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::blockdata::transaction::{Transaction, TxOut, TxIn, EcdsaSighashType};
16 use bitcoin::blockdata::script::{Script, Builder};
17 use bitcoin::blockdata::opcodes;
18 use bitcoin::network::constants::Network;
19 use bitcoin::psbt::PartiallySignedTransaction;
20 use bitcoin::util::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber};
21 use bitcoin::util::sighash;
23 use bitcoin::bech32::u5;
24 use bitcoin::hashes::{Hash, HashEngine};
25 use bitcoin::hashes::sha256::Hash as Sha256;
26 use bitcoin::hashes::sha256d::Hash as Sha256dHash;
27 use bitcoin::hash_types::WPubkeyHash;
29 use bitcoin::secp256k1::{KeyPair, PublicKey, Scalar, Secp256k1, SecretKey, Signing};
30 use bitcoin::secp256k1::ecdh::SharedSecret;
31 use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature};
32 use bitcoin::secp256k1::schnorr;
33 use bitcoin::{PackedLockTime, secp256k1, Sequence, Witness};
35 use crate::util::transaction_utils;
36 use crate::util::crypto::{hkdf_extract_expand_twice, sign, sign_with_aux_rand};
37 use crate::util::ser::{Writeable, Writer, Readable, ReadableArgs};
38 use crate::chain::transaction::OutPoint;
39 use crate::events::bump_transaction::HTLCDescriptor;
40 use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
41 use crate::ln::{chan_utils, PaymentPreimage};
42 use crate::ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction, ClosingTransaction};
43 use crate::ln::msgs::{UnsignedChannelAnnouncement, UnsignedGossipMessage};
44 use crate::ln::script::ShutdownScript;
45 use crate::offers::invoice::UnsignedBolt12Invoice;
46 use crate::offers::invoice_request::UnsignedInvoiceRequest;
48 use crate::prelude::*;
49 use core::convert::TryInto;
51 use core::sync::atomic::{AtomicUsize, Ordering};
52 use crate::io::{self, Error};
53 use crate::ln::features::ChannelTypeFeatures;
54 use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
55 use crate::util::atomic_counter::AtomicCounter;
56 use crate::util::chacha20::ChaCha20;
57 use crate::util::invoice::construct_invoice_preimage;
59 pub(crate) mod type_resolver;
61 /// Used as initial key material, to be expanded into multiple secret keys (but not to be used
62 /// directly). This is used within LDK to encrypt/decrypt inbound payment data.
64 /// This is not exported to bindings users as we just use `[u8; 32]` directly
65 #[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
66 pub struct KeyMaterial(pub [u8; 32]);
68 /// Information about a spendable output to a P2WSH script.
70 /// See [`SpendableOutputDescriptor::DelayedPaymentOutput`] for more details on how to spend this.
71 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
72 pub struct DelayedPaymentOutputDescriptor {
73 /// The outpoint which is spendable.
74 pub outpoint: OutPoint,
75 /// Per commitment point to derive the delayed payment key by key holder.
76 pub per_commitment_point: PublicKey,
77 /// The `nSequence` value which must be set in the spending input to satisfy the `OP_CSV` in
78 /// the witness_script.
79 pub to_self_delay: u16,
80 /// The output which is referenced by the given outpoint.
82 /// The revocation point specific to the commitment transaction which was broadcast. Used to
83 /// derive the witnessScript for this output.
84 pub revocation_pubkey: PublicKey,
85 /// Arbitrary identification information returned by a call to [`ChannelSigner::channel_keys_id`].
86 /// This may be useful in re-deriving keys used in the channel to spend the output.
87 pub channel_keys_id: [u8; 32],
88 /// The value of the channel which this output originated from, possibly indirectly.
89 pub channel_value_satoshis: u64,
91 impl DelayedPaymentOutputDescriptor {
92 /// The maximum length a well-formed witness spending one of these should have.
93 /// Note: If you have the grind_signatures feature enabled, this will be at least 1 byte
95 // Calculated as 1 byte length + 73 byte signature, 1 byte empty vec push, 1 byte length plus
96 // redeemscript push length.
97 pub const MAX_WITNESS_LENGTH: usize = 1 + 73 + 1 + chan_utils::REVOKEABLE_REDEEMSCRIPT_MAX_LENGTH + 1;
100 impl_writeable_tlv_based!(DelayedPaymentOutputDescriptor, {
101 (0, outpoint, required),
102 (2, per_commitment_point, required),
103 (4, to_self_delay, required),
104 (6, output, required),
105 (8, revocation_pubkey, required),
106 (10, channel_keys_id, required),
107 (12, channel_value_satoshis, required),
110 pub(crate) const P2WPKH_WITNESS_WEIGHT: u64 = 1 /* num stack items */ +
112 73 /* sig including sighash flag */ +
113 1 /* pubkey length */ +
116 /// Information about a spendable output to our "payment key".
118 /// See [`SpendableOutputDescriptor::StaticPaymentOutput`] for more details on how to spend this.
119 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
120 pub struct StaticPaymentOutputDescriptor {
121 /// The outpoint which is spendable.
122 pub outpoint: OutPoint,
123 /// The output which is referenced by the given outpoint.
125 /// Arbitrary identification information returned by a call to [`ChannelSigner::channel_keys_id`].
126 /// This may be useful in re-deriving keys used in the channel to spend the output.
127 pub channel_keys_id: [u8; 32],
128 /// The value of the channel which this transactions spends.
129 pub channel_value_satoshis: u64,
130 /// The necessary channel parameters that need to be provided to the re-derived signer through
131 /// [`ChannelSigner::provide_channel_parameters`].
133 /// Added as optional, but always `Some` if the descriptor was produced in v0.0.117 or later.
134 pub channel_transaction_parameters: Option<ChannelTransactionParameters>,
136 impl StaticPaymentOutputDescriptor {
137 /// Returns the `witness_script` of the spendable output.
139 /// Note that this will only return `Some` for [`StaticPaymentOutputDescriptor`]s that
140 /// originated from an anchor outputs channel, as they take the form of a P2WSH script.
141 pub fn witness_script(&self) -> Option<Script> {
142 self.channel_transaction_parameters.as_ref()
143 .and_then(|channel_params|
144 if channel_params.channel_type_features.supports_anchors_zero_fee_htlc_tx() {
145 let payment_point = channel_params.holder_pubkeys.payment_point;
146 Some(chan_utils::get_to_countersignatory_with_anchors_redeemscript(&payment_point))
153 /// The maximum length a well-formed witness spending one of these should have.
154 /// Note: If you have the grind_signatures feature enabled, this will be at least 1 byte
156 pub fn max_witness_length(&self) -> usize {
157 if self.channel_transaction_parameters.as_ref()
158 .map(|channel_params| channel_params.channel_type_features.supports_anchors_zero_fee_htlc_tx())
161 let witness_script_weight = 1 /* pubkey push */ + 33 /* pubkey */ +
162 1 /* OP_CHECKSIGVERIFY */ + 1 /* OP_1 */ + 1 /* OP_CHECKSEQUENCEVERIFY */;
163 1 /* num witness items */ + 1 /* sig push */ + 73 /* sig including sighash flag */ +
164 1 /* witness script push */ + witness_script_weight
166 P2WPKH_WITNESS_WEIGHT as usize
170 impl_writeable_tlv_based!(StaticPaymentOutputDescriptor, {
171 (0, outpoint, required),
172 (2, output, required),
173 (4, channel_keys_id, required),
174 (6, channel_value_satoshis, required),
175 (7, channel_transaction_parameters, option),
178 /// Describes the necessary information to spend a spendable output.
180 /// When on-chain outputs are created by LDK (which our counterparty is not able to claim at any
181 /// point in the future) a [`SpendableOutputs`] event is generated which you must track and be able
182 /// to spend on-chain. The information needed to do this is provided in this enum, including the
183 /// outpoint describing which `txid` and output `index` is available, the full output which exists
184 /// at that `txid`/`index`, and any keys or other information required to sign.
186 /// [`SpendableOutputs`]: crate::events::Event::SpendableOutputs
187 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
188 pub enum SpendableOutputDescriptor {
189 /// An output to a script which was provided via [`SignerProvider`] directly, either from
190 /// [`get_destination_script`] or [`get_shutdown_scriptpubkey`], thus you should already
191 /// know how to spend it. No secret keys are provided as LDK was never given any key.
192 /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
193 /// on-chain using the payment preimage or after it has timed out.
195 /// [`get_shutdown_scriptpubkey`]: SignerProvider::get_shutdown_scriptpubkey
196 /// [`get_destination_script`]: SignerProvider::get_shutdown_scriptpubkey
198 /// The outpoint which is spendable.
200 /// The output which is referenced by the given outpoint.
203 /// An output to a P2WSH script which can be spent with a single signature after an `OP_CSV`
206 /// The witness in the spending input should be:
208 /// <BIP 143 signature> <empty vector> (MINIMALIF standard rule) <provided witnessScript>
211 /// Note that the `nSequence` field in the spending input must be set to
212 /// [`DelayedPaymentOutputDescriptor::to_self_delay`] (which means the transaction is not
213 /// broadcastable until at least [`DelayedPaymentOutputDescriptor::to_self_delay`] blocks after
214 /// the outpoint confirms, see [BIP
215 /// 68](https://github.com/bitcoin/bips/blob/master/bip-0068.mediawiki)). Also note that LDK
216 /// won't generate a [`SpendableOutputDescriptor`] until the corresponding block height
219 /// These are generally the result of a "revocable" output to us, spendable only by us unless
220 /// it is an output from an old state which we broadcast (which should never happen).
222 /// To derive the delayed payment key which is used to sign this input, you must pass the
223 /// holder [`InMemorySigner::delayed_payment_base_key`] (i.e., the private key which corresponds to the
224 /// [`ChannelPublicKeys::delayed_payment_basepoint`] in [`ChannelSigner::pubkeys`]) and the provided
225 /// [`DelayedPaymentOutputDescriptor::per_commitment_point`] to [`chan_utils::derive_private_key`]. The public key can be
226 /// generated without the secret key using [`chan_utils::derive_public_key`] and only the
227 /// [`ChannelPublicKeys::delayed_payment_basepoint`] which appears in [`ChannelSigner::pubkeys`].
