// An external signer implementation should error here if the commitment was already signed
645 /// and should refuse to sign it in the future.
647 /// May be called more than once for the same index.
649 /// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
650 // TODO: return a Result so we can signal a validation error
651 fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
653 /// Validate the counterparty's signatures on the holder commitment transaction and HTLCs.
655 /// This is required in order for the signer to make sure that releasing a commitment
656 /// secret won't leave us without a broadcastable holder transaction.
657 /// Policy checks should be implemented in this function, including checking the amount
658 /// sent to us and checking the HTLCs.
660 /// The preimages of outbound HTLCs that were fulfilled since the last commitment are provided.
661 /// A validating signer should ensure that an HTLC output is removed only when the matching
662 /// preimage is provided, or when the value to holder is restored.
664 /// Note that all the relevant preimages will be provided, but there may also be additional
665 /// irrelevant or duplicate preimages.
666 fn validate_holder_commitment(
667 &self, holder_tx: &HolderCommitmentTransaction,
668 outbound_htlc_preimages: Vec<PaymentPreimage>,
671 /// Validate the counterparty's revocation.
673 /// This is required in order for the signer to make sure that the state has moved
674 /// forward and it is safe to sign the next counterparty commitment.
675 fn validate_counterparty_revocation(&self, idx: u64, secret: &SecretKey) -> Result<(), ()>;
677 /// Returns the holder's channel public keys and basepoints.
678 fn pubkeys(&self) -> &ChannelPublicKeys;
680 /// Returns an arbitrary identifier describing the set of keys which are provided back to you in
681 /// some [`SpendableOutputDescriptor`] types. This should be sufficient to identify this
682 /// [`EcdsaChannelSigner`] object uniquely and lookup or re-derive its keys.
683 fn channel_keys_id(&self) -> [u8; 32];
685 /// Set the counterparty static channel data, including basepoints,
686 /// `counterparty_selected`/`holder_selected_contest_delay` and funding outpoint.
688 /// This data is static, and will never change for a channel once set. For a given [`ChannelSigner`]
689 /// instance, LDK will call this method exactly once - either immediately after construction
690 /// (not including if done via [`SignerProvider::read_chan_signer`]) or when the funding
691 /// information has been generated.
693 /// channel_parameters.is_populated() MUST be true.
694 fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters);
697 /// Specifies the recipient of an invoice.
699 /// This indicates to [`NodeSigner::sign_invoice`] what node secret key should be used to sign
702 /// The invoice should be signed with the local node secret key.
704 /// The invoice should be signed with the phantom node secret key. This secret key must be the
705 /// same for all nodes participating in the [phantom node payment].
707 /// [phantom node payment]: PhantomKeysManager
711 /// A trait that describes a source of entropy.
712 pub trait EntropySource {
713 /// Gets a unique, cryptographically-secure, random 32-byte value. This method must return a
714 /// different value each time it is called.
715 fn get_secure_random_bytes(&self) -> [u8; 32];
718 /// A trait that can handle cryptographic operations at the scope level of a node.
719 pub trait NodeSigner {
720 /// Get secret key material as bytes for use in encrypting and decrypting inbound payment data.
722 /// If the implementor of this trait supports [phantom node payments], then every node that is
723 /// intended to be included in the phantom invoice route hints must return the same value from
725 // This is because LDK avoids storing inbound payment data by encrypting payment data in the
726 // payment hash and/or payment secret, therefore for a payment to be receivable by multiple
727 // nodes, they must share the key that encrypts this payment data.
729 /// This method must return the same value each time it is called.
731 /// [phantom node payments]: PhantomKeysManager
732 fn get_inbound_payment_key_material(&self) -> KeyMaterial;
734 /// Get node id based on the provided [`Recipient`].
736 /// This method must return the same value each time it is called with a given [`Recipient`]
739 /// Errors if the [`Recipient`] variant is not supported by the implementation.
740 fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()>;
742 /// Gets the ECDH shared secret of our node secret and `other_key`, multiplying by `tweak` if
743 /// one is provided. Note that this tweak can be applied to `other_key` instead of our node
744 /// secret, though this is less efficient.
746 /// Note that if this fails while attempting to forward an HTLC, LDK will panic. The error
747 /// should be resolved to allow LDK to resume forwarding HTLCs.
749 /// Errors if the [`Recipient`] variant is not supported by the implementation.
751 &self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>,
752 ) -> Result<SharedSecret, ()>;
756 /// By parameterizing by the raw invoice bytes instead of the hash, we allow implementors of
757 /// this trait to parse the invoice and make sure they're signing what they expect, rather than
758 /// blindly signing the hash.
760 /// The `hrp_bytes` are ASCII bytes, while the `invoice_data` is base32.
762 /// The secret key used to sign the invoice is dependent on the [`Recipient`].
764 /// Errors if the [`Recipient`] variant is not supported by the implementation.
766 &self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient,
767 ) -> Result<RecoverableSignature, ()>;
769 /// Signs the [`TaggedHash`] of a BOLT 12 invoice request.
771 /// May be called by a function passed to [`UnsignedInvoiceRequest::sign`] where
772 /// `invoice_request` is the callee.
774 /// Implementors may check that the `invoice_request` is expected rather than blindly signing
775 /// the tagged hash. An `Ok` result should sign `invoice_request.tagged_hash().as_digest()` with
776 /// the node's signing key or an ephemeral key to preserve privacy, whichever is associated with
777 /// [`UnsignedInvoiceRequest::payer_id`].
779 /// [`TaggedHash`]: crate::offers::merkle::TaggedHash
780 fn sign_bolt12_invoice_request(
781 &self, invoice_request: &UnsignedInvoiceRequest,
782 ) -> Result<schnorr::Signature, ()>;
784 /// Signs the [`TaggedHash`] of a BOLT 12 invoice.
786 /// May be called by a function passed to [`UnsignedBolt12Invoice::sign`] where `invoice` is the
789 /// Implementors may check that the `invoice` is expected rather than blindly signing the tagged
790 /// hash. An `Ok` result should sign `invoice.tagged_hash().as_digest()` with the node's signing
791 /// key or an ephemeral key to preserve privacy, whichever is associated with
792 /// [`UnsignedBolt12Invoice::signing_pubkey`].
794 /// [`TaggedHash`]: crate::offers::merkle::TaggedHash
795 fn sign_bolt12_invoice(
796 &self, invoice: &UnsignedBolt12Invoice,
797 ) -> Result<schnorr::Signature, ()>;
799 /// Sign a gossip message.
801 /// Note that if this fails, LDK may panic and the message will not be broadcast to the network
802 /// or a possible channel counterparty. If LDK panics, the error should be resolved to allow the
803 /// message to be broadcast, as otherwise it may prevent one from receiving funds over the
804 /// corresponding channel.
805 fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()>;
808 /// A trait that describes a wallet capable of creating a spending [`Transaction`] from a set of
809 /// [`SpendableOutputDescriptor`]s.
810 pub trait OutputSpender {
811 /// Creates a [`Transaction`] which spends the given descriptors to the given outputs, plus an
812 /// output to the given change destination (if sufficient change value remains). The
813 /// transaction will have a feerate, at least, of the given value.
815 /// The `locktime` argument is used to set the transaction's locktime. If `None`, the
816 /// transaction will have a locktime of 0. It it recommended to set this to the current block
817 /// height to avoid fee sniping, unless you have some specific reason to use a different
820 /// Returns `Err(())` if the output value is greater than the input value minus required fee,
821 /// if a descriptor was duplicated, or if an output descriptor `script_pubkey`
822 /// does not match the one we can spend.
823 fn spend_spendable_outputs<C: Signing>(
824 &self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
825 change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
826 locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>,
827 ) -> Result<Transaction, ()>;
830 // Primarily needed in doctests because of https://github.com/rust-lang/rust/issues/67295
831 /// A dynamic [`SignerProvider`] temporarily needed for doc tests.
834 #[deprecated(note = "Remove once taproot cfg is removed")]
835 pub type DynSignerProvider =
836 dyn SignerProvider<EcdsaSigner = InMemorySigner, TaprootSigner = InMemorySigner>;
838 /// A dynamic [`SignerProvider`] temporarily needed for doc tests.
