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 //! keysinterface provides keys into rust-lightning and defines some useful enums which describe
11 //! spendable on-chain outputs which the user owns and is responsible for using just as any other
12 //! on-chain output which is theirs.
14 use bitcoin::blockdata::transaction::{Transaction, TxOut, SigHashType};
15 use bitcoin::blockdata::script::{Script, Builder};
16 use bitcoin::blockdata::opcodes;
17 use bitcoin::network::constants::Network;
18 use bitcoin::util::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber};
19 use bitcoin::util::bip143;
21 use bitcoin::hashes::{Hash, HashEngine};
22 use bitcoin::hashes::sha256::HashEngine as Sha256State;
23 use bitcoin::hashes::sha256::Hash as Sha256;
24 use bitcoin::hashes::sha256d::Hash as Sha256dHash;
25 use bitcoin::hash_types::WPubkeyHash;
27 use bitcoin::secp256k1::key::{SecretKey, PublicKey};
28 use bitcoin::secp256k1::{Secp256k1, Signature, Signing};
29 use bitcoin::secp256k1;
32 use util::ser::{Writeable, Writer, Readable};
34 use chain::transaction::OutPoint;
36 use ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction};
37 use ln::msgs::UnsignedChannelAnnouncement;
39 use std::sync::atomic::{AtomicUsize, Ordering};
41 use ln::msgs::DecodeError;
43 /// When on-chain outputs are created by rust-lightning (which our counterparty is not able to
44 /// claim at any point in the future) an event is generated which you must track and be able to
45 /// spend on-chain. The information needed to do this is provided in this enum, including the
46 /// outpoint describing which txid and output index is available, the full output which exists at
47 /// that txid/index, and any keys or other information required to sign.
48 #[derive(Clone, Debug, PartialEq)]
49 pub enum SpendableOutputDescriptor {
50 /// An output to a script which was provided via KeysInterface, thus you should already know
51 /// how to spend it. No keys are provided as rust-lightning was never given any keys - only the
52 /// script_pubkey as it appears in the output.
53 /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
54 /// on-chain using the payment preimage or after it has timed out.
56 /// The outpoint which is spendable
58 /// The output which is referenced by the given outpoint.
61 /// An output to a P2WSH script which can be spent with a single signature after a CSV delay.
63 /// The witness in the spending input should be:
64 /// <BIP 143 signature> <empty vector> (MINIMALIF standard rule) <provided witnessScript>
66 /// Note that the nSequence field in the spending input must be set to to_self_delay
67 /// (which means the transaction is not broadcastable until at least to_self_delay
68 /// blocks after the outpoint confirms).
70 /// These are generally the result of a "revocable" output to us, spendable only by us unless
71 /// it is an output from an old state which we broadcast (which should never happen).
73 /// To derive the delayed_payment key which is used to sign for this input, you must pass the
74 /// holder delayed_payment_base_key (ie the private key which corresponds to the pubkey in
75 /// ChannelKeys::pubkeys().delayed_payment_basepoint) and the provided per_commitment_point to
76 /// chan_utils::derive_private_key. The public key can be generated without the secret key
77 /// using chan_utils::derive_public_key and only the delayed_payment_basepoint which appears in
78 /// ChannelKeys::pubkeys().
80 /// To derive the revocation_pubkey provided here (which is used in the witness
81 /// script generation), you must pass the counterparty revocation_basepoint (which appears in the
82 /// call to ChannelKeys::ready_channel) and the provided per_commitment point
83 /// to chan_utils::derive_public_revocation_key.
85 /// The witness script which is hashed and included in the output script_pubkey may be
86 /// regenerated by passing the revocation_pubkey (derived as above), our delayed_payment pubkey
87 /// (derived as above), and the to_self_delay contained here to
88 /// chan_utils::get_revokeable_redeemscript.
90 // TODO: we need to expose utility methods in KeyManager to do all the relevant derivation.
92 /// The outpoint which is spendable
94 /// Per commitment point to derive delayed_payment_key by key holder
95 per_commitment_point: PublicKey,
96 /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in
97 /// the witness_script.
99 /// The output which is referenced by the given outpoint
101 /// The channel keys state used to proceed to derivation of signing key. Must
102 /// be pass to KeysInterface::derive_channel_keys.