229 /// To derive the [`DelayedPaymentOutputDescriptor::revocation_pubkey`] provided here (which is
230 /// used in the witness script generation), you must pass the counterparty
231 /// [`ChannelPublicKeys::revocation_basepoint`] (which appears in the call to
232 /// [`ChannelSigner::provide_channel_parameters`]) and the provided
233 /// [`DelayedPaymentOutputDescriptor::per_commitment_point`] to
234 /// [`chan_utils::derive_public_revocation_key`].
236 /// The witness script which is hashed and included in the output `script_pubkey` may be
237 /// regenerated by passing the [`DelayedPaymentOutputDescriptor::revocation_pubkey`] (derived
238 /// as explained above), our delayed payment pubkey (derived as explained above), and the
239 /// [`DelayedPaymentOutputDescriptor::to_self_delay`] contained here to
240 /// [`chan_utils::get_revokeable_redeemscript`].
241 DelayedPaymentOutput(DelayedPaymentOutputDescriptor),
242 /// An output spendable exclusively by our payment key (i.e., the private key that corresponds
243 /// to the `payment_point` in [`ChannelSigner::pubkeys`]). The output type depends on the
244 /// channel type negotiated.
246 /// On an anchor outputs channel, the witness in the spending input is:
248 /// <BIP 143 signature> <witness script>
251 /// Otherwise, it is:
253 /// <BIP 143 signature> <payment key>
256 /// These are generally the result of our counterparty having broadcast the current state,
257 /// allowing us to claim the non-HTLC-encumbered outputs immediately, or after one confirmation
258 /// in the case of anchor outputs channels.
259 StaticPaymentOutput(StaticPaymentOutputDescriptor),
262 impl_writeable_tlv_based_enum!(SpendableOutputDescriptor,
263 (0, StaticOutput) => {
264 (0, outpoint, required),
265 (2, output, required),
268 (1, DelayedPaymentOutput),
269 (2, StaticPaymentOutput),
272 impl SpendableOutputDescriptor {
273 /// Turns this into a [`bitcoin::psbt::Input`] which can be used to create a
274 /// [`PartiallySignedTransaction`] which spends the given descriptor.
276 /// Note that this does not include any signatures, just the information required to
277 /// construct the transaction and sign it.
278 pub fn to_psbt_input(&self) -> bitcoin::psbt::Input {
280 SpendableOutputDescriptor::StaticOutput { output, .. } => {
281 // Is a standard P2WPKH, no need for witness script
282 bitcoin::psbt::Input {
283 witness_utxo: Some(output.clone()),
287 SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
288 // TODO we could add the witness script as well
289 bitcoin::psbt::Input {
290 witness_utxo: Some(descriptor.output.clone()),
294 SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
295 // TODO we could add the witness script as well
296 bitcoin::psbt::Input {
297 witness_utxo: Some(descriptor.output.clone()),
304 /// Creates an unsigned [`PartiallySignedTransaction`] which spends the given descriptors to
305 /// the given outputs, plus an output to the given change destination (if sufficient
306 /// change value remains). The PSBT will have a feerate, at least, of the given value.
308 /// The `locktime` argument is used to set the transaction's locktime. If `None`, the
309 /// transaction will have a locktime of 0. It it recommended to set this to the current block
310 /// height to avoid fee sniping, unless you have some specific reason to use a different
313 /// Returns the PSBT and expected max transaction weight.
315 /// Returns `Err(())` if the output value is greater than the input value minus required fee,
316 /// if a descriptor was duplicated, or if an output descriptor `script_pubkey`
317 /// does not match the one we can spend.
319 /// We do not enforce that outputs meet the dust limit or that any output scripts are standard.
320 pub fn create_spendable_outputs_psbt(descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>, change_destination_script: Script, feerate_sat_per_1000_weight: u32, locktime: Option<PackedLockTime>) -> Result<(PartiallySignedTransaction, usize), ()> {
321 let mut input = Vec::with_capacity(descriptors.len());
322 let mut input_value = 0;
323 let mut witness_weight = 0;
324 let mut output_set = HashSet::with_capacity(descriptors.len());
325 for outp in descriptors {
327 SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
328 if !output_set.insert(descriptor.outpoint) { return Err(()); }
330 if descriptor.channel_transaction_parameters.as_ref()
331 .map(|channel_params| channel_params.channel_type_features.supports_anchors_zero_fee_htlc_tx())
334 Sequence::from_consensus(1)
339 previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
340 script_sig: Script::new(),
342 witness: Witness::new(),
344 witness_weight += descriptor.max_witness_length();
345 #[cfg(feature = "grind_signatures")]
346 { witness_weight -= 1; } // Guarantees a low R signature
347 input_value += descriptor.output.value;
349 SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
350 if !output_set.insert(descriptor.outpoint) { return Err(()); }
352 previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
353 script_sig: Script::new(),
354 sequence: Sequence(descriptor.to_self_delay as u32),
355 witness: Witness::new(),
357 witness_weight += DelayedPaymentOutputDescriptor::MAX_WITNESS_LENGTH;
358 #[cfg(feature = "grind_signatures")]
359 { witness_weight -= 1; } // Guarantees a low R signature
360 input_value += descriptor.output.value;
362 SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
363 if !output_set.insert(*outpoint) { return Err(()); }
365 previous_output: outpoint.into_bitcoin_outpoint(),
366 script_sig: Script::new(),
367 sequence: Sequence::ZERO,
368 witness: Witness::new(),
370 witness_weight += 1 + 73 + 34;
371 #[cfg(feature = "grind_signatures")]
372 { witness_weight -= 1; } // Guarantees a low R signature
373 input_value += output.value;
376 if input_value > MAX_VALUE_MSAT / 1000 { return Err(()); }
378 let mut tx = Transaction {
380 lock_time: locktime.unwrap_or(PackedLockTime::ZERO),
384 let expected_max_weight =
385 transaction_utils::maybe_add_change_output(&mut tx, input_value, witness_weight, feerate_sat_per_1000_weight, change_destination_script)?;
387 let psbt_inputs = descriptors.iter().map(|d| d.to_psbt_input()).collect::<Vec<_>>();
388 let psbt = PartiallySignedTransaction {
390 outputs: vec![Default::default(); tx.output.len()],
392 xpub: Default::default(),
394 proprietary: Default::default(),
395 unknown: Default::default(),
397 Ok((psbt, expected_max_weight))
401 /// A trait to handle Lightning channel key material without concretizing the channel type or
402 /// the signature mechanism.
403 pub trait ChannelSigner {
404 /// Gets the per-commitment point for a specific commitment number
406 /// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
407 fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey;
409 /// Gets the commitment secret for a specific commitment number as part of the revocation process
411 /// An external signer implementation should error here if the commitment was already signed
412 /// and should refuse to sign it in the future.
414 /// May be called more than once for the same index.
416 /// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
417 // TODO: return a Result so we can signal a validation error
418 fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
420 /// Validate the counterparty's signatures on the holder commitment transaction and HTLCs.
422 /// This is required in order for the signer to make sure that releasing a commitment
423 /// secret won't leave us without a broadcastable holder transaction.
424 /// Policy checks should be implemented in this function, including checking the amount
425 /// sent to us and checking the HTLCs.
427 /// The preimages of outgoing HTLCs that were fulfilled since the last commitment are provided.
428 /// A validating signer should ensure that an HTLC output is removed only when the matching
429 /// preimage is provided, or when the value to holder is restored.
431 /// Note that all the relevant preimages will be provided, but there may also be additional
432 /// irrelevant or duplicate preimages.
433 fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction,
434 preimages: Vec<PaymentPreimage>) -> Result<(), ()>;
436 /// Returns the holder's channel public keys and basepoints.
437 fn pubkeys(&self) -> &ChannelPublicKeys;
439 /// Returns an arbitrary identifier describing the set of keys which are provided back to you in
440 /// some [`SpendableOutputDescriptor`] types. This should be sufficient to identify this
441 /// [`EcdsaChannelSigner`] object uniquely and lookup or re-derive its keys.
442 fn channel_keys_id(&self) -> [u8; 32];
444 /// Set the counterparty static channel data, including basepoints,
445 /// `counterparty_selected`/`holder_selected_contest_delay` and funding outpoint.
447 /// This data is static, and will never change for a channel once set. For a given [`ChannelSigner`]
448 /// instance, LDK will call this method exactly once - either immediately after construction
449 /// (not including if done via [`SignerProvider::read_chan_signer`]) or when the funding
450 /// information has been generated.
452 /// channel_parameters.is_populated() MUST be true.
453 fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters);
456 /// A trait to sign Lightning channel transactions as described in
457 /// [BOLT 3](https://github.com/lightning/bolts/blob/master/03-transactions.md).
459 /// Signing services could be implemented on a hardware wallet and should implement signing
460 /// policies in order to be secure. Please refer to the [VLS Policy
461 /// Controls](https://gitlab.com/lightning-signer/validating-lightning-signer/-/blob/main/docs/policy-controls.md)
462 /// for an example of such policies.
463 pub trait EcdsaChannelSigner: ChannelSigner {
464 /// Create a signature for a counterparty's commitment transaction and associated HTLC transactions.
466 /// Note that if signing fails or is rejected, the channel will be force-closed.
468 /// Policy checks should be implemented in this function, including checking the amount
469 /// sent to us and checking the HTLCs.
471 /// The preimages of outgoing HTLCs that were fulfilled since the last commitment are provided.
472 /// A validating signer should ensure that an HTLC output is removed only when the matching
473 /// preimage is provided, or when the value to holder is restored.
475 /// Note that all the relevant preimages will be provided, but there may also be additional
476 /// irrelevant or duplicate preimages.
478 // TODO: Document the things someone using this interface should enforce before signing.