841 #[deprecated(note = "Remove once taproot cfg is removed")]
842 pub type DynSignerProvider = dyn SignerProvider<EcdsaSigner = InMemorySigner>;
844 /// A trait that can return signer instances for individual channels.
845 pub trait SignerProvider {
846 /// A type which implements [`WriteableEcdsaChannelSigner`] which will be returned by [`Self::derive_channel_signer`].
847 type EcdsaSigner: WriteableEcdsaChannelSigner;
849 /// A type which implements [`TaprootChannelSigner`]
850 type TaprootSigner: TaprootChannelSigner;
852 /// Generates a unique `channel_keys_id` that can be used to obtain a [`Self::EcdsaSigner`] through
853 /// [`SignerProvider::derive_channel_signer`]. The `user_channel_id` is provided to allow
854 /// implementations of [`SignerProvider`] to maintain a mapping between itself and the generated
855 /// `channel_keys_id`.
857 /// This method must return a different value each time it is called.
858 fn generate_channel_keys_id(
859 &self, inbound: bool, channel_value_satoshis: u64, user_channel_id: u128,
862 /// Derives the private key material backing a `Signer`.
864 /// To derive a new `Signer`, a fresh `channel_keys_id` should be obtained through
865 /// [`SignerProvider::generate_channel_keys_id`]. Otherwise, an existing `Signer` can be
866 /// re-derived from its `channel_keys_id`, which can be obtained through its trait method
867 /// [`ChannelSigner::channel_keys_id`].
868 fn derive_channel_signer(
869 &self, channel_value_satoshis: u64, channel_keys_id: [u8; 32],
870 ) -> Self::EcdsaSigner;
872 /// Reads a [`Signer`] for this [`SignerProvider`] from the given input stream.
873 /// This is only called during deserialization of other objects which contain
874 /// [`WriteableEcdsaChannelSigner`]-implementing objects (i.e., [`ChannelMonitor`]s and [`ChannelManager`]s).
875 /// The bytes are exactly those which `<Self::Signer as Writeable>::write()` writes, and
876 /// contain no versioning scheme. You may wish to include your own version prefix and ensure
877 /// you've read all of the provided bytes to ensure no corruption occurred.
879 /// This method is slowly being phased out -- it will only be called when reading objects
880 /// written by LDK versions prior to 0.0.113.
882 /// [`Signer`]: Self::EcdsaSigner
883 /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
884 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
885 fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::EcdsaSigner, DecodeError>;
887 /// Get a script pubkey which we send funds to when claiming on-chain contestable outputs.
889 /// If this function returns an error, this will result in a channel failing to open.
891 /// This method should return a different value each time it is called, to avoid linking
892 /// on-chain funds across channels as controlled to the same user. `channel_keys_id` may be
893 /// used to derive a unique value for each channel.
894 fn get_destination_script(&self, channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()>;
896 /// Get a script pubkey which we will send funds to when closing a channel.
898 /// If this function returns an error, this will result in a channel failing to open or close.
899 /// In the event of a failure when the counterparty is initiating a close, this can result in a
900 /// channel force close.
902 /// This method should return a different value each time it is called, to avoid linking
903 /// on-chain funds across channels as controlled to the same user.
904 fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()>;
907 /// A helper trait that describes an on-chain wallet capable of returning a (change) destination
909 pub trait ChangeDestinationSource {
910 /// Returns a script pubkey which can be used as a change destination for
911 /// [`OutputSpender::spend_spendable_outputs`].
913 /// This method should return a different value each time it is called, to avoid linking
914 /// on-chain funds controlled to the same user.
915 fn get_change_destination_script(&self) -> Result<ScriptBuf, ()>;
918 /// A simple implementation of [`WriteableEcdsaChannelSigner`] that just keeps the private keys in memory.
920 /// This implementation performs no policy checks and is insufficient by itself as
921 /// a secure external signer.
923 pub struct InMemorySigner {
924 /// Holder secret key in the 2-of-2 multisig script of a channel. This key also backs the
925 /// holder's anchor output in a commitment transaction, if one is present.
926 pub funding_key: SecretKey,
927 /// Holder secret key for blinded revocation pubkey.
928 pub revocation_base_key: SecretKey,
929 /// Holder secret key used for our balance in counterparty-broadcasted commitment transactions.
930 pub payment_key: SecretKey,
931 /// Holder secret key used in an HTLC transaction.
932 pub delayed_payment_base_key: SecretKey,
933 /// Holder HTLC secret key used in commitment transaction HTLC outputs.
934 pub htlc_base_key: SecretKey,
936 pub commitment_seed: [u8; 32],
937 /// Holder public keys and basepoints.
938 pub(crate) holder_channel_pubkeys: ChannelPublicKeys,
939 /// Counterparty public keys and counterparty/holder `selected_contest_delay`, populated on channel acceptance.
940 channel_parameters: Option<ChannelTransactionParameters>,
941 /// The total value of this channel.
942 channel_value_satoshis: u64,
943 /// Key derivation parameters.
944 channel_keys_id: [u8; 32],
945 /// A source of random bytes.
946 entropy_source: RandomBytes,
949 impl PartialEq for InMemorySigner {
950 fn eq(&self, other: &Self) -> bool {
951 self.funding_key == other.funding_key
952 && self.revocation_base_key == other.revocation_base_key
953 && self.payment_key == other.payment_key
954 && self.delayed_payment_base_key == other.delayed_payment_base_key
955 && self.htlc_base_key == other.htlc_base_key
956 && self.commitment_seed == other.commitment_seed
957 && self.holder_channel_pubkeys == other.holder_channel_pubkeys
958 && self.channel_parameters == other.channel_parameters
959 && self.channel_value_satoshis == other.channel_value_satoshis
960 && self.channel_keys_id == other.channel_keys_id
964 impl Clone for InMemorySigner {
965 fn clone(&self) -> Self {
967 funding_key: self.funding_key.clone(),
968 revocation_base_key: self.revocation_base_key.clone(),
969 payment_key: self.payment_key.clone(),
970 delayed_payment_base_key: self.delayed_payment_base_key.clone(),
971 htlc_base_key: self.htlc_base_key.clone(),
972 commitment_seed: self.commitment_seed.clone(),
973 holder_channel_pubkeys: self.holder_channel_pubkeys.clone(),
974 channel_parameters: self.channel_parameters.clone(),
975 channel_value_satoshis: self.channel_value_satoshis,
976 channel_keys_id: self.channel_keys_id,
977 entropy_source: RandomBytes::new(self.get_secure_random_bytes()),
982 impl InMemorySigner {
983 /// Creates a new [`InMemorySigner`].
984 pub fn new<C: Signing>(
985 secp_ctx: &Secp256k1<C>, funding_key: SecretKey, revocation_base_key: SecretKey,
986 payment_key: SecretKey, delayed_payment_base_key: SecretKey, htlc_base_key: SecretKey,
987 commitment_seed: [u8; 32], channel_value_satoshis: u64, channel_keys_id: [u8; 32],
988 rand_bytes_unique_start: [u8; 32],
989 ) -> InMemorySigner {
990 let holder_channel_pubkeys = InMemorySigner::make_holder_keys(
993 &revocation_base_key,
995 &delayed_payment_base_key,
1000 revocation_base_key,
1002 delayed_payment_base_key,
1005 channel_value_satoshis,
1006 holder_channel_pubkeys,
1007 channel_parameters: None,
1009 entropy_source: RandomBytes::new(rand_bytes_unique_start),
1013 fn make_holder_keys<C: Signing>(
1014 secp_ctx: &Secp256k1<C>, funding_key: &SecretKey, revocation_base_key: &SecretKey,
1015 payment_key: &SecretKey, delayed_payment_base_key: &SecretKey, htlc_base_key: &SecretKey,
1016 ) -> ChannelPublicKeys {
1017 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
1019 funding_pubkey: from_secret(&funding_key),
1020 revocation_basepoint: RevocationBasepoint::from(from_secret(&revocation_base_key)),
1021 payment_point: from_secret(&payment_key),
1022 delayed_payment_basepoint: DelayedPaymentBasepoint::from(from_secret(
1023 &delayed_payment_base_key,
1025 htlc_basepoint: HtlcBasepoint::from(from_secret(&htlc_base_key)),
1029 /// Returns the counterparty's pubkeys.
