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 directly, either from
51 /// `get_destination_script()` or `get_shutdown_pubkey()`, thus you should already know how to
52 /// spend it. No secret keys are provided as rust-lightning was never given any key.
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 revocation_pubkey used to derive witnessScript
102 revocation_pubkey: PublicKey,
103 /// Arbitrary identification information returned by a call to
104 /// `ChannelKeys::channel_keys_id()`. This may be useful in re-deriving keys used in
105 /// the channel to spend the output.
106 channel_keys_id: [u8; 32],
107 /// The value of the channel which this output originated from, possibly indirectly.
108 channel_value_satoshis: u64,
110 /// An output to a P2WPKH, spendable exclusively by our payment key (ie the private key which
111 /// corresponds to the public key in ChannelKeys::pubkeys().payment_point).
112 /// The witness in the spending input, is, thus, simply:
113 /// <BIP 143 signature> <payment key>
115 /// These are generally the result of our counterparty having broadcast the current state,
116 /// allowing us to claim the non-HTLC-encumbered outputs immediately.
117 StaticOutputCounterpartyPayment {
118 /// The outpoint which is spendable
120 /// The output which is reference by the given outpoint
122 /// Arbitrary identification information returned by a call to
123 /// `ChannelKeys::channel_keys_id()`. This may be useful in re-deriving keys used in
124 /// the channel to spend the output.
125 channel_keys_id: [u8; 32],
126 /// The value of the channel which this transactions spends.
127 channel_value_satoshis: u64,
131 impl Writeable for SpendableOutputDescriptor {
132 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
134 &SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
136 outpoint.write(writer)?;
137 output.write(writer)?;
139 &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref per_commitment_point, ref to_self_delay, ref output, ref revocation_pubkey, ref channel_keys_id, channel_value_satoshis } => {
141 outpoint.write(writer)?;
142 per_commitment_point.write(writer)?;
143 to_self_delay.write(writer)?;
144 output.write(writer)?;
145 revocation_pubkey.write(writer)?;
146 channel_keys_id.write(writer)?;
147 channel_value_satoshis.write(writer)?;
149 &SpendableOutputDescriptor::StaticOutputCounterpartyPayment { ref outpoint, ref output, ref channel_keys_id, channel_value_satoshis } => {
151 outpoint.write(writer)?;
152 output.write(writer)?;
153 channel_keys_id.write(writer)?;
154 channel_value_satoshis.write(writer)?;
161 impl Readable for SpendableOutputDescriptor {
162 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
163 match Readable::read(reader)? {
164 0u8 => Ok(SpendableOutputDescriptor::StaticOutput {
165 outpoint: Readable::read(reader)?,
166 output: Readable::read(reader)?,
168 1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH {
169 outpoint: Readable::read(reader)?,
170 per_commitment_point: Readable::read(reader)?,
171 to_self_delay: Readable::read(reader)?,
172 output: Readable::read(reader)?,
173 revocation_pubkey: Readable::read(reader)?,
174 channel_keys_id: Readable::read(reader)?,
175 channel_value_satoshis: Readable::read(reader)?,
177 2u8 => Ok(SpendableOutputDescriptor::StaticOutputCounterpartyPayment {
178 outpoint: Readable::read(reader)?,
179 output: Readable::read(reader)?,
180 channel_keys_id: Readable::read(reader)?,
181 channel_value_satoshis: Readable::read(reader)?,
183 _ => Err(DecodeError::InvalidValue),
188 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
190 /// Signing services could be implemented on a hardware wallet. In this case,
191 /// the current ChannelKeys would be a front-end on top of a communication
192 /// channel connected to your secure device and lightning key material wouldn't
193 /// reside on a hot server. Nevertheless, a this deployment would still need
194 /// to trust the ChannelManager to avoid loss of funds as this latest component
195 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
197 /// A more secure iteration would be to use hashlock (or payment points) to pair
198 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
199 /// at the price of more state and computation on the hardware wallet side. In the future,
200 /// we are looking forward to design such interface.