103 key_derivation_params: (u64, u64),
104 /// The revocation_pubkey used to derive witnessScript
105 revocation_pubkey: PublicKey
107 /// An output to a P2WPKH, spendable exclusively by our payment key (ie the private key which
108 /// corresponds to the public key in ChannelKeys::pubkeys().payment_point).
109 /// The witness in the spending input, is, thus, simply:
110 /// <BIP 143 signature> <payment key>
112 /// These are generally the result of our counterparty having broadcast the current state,
113 /// allowing us to claim the non-HTLC-encumbered outputs immediately.
114 StaticOutputCounterpartyPayment {
115 /// The outpoint which is spendable
117 /// The output which is reference by the given outpoint
119 /// The channel keys state used to proceed to derivation of signing key. Must
120 /// be pass to KeysInterface::derive_channel_keys.
121 key_derivation_params: (u64, u64),
125 impl Writeable for SpendableOutputDescriptor {
126 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
128 &SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
130 outpoint.write(writer)?;
131 output.write(writer)?;
133 &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref per_commitment_point, ref to_self_delay, ref output, ref key_derivation_params, ref revocation_pubkey } => {
135 outpoint.write(writer)?;
136 per_commitment_point.write(writer)?;
137 to_self_delay.write(writer)?;
138 output.write(writer)?;
139 key_derivation_params.0.write(writer)?;
140 key_derivation_params.1.write(writer)?;
141 revocation_pubkey.write(writer)?;
143 &SpendableOutputDescriptor::StaticOutputCounterpartyPayment { ref outpoint, ref output, ref key_derivation_params } => {
145 outpoint.write(writer)?;
146 output.write(writer)?;
147 key_derivation_params.0.write(writer)?;
148 key_derivation_params.1.write(writer)?;
155 impl Readable for SpendableOutputDescriptor {
156 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
157 match Readable::read(reader)? {
158 0u8 => Ok(SpendableOutputDescriptor::StaticOutput {
159 outpoint: Readable::read(reader)?,
160 output: Readable::read(reader)?,
162 1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH {
163 outpoint: Readable::read(reader)?,
164 per_commitment_point: Readable::read(reader)?,
165 to_self_delay: Readable::read(reader)?,
166 output: Readable::read(reader)?,
167 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
168 revocation_pubkey: Readable::read(reader)?,
170 2u8 => Ok(SpendableOutputDescriptor::StaticOutputCounterpartyPayment {
171 outpoint: Readable::read(reader)?,
172 output: Readable::read(reader)?,
173 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
175 _ => Err(DecodeError::InvalidValue),
180 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
182 /// Signing services could be implemented on a hardware wallet. In this case,
183 /// the current ChannelKeys would be a front-end on top of a communication
184 /// channel connected to your secure device and lightning key material wouldn't
185 /// reside on a hot server. Nevertheless, a this deployment would still need
186 /// to trust the ChannelManager to avoid loss of funds as this latest component
187 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
189 /// A more secure iteration would be to use hashlock (or payment points) to pair
190 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
191 /// at the price of more state and computation on the hardware wallet side. In the future,
192 /// we are looking forward to design such interface.
194 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
195 /// to act, as liveness and breach reply correctness are always going to be hard requirements
196 /// of LN security model, orthogonal of key management issues.
198 /// If you're implementing a custom signer, you almost certainly want to implement
199 /// Readable/Writable to serialize out a unique reference to this set of keys so
200 /// that you can serialize the full ChannelManager object.
202 // (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
203 // to the possibility of reentrancy issues by calling the user's code during our deserialization
205 // TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
206 // ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
207 pub trait ChannelKeys : Send+Clone + Writeable {
208 /// Gets the per-commitment point for a specific commitment number
210 /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards.
211 fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey;
212 /// Gets the commitment secret for a specific commitment number as part of the revocation process
214 /// An external signer implementation should error here if the commitment was already signed
215 /// and should refuse to sign it in the future.
217 /// May be called more than once for the same index.
219 /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards.
220 /// TODO: return a Result so we can signal a validation error
221 fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
222 /// Gets the holder's channel public keys and basepoints
223 fn pubkeys(&self) -> &ChannelPublicKeys;
224 /// Gets arbitrary identifiers describing the set of keys which are provided back to you in
225 /// some SpendableOutputDescriptor types. These should be sufficient to identify this
226 /// ChannelKeys object uniquely and lookup or re-derive its keys.