1031 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1032 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1033 pub fn counterparty_pubkeys(&self) -> Option<&ChannelPublicKeys> {
1034 self.get_channel_parameters().and_then(|params| {
1035 params.counterparty_parameters.as_ref().map(|params| ¶ms.pubkeys)
1039 /// Returns the `contest_delay` value specified by our counterparty and applied on holder-broadcastable
1040 /// transactions, i.e., the amount of time that we have to wait to recover our funds if we
1041 /// broadcast a transaction.
1043 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1044 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1045 pub fn counterparty_selected_contest_delay(&self) -> Option<u16> {
1046 self.get_channel_parameters().and_then(|params| {
1047 params.counterparty_parameters.as_ref().map(|params| params.selected_contest_delay)
1051 /// Returns the `contest_delay` value specified by us and applied on transactions broadcastable
1052 /// by our counterparty, i.e., the amount of time that they have to wait to recover their funds
1053 /// if they broadcast a transaction.
1055 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1056 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1057 pub fn holder_selected_contest_delay(&self) -> Option<u16> {
1058 self.get_channel_parameters().map(|params| params.holder_selected_contest_delay)
1061 /// Returns whether the holder is the initiator.
1063 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1064 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1065 pub fn is_outbound(&self) -> Option<bool> {
1066 self.get_channel_parameters().map(|params| params.is_outbound_from_holder)
1069 /// Funding outpoint
1071 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1072 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1073 pub fn funding_outpoint(&self) -> Option<&OutPoint> {
1074 self.get_channel_parameters().map(|params| params.funding_outpoint.as_ref()).flatten()
1077 /// Returns a [`ChannelTransactionParameters`] for this channel, to be used when verifying or
1078 /// building transactions.
1080 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1081 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1082 pub fn get_channel_parameters(&self) -> Option<&ChannelTransactionParameters> {
1083 self.channel_parameters.as_ref()
1086 /// Returns the channel type features of the channel parameters. Should be helpful for
1087 /// determining a channel's category, i. e. legacy/anchors/taproot/etc.
1089 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
1090 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
1091 pub fn channel_type_features(&self) -> Option<&ChannelTypeFeatures> {
1092 self.get_channel_parameters().map(|params| ¶ms.channel_type_features)
1095 /// Sign the single input of `spend_tx` at index `input_idx`, which spends the output described
1096 /// by `descriptor`, returning the witness stack for the input.
1098 /// Returns an error if the input at `input_idx` does not exist, has a non-empty `script_sig`,
1099 /// is not spending the outpoint described by [`descriptor.outpoint`],
1100 /// or if an output descriptor `script_pubkey` does not match the one we can spend.
1102 /// [`descriptor.outpoint`]: StaticPaymentOutputDescriptor::outpoint
1103 pub fn sign_counterparty_payment_input<C: Signing>(
1104 &self, spend_tx: &Transaction, input_idx: usize,
1105 descriptor: &StaticPaymentOutputDescriptor, secp_ctx: &Secp256k1<C>,
1106 ) -> Result<Witness, ()> {
1107 // TODO: We really should be taking the SigHashCache as a parameter here instead of
1108 // spend_tx, but ideally the SigHashCache would expose the transaction's inputs read-only
1109 // so that we can check them. This requires upstream rust-bitcoin changes (as well as
1110 // bindings updates to support SigHashCache objects).
1111 if spend_tx.input.len() <= input_idx {
1114 if !spend_tx.input[input_idx].script_sig.is_empty() {
1117 if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint()
1122 let remotepubkey = bitcoin::PublicKey::new(self.pubkeys().payment_point);
1123 // We cannot always assume that `channel_parameters` is set, so can't just call
1124 // `self.channel_parameters()` or anything that relies on it
1125 let supports_anchors_zero_fee_htlc_tx = self
1126 .channel_type_features()
1127 .map(|features| features.supports_anchors_zero_fee_htlc_tx())
1130 let witness_script = if supports_anchors_zero_fee_htlc_tx {
1131 chan_utils::get_to_countersignatory_with_anchors_redeemscript(&remotepubkey.inner)
1133 ScriptBuf::new_p2pkh(&remotepubkey.pubkey_hash())
1135 let sighash = hash_to_message!(
1136 &sighash::SighashCache::new(spend_tx)
1137 .segwit_signature_hash(
1140 descriptor.output.value,
1141 EcdsaSighashType::All
1145 let remotesig = sign_with_aux_rand(secp_ctx, &sighash, &self.payment_key, &self);
1146 let payment_script = if supports_anchors_zero_fee_htlc_tx {
1147 witness_script.to_v0_p2wsh()
1149 ScriptBuf::new_v0_p2wpkh(&remotepubkey.wpubkey_hash().unwrap())
1152 if payment_script != descriptor.output.script_pubkey {
1156 let mut witness = Vec::with_capacity(2);
1157 witness.push(remotesig.serialize_der().to_vec());
1158 witness[0].push(EcdsaSighashType::All as u8);
1159 if supports_anchors_zero_fee_htlc_tx {
1160 witness.push(witness_script.to_bytes());
1162 witness.push(remotepubkey.to_bytes());
1167 /// Sign the single input of `spend_tx` at index `input_idx` which spends the output
1168 /// described by `descriptor`, returning the witness stack for the input.
1170 /// Returns an error if the input at `input_idx` does not exist, has a non-empty `script_sig`,
1171 /// is not spending the outpoint described by [`descriptor.outpoint`], does not have a
1172 /// sequence set to [`descriptor.to_self_delay`], or if an output descriptor
1173 /// `script_pubkey` does not match the one we can spend.
1175 /// [`descriptor.outpoint`]: DelayedPaymentOutputDescriptor::outpoint
1176 /// [`descriptor.to_self_delay`]: DelayedPaymentOutputDescriptor::to_self_delay
1177 pub fn sign_dynamic_p2wsh_input<C: Signing>(
1178 &self, spend_tx: &Transaction, input_idx: usize,
1179 descriptor: &DelayedPaymentOutputDescriptor, secp_ctx: &Secp256k1<C>,
1180 ) -> Result<Witness, ()> {
1181 // TODO: We really should be taking the SigHashCache as a parameter here instead of
1182 // spend_tx, but ideally the SigHashCache would expose the transaction's inputs read-only
1183 // so that we can check them. This requires upstream rust-bitcoin changes (as well as
1184 // bindings updates to support SigHashCache objects).
1185 if spend_tx.input.len() <= input_idx {
1188 if !spend_tx.input[input_idx].script_sig.is_empty() {
1191 if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint()
1195 if spend_tx.input[input_idx].sequence.0 != descriptor.to_self_delay as u32 {
1199 let delayed_payment_key = chan_utils::derive_private_key(
1201 &descriptor.per_commitment_point,
1202 &self.delayed_payment_base_key,
1204 let delayed_payment_pubkey =
1205 DelayedPaymentKey::from_secret_key(&secp_ctx, &delayed_payment_key);
1206 let witness_script = chan_utils::get_revokeable_redeemscript(
1207 &descriptor.revocation_pubkey,
1208 descriptor.to_self_delay,
1209 &delayed_payment_pubkey,
1211 let sighash = hash_to_message!(
1212 &sighash::SighashCache::new(spend_tx)
1213 .segwit_signature_hash(
1216 descriptor.output.value,
1217 EcdsaSighashType::All
1221 let local_delayedsig = EcdsaSignature {
1222 sig: sign_with_aux_rand(secp_ctx, &sighash, &delayed_payment_key, &self),
1223 hash_ty: EcdsaSighashType::All,
1225 let payment_script =
1226 bitcoin::Address::p2wsh(&witness_script, Network::Bitcoin).script_pubkey();
1228 if descriptor.output.script_pubkey != payment_script {
1232 Ok(Witness::from_slice(&[
1233 &local_delayedsig.serialize()[..],
1235 witness_script.as_bytes(),
1240 impl EntropySource for InMemorySigner {
1241 fn get_secure_random_bytes(&self) -> [u8; 32] {
1242 self.entropy_source.get_secure_random_bytes()
1246 impl ChannelSigner for InMemorySigner {
1247 fn get_per_commitment_point(
1248 &self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>,
1250 let commitment_secret =
1251 SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx))
1253 PublicKey::from_secret_key(secp_ctx, &commitment_secret)
1256 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
1257 chan_utils::build_commitment_secret(&self.commitment_seed, idx)
1260 fn validate_holder_commitment(
1261 &self, _holder_tx: &HolderCommitmentTransaction,
1262 _outbound_htlc_preimages: Vec<PaymentPreimage>,
1263 ) -> Result<(), ()> {
1267 fn validate_counterparty_revocation(&self, _idx: u64, _secret: &SecretKey) -> Result<(), ()> {
1271 fn pubkeys(&self) -> &ChannelPublicKeys {
1272 &self.holder_channel_pubkeys
1275 fn channel_keys_id(&self) -> [u8; 32] {
1276 self.channel_keys_id
1279 fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
1281 self.channel_parameters.is_none()
1282 || self.channel_parameters.as_ref().unwrap() == channel_parameters
1284 if self.channel_parameters.is_some() {
1285 // The channel parameters were already set and they match, return early.