202 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
203 /// to act, as liveness and breach reply correctness are always going to be hard requirements
204 /// of LN security model, orthogonal of key management issues.
206 /// If you're implementing a custom signer, you almost certainly want to implement
207 /// Readable/Writable to serialize out a unique reference to this set of keys so
208 /// that you can serialize the full ChannelManager object.
210 // (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
211 // to the possibility of reentrancy issues by calling the user's code during our deserialization
213 // TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
214 // ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
215 pub trait ChannelKeys : Send+Clone + Writeable {
216 /// Gets the per-commitment point for a specific commitment number
218 /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards.
219 fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey;
220 /// Gets the commitment secret for a specific commitment number as part of the revocation process
222 /// An external signer implementation should error here if the commitment was already signed
223 /// and should refuse to sign it in the future.
225 /// May be called more than once for the same index.
227 /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards.
228 /// TODO: return a Result so we can signal a validation error
229 fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
230 /// Gets the holder's channel public keys and basepoints
231 fn pubkeys(&self) -> &ChannelPublicKeys;
232 /// Gets an arbitrary identifier describing the set of keys which are provided back to you in
233 /// some SpendableOutputDescriptor types. This should be sufficient to identify this
234 /// ChannelKeys object uniquely and lookup or re-derive its keys.
235 fn channel_keys_id(&self) -> [u8; 32];
237 /// Create a signature for a counterparty's commitment transaction and associated HTLC transactions.
239 /// Note that if signing fails or is rejected, the channel will be force-closed.
241 // TODO: Document the things someone using this interface should enforce before signing.
242 fn sign_counterparty_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
244 /// Create a signatures for a holder's commitment transaction and its claiming HTLC transactions.
245 /// This will only ever be called with a non-revoked commitment_tx. This will be called with the
246 /// latest commitment_tx when we initiate a force-close.
247 /// This will be called with the previous latest, just to get claiming HTLC signatures, if we are
248 /// reacting to a ChannelMonitor replica that decided to broadcast before it had been updated to
250 /// This may be called multiple times for the same transaction.
252 /// An external signer implementation should check that the commitment has not been revoked.
254 /// May return Err if key derivation fails. Callers, such as ChannelMonitor, will panic in such a case.
256 // TODO: Document the things someone using this interface should enforce before signing.
257 // TODO: Key derivation failure should panic rather than Err
258 fn sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
260 /// Same as sign_holder_commitment, but exists only for tests to get access to holder commitment
261 /// transactions which will be broadcasted later, after the channel has moved on to a newer
262 /// state. Thus, needs its own method as sign_holder_commitment may enforce that we only ever
264 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
265 fn unsafe_sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
267 /// Create a signature for the given input in a transaction spending an HTLC or commitment
268 /// transaction output when our counterparty broadcasts an old state.
270 /// A justice transaction may claim multiples outputs at the same time if timelocks are
271 /// similar, but only a signature for the input at index `input` should be signed for here.
272 /// It may be called multiples time for same output(s) if a fee-bump is needed with regards
273 /// to an upcoming timelock expiration.
275 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
277 /// per_commitment_key is revocation secret which was provided by our counterparty when they
278 /// revoked the state which they eventually broadcast. It's not a _holder_ secret key and does
279 /// not allow the spending of any funds by itself (you need our holder revocation_secret to do
282 /// htlc holds HTLC elements (hash, timelock) if the output being spent is a HTLC output, thus
283 /// changing the format of the witness script (which is committed to in the BIP 143
285 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, ()>;
287 /// Create a signature for a claiming transaction for a HTLC output on a counterparty's commitment
288 /// transaction, either offered or received.
290 /// Such a transaction may claim multiples offered outputs at same time if we know the
291 /// preimage for each when we create it, but only the input at index `input` should be
292 /// signed for here. It may be called multiple times for same output(s) if a fee-bump is
293 /// needed with regards to an upcoming timelock expiration.