227 fn key_derivation_params(&self) -> (u64, u64);
229 /// Create a signature for a counterparty's commitment transaction and associated HTLC transactions.
231 /// Note that if signing fails or is rejected, the channel will be force-closed.
233 // TODO: Document the things someone using this interface should enforce before signing.
234 fn sign_counterparty_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
236 /// Create a signature for a holder's commitment transaction. This will only ever be called with
237 /// the same commitment_tx (or a copy thereof), though there are currently no guarantees
238 /// that it will not be called multiple times.
239 /// An external signer implementation should check that the commitment has not been revoked.
241 // TODO: Document the things someone using this interface should enforce before signing.
242 fn sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
244 /// Same as sign_holder_commitment, but exists only for tests to get access to holder commitment
245 /// transactions which will be broadcasted later, after the channel has moved on to a newer
246 /// state. Thus, needs its own method as sign_holder_commitment may enforce that we only ever
248 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
249 fn unsafe_sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
251 /// Create a signature for each HTLC transaction spending a holder's commitment transaction.
253 /// Unlike sign_holder_commitment, this may be called multiple times with *different*
254 /// commitment_tx values. While this will never be called with a revoked
255 /// commitment_tx, it is possible that it is called with the second-latest
256 /// commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary
257 /// ChannelMonitor decided to broadcast before it had been updated to the latest.
259 /// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in
261 fn sign_holder_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Vec<Signature>, ()>;
263 /// Create a signature for the given input in a transaction spending an HTLC or commitment
264 /// transaction output when our counterparty broadcasts an old state.
266 /// A justice transaction may claim multiples outputs at the same time if timelocks are
267 /// similar, but only a signature for the input at index `input` should be signed for here.
268 /// It may be called multiples time for same output(s) if a fee-bump is needed with regards
269 /// to an upcoming timelock expiration.
271 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
273 /// per_commitment_key is revocation secret which was provided by our counterparty when they
274 /// revoked the state which they eventually broadcast. It's not a _holder_ secret key and does
275 /// not allow the spending of any funds by itself (you need our holder revocation_secret to do
278 /// htlc holds HTLC elements (hash, timelock) if the output being spent is a HTLC output, thus
279 /// changing the format of the witness script (which is committed to in the BIP 143
281 fn sign_justice_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option<HTLCOutputInCommitment>, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
283 /// Create a signature for a claiming transaction for a HTLC output on a counterparty's commitment
284 /// transaction, either offered or received.
286 /// Such a transaction may claim multiples offered outputs at same time if we know the
287 /// preimage for each when we create it, but only the input at index `input` should be
288 /// signed for here. It may be called multiple times for same output(s) if a fee-bump is
289 /// needed with regards to an upcoming timelock expiration.
291 /// Witness_script is either a offered or received script as defined in BOLT3 for HTLC
294 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
296 /// Per_commitment_point is the dynamic point corresponding to the channel state
297 /// detected onchain. It has been generated by our counterparty and is used to derive
298 /// channel state keys, which are then included in the witness script and committed to in the
299 /// BIP 143 signature.
300 fn sign_counterparty_htlc_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
302 /// Create a signature for a (proposed) closing transaction.
304 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
305 /// chosen to forgo their output as dust.
306 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
308 /// Signs a channel announcement message with our funding key, proving it comes from one
309 /// of the channel participants.
311 /// Note that if this fails or is rejected, the channel will not be publicly announced and
312 /// our counterparty may (though likely will not) close the channel on us for violating the
314 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
316 /// Set the counterparty static channel data, including basepoints,
317 /// counterparty_selected/holder_selected_contest_delay and funding outpoint.
318 /// This is done as soon as the funding outpoint is known. Since these are static channel data,
319 /// they MUST NOT be allowed to change to different values once set.
321 /// channel_parameters.is_populated() MUST be true.
323 /// We bind holder_selected_contest_delay late here for API convenience.
325 /// Will be called before any signatures are applied.
326 fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters);
329 /// A trait to describe an object which can get user secrets and key material.