1288 assert!(channel_parameters.is_populated(), "Channel parameters must be fully populated");
1289 self.channel_parameters = Some(channel_parameters.clone());
1293 const MISSING_PARAMS_ERR: &'static str =
1294 "ChannelSigner::provide_channel_parameters must be called before signing operations";
1296 impl EcdsaChannelSigner for InMemorySigner {
1297 fn sign_counterparty_commitment(
1298 &self, commitment_tx: &CommitmentTransaction,
1299 _inbound_htlc_preimages: Vec<PaymentPreimage>,
1300 _outbound_htlc_preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>,
1301 ) -> Result<(Signature, Vec<Signature>), ()> {
1302 let trusted_tx = commitment_tx.trust();
1303 let keys = trusted_tx.keys();
1305 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1306 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1307 let channel_funding_redeemscript =
1308 make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1310 let built_tx = trusted_tx.built_transaction();
1311 let commitment_sig = built_tx.sign_counterparty_commitment(
1313 &channel_funding_redeemscript,
1314 self.channel_value_satoshis,
1317 let commitment_txid = built_tx.txid;
1319 let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len());
1320 for htlc in commitment_tx.htlcs() {
1321 let channel_parameters = self.get_channel_parameters().expect(MISSING_PARAMS_ERR);
1322 let holder_selected_contest_delay =
1323 self.holder_selected_contest_delay().expect(MISSING_PARAMS_ERR);
1324 let chan_type = &channel_parameters.channel_type_features;
1325 let htlc_tx = chan_utils::build_htlc_transaction(
1327 commitment_tx.feerate_per_kw(),
1328 holder_selected_contest_delay,
1331 &keys.broadcaster_delayed_payment_key,
1332 &keys.revocation_key,
1334 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, chan_type, &keys);
1335 let htlc_sighashtype = if chan_type.supports_anchors_zero_fee_htlc_tx() {
1336 EcdsaSighashType::SinglePlusAnyoneCanPay
1338 EcdsaSighashType::All
1340 let htlc_sighash = hash_to_message!(
1341 &sighash::SighashCache::new(&htlc_tx)
1342 .segwit_signature_hash(
1345 htlc.amount_msat / 1000,
1350 let holder_htlc_key = chan_utils::derive_private_key(
1352 &keys.per_commitment_point,
1353 &self.htlc_base_key,
1355 htlc_sigs.push(sign(secp_ctx, &htlc_sighash, &holder_htlc_key));
1358 Ok((commitment_sig, htlc_sigs))
1361 fn sign_holder_commitment(
1362 &self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>,
1363 ) -> Result<Signature, ()> {
1364 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1365 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1366 let funding_redeemscript =
1367 make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1368 let trusted_tx = commitment_tx.trust();
1369 Ok(trusted_tx.built_transaction().sign_holder_commitment(
1371 &funding_redeemscript,
1372 self.channel_value_satoshis,
1378 #[cfg(any(test, feature = "unsafe_revoked_tx_signing"))]
1379 fn unsafe_sign_holder_commitment(
1380 &self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>,
1381 ) -> Result<Signature, ()> {
1382 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1383 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1384 let funding_redeemscript =
1385 make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1386 let trusted_tx = commitment_tx.trust();
1387 Ok(trusted_tx.built_transaction().sign_holder_commitment(
1389 &funding_redeemscript,
1390 self.channel_value_satoshis,
1396 fn sign_justice_revoked_output(
1397 &self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
1398 secp_ctx: &Secp256k1<secp256k1::All>,
1399 ) -> Result<Signature, ()> {
1400 let revocation_key = chan_utils::derive_private_revocation_key(
1402 &per_commitment_key,
1403 &self.revocation_base_key,
1405 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
1406 let revocation_pubkey = RevocationKey::from_basepoint(
1408 &self.pubkeys().revocation_basepoint,
1409 &per_commitment_point,
1411 let witness_script = {
1412 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1413 let holder_selected_contest_delay =
1414 self.holder_selected_contest_delay().expect(MISSING_PARAMS_ERR);
1415 let counterparty_delayedpubkey = DelayedPaymentKey::from_basepoint(
1417 &counterparty_keys.delayed_payment_basepoint,
1418 &per_commitment_point,
1420 chan_utils::get_revokeable_redeemscript(
1422 holder_selected_contest_delay,
1423 &counterparty_delayedpubkey,
1426 let mut sighash_parts = sighash::SighashCache::new(justice_tx);
1427 let sighash = hash_to_message!(
1429 .segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All)
1432 return Ok(sign_with_aux_rand(secp_ctx, &sighash, &revocation_key, &self));
1435 fn sign_justice_revoked_htlc(
1436 &self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
1437 htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>,
1438 ) -> Result<Signature, ()> {
1439 let revocation_key = chan_utils::derive_private_revocation_key(
1441 &per_commitment_key,
1442 &self.revocation_base_key,
1444 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
1445 let revocation_pubkey = RevocationKey::from_basepoint(
1447 &self.pubkeys().revocation_basepoint,
1448 &per_commitment_point,
1450 let witness_script = {
1451 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1452 let counterparty_htlcpubkey = HtlcKey::from_basepoint(
1454 &counterparty_keys.htlc_basepoint,
1455 &per_commitment_point,
1457 let holder_htlcpubkey = HtlcKey::from_basepoint(
1459 &self.pubkeys().htlc_basepoint,
1460 &per_commitment_point,
1462 let chan_type = self.channel_type_features().expect(MISSING_PARAMS_ERR);
1463 chan_utils::get_htlc_redeemscript_with_explicit_keys(
1466 &counterparty_htlcpubkey,
1471 let mut sighash_parts = sighash::SighashCache::new(justice_tx);
1472 let sighash = hash_to_message!(
1474 .segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All)
1477 return Ok(sign_with_aux_rand(secp_ctx, &sighash, &revocation_key, &self));
1480 fn sign_holder_htlc_transaction(
1481 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
1482 secp_ctx: &Secp256k1<secp256k1::All>,
1483 ) -> Result<Signature, ()> {
1484 let witness_script = htlc_descriptor.witness_script(secp_ctx);
1485 let sighash = &sighash::SighashCache::new(&*htlc_tx)
1486 .segwit_signature_hash(
1489 htlc_descriptor.htlc.amount_msat / 1000,
1490 EcdsaSighashType::All,
1493 let our_htlc_private_key = chan_utils::derive_private_key(
1495 &htlc_descriptor.per_commitment_point,
1496 &self.htlc_base_key,
1498 let sighash = hash_to_message!(sighash.as_byte_array());
1499 Ok(sign_with_aux_rand(&secp_ctx, &sighash, &our_htlc_private_key, &self))
1502 fn sign_counterparty_htlc_transaction(
1503 &self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey,
1504 htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>,
1505 ) -> Result<Signature, ()> {
1507 chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key);
1508 let revocation_pubkey = RevocationKey::from_basepoint(
1510 &self.pubkeys().revocation_basepoint,
1511 &per_commitment_point,
1513 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1514 let counterparty_htlcpubkey = HtlcKey::from_basepoint(
1516 &counterparty_keys.htlc_basepoint,
1517 &per_commitment_point,