295 /// Witness_script is either a offered or received script as defined in BOLT3 for HTLC
298 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
300 /// Per_commitment_point is the dynamic point corresponding to the channel state
301 /// detected onchain. It has been generated by our counterparty and is used to derive
302 /// channel state keys, which are then included in the witness script and committed to in the
303 /// BIP 143 signature.
304 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, ()>;
306 /// Create a signature for a (proposed) closing transaction.
308 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
309 /// chosen to forgo their output as dust.
310 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
312 /// Signs a channel announcement message with our funding key, proving it comes from one
313 /// of the channel participants.
315 /// Note that if this fails or is rejected, the channel will not be publicly announced and
316 /// our counterparty may (though likely will not) close the channel on us for violating the
318 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
320 /// Set the counterparty static channel data, including basepoints,
321 /// counterparty_selected/holder_selected_contest_delay and funding outpoint.
322 /// This is done as soon as the funding outpoint is known. Since these are static channel data,
323 /// they MUST NOT be allowed to change to different values once set.
325 /// channel_parameters.is_populated() MUST be true.
327 /// We bind holder_selected_contest_delay late here for API convenience.
329 /// Will be called before any signatures are applied.
330 fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters);
333 /// A trait to describe an object which can get user secrets and key material.
334 pub trait KeysInterface: Send + Sync {
335 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
336 type ChanKeySigner : ChannelKeys;
338 /// Get node secret key (aka node_id or network_key).
340 /// This method must return the same value each time it is called.
341 fn get_node_secret(&self) -> SecretKey;
342 /// Get a script pubkey which we send funds to when claiming on-chain contestable outputs.
344 /// This method should return a different value each time it is called, to avoid linking
345 /// on-chain funds across channels as controlled to the same user.
346 fn get_destination_script(&self) -> Script;
347 /// Get a public key which we will send funds to (in the form of a P2WPKH output) when closing
350 /// This method should return a different value each time it is called, to avoid linking
351 /// on-chain funds across channels as controlled to the same user.
352 fn get_shutdown_pubkey(&self) -> PublicKey;
353 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
354 /// restarted with some stale data!
356 /// This method must return a different value each time it is called.
357 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
358 /// Gets a unique, cryptographically-secure, random 32 byte value. This is used for encrypting
359 /// onion packets and for temporary channel IDs. There is no requirement that these be
360 /// persisted anywhere, though they must be unique across restarts.
362 /// This method must return a different value each time it is called.
363 fn get_secure_random_bytes(&self) -> [u8; 32];
365 /// Reads a `ChanKeySigner` for this `KeysInterface` from the given input stream.
366 /// This is only called during deserialization of other objects which contain
367 /// `ChannelKeys`-implementing objects (ie `ChannelMonitor`s and `ChannelManager`s).
368 /// The bytes are exactly those which `<Self::ChanKeySigner as Writeable>::write()` writes, and
369 /// contain no versioning scheme. You may wish to include your own version prefix and ensure
370 /// you've read all of the provided bytes to ensure no corruption occurred.
371 fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::ChanKeySigner, DecodeError>;
375 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
377 /// This implementation performs no policy checks and is insufficient by itself as
378 /// a secure external signer.