330 pub trait KeysInterface: Send + Sync {
331 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
332 type ChanKeySigner : ChannelKeys;
334 /// Get node secret key (aka node_id or network_key)
335 fn get_node_secret(&self) -> SecretKey;
336 /// Get destination redeemScript to encumber static protocol exit points.
337 fn get_destination_script(&self) -> Script;
338 /// Get shutdown_pubkey to use as PublicKey at channel closure
339 fn get_shutdown_pubkey(&self) -> PublicKey;
340 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
341 /// restarted with some stale data!
342 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
343 /// Gets a unique, cryptographically-secure, random 32 byte value. This is used for encrypting
344 /// onion packets and for temporary channel IDs. There is no requirement that these be
345 /// persisted anywhere, though they must be unique across restarts.
346 fn get_secure_random_bytes(&self) -> [u8; 32];
348 /// Reads a `ChanKeySigner` for this `KeysInterface` from the given input stream.
349 /// This is only called during deserialization of other objects which contain
350 /// `ChannelKeys`-implementing objects (ie `ChannelMonitor`s and `ChannelManager`s).
351 /// The bytes are exactly those which `<Self::ChanKeySigner as Writeable>::write()` writes, and
352 /// contain no versioning scheme. You may wish to include your own version prefix and ensure
353 /// you've read all of the provided bytes to ensure no corruption occurred.
354 fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::ChanKeySigner, DecodeError>;
358 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
360 /// This implementation performs no policy checks and is insufficient by itself as
361 /// a secure external signer.
362 pub struct InMemoryChannelKeys {
363 /// Private key of anchor tx
364 pub funding_key: SecretKey,
365 /// Holder secret key for blinded revocation pubkey
366 pub revocation_base_key: SecretKey,
367 /// Holder secret key used for our balance in counterparty-broadcasted commitment transactions
368 pub payment_key: SecretKey,
369 /// Holder secret key used in HTLC tx
370 pub delayed_payment_base_key: SecretKey,
371 /// Holder htlc secret key used in commitment tx htlc outputs
372 pub htlc_base_key: SecretKey,
374 pub commitment_seed: [u8; 32],
375 /// Holder public keys and basepoints
376 pub(crate) holder_channel_pubkeys: ChannelPublicKeys,
377 /// Counterparty public keys and counterparty/holder selected_contest_delay, populated on channel acceptance
378 channel_parameters: Option<ChannelTransactionParameters>,
379 /// The total value of this channel
380 channel_value_satoshis: u64,
381 /// Key derivation parameters
382 key_derivation_params: (u64, u64),
385 impl InMemoryChannelKeys {
386 /// Create a new InMemoryChannelKeys
387 pub fn new<C: Signing>(
388 secp_ctx: &Secp256k1<C>,
389 funding_key: SecretKey,
390 revocation_base_key: SecretKey,
391 payment_key: SecretKey,
392 delayed_payment_base_key: SecretKey,
393 htlc_base_key: SecretKey,
394 commitment_seed: [u8; 32],
395 channel_value_satoshis: u64,
396 key_derivation_params: (u64, u64)) -> InMemoryChannelKeys {
397 let holder_channel_pubkeys =
398 InMemoryChannelKeys::make_holder_keys(secp_ctx, &funding_key, &revocation_base_key,
399 &payment_key, &delayed_payment_base_key,
401 InMemoryChannelKeys {
405 delayed_payment_base_key,
408 channel_value_satoshis,
409 holder_channel_pubkeys,
410 channel_parameters: None,
411 key_derivation_params,
415 fn make_holder_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
416 funding_key: &SecretKey,
417 revocation_base_key: &SecretKey,
418 payment_key: &SecretKey,
419 delayed_payment_base_key: &SecretKey,
420 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
421 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
423 funding_pubkey: from_secret(&funding_key),
424 revocation_basepoint: from_secret(&revocation_base_key),
425 payment_point: from_secret(&payment_key),
426 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
427 htlc_basepoint: from_secret(&htlc_base_key),
431 /// Counterparty pubkeys.
432 /// Will panic if ready_channel wasn't called.
433 pub fn counterparty_pubkeys(&self) -> &ChannelPublicKeys { &self.get_channel_parameters().counterparty_parameters.as_ref().unwrap().pubkeys }
435 /// The contest_delay value specified by our counterparty and applied on holder-broadcastable
436 /// transactions, ie the amount of time that we have to wait to recover our funds if we
437 /// broadcast a transaction.