479 fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction,
480 preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>
481 ) -> Result<(Signature, Vec<Signature>), ()>;
482 /// Validate the counterparty's revocation.
484 /// This is required in order for the signer to make sure that the state has moved
485 /// forward and it is safe to sign the next counterparty commitment.
486 fn validate_counterparty_revocation(&self, idx: u64, secret: &SecretKey) -> Result<(), ()>;
487 /// Creates a signature for a holder's commitment transaction and its claiming HTLC transactions.
489 /// This will be called
490 /// - with a non-revoked `commitment_tx`.
491 /// - with the latest `commitment_tx` when we initiate a force-close.
492 /// - with the previous `commitment_tx`, just to get claiming HTLC
493 /// signatures, if we are reacting to a [`ChannelMonitor`]
494 /// [replica](https://github.com/lightningdevkit/rust-lightning/blob/main/GLOSSARY.md#monitor-replicas)
495 /// that decided to broadcast before it had been updated to the latest `commitment_tx`.
497 /// This may be called multiple times for the same transaction.
499 /// An external signer implementation should check that the commitment has not been revoked.
501 /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
502 // TODO: Document the things someone using this interface should enforce before signing.
503 fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction,
504 secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()>;
505 /// Same as [`sign_holder_commitment_and_htlcs`], but exists only for tests to get access to
506 /// holder commitment transactions which will be broadcasted later, after the channel has moved
507 /// on to a newer state. Thus, needs its own method as [`sign_holder_commitment_and_htlcs`] may
508 /// enforce that we only ever get called once.
509 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
510 fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction,
511 secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()>;
512 /// Create a signature for the given input in a transaction spending an HTLC transaction output
513 /// or a commitment transaction `to_local` output when our counterparty broadcasts an old state.
515 /// A justice transaction may claim multiple outputs at the same time if timelocks are
516 /// similar, but only a signature for the input at index `input` should be signed for here.
517 /// It may be called multiple times for same output(s) if a fee-bump is needed with regards
518 /// to an upcoming timelock expiration.
520 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
522 /// `per_commitment_key` is revocation secret which was provided by our counterparty when they
523 /// revoked the state which they eventually broadcast. It's not a _holder_ secret key and does
524 /// not allow the spending of any funds by itself (you need our holder `revocation_secret` to do
526 fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64,
527 per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>
528 ) -> Result<Signature, ()>;
529 /// Create a signature for the given input in a transaction spending a commitment transaction
530 /// HTLC output when our counterparty broadcasts an old state.
532 /// A justice transaction may claim multiple outputs at the same time if timelocks are
533 /// similar, but only a signature for the input at index `input` should be signed for here.
534 /// It may be called multiple times for same output(s) if a fee-bump is needed with regards
535 /// to an upcoming timelock expiration.
537 /// `amount` is the value of the output spent by this input, committed to in the BIP 143
540 /// `per_commitment_key` is revocation secret which was provided by our counterparty when they
541 /// revoked the state which they eventually broadcast. It's not a _holder_ secret key and does
542 /// not allow the spending of any funds by itself (you need our holder revocation_secret to do
545 /// `htlc` holds HTLC elements (hash, timelock), thus changing the format of the witness script
546 /// (which is committed to in the BIP 143 signatures).
547 fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64,
548 per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment,
549 secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
550 /// Computes the signature for a commitment transaction's HTLC output used as an input within
551 /// `htlc_tx`, which spends the commitment transaction at index `input`. The signature returned
552 /// must be be computed using [`EcdsaSighashType::All`]. Note that this should only be used to
553 /// sign HTLC transactions from channels supporting anchor outputs after all additional
554 /// inputs/outputs have been added to the transaction.
556 /// [`EcdsaSighashType::All`]: bitcoin::blockdata::transaction::EcdsaSighashType::All
557 fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize,
558 htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<secp256k1::All>
559 ) -> Result<Signature, ()>;
560 /// Create a signature for a claiming transaction for a HTLC output on a counterparty's commitment
561 /// transaction, either offered or received.
563 /// Such a transaction may claim multiples offered outputs at same time if we know the
564 /// preimage for each when we create it, but only the input at index `input` should be
565 /// signed for here. It may be called multiple times for same output(s) if a fee-bump is
566 /// needed with regards to an upcoming timelock expiration.
568 /// `witness_script` is either an offered or received script as defined in BOLT3 for HTLC
571 /// `amount` is value of the output spent by this input, committed to in the BIP 143 signature.
573 /// `per_commitment_point` is the dynamic point corresponding to the channel state
574 /// detected onchain. It has been generated by our counterparty and is used to derive
575 /// channel state keys, which are then included in the witness script and committed to in the
576 /// BIP 143 signature.
577 fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64,
578 per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment,
579 secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
580 /// Create a signature for a (proposed) closing transaction.
582 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
583 /// chosen to forgo their output as dust.
584 fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction,
585 secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
586 /// Computes the signature for a commitment transaction's anchor output used as an
587 /// input within `anchor_tx`, which spends the commitment transaction, at index `input`.
588 fn sign_holder_anchor_input(
589 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
590 ) -> Result<Signature, ()>;
591 /// Signs a channel announcement message with our funding key proving it comes from one of the
592 /// channel participants.
594 /// Channel announcements also require a signature from each node's network key. Our node
595 /// signature is computed through [`NodeSigner::sign_gossip_message`].
597 /// Note that if this fails or is rejected, the channel will not be publicly announced and
598 /// our counterparty may (though likely will not) close the channel on us for violating the
600 fn sign_channel_announcement_with_funding_key(
601 &self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
602 ) -> Result<Signature, ()>;
605 /// A writeable signer.
607 /// There will always be two instances of a signer per channel, one occupied by the
608 /// [`ChannelManager`] and another by the channel's [`ChannelMonitor`].
610 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
611 /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
612 pub trait WriteableEcdsaChannelSigner: EcdsaChannelSigner + Writeable {}
614 /// Specifies the recipient of an invoice.
616 /// This indicates to [`NodeSigner::sign_invoice`] what node secret key should be used to sign
619 /// The invoice should be signed with the local node secret key.
621 /// The invoice should be signed with the phantom node secret key. This secret key must be the
622 /// same for all nodes participating in the [phantom node payment].
624 /// [phantom node payment]: PhantomKeysManager
628 /// A trait that describes a source of entropy.
629 pub trait EntropySource {
630 /// Gets a unique, cryptographically-secure, random 32-byte value. This method must return a
631 /// different value each time it is called.
632 fn get_secure_random_bytes(&self) -> [u8; 32];
635 /// A trait that can handle cryptographic operations at the scope level of a node.
636 pub trait NodeSigner {
637 /// Get secret key material as bytes for use in encrypting and decrypting inbound payment data.
639 /// If the implementor of this trait supports [phantom node payments], then every node that is
640 /// intended to be included in the phantom invoice route hints must return the same value from
642 // This is because LDK avoids storing inbound payment data by encrypting payment data in the
643 // payment hash and/or payment secret, therefore for a payment to be receivable by multiple
644 // nodes, they must share the key that encrypts this payment data.
646 /// This method must return the same value each time it is called.
648 /// [phantom node payments]: PhantomKeysManager
649 fn get_inbound_payment_key_material(&self) -> KeyMaterial;
651 /// Get node id based on the provided [`Recipient`].
653 /// This method must return the same value each time it is called with a given [`Recipient`]
656 /// Errors if the [`Recipient`] variant is not supported by the implementation.
657 fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()>;
659 /// Gets the ECDH shared secret of our node secret and `other_key`, multiplying by `tweak` if
660 /// one is provided. Note that this tweak can be applied to `other_key` instead of our node
661 /// secret, though this is less efficient.
663 /// Note that if this fails while attempting to forward an HTLC, LDK will panic. The error
664 /// should be resolved to allow LDK to resume forwarding HTLCs.
666 /// Errors if the [`Recipient`] variant is not supported by the implementation.
667 fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result<SharedSecret, ()>;
671 /// By parameterizing by the raw invoice bytes instead of the hash, we allow implementors of
672 /// this trait to parse the invoice and make sure they're signing what they expect, rather than
673 /// blindly signing the hash.
675 /// The `hrp_bytes` are ASCII bytes, while the `invoice_data` is base32.
677 /// The secret key used to sign the invoice is dependent on the [`Recipient`].
679 /// Errors if the [`Recipient`] variant is not supported by the implementation.
680 fn sign_invoice(&self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient) -> Result<RecoverableSignature, ()>;
682 /// Signs the [`TaggedHash`] of a BOLT 12 invoice request.
684 /// May be called by a function passed to [`UnsignedInvoiceRequest::sign`] where
685 /// `invoice_request` is the callee.
687 /// Implementors may check that the `invoice_request` is expected rather than blindly signing
688 /// the tagged hash. An `Ok` result should sign `invoice_request.tagged_hash().as_digest()` with
689 /// the node's signing key or an ephemeral key to preserve privacy, whichever is associated with
690 /// [`UnsignedInvoiceRequest::payer_id`].
692 /// [`TaggedHash`]: crate::offers::merkle::TaggedHash
693 fn sign_bolt12_invoice_request(
694 &self, invoice_request: &UnsignedInvoiceRequest
695 ) -> Result<schnorr::Signature, ()>;
697 /// Signs the [`TaggedHash`] of a BOLT 12 invoice.
699 /// May be called by a function passed to [`UnsignedBolt12Invoice::sign`] where `invoice` is the
702 /// Implementors may check that the `invoice` is expected rather than blindly signing the tagged
703 /// hash. An `Ok` result should sign `invoice.tagged_hash().as_digest()` with the node's signing
704 /// key or an ephemeral key to preserve privacy, whichever is associated with
705 /// [`UnsignedBolt12Invoice::signing_pubkey`].
707 /// [`TaggedHash`]: crate::offers::merkle::TaggedHash
708 fn sign_bolt12_invoice(
709 &self, invoice: &UnsignedBolt12Invoice
710 ) -> Result<schnorr::Signature, ()>;
712 /// Sign a gossip message.