379 pub struct InMemoryChannelKeys {
380 /// Private key of anchor tx
381 pub funding_key: SecretKey,
382 /// Holder secret key for blinded revocation pubkey
383 pub revocation_base_key: SecretKey,
384 /// Holder secret key used for our balance in counterparty-broadcasted commitment transactions
385 pub payment_key: SecretKey,
386 /// Holder secret key used in HTLC tx
387 pub delayed_payment_base_key: SecretKey,
388 /// Holder htlc secret key used in commitment tx htlc outputs
389 pub htlc_base_key: SecretKey,
391 pub commitment_seed: [u8; 32],
392 /// Holder public keys and basepoints
393 pub(crate) holder_channel_pubkeys: ChannelPublicKeys,
394 /// Counterparty public keys and counterparty/holder selected_contest_delay, populated on channel acceptance
395 channel_parameters: Option<ChannelTransactionParameters>,
396 /// The total value of this channel
397 channel_value_satoshis: u64,
398 /// Key derivation parameters
399 channel_keys_id: [u8; 32],
402 impl InMemoryChannelKeys {
403 /// Create a new InMemoryChannelKeys
404 pub fn new<C: Signing>(
405 secp_ctx: &Secp256k1<C>,
406 funding_key: SecretKey,
407 revocation_base_key: SecretKey,
408 payment_key: SecretKey,
409 delayed_payment_base_key: SecretKey,
410 htlc_base_key: SecretKey,
411 commitment_seed: [u8; 32],
412 channel_value_satoshis: u64,
413 channel_keys_id: [u8; 32]) -> InMemoryChannelKeys {
414 let holder_channel_pubkeys =
415 InMemoryChannelKeys::make_holder_keys(secp_ctx, &funding_key, &revocation_base_key,
416 &payment_key, &delayed_payment_base_key,
418 InMemoryChannelKeys {
422 delayed_payment_base_key,
425 channel_value_satoshis,
426 holder_channel_pubkeys,
427 channel_parameters: None,
432 fn make_holder_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
433 funding_key: &SecretKey,
434 revocation_base_key: &SecretKey,
435 payment_key: &SecretKey,
436 delayed_payment_base_key: &SecretKey,
437 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
438 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
440 funding_pubkey: from_secret(&funding_key),
441 revocation_basepoint: from_secret(&revocation_base_key),
442 payment_point: from_secret(&payment_key),
443 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
444 htlc_basepoint: from_secret(&htlc_base_key),
448 /// Counterparty pubkeys.
449 /// Will panic if ready_channel wasn't called.
450 pub fn counterparty_pubkeys(&self) -> &ChannelPublicKeys { &self.get_channel_parameters().counterparty_parameters.as_ref().unwrap().pubkeys }
452 /// The contest_delay value specified by our counterparty and applied on holder-broadcastable
453 /// transactions, ie the amount of time that we have to wait to recover our funds if we
454 /// broadcast a transaction.
455 /// Will panic if ready_channel wasn't called.
456 pub fn counterparty_selected_contest_delay(&self) -> u16 { self.get_channel_parameters().counterparty_parameters.as_ref().unwrap().selected_contest_delay }
458 /// The contest_delay value specified by us and applied on transactions broadcastable
459 /// by our counterparty, ie the amount of time that they have to wait to recover their funds
460 /// if they broadcast a transaction.
461 /// Will panic if ready_channel wasn't called.
462 pub fn holder_selected_contest_delay(&self) -> u16 { self.get_channel_parameters().holder_selected_contest_delay }
464 /// Whether the holder is the initiator
465 /// Will panic if ready_channel wasn't called.
466 pub fn is_outbound(&self) -> bool { self.get_channel_parameters().is_outbound_from_holder }
469 /// Will panic if ready_channel wasn't called.
470 pub fn funding_outpoint(&self) -> &OutPoint { self.get_channel_parameters().funding_outpoint.as_ref().unwrap() }
472 /// Obtain a ChannelTransactionParameters for this channel, to be used when verifying or
473 /// building transactions.
475 /// Will panic if ready_channel wasn't called.