438 /// Will panic if ready_channel wasn't called.
439 pub fn counterparty_selected_contest_delay(&self) -> u16 { self.get_channel_parameters().counterparty_parameters.as_ref().unwrap().selected_contest_delay }
441 /// The contest_delay value specified by us and applied on transactions broadcastable
442 /// by our counterparty, ie the amount of time that they have to wait to recover their funds
443 /// if they broadcast a transaction.
444 /// Will panic if ready_channel wasn't called.
445 pub fn holder_selected_contest_delay(&self) -> u16 { self.get_channel_parameters().holder_selected_contest_delay }
447 /// Whether the holder is the initiator
448 /// Will panic if ready_channel wasn't called.
449 pub fn is_outbound(&self) -> bool { self.get_channel_parameters().is_outbound_from_holder }
452 /// Will panic if ready_channel wasn't called.
453 pub fn funding_outpoint(&self) -> &OutPoint { self.get_channel_parameters().funding_outpoint.as_ref().unwrap() }
455 /// Obtain a ChannelTransactionParameters for this channel, to be used when verifying or
456 /// building transactions.
458 /// Will panic if ready_channel wasn't called.
459 pub fn get_channel_parameters(&self) -> &ChannelTransactionParameters {
460 self.channel_parameters.as_ref().unwrap()
464 impl ChannelKeys for InMemoryChannelKeys {
465 fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey {
466 let commitment_secret = SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx)).unwrap();
467 PublicKey::from_secret_key(secp_ctx, &commitment_secret)
470 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
471 chan_utils::build_commitment_secret(&self.commitment_seed, idx)
474 fn pubkeys(&self) -> &ChannelPublicKeys { &self.holder_channel_pubkeys }
475 fn key_derivation_params(&self) -> (u64, u64) { self.key_derivation_params }
477 fn sign_counterparty_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
478 let trusted_tx = commitment_tx.trust();
479 let keys = trusted_tx.keys();
481 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
482 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
484 let built_tx = trusted_tx.built_transaction();
485 let commitment_sig = built_tx.sign(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx);
486 let commitment_txid = built_tx.txid;
488 let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len());
489 for htlc in commitment_tx.htlcs() {
490 let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), self.holder_selected_contest_delay(), htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
491 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
492 let htlc_sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, SigHashType::All)[..]);
493 let holder_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
495 Err(_) => return Err(()),
497 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &holder_htlc_key));
500 Ok((commitment_sig, htlc_sigs))
503 fn sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
504 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
505 let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
506 let sig = commitment_tx.trust().built_transaction().sign(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, secp_ctx);
510 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
511 fn unsafe_sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
512 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
513 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
514 Ok(commitment_tx.trust().built_transaction().sign(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
517 fn sign_holder_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Vec<Signature>, ()> {
518 let channel_parameters = self.get_channel_parameters();
519 let trusted_tx = commitment_tx.trust();
520 trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), secp_ctx)
523 fn sign_justice_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option<HTLCOutputInCommitment>, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
524 let revocation_key = match chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
525 Ok(revocation_key) => revocation_key,
526 Err(_) => return Err(())
528 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
529 let revocation_pubkey = match chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
530 Ok(revocation_pubkey) => revocation_pubkey,
531 Err(_) => return Err(())
533 let witness_script = if let &Some(ref htlc) = htlc {
534 let counterparty_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint) {
535 Ok(counterparty_htlcpubkey) => counterparty_htlcpubkey,
536 Err(_) => return Err(())
538 let holder_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
539 Ok(holder_htlcpubkey) => holder_htlcpubkey,
540 Err(_) => return Err(())
542 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
544 let counterparty_delayedpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().delayed_payment_basepoint) {
545 Ok(counterparty_delayedpubkey) => counterparty_delayedpubkey,
546 Err(_) => return Err(())
548 chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.holder_selected_contest_delay(), &counterparty_delayedpubkey)