714 /// Note that if this fails, LDK may panic and the message will not be broadcast to the network
715 /// or a possible channel counterparty. If LDK panics, the error should be resolved to allow the
716 /// message to be broadcast, as otherwise it may prevent one from receiving funds over the
717 /// corresponding channel.
718 fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()>;
721 /// A trait that can return signer instances for individual channels.
722 pub trait SignerProvider {
723 /// A type which implements [`WriteableEcdsaChannelSigner`] which will be returned by [`Self::derive_channel_signer`].
724 type Signer : WriteableEcdsaChannelSigner;
726 /// Generates a unique `channel_keys_id` that can be used to obtain a [`Self::Signer`] through
727 /// [`SignerProvider::derive_channel_signer`]. The `user_channel_id` is provided to allow
728 /// implementations of [`SignerProvider`] to maintain a mapping between itself and the generated
729 /// `channel_keys_id`.
731 /// This method must return a different value each time it is called.
732 fn generate_channel_keys_id(&self, inbound: bool, channel_value_satoshis: u64, user_channel_id: u128) -> [u8; 32];
734 /// Derives the private key material backing a `Signer`.
736 /// To derive a new `Signer`, a fresh `channel_keys_id` should be obtained through
737 /// [`SignerProvider::generate_channel_keys_id`]. Otherwise, an existing `Signer` can be
738 /// re-derived from its `channel_keys_id`, which can be obtained through its trait method
739 /// [`ChannelSigner::channel_keys_id`].
740 fn derive_channel_signer(&self, channel_value_satoshis: u64, channel_keys_id: [u8; 32]) -> Self::Signer;
742 /// Reads a [`Signer`] for this [`SignerProvider`] from the given input stream.
743 /// This is only called during deserialization of other objects which contain
744 /// [`WriteableEcdsaChannelSigner`]-implementing objects (i.e., [`ChannelMonitor`]s and [`ChannelManager`]s).
745 /// The bytes are exactly those which `<Self::Signer as Writeable>::write()` writes, and
746 /// contain no versioning scheme. You may wish to include your own version prefix and ensure
747 /// you've read all of the provided bytes to ensure no corruption occurred.
749 /// This method is slowly being phased out -- it will only be called when reading objects
750 /// written by LDK versions prior to 0.0.113.
752 /// [`Signer`]: Self::Signer
753 /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
754 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
755 fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::Signer, DecodeError>;
757 /// Get a script pubkey which we send funds to when claiming on-chain contestable outputs.
759 /// If this function returns an error, this will result in a channel failing to open.
761 /// This method should return a different value each time it is called, to avoid linking
762 /// on-chain funds across channels as controlled to the same user.
763 fn get_destination_script(&self) -> Result<Script, ()>;
765 /// Get a script pubkey which we will send funds to when closing a channel.
767 /// If this function returns an error, this will result in a channel failing to open or close.
768 /// In the event of a failure when the counterparty is initiating a close, this can result in a
769 /// channel force close.
771 /// This method should return a different value each time it is called, to avoid linking
772 /// on-chain funds across channels as controlled to the same user.
773 fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()>;
776 /// A simple implementation of [`WriteableEcdsaChannelSigner`] that just keeps the private keys in memory.
778 /// This implementation performs no policy checks and is insufficient by itself as
779 /// a secure external signer.
781 pub struct InMemorySigner {
782 /// Holder secret key in the 2-of-2 multisig script of a channel. This key also backs the
783 /// holder's anchor output in a commitment transaction, if one is present.
784 pub funding_key: SecretKey,
785 /// Holder secret key for blinded revocation pubkey.
786 pub revocation_base_key: SecretKey,
787 /// Holder secret key used for our balance in counterparty-broadcasted commitment transactions.
788 pub payment_key: SecretKey,
789 /// Holder secret key used in an HTLC transaction.
790 pub delayed_payment_base_key: SecretKey,
791 /// Holder HTLC secret key used in commitment transaction HTLC outputs.
792 pub htlc_base_key: SecretKey,
794 pub commitment_seed: [u8; 32],
795 /// Holder public keys and basepoints.
796 pub(crate) holder_channel_pubkeys: ChannelPublicKeys,
797 /// Counterparty public keys and counterparty/holder `selected_contest_delay`, populated on channel acceptance.
798 channel_parameters: Option<ChannelTransactionParameters>,
799 /// The total value of this channel.
800 channel_value_satoshis: u64,
801 /// Key derivation parameters.
802 channel_keys_id: [u8; 32],
803 /// Seed from which all randomness produced is derived from.
804 rand_bytes_unique_start: [u8; 32],
805 /// Tracks the number of times we've produced randomness to ensure we don't return the same
807 rand_bytes_index: AtomicCounter,
810 impl PartialEq for InMemorySigner {
811 fn eq(&self, other: &Self) -> bool {
812 self.funding_key == other.funding_key &&
813 self.revocation_base_key == other.revocation_base_key &&
814 self.payment_key == other.payment_key &&
815 self.delayed_payment_base_key == other.delayed_payment_base_key &&
816 self.htlc_base_key == other.htlc_base_key &&
817 self.commitment_seed == other.commitment_seed &&
818 self.holder_channel_pubkeys == other.holder_channel_pubkeys &&
819 self.channel_parameters == other.channel_parameters &&
820 self.channel_value_satoshis == other.channel_value_satoshis &&
821 self.channel_keys_id == other.channel_keys_id
825 impl Clone for InMemorySigner {
826 fn clone(&self) -> Self {
828 funding_key: self.funding_key.clone(),
829 revocation_base_key: self.revocation_base_key.clone(),
830 payment_key: self.payment_key.clone(),
831 delayed_payment_base_key: self.delayed_payment_base_key.clone(),
832 htlc_base_key: self.htlc_base_key.clone(),
833 commitment_seed: self.commitment_seed.clone(),
834 holder_channel_pubkeys: self.holder_channel_pubkeys.clone(),
835 channel_parameters: self.channel_parameters.clone(),
836 channel_value_satoshis: self.channel_value_satoshis,
837 channel_keys_id: self.channel_keys_id,
838 rand_bytes_unique_start: self.get_secure_random_bytes(),
839 rand_bytes_index: AtomicCounter::new(),
844 impl InMemorySigner {
845 /// Creates a new [`InMemorySigner`].
846 pub fn new<C: Signing>(
847 secp_ctx: &Secp256k1<C>,
848 funding_key: SecretKey,
849 revocation_base_key: SecretKey,
850 payment_key: SecretKey,
851 delayed_payment_base_key: SecretKey,
852 htlc_base_key: SecretKey,
853 commitment_seed: [u8; 32],
854 channel_value_satoshis: u64,
855 channel_keys_id: [u8; 32],
856 rand_bytes_unique_start: [u8; 32],
857 ) -> InMemorySigner {
858 let holder_channel_pubkeys =
859 InMemorySigner::make_holder_keys(secp_ctx, &funding_key, &revocation_base_key,
860 &payment_key, &delayed_payment_base_key,
866 delayed_payment_base_key,
869 channel_value_satoshis,
870 holder_channel_pubkeys,
871 channel_parameters: None,
873 rand_bytes_unique_start,
874 rand_bytes_index: AtomicCounter::new(),
878 fn make_holder_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
879 funding_key: &SecretKey,
880 revocation_base_key: &SecretKey,
881 payment_key: &SecretKey,
882 delayed_payment_base_key: &SecretKey,
883 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
884 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
886 funding_pubkey: from_secret(&funding_key),
887 revocation_basepoint: from_secret(&revocation_base_key),
888 payment_point: from_secret(&payment_key),
889 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
890 htlc_basepoint: from_secret(&htlc_base_key),
894 /// Returns the counterparty's pubkeys.
896 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
897 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
898 pub fn counterparty_pubkeys(&self) -> Option<&ChannelPublicKeys> {
899 self.get_channel_parameters()
900 .and_then(|params| params.counterparty_parameters.as_ref().map(|params| ¶ms.pubkeys))
903 /// Returns the `contest_delay` value specified by our counterparty and applied on holder-broadcastable
904 /// transactions, i.e., the amount of time that we have to wait to recover our funds if we
905 /// broadcast a transaction.
907 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
908 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
909 pub fn counterparty_selected_contest_delay(&self) -> Option<u16> {
910 self.get_channel_parameters()
911 .and_then(|params| params.counterparty_parameters.as_ref().map(|params| params.selected_contest_delay))
914 /// Returns the `contest_delay` value specified by us and applied on transactions broadcastable
915 /// by our counterparty, i.e., the amount of time that they have to wait to recover their funds
916 /// if they broadcast a transaction.
918 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
919 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
920 pub fn holder_selected_contest_delay(&self) -> Option<u16> {
921 self.get_channel_parameters().map(|params| params.holder_selected_contest_delay)
924 /// Returns whether the holder is the initiator.
926 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
927 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
928 pub fn is_outbound(&self) -> Option<bool> {
929 self.get_channel_parameters().map(|params| params.is_outbound_from_holder)
934 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
935 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
936 pub fn funding_outpoint(&self) -> Option<&OutPoint> {
937 self.get_channel_parameters().map(|params| params.funding_outpoint.as_ref()).flatten()
940 /// Returns a [`ChannelTransactionParameters`] for this channel, to be used when verifying or
941 /// building transactions.
943 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
944 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
945 pub fn get_channel_parameters(&self) -> Option<&ChannelTransactionParameters> {
946 self.channel_parameters.as_ref()
949 /// Returns the channel type features of the channel parameters. Should be helpful for
950 /// determining a channel's category, i. e. legacy/anchors/taproot/etc.
952 /// Will return `None` if [`ChannelSigner::provide_channel_parameters`] has not been called.
953 /// In general, this is safe to `unwrap` only in [`ChannelSigner`] implementation.
954 pub fn channel_type_features(&self) -> Option<&ChannelTypeFeatures> {
955 self.get_channel_parameters().map(|params| ¶ms.channel_type_features)
958 /// Sign the single input of `spend_tx` at index `input_idx`, which spends the output described
959 /// by `descriptor`, returning the witness stack for the input.