1519 let htlc_basepoint = self.pubkeys().htlc_basepoint;
1520 let htlcpubkey = HtlcKey::from_basepoint(&secp_ctx, &htlc_basepoint, &per_commitment_point);
1521 let chan_type = self.channel_type_features().expect(MISSING_PARAMS_ERR);
1522 let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(
1525 &counterparty_htlcpubkey,
1529 let mut sighash_parts = sighash::SighashCache::new(htlc_tx);
1530 let sighash = hash_to_message!(
1532 .segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All)
1535 Ok(sign_with_aux_rand(secp_ctx, &sighash, &htlc_key, &self))
1538 fn sign_closing_transaction(
1539 &self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>,
1540 ) -> Result<Signature, ()> {
1541 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1542 let counterparty_funding_key =
1543 &self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR).funding_pubkey;
1544 let channel_funding_redeemscript =
1545 make_funding_redeemscript(&funding_pubkey, counterparty_funding_key);
1546 Ok(closing_tx.trust().sign(
1548 &channel_funding_redeemscript,
1549 self.channel_value_satoshis,
1554 fn sign_holder_anchor_input(
1555 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
1556 ) -> Result<Signature, ()> {
1557 let witness_script =
1558 chan_utils::get_anchor_redeemscript(&self.holder_channel_pubkeys.funding_pubkey);
1559 let sighash = sighash::SighashCache::new(&*anchor_tx)
1560 .segwit_signature_hash(
1563 ANCHOR_OUTPUT_VALUE_SATOSHI,
1564 EcdsaSighashType::All,
1567 Ok(sign_with_aux_rand(secp_ctx, &hash_to_message!(&sighash[..]), &self.funding_key, &self))
1570 fn sign_channel_announcement_with_funding_key(
1571 &self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>,
1572 ) -> Result<Signature, ()> {
1573 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
1574 Ok(secp_ctx.sign_ecdsa(&msghash, &self.funding_key))
1579 impl TaprootChannelSigner for InMemorySigner {
1580 fn generate_local_nonce_pair(
1581 &self, commitment_number: u64, secp_ctx: &Secp256k1<All>,
1586 fn partially_sign_counterparty_commitment(
1587 &self, counterparty_nonce: PublicNonce, commitment_tx: &CommitmentTransaction,
1588 inbound_htlc_preimages: Vec<PaymentPreimage>,
1589 outbound_htlc_preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<All>,
1590 ) -> Result<(PartialSignatureWithNonce, Vec<schnorr::Signature>), ()> {
1594 fn finalize_holder_commitment(
1595 &self, commitment_tx: &HolderCommitmentTransaction,
1596 counterparty_partial_signature: PartialSignatureWithNonce, secp_ctx: &Secp256k1<All>,
1597 ) -> Result<PartialSignature, ()> {
1601 fn sign_justice_revoked_output(
1602 &self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
1603 secp_ctx: &Secp256k1<All>,
1604 ) -> Result<schnorr::Signature, ()> {
1608 fn sign_justice_revoked_htlc(
1609 &self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey,
1610 htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<All>,
1611 ) -> Result<schnorr::Signature, ()> {
1615 fn sign_holder_htlc_transaction(
1616 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
1617 secp_ctx: &Secp256k1<All>,
1618 ) -> Result<schnorr::Signature, ()> {
1622 fn sign_counterparty_htlc_transaction(
1623 &self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey,
1624 htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<All>,
1625 ) -> Result<schnorr::Signature, ()> {
1629 fn partially_sign_closing_transaction(
1630 &self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<All>,
1631 ) -> Result<PartialSignature, ()> {
1635 fn sign_holder_anchor_input(
1636 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<All>,
1637 ) -> Result<schnorr::Signature, ()> {
1642 const SERIALIZATION_VERSION: u8 = 1;
1644 const MIN_SERIALIZATION_VERSION: u8 = 1;
1646 impl WriteableEcdsaChannelSigner for InMemorySigner {}
1648 impl Writeable for InMemorySigner {
1649 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
1650 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
1652 self.funding_key.write(writer)?;
1653 self.revocation_base_key.write(writer)?;
1654 self.payment_key.write(writer)?;
1655 self.delayed_payment_base_key.write(writer)?;
1656 self.htlc_base_key.write(writer)?;
1657 self.commitment_seed.write(writer)?;
1658 self.channel_parameters.write(writer)?;
1659 self.channel_value_satoshis.write(writer)?;
1660 self.channel_keys_id.write(writer)?;
1662 write_tlv_fields!(writer, {});
1668 impl<ES: Deref> ReadableArgs<ES> for InMemorySigner
1670 ES::Target: EntropySource,
1672 fn read<R: io::Read>(reader: &mut R, entropy_source: ES) -> Result<Self, DecodeError> {
1673 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
1675 let funding_key = Readable::read(reader)?;
1676 let revocation_base_key = Readable::read(reader)?;
1677 let payment_key = Readable::read(reader)?;
1678 let delayed_payment_base_key = Readable::read(reader)?;
1679 let htlc_base_key = Readable::read(reader)?;
1680 let commitment_seed = Readable::read(reader)?;
1681 let counterparty_channel_data = Readable::read(reader)?;
1682 let channel_value_satoshis = Readable::read(reader)?;
1683 let secp_ctx = Secp256k1::signing_only();
1684 let holder_channel_pubkeys = InMemorySigner::make_holder_keys(
1687 &revocation_base_key,
1689 &delayed_payment_base_key,
1692 let keys_id = Readable::read(reader)?;
1694 read_tlv_fields!(reader, {});
1698 revocation_base_key,
1700 delayed_payment_base_key,
1703 channel_value_satoshis,
1704 holder_channel_pubkeys,
1705 channel_parameters: counterparty_channel_data,
1706 channel_keys_id: keys_id,
1707 entropy_source: RandomBytes::new(entropy_source.get_secure_random_bytes()),
1712 /// Simple implementation of [`EntropySource`], [`NodeSigner`], and [`SignerProvider`] that takes a
1713 /// 32-byte seed for use as a BIP 32 extended key and derives keys from that.
1715 /// Your `node_id` is seed/0'.
1716 /// Unilateral closes may use seed/1'.
1717 /// Cooperative closes may use seed/2'.
1718 /// The two close keys may be needed to claim on-chain funds!
1720 /// This struct cannot be used for nodes that wish to support receiving phantom payments;
1721 /// [`PhantomKeysManager`] must be used instead.
1723 /// Note that switching between this struct and [`PhantomKeysManager`] will invalidate any
1724 /// previously issued invoices and attempts to pay previous invoices will fail.
1725 pub struct KeysManager {
1726 secp_ctx: Secp256k1<secp256k1::All>,
1727 node_secret: SecretKey,
1729 inbound_payment_key: KeyMaterial,
1730 destination_script: ScriptBuf,
1731 shutdown_pubkey: PublicKey,
1732 channel_master_key: ExtendedPrivKey,
1733 channel_child_index: AtomicUsize,
1735 entropy_source: RandomBytes,
1738 starting_time_secs: u64,
1739 starting_time_nanos: u32,
1743 /// Constructs a [`KeysManager`] from a 32-byte seed. If the seed is in some way biased (e.g.,
1744 /// your CSRNG is busted) this may panic (but more importantly, you will possibly lose funds).
1745 /// `starting_time` isn't strictly required to actually be a time, but it must absolutely,
1746 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
1747 /// `seed`, `starting_time` must be unique to each run. Thus, the easiest way to achieve this
1748 /// is to simply use the current time (with very high precision).