550 let mut sighash_parts = bip143::SigHashCache::new(justice_tx);
551 let sighash = hash_to_message!(&sighash_parts.signature_hash(input, &witness_script, amount, SigHashType::All)[..]);
552 return Ok(secp_ctx.sign(&sighash, &revocation_key))
555 fn sign_counterparty_htlc_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
556 if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) {
557 let witness_script = if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
558 if let Ok(counterparty_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint) {
559 if let Ok(htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
560 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey)
561 } else { return Err(()) }
562 } else { return Err(()) }
563 } else { return Err(()) };
564 let mut sighash_parts = bip143::SigHashCache::new(htlc_tx);
565 let sighash = hash_to_message!(&sighash_parts.signature_hash(input, &witness_script, amount, SigHashType::All)[..]);
566 return Ok(secp_ctx.sign(&sighash, &htlc_key))
571 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
572 if closing_tx.input.len() != 1 { return Err(()); }
573 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
574 if closing_tx.output.len() > 2 { return Err(()); }
576 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
577 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
579 let sighash = hash_to_message!(&bip143::SigHashCache::new(closing_tx)
580 .signature_hash(0, &channel_funding_redeemscript, self.channel_value_satoshis, SigHashType::All)[..]);
581 Ok(secp_ctx.sign(&sighash, &self.funding_key))
584 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
585 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
586 Ok(secp_ctx.sign(&msghash, &self.funding_key))
589 fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters) {
590 assert!(self.channel_parameters.is_none(), "Acceptance already noted");
591 assert!(channel_parameters.is_populated(), "Channel parameters must be fully populated");
592 self.channel_parameters = Some(channel_parameters.clone());
596 impl Writeable for InMemoryChannelKeys {
597 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
598 self.funding_key.write(writer)?;
599 self.revocation_base_key.write(writer)?;
600 self.payment_key.write(writer)?;
601 self.delayed_payment_base_key.write(writer)?;
602 self.htlc_base_key.write(writer)?;
603 self.commitment_seed.write(writer)?;
604 self.channel_parameters.write(writer)?;
605 self.channel_value_satoshis.write(writer)?;
606 self.key_derivation_params.0.write(writer)?;
607 self.key_derivation_params.1.write(writer)?;
613 impl Readable for InMemoryChannelKeys {
614 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
615 let funding_key = Readable::read(reader)?;
616 let revocation_base_key = Readable::read(reader)?;
617 let payment_key = Readable::read(reader)?;
618 let delayed_payment_base_key = Readable::read(reader)?;
619 let htlc_base_key = Readable::read(reader)?;
620 let commitment_seed = Readable::read(reader)?;
621 let counterparty_channel_data = Readable::read(reader)?;
622 let channel_value_satoshis = Readable::read(reader)?;
623 let secp_ctx = Secp256k1::signing_only();
624 let holder_channel_pubkeys =
625 InMemoryChannelKeys::make_holder_keys(&secp_ctx, &funding_key, &revocation_base_key,
626 &payment_key, &delayed_payment_base_key,
628 let params_1 = Readable::read(reader)?;
629 let params_2 = Readable::read(reader)?;
631 Ok(InMemoryChannelKeys {
635 delayed_payment_base_key,
638 channel_value_satoshis,
639 holder_channel_pubkeys,
640 channel_parameters: counterparty_channel_data,
641 key_derivation_params: (params_1, params_2),
646 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
647 /// and derives keys from that.
649 /// Your node_id is seed/0'
650 /// ChannelMonitor closes may use seed/1'
651 /// Cooperative closes may use seed/2'
652 /// The two close keys may be needed to claim on-chain funds!
653 pub struct KeysManager {
654 secp_ctx: Secp256k1<secp256k1::SignOnly>,
655 node_secret: SecretKey,
656 destination_script: Script,
657 shutdown_pubkey: PublicKey,
658 channel_master_key: ExtendedPrivKey,
659 channel_child_index: AtomicUsize,
660 rand_bytes_master_key: ExtendedPrivKey,
661 rand_bytes_child_index: AtomicUsize,
664 starting_time_secs: u64,
665 starting_time_nanos: u32,
669 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
670 /// CSRNG is busted) this may panic (but more importantly, you will possibly lose funds).
671 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
672 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
673 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
674 /// simply use the current time (with very high precision).
676 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
677 /// obviously, starting_time should be unique every time you reload the library - it is only
678 /// used to generate new ephemeral key data (which will be stored by the individual channel if
681 /// Note that the seed is required to recover certain on-chain funds independent of
682 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
683 /// channel, and some on-chain during-closing funds.