961 /// Returns an error if the input at `input_idx` does not exist, has a non-empty `script_sig`,
962 /// is not spending the outpoint described by [`descriptor.outpoint`],
963 /// or if an output descriptor `script_pubkey` does not match the one we can spend.
965 /// [`descriptor.outpoint`]: StaticPaymentOutputDescriptor::outpoint
966 pub fn sign_counterparty_payment_input<C: Signing>(&self, spend_tx: &Transaction, input_idx: usize, descriptor: &StaticPaymentOutputDescriptor, secp_ctx: &Secp256k1<C>) -> Result<Vec<Vec<u8>>, ()> {
967 // TODO: We really should be taking the SigHashCache as a parameter here instead of
968 // spend_tx, but ideally the SigHashCache would expose the transaction's inputs read-only
969 // so that we can check them. This requires upstream rust-bitcoin changes (as well as
970 // bindings updates to support SigHashCache objects).
971 if spend_tx.input.len() <= input_idx { return Err(()); }
972 if !spend_tx.input[input_idx].script_sig.is_empty() { return Err(()); }
973 if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint() { return Err(()); }
975 let remotepubkey = bitcoin::PublicKey::new(self.pubkeys().payment_point);
976 // We cannot always assume that `channel_parameters` is set, so can't just call
977 // `self.channel_parameters()` or anything that relies on it
978 let supports_anchors_zero_fee_htlc_tx = self.channel_type_features()
979 .map(|features| features.supports_anchors_zero_fee_htlc_tx())
982 let witness_script = if supports_anchors_zero_fee_htlc_tx {
983 chan_utils::get_to_countersignatory_with_anchors_redeemscript(&remotepubkey.inner)
985 Script::new_p2pkh(&remotepubkey.pubkey_hash())
987 let sighash = hash_to_message!(&sighash::SighashCache::new(spend_tx).segwit_signature_hash(input_idx, &witness_script, descriptor.output.value, EcdsaSighashType::All).unwrap()[..]);
988 let remotesig = sign_with_aux_rand(secp_ctx, &sighash, &self.payment_key, &self);
989 let payment_script = if supports_anchors_zero_fee_htlc_tx {
990 witness_script.to_v0_p2wsh()
992 Script::new_v0_p2wpkh(&remotepubkey.wpubkey_hash().unwrap())
995 if payment_script != descriptor.output.script_pubkey { return Err(()); }
997 let mut witness = Vec::with_capacity(2);
998 witness.push(remotesig.serialize_der().to_vec());
999 witness[0].push(EcdsaSighashType::All as u8);
1000 if supports_anchors_zero_fee_htlc_tx {
1001 witness.push(witness_script.to_bytes());
1003 witness.push(remotepubkey.to_bytes());
1008 /// Sign the single input of `spend_tx` at index `input_idx` which spends the output
1009 /// described by `descriptor`, returning the witness stack for the input.
1011 /// Returns an error if the input at `input_idx` does not exist, has a non-empty `script_sig`,
1012 /// is not spending the outpoint described by [`descriptor.outpoint`], does not have a
1013 /// sequence set to [`descriptor.to_self_delay`], or if an output descriptor
1014 /// `script_pubkey` does not match the one we can spend.
1016 /// [`descriptor.outpoint`]: DelayedPaymentOutputDescriptor::outpoint
1017 /// [`descriptor.to_self_delay`]: DelayedPaymentOutputDescriptor::to_self_delay
1018 pub fn sign_dynamic_p2wsh_input<C: Signing>(&self, spend_tx: &Transaction, input_idx: usize, descriptor: &DelayedPaymentOutputDescriptor, secp_ctx: &Secp256k1<C>) -> Result<Vec<Vec<u8>>, ()> {
1019 // TODO: We really should be taking the SigHashCache as a parameter here instead of
1020 // spend_tx, but ideally the SigHashCache would expose the transaction's inputs read-only
1021 // so that we can check them. This requires upstream rust-bitcoin changes (as well as
1022 // bindings updates to support SigHashCache objects).
1023 if spend_tx.input.len() <= input_idx { return Err(()); }
1024 if !spend_tx.input[input_idx].script_sig.is_empty() { return Err(()); }
1025 if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint() { return Err(()); }
1026 if spend_tx.input[input_idx].sequence.0 != descriptor.to_self_delay as u32 { return Err(()); }
1028 let delayed_payment_key = chan_utils::derive_private_key(&secp_ctx, &descriptor.per_commitment_point, &self.delayed_payment_base_key);
1029 let delayed_payment_pubkey = PublicKey::from_secret_key(&secp_ctx, &delayed_payment_key);
1030 let witness_script = chan_utils::get_revokeable_redeemscript(&descriptor.revocation_pubkey, descriptor.to_self_delay, &delayed_payment_pubkey);
1031 let sighash = hash_to_message!(&sighash::SighashCache::new(spend_tx).segwit_signature_hash(input_idx, &witness_script, descriptor.output.value, EcdsaSighashType::All).unwrap()[..]);
1032 let local_delayedsig = sign_with_aux_rand(secp_ctx, &sighash, &delayed_payment_key, &self);
1033 let payment_script = bitcoin::Address::p2wsh(&witness_script, Network::Bitcoin).script_pubkey();
1035 if descriptor.output.script_pubkey != payment_script { return Err(()); }
1037 let mut witness = Vec::with_capacity(3);
1038 witness.push(local_delayedsig.serialize_der().to_vec());
1039 witness[0].push(EcdsaSighashType::All as u8);
1040 witness.push(vec!()); //MINIMALIF
1041 witness.push(witness_script.clone().into_bytes());
1046 impl EntropySource for InMemorySigner {
1047 fn get_secure_random_bytes(&self) -> [u8; 32] {
1048 let index = self.rand_bytes_index.get_increment();
1049 let mut nonce = [0u8; 16];
1050 nonce[..8].copy_from_slice(&index.to_be_bytes());
1051 ChaCha20::get_single_block(&self.rand_bytes_unique_start, &nonce)
1055 impl ChannelSigner for InMemorySigner {
1056 fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
1057 let commitment_secret = SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx)).unwrap();
1058 PublicKey::from_secret_key(secp_ctx, &commitment_secret)
1061 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
1062 chan_utils::build_commitment_secret(&self.commitment_seed, idx)
1065 fn validate_holder_commitment(&self, _holder_tx: &HolderCommitmentTransaction, _preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
1069 fn pubkeys(&self) -> &ChannelPublicKeys { &self.holder_channel_pubkeys }
1071 fn channel_keys_id(&self) -> [u8; 32] { self.channel_keys_id }
1073 fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
1074 assert!(self.channel_parameters.is_none() || self.channel_parameters.as_ref().unwrap() == channel_parameters);
1075 if self.channel_parameters.is_some() {
1076 // The channel parameters were already set and they match, return early.
1079 assert!(channel_parameters.is_populated(), "Channel parameters must be fully populated");
1080 self.channel_parameters = Some(channel_parameters.clone());
1084 const MISSING_PARAMS_ERR: &'static str = "ChannelSigner::provide_channel_parameters must be called before signing operations";
1086 impl EcdsaChannelSigner for InMemorySigner {
1087 fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, _preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
1088 let trusted_tx = commitment_tx.trust();
1089 let keys = trusted_tx.keys();
1091 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1092 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1093 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1095 let built_tx = trusted_tx.built_transaction();
1096 let commitment_sig = built_tx.sign_counterparty_commitment(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx);
1097 let commitment_txid = built_tx.txid;
1099 let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len());
1100 for htlc in commitment_tx.htlcs() {
1101 let channel_parameters = self.get_channel_parameters().expect(MISSING_PARAMS_ERR);
1102 let holder_selected_contest_delay =
1103 self.holder_selected_contest_delay().expect(MISSING_PARAMS_ERR);
1104 let chan_type = &channel_parameters.channel_type_features;
1105 let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), holder_selected_contest_delay, htlc, chan_type, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
1106 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, chan_type, &keys);
1107 let htlc_sighashtype = if chan_type.supports_anchors_zero_fee_htlc_tx() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
1108 let htlc_sighash = hash_to_message!(&sighash::SighashCache::new(&htlc_tx).segwit_signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, htlc_sighashtype).unwrap()[..]);
1109 let holder_htlc_key = chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key);
1110 htlc_sigs.push(sign(secp_ctx, &htlc_sighash, &holder_htlc_key));
1113 Ok((commitment_sig, htlc_sigs))
1116 fn validate_counterparty_revocation(&self, _idx: u64, _secret: &SecretKey) -> Result<(), ()> {
1120 fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
1121 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1122 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1123 let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1124 let trusted_tx = commitment_tx.trust();
1125 let sig = trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx);
1126 let channel_parameters = self.get_channel_parameters().expect(MISSING_PARAMS_ERR);
1127 let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), &self, secp_ctx)?;
1128 Ok((sig, htlc_sigs))
1131 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
1132 fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
1133 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1134 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1135 let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey);
1136 let trusted_tx = commitment_tx.trust();
1137 let sig = trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx);
1138 let channel_parameters = self.get_channel_parameters().expect(MISSING_PARAMS_ERR);
1139 let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), &self, secp_ctx)?;
1140 Ok((sig, htlc_sigs))
1143 fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
1144 let revocation_key = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key);
1145 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
1146 let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint);
1147 let witness_script = {
1148 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1149 let holder_selected_contest_delay =
1150 self.holder_selected_contest_delay().expect(MISSING_PARAMS_ERR);
1151 let counterparty_delayedpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &counterparty_keys.delayed_payment_basepoint);
1152 chan_utils::get_revokeable_redeemscript(&revocation_pubkey, holder_selected_contest_delay, &counterparty_delayedpubkey)
1154 let mut sighash_parts = sighash::SighashCache::new(justice_tx);
1155 let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
1156 return Ok(sign_with_aux_rand(secp_ctx, &sighash, &revocation_key, &self))
1159 fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