1750 /// The `seed` MUST be backed up safely prior to use so that the keys can be re-created, however,
1751 /// obviously, `starting_time` should be unique every time you reload the library - it is only
1752 /// used to generate new ephemeral key data (which will be stored by the individual channel if
1755 /// Note that the seed is required to recover certain on-chain funds independent of
1756 /// [`ChannelMonitor`] data, though a current copy of [`ChannelMonitor`] data is also required
1757 /// for any channel, and some on-chain during-closing funds.
1759 /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
1760 pub fn new(seed: &[u8; 32], starting_time_secs: u64, starting_time_nanos: u32) -> Self {
1761 let secp_ctx = Secp256k1::new();
1762 // Note that when we aren't serializing the key, network doesn't matter
1763 match ExtendedPrivKey::new_master(Network::Testnet, seed) {
1765 let node_secret = master_key
1766 .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap())
1767 .expect("Your RNG is busted")
1769 let node_id = PublicKey::from_secret_key(&secp_ctx, &node_secret);
1770 let destination_script = match master_key
1771 .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap())
1773 Ok(destination_key) => {
1774 let wpubkey_hash = WPubkeyHash::hash(
1775 &ExtendedPubKey::from_priv(&secp_ctx, &destination_key)
1780 .push_opcode(opcodes::all::OP_PUSHBYTES_0)
1781 .push_slice(&wpubkey_hash.to_byte_array())
1784 Err(_) => panic!("Your RNG is busted"),
1786 let shutdown_pubkey = match master_key
1787 .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap())
1789 Ok(shutdown_key) => {
1790 ExtendedPubKey::from_priv(&secp_ctx, &shutdown_key).public_key
1792 Err(_) => panic!("Your RNG is busted"),
1794 let channel_master_key = master_key
1795 .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap())
1796 .expect("Your RNG is busted");
1797 let inbound_payment_key: SecretKey = master_key
1798 .ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap())
1799 .expect("Your RNG is busted")
1801 let mut inbound_pmt_key_bytes = [0; 32];
1802 inbound_pmt_key_bytes.copy_from_slice(&inbound_payment_key[..]);
1804 let mut rand_bytes_engine = Sha256::engine();
1805 rand_bytes_engine.input(&starting_time_secs.to_be_bytes());
1806 rand_bytes_engine.input(&starting_time_nanos.to_be_bytes());
1807 rand_bytes_engine.input(seed);
1808 rand_bytes_engine.input(b"LDK PRNG Seed");
1809 let rand_bytes_unique_start =
1810 Sha256::from_engine(rand_bytes_engine).to_byte_array();
1812 let mut res = KeysManager {
1816 inbound_payment_key: KeyMaterial(inbound_pmt_key_bytes),
1822 channel_child_index: AtomicUsize::new(0),
1824 entropy_source: RandomBytes::new(rand_bytes_unique_start),
1828 starting_time_nanos,
1830 let secp_seed = res.get_secure_random_bytes();
1831 res.secp_ctx.seeded_randomize(&secp_seed);
1834 Err(_) => panic!("Your rng is busted"),
1838 /// Gets the "node_id" secret key used to sign gossip announcements, decode onion data, etc.
1839 pub fn get_node_secret_key(&self) -> SecretKey {
1843 /// Derive an old [`WriteableEcdsaChannelSigner`] containing per-channel secrets based on a key derivation parameters.
1844 pub fn derive_channel_keys(
1845 &self, channel_value_satoshis: u64, params: &[u8; 32],
1846 ) -> InMemorySigner {
1847 let chan_id = u64::from_be_bytes(params[0..8].try_into().unwrap());
1848 let mut unique_start = Sha256::engine();
1849 unique_start.input(params);
1850 unique_start.input(&self.seed);
1852 // We only seriously intend to rely on the channel_master_key for true secure
1853 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
1854 // starting_time provided in the constructor) to be unique.
1855 let child_privkey = self
1859 ChildNumber::from_hardened_idx((chan_id as u32) % (1 << 31))
1860 .expect("key space exhausted"),
1862 .expect("Your RNG is busted");
1863 unique_start.input(&child_privkey.private_key[..]);
1865 let seed = Sha256::from_engine(unique_start).to_byte_array();
1867 let commitment_seed = {
1868 let mut sha = Sha256::engine();
1870 sha.input(&b"commitment seed"[..]);
1871 Sha256::from_engine(sha).to_byte_array()
1873 macro_rules! key_step {
1874 ($info: expr, $prev_key: expr) => {{
1875 let mut sha = Sha256::engine();
1877 sha.input(&$prev_key[..]);
1878 sha.input(&$info[..]);
1879 SecretKey::from_slice(&Sha256::from_engine(sha).to_byte_array())
1880 .expect("SHA-256 is busted")
1883 let funding_key = key_step!(b"funding key", commitment_seed);
1884 let revocation_base_key = key_step!(b"revocation base key", funding_key);
1885 let payment_key = key_step!(b"payment key", revocation_base_key);
1886 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
1887 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
1888 let prng_seed = self.get_secure_random_bytes();
1890 InMemorySigner::new(
1893 revocation_base_key,
1895 delayed_payment_base_key,
1898 channel_value_satoshis,
1904 /// Signs the given [`PartiallySignedTransaction`] which spends the given [`SpendableOutputDescriptor`]s.
1905 /// The resulting inputs will be finalized and the PSBT will be ready for broadcast if there
1906 /// are no other inputs that need signing.
1908 /// Returns `Err(())` if the PSBT is missing a descriptor or if we fail to sign.
1910 /// May panic if the [`SpendableOutputDescriptor`]s were not generated by channels which used
1911 /// this [`KeysManager`] or one of the [`InMemorySigner`] created by this [`KeysManager`].
1912 pub fn sign_spendable_outputs_psbt<C: Signing>(
1913 &self, descriptors: &[&SpendableOutputDescriptor], mut psbt: PartiallySignedTransaction,
1914 secp_ctx: &Secp256k1<C>,
1915 ) -> Result<PartiallySignedTransaction, ()> {
1916 let mut keys_cache: Option<(InMemorySigner, [u8; 32])> = None;
1917 for outp in descriptors {
1918 let get_input_idx = |outpoint: &OutPoint| {
1922 .position(|i| i.previous_output == outpoint.into_bitcoin_outpoint())
1926 SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
1927 let input_idx = get_input_idx(&descriptor.outpoint)?;
1928 if keys_cache.is_none()
1929 || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id
1931 let mut signer = self.derive_channel_keys(
1932 descriptor.channel_value_satoshis,
1933 &descriptor.channel_keys_id,
1935 if let Some(channel_params) =
1936 descriptor.channel_transaction_parameters.as_ref()
1938 signer.provide_channel_parameters(channel_params);
1940 keys_cache = Some((signer, descriptor.channel_keys_id));
1942 let witness = keys_cache.as_ref().unwrap().0.sign_counterparty_payment_input(
1948 psbt.inputs[input_idx].final_script_witness = Some(witness);
1950 SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
1951 let input_idx = get_input_idx(&descriptor.outpoint)?;
1952 if keys_cache.is_none()
1953 || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id
1956 self.derive_channel_keys(
1957 descriptor.channel_value_satoshis,
1958 &descriptor.channel_keys_id,
1960 descriptor.channel_keys_id,
1963 let witness = keys_cache.as_ref().unwrap().0.sign_dynamic_p2wsh_input(
1969 psbt.inputs[input_idx].final_script_witness = Some(witness);
1971 SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output, .. } => {
1972 let input_idx = get_input_idx(outpoint)?;
1973 let derivation_idx =
1974 if output.script_pubkey == self.destination_script { 1 } else { 2 };
1976 // Note that when we aren't serializing the key, network doesn't matter
1977 match ExtendedPrivKey::new_master(Network::Testnet, &self.seed) {
1979 match master_key.ckd_priv(
1981 ChildNumber::from_hardened_idx(derivation_idx)
1982 .expect("key space exhausted"),
1985 Err(_) => panic!("Your RNG is busted"),
1988 Err(_) => panic!("Your rng is busted"),
1991 let pubkey = ExtendedPubKey::from_priv(&secp_ctx, &secret).to_pub();