685 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
686 /// versions. Once the library is more fully supported, the docs will be updated to include a
687 /// detailed description of the guarantee.
688 pub fn new(seed: &[u8; 32], network: Network, starting_time_secs: u64, starting_time_nanos: u32) -> Self {
689 let secp_ctx = Secp256k1::signing_only();
690 match ExtendedPrivKey::new_master(network.clone(), seed) {
692 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
693 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
694 Ok(destination_key) => {
695 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
696 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
697 .push_slice(&wpubkey_hash.into_inner())
700 Err(_) => panic!("Your RNG is busted"),
702 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
703 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
704 Err(_) => panic!("Your RNG is busted"),
706 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
707 let rand_bytes_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
715 channel_child_index: AtomicUsize::new(0),
716 rand_bytes_master_key,
717 rand_bytes_child_index: AtomicUsize::new(0),
724 Err(_) => panic!("Your rng is busted"),
727 fn derive_unique_start(&self) -> Sha256State {
728 let mut unique_start = Sha256::engine();
729 unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs));
730 unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos));
731 unique_start.input(&self.seed);
734 /// Derive an old set of ChannelKeys for per-channel secrets based on a key derivation
736 /// Key derivation parameters are accessible through a per-channel secrets
737 /// ChannelKeys::key_derivation_params and is provided inside DynamicOuputP2WSH in case of
738 /// onchain output detection for which a corresponding delayed_payment_key must be derived.
739 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params_1: u64, params_2: u64) -> InMemoryChannelKeys {
740 let chan_id = ((params_1 & 0xFFFF_FFFF_0000_0000) >> 32) as u32;
741 let mut unique_start = Sha256::engine();
742 unique_start.input(&byte_utils::be64_to_array(params_2));
743 unique_start.input(&byte_utils::be32_to_array(params_1 as u32));
744 unique_start.input(&self.seed);
746 // We only seriously intend to rely on the channel_master_key for true secure
747 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
748 // starting_time provided in the constructor) to be unique.
749 let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(chan_id).expect("key space exhausted")).expect("Your RNG is busted");
750 unique_start.input(&child_privkey.private_key.key[..]);
752 let seed = Sha256::from_engine(unique_start).into_inner();
754 let commitment_seed = {
755 let mut sha = Sha256::engine();
757 sha.input(&b"commitment seed"[..]);
758 Sha256::from_engine(sha).into_inner()
760 macro_rules! key_step {
761 ($info: expr, $prev_key: expr) => {{
762 let mut sha = Sha256::engine();
764 sha.input(&$prev_key[..]);
765 sha.input(&$info[..]);
766 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
769 let funding_key = key_step!(b"funding key", commitment_seed);
770 let revocation_base_key = key_step!(b"revocation base key", funding_key);
771 let payment_key = key_step!(b"payment key", revocation_base_key);
772 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
773 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
775 InMemoryChannelKeys::new(
780 delayed_payment_base_key,
783 channel_value_satoshis,
784 (params_1, params_2),
789 impl KeysInterface for KeysManager {
790 type ChanKeySigner = InMemoryChannelKeys;
792 fn get_node_secret(&self) -> SecretKey {
793 self.node_secret.clone()
796 fn get_destination_script(&self) -> Script {
797 self.destination_script.clone()
800 fn get_shutdown_pubkey(&self) -> PublicKey {
801 self.shutdown_pubkey.clone()
804 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner {
805 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
806 let ix_and_nanos: u64 = (child_ix as u64) << 32 | (self.starting_time_nanos as u64);
807 self.derive_channel_keys(channel_value_satoshis, ix_and_nanos, self.starting_time_secs)
810 fn get_secure_random_bytes(&self) -> [u8; 32] {
811 let mut sha = self.derive_unique_start();
813 let child_ix = self.rand_bytes_child_index.fetch_add(1, Ordering::AcqRel);
814 let child_privkey = self.rand_bytes_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted");
815 sha.input(&child_privkey.private_key.key[..]);
817 sha.input(b"Unique Secure Random Bytes Salt");
818 Sha256::from_engine(sha).into_inner()
821 fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::ChanKeySigner, DecodeError> {
822 InMemoryChannelKeys::read(&mut std::io::Cursor::new(reader))