1160 let revocation_key = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key);
1161 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
1162 let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint);
1163 let witness_script = {
1164 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1165 let counterparty_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &counterparty_keys.htlc_basepoint);
1166 let holder_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint);
1167 let chan_type = self.channel_type_features().expect(MISSING_PARAMS_ERR);
1168 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, chan_type, &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
1170 let mut sighash_parts = sighash::SighashCache::new(justice_tx);
1171 let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
1172 return Ok(sign_with_aux_rand(secp_ctx, &sighash, &revocation_key, &self))
1175 fn sign_holder_htlc_transaction(
1176 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
1177 secp_ctx: &Secp256k1<secp256k1::All>
1178 ) -> Result<Signature, ()> {
1179 let witness_script = htlc_descriptor.witness_script(secp_ctx);
1180 let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
1181 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, EcdsaSighashType::All
1183 let our_htlc_private_key = chan_utils::derive_private_key(
1184 &secp_ctx, &htlc_descriptor.per_commitment_point, &self.htlc_base_key
1186 Ok(sign_with_aux_rand(&secp_ctx, &hash_to_message!(sighash), &our_htlc_private_key, &self))
1189 fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
1190 let htlc_key = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key);
1191 let revocation_pubkey = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint);
1192 let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR);
1193 let counterparty_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &counterparty_keys.htlc_basepoint);
1194 let htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint);
1195 let chan_type = self.channel_type_features().expect(MISSING_PARAMS_ERR);
1196 let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, chan_type, &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey);
1197 let mut sighash_parts = sighash::SighashCache::new(htlc_tx);
1198 let sighash = hash_to_message!(&sighash_parts.segwit_signature_hash(input, &witness_script, amount, EcdsaSighashType::All).unwrap()[..]);
1199 Ok(sign_with_aux_rand(secp_ctx, &sighash, &htlc_key, &self))
1202 fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
1203 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
1204 let counterparty_funding_key = &self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR).funding_pubkey;
1205 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, counterparty_funding_key);
1206 Ok(closing_tx.trust().sign(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
1209 fn sign_holder_anchor_input(
1210 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
1211 ) -> Result<Signature, ()> {
1212 let witness_script = chan_utils::get_anchor_redeemscript(&self.holder_channel_pubkeys.funding_pubkey);
1213 let sighash = sighash::SighashCache::new(&*anchor_tx).segwit_signature_hash(
1214 input, &witness_script, ANCHOR_OUTPUT_VALUE_SATOSHI, EcdsaSighashType::All,
1216 Ok(sign_with_aux_rand(secp_ctx, &hash_to_message!(&sighash[..]), &self.funding_key, &self))
1219 fn sign_channel_announcement_with_funding_key(
1220 &self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
1221 ) -> Result<Signature, ()> {
1222 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
1223 Ok(secp_ctx.sign_ecdsa(&msghash, &self.funding_key))
1227 const SERIALIZATION_VERSION: u8 = 1;
1229 const MIN_SERIALIZATION_VERSION: u8 = 1;
1231 impl WriteableEcdsaChannelSigner for InMemorySigner {}
1233 impl Writeable for InMemorySigner {
1234 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
1235 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
1237 self.funding_key.write(writer)?;
1238 self.revocation_base_key.write(writer)?;
1239 self.payment_key.write(writer)?;
1240 self.delayed_payment_base_key.write(writer)?;
1241 self.htlc_base_key.write(writer)?;
1242 self.commitment_seed.write(writer)?;
1243 self.channel_parameters.write(writer)?;
1244 self.channel_value_satoshis.write(writer)?;
1245 self.channel_keys_id.write(writer)?;
1247 write_tlv_fields!(writer, {});
1253 impl<ES: Deref> ReadableArgs<ES> for InMemorySigner where ES::Target: EntropySource {
1254 fn read<R: io::Read>(reader: &mut R, entropy_source: ES) -> Result<Self, DecodeError> {
1255 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
1257 let funding_key = Readable::read(reader)?;
1258 let revocation_base_key = Readable::read(reader)?;
1259 let payment_key = Readable::read(reader)?;
1260 let delayed_payment_base_key = Readable::read(reader)?;
1261 let htlc_base_key = Readable::read(reader)?;
1262 let commitment_seed = Readable::read(reader)?;
1263 let counterparty_channel_data = Readable::read(reader)?;
1264 let channel_value_satoshis = Readable::read(reader)?;
1265 let secp_ctx = Secp256k1::signing_only();
1266 let holder_channel_pubkeys =
1267 InMemorySigner::make_holder_keys(&secp_ctx, &funding_key, &revocation_base_key,
1268 &payment_key, &delayed_payment_base_key, &htlc_base_key);
1269 let keys_id = Readable::read(reader)?;
1271 read_tlv_fields!(reader, {});
1275 revocation_base_key,
1277 delayed_payment_base_key,
1280 channel_value_satoshis,
1281 holder_channel_pubkeys,
1282 channel_parameters: counterparty_channel_data,
1283 channel_keys_id: keys_id,
1284 rand_bytes_unique_start: entropy_source.get_secure_random_bytes(),
1285 rand_bytes_index: AtomicCounter::new(),
1290 /// Simple implementation of [`EntropySource`], [`NodeSigner`], and [`SignerProvider`] that takes a
1291 /// 32-byte seed for use as a BIP 32 extended key and derives keys from that.
1293 /// Your `node_id` is seed/0'.
1294 /// Unilateral closes may use seed/1'.
1295 /// Cooperative closes may use seed/2'.
1296 /// The two close keys may be needed to claim on-chain funds!
1298 /// This struct cannot be used for nodes that wish to support receiving phantom payments;
1299 /// [`PhantomKeysManager`] must be used instead.
1301 /// Note that switching between this struct and [`PhantomKeysManager`] will invalidate any
1302 /// previously issued invoices and attempts to pay previous invoices will fail.
1303 pub struct KeysManager {
1304 secp_ctx: Secp256k1<secp256k1::All>,
1305 node_secret: SecretKey,
1307 inbound_payment_key: KeyMaterial,
1308 destination_script: Script,
1309 shutdown_pubkey: PublicKey,
1310 channel_master_key: ExtendedPrivKey,
1311 channel_child_index: AtomicUsize,
1313 rand_bytes_unique_start: [u8; 32],
1314 rand_bytes_index: AtomicCounter,
1317 starting_time_secs: u64,
1318 starting_time_nanos: u32,
1322 /// Constructs a [`KeysManager`] from a 32-byte seed. If the seed is in some way biased (e.g.,
1323 /// your CSRNG is busted) this may panic (but more importantly, you will possibly lose funds).
1324 /// `starting_time` isn't strictly required to actually be a time, but it must absolutely,
1325 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
1326 /// `seed`, `starting_time` must be unique to each run. Thus, the easiest way to achieve this
1327 /// is to simply use the current time (with very high precision).
1329 /// The `seed` MUST be backed up safely prior to use so that the keys can be re-created, however,
1330 /// obviously, `starting_time` should be unique every time you reload the library - it is only
1331 /// used to generate new ephemeral key data (which will be stored by the individual channel if
1334 /// Note that the seed is required to recover certain on-chain funds independent of
1335 /// [`ChannelMonitor`] data, though a current copy of [`ChannelMonitor`] data is also required
1336 /// for any channel, and some on-chain during-closing funds.
1338 /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
1339 pub fn new(seed: &[u8; 32], starting_time_secs: u64, starting_time_nanos: u32) -> Self {
1340 let secp_ctx = Secp256k1::new();
1341 // Note that when we aren't serializing the key, network doesn't matter
1342 match ExtendedPrivKey::new_master(Network::Testnet, seed) {
1344 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key;
1345 let node_id = PublicKey::from_secret_key(&secp_ctx, &node_secret);
1346 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
1347 Ok(destination_key) => {
1348 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_priv(&secp_ctx, &destination_key).to_pub().to_bytes());
1349 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
1350 .push_slice(&wpubkey_hash.into_inner())
1353 Err(_) => panic!("Your RNG is busted"),
1355 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
1356 Ok(shutdown_key) => ExtendedPubKey::from_priv(&secp_ctx, &shutdown_key).public_key,
1357 Err(_) => panic!("Your RNG is busted"),
1359 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
1360 let inbound_payment_key: SecretKey = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted").private_key;
1361 let mut inbound_pmt_key_bytes = [0; 32];
1362 inbound_pmt_key_bytes.copy_from_slice(&inbound_payment_key[..]);
1364 let mut rand_bytes_engine = Sha256::engine();
1365 rand_bytes_engine.input(&starting_time_secs.to_be_bytes());
1366 rand_bytes_engine.input(&starting_time_nanos.to_be_bytes());
1367 rand_bytes_engine.input(seed);
1368 rand_bytes_engine.input(b"LDK PRNG Seed");
1369 let rand_bytes_unique_start = Sha256::from_engine(rand_bytes_engine).into_inner();
1371 let mut res = KeysManager {
1375 inbound_payment_key: KeyMaterial(inbound_pmt_key_bytes),
1381 channel_child_index: AtomicUsize::new(0),
1383 rand_bytes_unique_start,
1384 rand_bytes_index: AtomicCounter::new(),
1388 starting_time_nanos,
1390 let secp_seed = res.get_secure_random_bytes();
1391 res.secp_ctx.seeded_randomize(&secp_seed);
1394 Err(_) => panic!("Your rng is busted"),
1398 /// Gets the "node_id" secret key used to sign gossip announcements, decode onion data, etc.
1399 pub fn get_node_secret_key(&self) -> SecretKey {
1403 /// Derive an old [`WriteableEcdsaChannelSigner`] containing per-channel secrets based on a key derivation parameters.
1404 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params: &[u8; 32]) -> InMemorySigner {
1405 let chan_id = u64::from_be_bytes(params[0..8].try_into().unwrap());
1406 let mut unique_start = Sha256::engine();
1407 unique_start.input(params);
1408 unique_start.input(&self.seed);
1410 // We only seriously intend to rely on the channel_master_key for true secure
1411 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
1412 // starting_time provided in the constructor) to be unique.