1992 if derivation_idx == 2 {
1993 assert_eq!(pubkey.inner, self.shutdown_pubkey);
1995 let witness_script =
1996 bitcoin::Address::p2pkh(&pubkey, Network::Testnet).script_pubkey();
1997 let payment_script = bitcoin::Address::p2wpkh(&pubkey, Network::Testnet)
1998 .expect("uncompressed key found")
2001 if payment_script != output.script_pubkey {
2005 let sighash = hash_to_message!(
2006 &sighash::SighashCache::new(&psbt.unsigned_tx)
2007 .segwit_signature_hash(
2011 EcdsaSighashType::All
2015 let sig = sign_with_aux_rand(secp_ctx, &sighash, &secret.private_key, &self);
2016 let mut sig_ser = sig.serialize_der().to_vec();
2017 sig_ser.push(EcdsaSighashType::All as u8);
2019 Witness::from_slice(&[&sig_ser, &pubkey.inner.serialize().to_vec()]);
2020 psbt.inputs[input_idx].final_script_witness = Some(witness);
2029 impl EntropySource for KeysManager {
2030 fn get_secure_random_bytes(&self) -> [u8; 32] {
2031 self.entropy_source.get_secure_random_bytes()
2035 impl NodeSigner for KeysManager {
2036 fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()> {
2038 Recipient::Node => Ok(self.node_id.clone()),
2039 Recipient::PhantomNode => Err(()),
2044 &self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>,
2045 ) -> Result<SharedSecret, ()> {
2046 let mut node_secret = match recipient {
2047 Recipient::Node => Ok(self.node_secret.clone()),
2048 Recipient::PhantomNode => Err(()),
2050 if let Some(tweak) = tweak {
2051 node_secret = node_secret.mul_tweak(tweak).map_err(|_| ())?;
2053 Ok(SharedSecret::new(other_key, &node_secret))
2056 fn get_inbound_payment_key_material(&self) -> KeyMaterial {
2057 self.inbound_payment_key.clone()
2061 &self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient,
2062 ) -> Result<RecoverableSignature, ()> {
2063 let preimage = construct_invoice_preimage(&hrp_bytes, &invoice_data);
2064 let secret = match recipient {
2065 Recipient::Node => Ok(&self.node_secret),
2066 Recipient::PhantomNode => Err(()),
2068 Ok(self.secp_ctx.sign_ecdsa_recoverable(
2069 &hash_to_message!(&Sha256::hash(&preimage).to_byte_array()),
2074 fn sign_bolt12_invoice_request(
2075 &self, invoice_request: &UnsignedInvoiceRequest,
2076 ) -> Result<schnorr::Signature, ()> {
2077 let message = invoice_request.tagged_hash().as_digest();
2078 let keys = KeyPair::from_secret_key(&self.secp_ctx, &self.node_secret);
2079 let aux_rand = self.get_secure_random_bytes();
2080 Ok(self.secp_ctx.sign_schnorr_with_aux_rand(message, &keys, &aux_rand))
2083 fn sign_bolt12_invoice(
2084 &self, invoice: &UnsignedBolt12Invoice,
2085 ) -> Result<schnorr::Signature, ()> {
2086 let message = invoice.tagged_hash().as_digest();
2087 let keys = KeyPair::from_secret_key(&self.secp_ctx, &self.node_secret);
2088 let aux_rand = self.get_secure_random_bytes();
2089 Ok(self.secp_ctx.sign_schnorr_with_aux_rand(message, &keys, &aux_rand))
2092 fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()> {
2093 let msg_hash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
2094 Ok(self.secp_ctx.sign_ecdsa(&msg_hash, &self.node_secret))
2098 impl OutputSpender for KeysManager {
2099 /// Creates a [`Transaction`] which spends the given descriptors to the given outputs, plus an
2100 /// output to the given change destination (if sufficient change value remains).
2102 /// See [`OutputSpender::spend_spendable_outputs`] documentation for more information.
2104 /// We do not enforce that outputs meet the dust limit or that any output scripts are standard.
2106 /// May panic if the [`SpendableOutputDescriptor`]s were not generated by channels which used
2107 /// this [`KeysManager`] or one of the [`InMemorySigner`] created by this [`KeysManager`].
2108 fn spend_spendable_outputs<C: Signing>(
2109 &self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
2110 change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
2111 locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>,
2112 ) -> Result<Transaction, ()> {
2113 let (mut psbt, expected_max_weight) =
2114 SpendableOutputDescriptor::create_spendable_outputs_psbt(
2117 change_destination_script,
2118 feerate_sat_per_1000_weight,
2121 psbt = self.sign_spendable_outputs_psbt(descriptors, psbt, secp_ctx)?;
2123 let spend_tx = psbt.extract_tx();
2125 debug_assert!(expected_max_weight >= spend_tx.weight().to_wu());
2126 // Note that witnesses with a signature vary somewhat in size, so allow
2127 // `expected_max_weight` to overshoot by up to 3 bytes per input.
2129 expected_max_weight <= spend_tx.weight().to_wu() + descriptors.len() as u64 * 3
2136 impl SignerProvider for KeysManager {
2137 type EcdsaSigner = InMemorySigner;
2139 type TaprootSigner = InMemorySigner;
2141 fn generate_channel_keys_id(
2142 &self, _inbound: bool, _channel_value_satoshis: u64, user_channel_id: u128,
2144 let child_idx = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
2145 // `child_idx` is the only thing guaranteed to make each channel unique without a restart
2146 // (though `user_channel_id` should help, depending on user behavior). If it manages to
2147 // roll over, we may generate duplicate keys for two different channels, which could result
2148 // in loss of funds. Because we only support 32-bit+ systems, assert that our `AtomicUsize`
2149 // doesn't reach `u32::MAX`.
2150 assert!(child_idx < core::u32::MAX as usize, "2^32 channels opened without restart");
2151 let mut id = [0; 32];
2152 id[0..4].copy_from_slice(&(child_idx as u32).to_be_bytes());
2153 id[4..8].copy_from_slice(&self.starting_time_nanos.to_be_bytes());
2154 id[8..16].copy_from_slice(&self.starting_time_secs.to_be_bytes());
2155 id[16..32].copy_from_slice(&user_channel_id.to_be_bytes());
2159 fn derive_channel_signer(
2160 &self, channel_value_satoshis: u64, channel_keys_id: [u8; 32],
2161 ) -> Self::EcdsaSigner {
2162 self.derive_channel_keys(channel_value_satoshis, &channel_keys_id)
2165 fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::EcdsaSigner, DecodeError> {
2166 InMemorySigner::read(&mut io::Cursor::new(reader), self)
2169 fn get_destination_script(&self, _channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()> {
2170 Ok(self.destination_script.clone())
2173 fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
2174 Ok(ShutdownScript::new_p2wpkh_from_pubkey(self.shutdown_pubkey.clone()))
2178 /// Similar to [`KeysManager`], but allows the node using this struct to receive phantom node
2181 /// A phantom node payment is a payment made to a phantom invoice, which is an invoice that can be
2182 /// paid to one of multiple nodes. This works because we encode the invoice route hints such that
2183 /// LDK will recognize an incoming payment as destined for a phantom node, and collect the payment
2184 /// itself without ever needing to forward to this fake node.
2186 /// Phantom node payments are useful for load balancing between multiple LDK nodes. They also
2187 /// provide some fault tolerance, because payers will automatically retry paying other provided
2188 /// nodes in the case that one node goes down.
2190 /// Note that multi-path payments are not supported in phantom invoices for security reasons.
2191 // In the hypothetical case that we did support MPP phantom payments, there would be no way for
2192 // nodes to know when the full payment has been received (and the preimage can be released) without
2193 // significantly compromising on our safety guarantees. I.e., if we expose the ability for the user
2194 // to tell LDK when the preimage can be released, we open ourselves to attacks where the preimage
2195 // is released too early.
2197 /// Switching between this struct and [`KeysManager`] will invalidate any previously issued
2198 /// invoices and attempts to pay previous invoices will fail.