1413 let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx,
1414 ChildNumber::from_hardened_idx((chan_id as u32) % (1 << 31)).expect("key space exhausted")
1415 ).expect("Your RNG is busted");
1416 unique_start.input(&child_privkey.private_key[..]);
1418 let seed = Sha256::from_engine(unique_start).into_inner();
1420 let commitment_seed = {
1421 let mut sha = Sha256::engine();
1423 sha.input(&b"commitment seed"[..]);
1424 Sha256::from_engine(sha).into_inner()
1426 macro_rules! key_step {
1427 ($info: expr, $prev_key: expr) => {{
1428 let mut sha = Sha256::engine();
1430 sha.input(&$prev_key[..]);
1431 sha.input(&$info[..]);
1432 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
1435 let funding_key = key_step!(b"funding key", commitment_seed);
1436 let revocation_base_key = key_step!(b"revocation base key", funding_key);
1437 let payment_key = key_step!(b"payment key", revocation_base_key);
1438 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
1439 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
1440 let prng_seed = self.get_secure_random_bytes();
1442 InMemorySigner::new(
1445 revocation_base_key,
1447 delayed_payment_base_key,
1450 channel_value_satoshis,
1456 /// Signs the given [`PartiallySignedTransaction`] which spends the given [`SpendableOutputDescriptor`]s.
1457 /// The resulting inputs will be finalized and the PSBT will be ready for broadcast if there
1458 /// are no other inputs that need signing.
1460 /// Returns `Err(())` if the PSBT is missing a descriptor or if we fail to sign.
1462 /// May panic if the [`SpendableOutputDescriptor`]s were not generated by channels which used
1463 /// this [`KeysManager`] or one of the [`InMemorySigner`] created by this [`KeysManager`].
1464 pub fn sign_spendable_outputs_psbt<C: Signing>(&self, descriptors: &[&SpendableOutputDescriptor], mut psbt: PartiallySignedTransaction, secp_ctx: &Secp256k1<C>) -> Result<PartiallySignedTransaction, ()> {
1465 let mut keys_cache: Option<(InMemorySigner, [u8; 32])> = None;
1466 for outp in descriptors {
1468 SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
1469 let input_idx = psbt.unsigned_tx.input.iter().position(|i| i.previous_output == descriptor.outpoint.into_bitcoin_outpoint()).ok_or(())?;
1470 if keys_cache.is_none() || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id {
1471 let mut signer = self.derive_channel_keys(descriptor.channel_value_satoshis, &descriptor.channel_keys_id);
1472 if let Some(channel_params) = descriptor.channel_transaction_parameters.as_ref() {
1473 signer.provide_channel_parameters(channel_params);
1475 keys_cache = Some((signer, descriptor.channel_keys_id));
1477 let witness = Witness::from_vec(keys_cache.as_ref().unwrap().0.sign_counterparty_payment_input(&psbt.unsigned_tx, input_idx, &descriptor, &secp_ctx)?);
1478 psbt.inputs[input_idx].final_script_witness = Some(witness);
1480 SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
1481 let input_idx = psbt.unsigned_tx.input.iter().position(|i| i.previous_output == descriptor.outpoint.into_bitcoin_outpoint()).ok_or(())?;
1482 if keys_cache.is_none() || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id {
1484 self.derive_channel_keys(descriptor.channel_value_satoshis, &descriptor.channel_keys_id),
1485 descriptor.channel_keys_id));
1487 let witness = Witness::from_vec(keys_cache.as_ref().unwrap().0.sign_dynamic_p2wsh_input(&psbt.unsigned_tx, input_idx, &descriptor, &secp_ctx)?);
1488 psbt.inputs[input_idx].final_script_witness = Some(witness);
1490 SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
1491 let input_idx = psbt.unsigned_tx.input.iter().position(|i| i.previous_output == outpoint.into_bitcoin_outpoint()).ok_or(())?;
1492 let derivation_idx = if output.script_pubkey == self.destination_script {
1498 // Note that when we aren't serializing the key, network doesn't matter
1499 match ExtendedPrivKey::new_master(Network::Testnet, &self.seed) {
1501 match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(derivation_idx).expect("key space exhausted")) {
1503 Err(_) => panic!("Your RNG is busted"),
1506 Err(_) => panic!("Your rng is busted"),
1509 let pubkey = ExtendedPubKey::from_priv(&secp_ctx, &secret).to_pub();
1510 if derivation_idx == 2 {
1511 assert_eq!(pubkey.inner, self.shutdown_pubkey);
1513 let witness_script = bitcoin::Address::p2pkh(&pubkey, Network::Testnet).script_pubkey();
1514 let payment_script = bitcoin::Address::p2wpkh(&pubkey, Network::Testnet).expect("uncompressed key found").script_pubkey();
1516 if payment_script != output.script_pubkey { return Err(()); };
1518 let sighash = hash_to_message!(&sighash::SighashCache::new(&psbt.unsigned_tx).segwit_signature_hash(input_idx, &witness_script, output.value, EcdsaSighashType::All).unwrap()[..]);
1519 let sig = sign_with_aux_rand(secp_ctx, &sighash, &secret.private_key, &self);
1520 let mut sig_ser = sig.serialize_der().to_vec();
1521 sig_ser.push(EcdsaSighashType::All as u8);
1522 let witness = Witness::from_vec(vec![sig_ser, pubkey.inner.serialize().to_vec()]);
1523 psbt.inputs[input_idx].final_script_witness = Some(witness);
1531 /// Creates a [`Transaction`] which spends the given descriptors to the given outputs, plus an
1532 /// output to the given change destination (if sufficient change value remains). The
1533 /// transaction will have a feerate, at least, of the given value.
1535 /// The `locktime` argument is used to set the transaction's locktime. If `None`, the
1536 /// transaction will have a locktime of 0. It it recommended to set this to the current block
1537 /// height to avoid fee sniping, unless you have some specific reason to use a different
1540 /// Returns `Err(())` if the output value is greater than the input value minus required fee,
1541 /// if a descriptor was duplicated, or if an output descriptor `script_pubkey`
1542 /// does not match the one we can spend.
1544 /// We do not enforce that outputs meet the dust limit or that any output scripts are standard.
1546 /// May panic if the [`SpendableOutputDescriptor`]s were not generated by channels which used
1547 /// this [`KeysManager`] or one of the [`InMemorySigner`] created by this [`KeysManager`].
1548 pub fn spend_spendable_outputs<C: Signing>(&self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>, change_destination_script: Script, feerate_sat_per_1000_weight: u32, locktime: Option<PackedLockTime>, secp_ctx: &Secp256k1<C>) -> Result<Transaction, ()> {
1549 let (mut psbt, expected_max_weight) = SpendableOutputDescriptor::create_spendable_outputs_psbt(descriptors, outputs, change_destination_script, feerate_sat_per_1000_weight, locktime)?;
1550 psbt = self.sign_spendable_outputs_psbt(descriptors, psbt, secp_ctx)?;
1552 let spend_tx = psbt.extract_tx();
1554 debug_assert!(expected_max_weight >= spend_tx.weight());
1555 // Note that witnesses with a signature vary somewhat in size, so allow
1556 // `expected_max_weight` to overshoot by up to 3 bytes per input.
1557 debug_assert!(expected_max_weight <= spend_tx.weight() + descriptors.len() * 3);
1563 impl EntropySource for KeysManager {
1564 fn get_secure_random_bytes(&self) -> [u8; 32] {
1565 let index = self.rand_bytes_index.get_increment();
1566 let mut nonce = [0u8; 16];
1567 nonce[..8].copy_from_slice(&index.to_be_bytes());
1568 ChaCha20::get_single_block(&self.rand_bytes_unique_start, &nonce)
1572 impl NodeSigner for KeysManager {
1573 fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()> {
1575 Recipient::Node => Ok(self.node_id.clone()),
1576 Recipient::PhantomNode => Err(())
1580 fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result<SharedSecret, ()> {
1581 let mut node_secret = match recipient {
1582 Recipient::Node => Ok(self.node_secret.clone()),
1583 Recipient::PhantomNode => Err(())
1585 if let Some(tweak) = tweak {
1586 node_secret = node_secret.mul_tweak(tweak).map_err(|_| ())?;
1588 Ok(SharedSecret::new(other_key, &node_secret))
1591 fn get_inbound_payment_key_material(&self) -> KeyMaterial {
1592 self.inbound_payment_key.clone()
1595 fn sign_invoice(&self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient) -> Result<RecoverableSignature, ()> {
1596 let preimage = construct_invoice_preimage(&hrp_bytes, &invoice_data);
1597 let secret = match recipient {
1598 Recipient::Node => Ok(&self.node_secret),
1599 Recipient::PhantomNode => Err(())
1601 Ok(self.secp_ctx.sign_ecdsa_recoverable(&hash_to_message!(&Sha256::hash(&preimage)), secret))
1604 fn sign_bolt12_invoice_request(
1605 &self, invoice_request: &UnsignedInvoiceRequest
1606 ) -> Result<schnorr::Signature, ()> {
1607 let message = invoice_request.tagged_hash().as_digest();
1608 let keys = KeyPair::from_secret_key(&self.secp_ctx, &self.node_secret);
1609 let aux_rand = self.get_secure_random_bytes();
1610 Ok(self.secp_ctx.sign_schnorr_with_aux_rand(message, &keys, &aux_rand))
1613 fn sign_bolt12_invoice(
1614 &self, invoice: &UnsignedBolt12Invoice
1615 ) -> Result<schnorr::Signature, ()> {
1616 let message = invoice.tagged_hash().as_digest();
1617 let keys = KeyPair::from_secret_key(&self.secp_ctx, &self.node_secret);
1618 let aux_rand = self.get_secure_random_bytes();
1619 Ok(self.secp_ctx.sign_schnorr_with_aux_rand(message, &keys, &aux_rand))
1622 fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()> {
1623 let msg_hash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
1624 Ok(self.secp_ctx.sign_ecdsa(&msg_hash, &self.node_secret))
1628 impl SignerProvider for KeysManager {
1629 type Signer = InMemorySigner;
1631 fn generate_channel_keys_id(&self, _inbound: bool, _channel_value_satoshis: u64, user_channel_id: u128) -> [u8; 32] {
1632 let child_idx = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
1633 // `child_idx` is the only thing guaranteed to make each channel unique without a restart
1634 // (though `user_channel_id` should help, depending on user behavior). If it manages to
1635 // roll over, we may generate duplicate keys for two different channels, which could result
1636 // in loss of funds. Because we only support 32-bit+ systems, assert that our `AtomicUsize`
1637 // doesn't reach `u32::MAX`.