2199 pub struct PhantomKeysManager {
2201 inbound_payment_key: KeyMaterial,
2202 phantom_secret: SecretKey,
2203 phantom_node_id: PublicKey,
2206 impl EntropySource for PhantomKeysManager {
2207 fn get_secure_random_bytes(&self) -> [u8; 32] {
2208 self.inner.get_secure_random_bytes()
2212 impl NodeSigner for PhantomKeysManager {
2213 fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()> {
2215 Recipient::Node => self.inner.get_node_id(Recipient::Node),
2216 Recipient::PhantomNode => Ok(self.phantom_node_id.clone()),
2221 &self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>,
2222 ) -> Result<SharedSecret, ()> {
2223 let mut node_secret = match recipient {
2224 Recipient::Node => self.inner.node_secret.clone(),
2225 Recipient::PhantomNode => self.phantom_secret.clone(),
2227 if let Some(tweak) = tweak {
2228 node_secret = node_secret.mul_tweak(tweak).map_err(|_| ())?;
2230 Ok(SharedSecret::new(other_key, &node_secret))
2233 fn get_inbound_payment_key_material(&self) -> KeyMaterial {
2234 self.inbound_payment_key.clone()
2238 &self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient,
2239 ) -> Result<RecoverableSignature, ()> {
2240 let preimage = construct_invoice_preimage(&hrp_bytes, &invoice_data);
2241 let secret = match recipient {
2242 Recipient::Node => &self.inner.node_secret,
2243 Recipient::PhantomNode => &self.phantom_secret,
2245 Ok(self.inner.secp_ctx.sign_ecdsa_recoverable(
2246 &hash_to_message!(&Sha256::hash(&preimage).to_byte_array()),
2251 fn sign_bolt12_invoice_request(
2252 &self, invoice_request: &UnsignedInvoiceRequest,
2253 ) -> Result<schnorr::Signature, ()> {
2254 self.inner.sign_bolt12_invoice_request(invoice_request)
2257 fn sign_bolt12_invoice(
2258 &self, invoice: &UnsignedBolt12Invoice,
2259 ) -> Result<schnorr::Signature, ()> {
2260 self.inner.sign_bolt12_invoice(invoice)
2263 fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()> {
2264 self.inner.sign_gossip_message(msg)
2268 impl OutputSpender for PhantomKeysManager {
2269 /// See [`OutputSpender::spend_spendable_outputs`] and [`KeysManager::spend_spendable_outputs`]
2270 /// for documentation on this method.
2271 fn spend_spendable_outputs<C: Signing>(
2272 &self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
2273 change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
2274 locktime: Option<LockTime>, secp_ctx: &Secp256k1<C>,
2275 ) -> Result<Transaction, ()> {
2276 self.inner.spend_spendable_outputs(
2279 change_destination_script,
2280 feerate_sat_per_1000_weight,
2287 impl SignerProvider for PhantomKeysManager {
2288 type EcdsaSigner = InMemorySigner;
2290 type TaprootSigner = InMemorySigner;
2292 fn generate_channel_keys_id(
2293 &self, inbound: bool, channel_value_satoshis: u64, user_channel_id: u128,
2295 self.inner.generate_channel_keys_id(inbound, channel_value_satoshis, user_channel_id)
2298 fn derive_channel_signer(
2299 &self, channel_value_satoshis: u64, channel_keys_id: [u8; 32],
2300 ) -> Self::EcdsaSigner {
2301 self.inner.derive_channel_signer(channel_value_satoshis, channel_keys_id)
2304 fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::EcdsaSigner, DecodeError> {
2305 self.inner.read_chan_signer(reader)
2308 fn get_destination_script(&self, channel_keys_id: [u8; 32]) -> Result<ScriptBuf, ()> {
2309 self.inner.get_destination_script(channel_keys_id)
2312 fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
2313 self.inner.get_shutdown_scriptpubkey()
2317 impl PhantomKeysManager {
2318 /// Constructs a [`PhantomKeysManager`] given a 32-byte seed and an additional `cross_node_seed`
2319 /// that is shared across all nodes that intend to participate in [phantom node payments]
2322 /// See [`KeysManager::new`] for more information on `seed`, `starting_time_secs`, and
2323 /// `starting_time_nanos`.
2325 /// `cross_node_seed` must be the same across all phantom payment-receiving nodes and also the
2326 /// same across restarts, or else inbound payments may fail.
2328 /// [phantom node payments]: PhantomKeysManager
2330 seed: &[u8; 32], starting_time_secs: u64, starting_time_nanos: u32,
2331 cross_node_seed: &[u8; 32],
2333 let inner = KeysManager::new(seed, starting_time_secs, starting_time_nanos);
2334 let (inbound_key, phantom_key) = hkdf_extract_expand_twice(
2335 b"LDK Inbound and Phantom Payment Key Expansion",
2338 let phantom_secret = SecretKey::from_slice(&phantom_key).unwrap();
2339 let phantom_node_id = PublicKey::from_secret_key(&inner.secp_ctx, &phantom_secret);
2342 inbound_payment_key: KeyMaterial(inbound_key),
2348 /// See [`KeysManager::derive_channel_keys`] for documentation on this method.
2349 pub fn derive_channel_keys(
2350 &self, channel_value_satoshis: u64, params: &[u8; 32],
2351 ) -> InMemorySigner {
2352 self.inner.derive_channel_keys(channel_value_satoshis, params)
2355 /// Gets the "node_id" secret key used to sign gossip announcements, decode onion data, etc.
2356 pub fn get_node_secret_key(&self) -> SecretKey {
2357 self.inner.get_node_secret_key()
2360 /// Gets the "node_id" secret key of the phantom node used to sign invoices, decode the
2361 /// last-hop onion data, etc.
2362 pub fn get_phantom_node_secret_key(&self) -> SecretKey {
2367 /// An implementation of [`EntropySource`] using ChaCha20.
2369 pub struct RandomBytes {
2370 /// Seed from which all randomness produced is derived from.
2372 /// Tracks the number of times we've produced randomness to ensure we don't return the same
2374 index: AtomicCounter,
2378 /// Creates a new instance using the given seed.
2379 pub fn new(seed: [u8; 32]) -> Self {
2380 Self { seed, index: AtomicCounter::new() }
2384 impl EntropySource for RandomBytes {
2385 fn get_secure_random_bytes(&self) -> [u8; 32] {
2386 let index = self.index.get_increment();
2387 let mut nonce = [0u8; 16];
2388 nonce[..8].copy_from_slice(&index.to_be_bytes());
2389 ChaCha20::get_single_block(&self.seed, &nonce)
2393 // Ensure that EcdsaChannelSigner can have a vtable
2396 let _signer: Box<dyn EcdsaChannelSigner>;
2401 use crate::sign::{EntropySource, KeysManager};
2402 use bitcoin::blockdata::constants::genesis_block;
2403 use bitcoin::Network;
2404 use std::sync::mpsc::TryRecvError;
2405 use std::sync::{mpsc, Arc};
2407 use std::time::Duration;
2409 use criterion::Criterion;
2411 pub fn bench_get_secure_random_bytes(bench: &mut Criterion) {
2412 let seed = [0u8; 32];
2413 let now = Duration::from_secs(genesis_block(Network::Testnet).header.time as u64);
2414 let keys_manager = Arc::new(KeysManager::new(&seed, now.as_secs(), now.subsec_micros()));
2416 let mut handles = Vec::new();
2417 let mut stops = Vec::new();
2419 let keys_manager_clone = Arc::clone(&keys_manager);
2420 let (stop_sender, stop_receiver) = mpsc::channel();
2421 let handle = thread::spawn(move || loop {
2422 keys_manager_clone.get_secure_random_bytes();
2423 match stop_receiver.try_recv() {
2424 Ok(_) | Err(TryRecvError::Disconnected) => {
2425 println!("Terminating.");
2428 Err(TryRecvError::Empty) => {},
2431 handles.push(handle);
2432 stops.push(stop_sender);
2435 bench.bench_function("get_secure_random_bytes", |b| {
2436 b.iter(|| keys_manager.get_secure_random_bytes())
2440 let _ = stop.send(());
2442 for handle in handles {
2443 handle.join().unwrap();