1638 assert!(child_idx < core::u32::MAX as usize, "2^32 channels opened without restart");
1639 let mut id = [0; 32];
1640 id[0..4].copy_from_slice(&(child_idx as u32).to_be_bytes());
1641 id[4..8].copy_from_slice(&self.starting_time_nanos.to_be_bytes());
1642 id[8..16].copy_from_slice(&self.starting_time_secs.to_be_bytes());
1643 id[16..32].copy_from_slice(&user_channel_id.to_be_bytes());
1647 fn derive_channel_signer(&self, channel_value_satoshis: u64, channel_keys_id: [u8; 32]) -> Self::Signer {
1648 self.derive_channel_keys(channel_value_satoshis, &channel_keys_id)
1651 fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::Signer, DecodeError> {
1652 InMemorySigner::read(&mut io::Cursor::new(reader), self)
1655 fn get_destination_script(&self) -> Result<Script, ()> {
1656 Ok(self.destination_script.clone())
1659 fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
1660 Ok(ShutdownScript::new_p2wpkh_from_pubkey(self.shutdown_pubkey.clone()))
1664 /// Similar to [`KeysManager`], but allows the node using this struct to receive phantom node
1667 /// A phantom node payment is a payment made to a phantom invoice, which is an invoice that can be
1668 /// paid to one of multiple nodes. This works because we encode the invoice route hints such that
1669 /// LDK will recognize an incoming payment as destined for a phantom node, and collect the payment
1670 /// itself without ever needing to forward to this fake node.
1672 /// Phantom node payments are useful for load balancing between multiple LDK nodes. They also
1673 /// provide some fault tolerance, because payers will automatically retry paying other provided
1674 /// nodes in the case that one node goes down.
1676 /// Note that multi-path payments are not supported in phantom invoices for security reasons.
1677 // In the hypothetical case that we did support MPP phantom payments, there would be no way for
1678 // nodes to know when the full payment has been received (and the preimage can be released) without
1679 // significantly compromising on our safety guarantees. I.e., if we expose the ability for the user
1680 // to tell LDK when the preimage can be released, we open ourselves to attacks where the preimage
1681 // is released too early.
1683 /// Switching between this struct and [`KeysManager`] will invalidate any previously issued
1684 /// invoices and attempts to pay previous invoices will fail.
1685 pub struct PhantomKeysManager {
1687 inbound_payment_key: KeyMaterial,
1688 phantom_secret: SecretKey,
1689 phantom_node_id: PublicKey,
1692 impl EntropySource for PhantomKeysManager {
1693 fn get_secure_random_bytes(&self) -> [u8; 32] {
1694 self.inner.get_secure_random_bytes()
1698 impl NodeSigner for PhantomKeysManager {
1699 fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()> {
1701 Recipient::Node => self.inner.get_node_id(Recipient::Node),
1702 Recipient::PhantomNode => Ok(self.phantom_node_id.clone()),
1706 fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result<SharedSecret, ()> {
1707 let mut node_secret = match recipient {
1708 Recipient::Node => self.inner.node_secret.clone(),
1709 Recipient::PhantomNode => self.phantom_secret.clone(),
1711 if let Some(tweak) = tweak {
1712 node_secret = node_secret.mul_tweak(tweak).map_err(|_| ())?;
1714 Ok(SharedSecret::new(other_key, &node_secret))
1717 fn get_inbound_payment_key_material(&self) -> KeyMaterial {
1718 self.inbound_payment_key.clone()
1721 fn sign_invoice(&self, hrp_bytes: &[u8], invoice_data: &[u5], recipient: Recipient) -> Result<RecoverableSignature, ()> {
1722 let preimage = construct_invoice_preimage(&hrp_bytes, &invoice_data);
1723 let secret = match recipient {
1724 Recipient::Node => &self.inner.node_secret,
1725 Recipient::PhantomNode => &self.phantom_secret,
1727 Ok(self.inner.secp_ctx.sign_ecdsa_recoverable(&hash_to_message!(&Sha256::hash(&preimage)), secret))
1730 fn sign_bolt12_invoice_request(
1731 &self, invoice_request: &UnsignedInvoiceRequest
1732 ) -> Result<schnorr::Signature, ()> {
1733 self.inner.sign_bolt12_invoice_request(invoice_request)
1736 fn sign_bolt12_invoice(
1737 &self, invoice: &UnsignedBolt12Invoice
1738 ) -> Result<schnorr::Signature, ()> {
1739 self.inner.sign_bolt12_invoice(invoice)
1742 fn sign_gossip_message(&self, msg: UnsignedGossipMessage) -> Result<Signature, ()> {
1743 self.inner.sign_gossip_message(msg)
1747 impl SignerProvider for PhantomKeysManager {
1748 type Signer = InMemorySigner;
1750 fn generate_channel_keys_id(&self, inbound: bool, channel_value_satoshis: u64, user_channel_id: u128) -> [u8; 32] {
1751 self.inner.generate_channel_keys_id(inbound, channel_value_satoshis, user_channel_id)
1754 fn derive_channel_signer(&self, channel_value_satoshis: u64, channel_keys_id: [u8; 32]) -> Self::Signer {
1755 self.inner.derive_channel_signer(channel_value_satoshis, channel_keys_id)
1758 fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::Signer, DecodeError> {
1759 self.inner.read_chan_signer(reader)
1762 fn get_destination_script(&self) -> Result<Script, ()> {
1763 self.inner.get_destination_script()
1766 fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
1767 self.inner.get_shutdown_scriptpubkey()
1771 impl PhantomKeysManager {
1772 /// Constructs a [`PhantomKeysManager`] given a 32-byte seed and an additional `cross_node_seed`
1773 /// that is shared across all nodes that intend to participate in [phantom node payments]
1776 /// See [`KeysManager::new`] for more information on `seed`, `starting_time_secs`, and
1777 /// `starting_time_nanos`.
1779 /// `cross_node_seed` must be the same across all phantom payment-receiving nodes and also the
1780 /// same across restarts, or else inbound payments may fail.
1782 /// [phantom node payments]: PhantomKeysManager
1783 pub fn new(seed: &[u8; 32], starting_time_secs: u64, starting_time_nanos: u32, cross_node_seed: &[u8; 32]) -> Self {
1784 let inner = KeysManager::new(seed, starting_time_secs, starting_time_nanos);
1785 let (inbound_key, phantom_key) = hkdf_extract_expand_twice(b"LDK Inbound and Phantom Payment Key Expansion", cross_node_seed);
1786 let phantom_secret = SecretKey::from_slice(&phantom_key).unwrap();
1787 let phantom_node_id = PublicKey::from_secret_key(&inner.secp_ctx, &phantom_secret);
1790 inbound_payment_key: KeyMaterial(inbound_key),
1796 /// See [`KeysManager::spend_spendable_outputs`] for documentation on this method.
1797 pub fn spend_spendable_outputs<C: Signing>(&self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>, change_destination_script: Script, feerate_sat_per_1000_weight: u32, locktime: Option<PackedLockTime>, secp_ctx: &Secp256k1<C>) -> Result<Transaction, ()> {
1798 self.inner.spend_spendable_outputs(descriptors, outputs, change_destination_script, feerate_sat_per_1000_weight, locktime, secp_ctx)
1801 /// See [`KeysManager::derive_channel_keys`] for documentation on this method.
1802 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params: &[u8; 32]) -> InMemorySigner {
1803 self.inner.derive_channel_keys(channel_value_satoshis, params)
1806 /// Gets the "node_id" secret key used to sign gossip announcements, decode onion data, etc.
1807 pub fn get_node_secret_key(&self) -> SecretKey {
1808 self.inner.get_node_secret_key()
1811 /// Gets the "node_id" secret key of the phantom node used to sign invoices, decode the
1812 /// last-hop onion data, etc.
1813 pub fn get_phantom_node_secret_key(&self) -> SecretKey {
1818 // Ensure that EcdsaChannelSigner can have a vtable
1821 let _signer: Box<dyn EcdsaChannelSigner>;
1826 use std::sync::{Arc, mpsc};
1827 use std::sync::mpsc::TryRecvError;
1829 use std::time::Duration;
1830 use bitcoin::blockdata::constants::genesis_block;
1831 use bitcoin::Network;
1832 use crate::sign::{EntropySource, KeysManager};
1834 use criterion::Criterion;
1836 pub fn bench_get_secure_random_bytes(bench: &mut Criterion) {
1837 let seed = [0u8; 32];
1838 let now = Duration::from_secs(genesis_block(Network::Testnet).header.time as u64);
1839 let keys_manager = Arc::new(KeysManager::new(&seed, now.as_secs(), now.subsec_micros()));
1841 let mut handles = Vec::new();
1842 let mut stops = Vec::new();
1844 let keys_manager_clone = Arc::clone(&keys_manager);
1845 let (stop_sender, stop_receiver) = mpsc::channel();
1846 let handle = thread::spawn(move || {
1848 keys_manager_clone.get_secure_random_bytes();
1849 match stop_receiver.try_recv() {
1850 Ok(_) | Err(TryRecvError::Disconnected) => {
1851 println!("Terminating.");
1854 Err(TryRecvError::Empty) => {}
1858 handles.push(handle);
1859 stops.push(stop_sender);
1862 bench.bench_function("get_secure_random_bytes", |b| b.iter(||
1863 keys_manager.get_secure_random_bytes()));
1866 let _ = stop.send(());
1868 for handle in handles {
1869 handle.join().unwrap();