476 pub fn get_channel_parameters(&self) -> &ChannelTransactionParameters {
477 self.channel_parameters.as_ref().unwrap()
481 impl ChannelKeys for InMemoryChannelKeys {
482 fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey {
483 let commitment_secret = SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx)).unwrap();
484 PublicKey::from_secret_key(secp_ctx, &commitment_secret)
487 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
488 chan_utils::build_commitment_secret(&self.commitment_seed, idx)
491 fn pubkeys(&self) -> &ChannelPublicKeys { &self.holder_channel_pubkeys }
492 fn channel_keys_id(&self) -> [u8; 32] { self.channel_keys_id }
494 fn sign_counterparty_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
495 let trusted_tx = commitment_tx.trust();
496 let keys = trusted_tx.keys();
498 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
499 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
501 let built_tx = trusted_tx.built_transaction();
502 let commitment_sig = built_tx.sign(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx);
503 let commitment_txid = built_tx.txid;
505 let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len());
506 for htlc in commitment_tx.htlcs() {
507 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);
508 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
509 let htlc_sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, SigHashType::All)[..]);
510 let holder_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
512 Err(_) => return Err(()),
514 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &holder_htlc_key));
517 Ok((commitment_sig, htlc_sigs))
520 fn sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
521 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
522 let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
523 let trusted_tx = commitment_tx.trust();
524 let sig = trusted_tx.built_transaction().sign(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, secp_ctx);
525 let channel_parameters = self.get_channel_parameters();
526 let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), secp_ctx)?;
530 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
531 fn unsafe_sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
532 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
533 let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
534 let trusted_tx = commitment_tx.trust();
535 let sig = trusted_tx.built_transaction().sign(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, secp_ctx);
536 let channel_parameters = self.get_channel_parameters();
537 let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), secp_ctx)?;
541 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, ()> {
542 let revocation_key = match chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
543 Ok(revocation_key) => revocation_key,
544 Err(_) => return Err(())
546 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
547 let revocation_pubkey = match chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
548 Ok(revocation_pubkey) => revocation_pubkey,
549 Err(_) => return Err(())
551 let witness_script = if let &Some(ref htlc) = htlc {
552 let counterparty_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint) {
553 Ok(counterparty_htlcpubkey) => counterparty_htlcpubkey,
554 Err(_) => return Err(())
556 let holder_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
557 Ok(holder_htlcpubkey) => holder_htlcpubkey,
558 Err(_) => return Err(())
560 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
562 let counterparty_delayedpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().delayed_payment_basepoint) {
563 Ok(counterparty_delayedpubkey) => counterparty_delayedpubkey,
564 Err(_) => return Err(())
566 chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.holder_selected_contest_delay(), &counterparty_delayedpubkey)
568 let mut sighash_parts = bip143::SigHashCache::new(justice_tx);
569 let sighash = hash_to_message!(&sighash_parts.signature_hash(input, &witness_script, amount, SigHashType::All)[..]);
570 return Ok(secp_ctx.sign(&sighash, &revocation_key))
573 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, ()> {
574 if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) {
575 let witness_script = if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
576 if let Ok(counterparty_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint) {
577 if let Ok(htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
578 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey)
579 } else { return Err(()) }
580 } else { return Err(()) }
581 } else { return Err(()) };
582 let mut sighash_parts = bip143::SigHashCache::new(htlc_tx);
583 let sighash = hash_to_message!(&sighash_parts.signature_hash(input, &witness_script, amount, SigHashType::All)[..]);
584 return Ok(secp_ctx.sign(&sighash, &htlc_key))
589 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
590 if closing_tx.input.len() != 1 { return Err(()); }
591 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
592 if closing_tx.output.len() > 2 { return Err(()); }
594 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
595 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
597 let sighash = hash_to_message!(&bip143::SigHashCache::new(closing_tx)
598 .signature_hash(0, &channel_funding_redeemscript, self.channel_value_satoshis, SigHashType::All)[..]);
599 Ok(secp_ctx.sign(&sighash, &self.funding_key))
602 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
603 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
604 Ok(secp_ctx.sign(&msghash, &self.funding_key))
607 fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters) {
608 assert!(self.channel_parameters.is_none(), "Acceptance already noted");
609 assert!(channel_parameters.is_populated(), "Channel parameters must be fully populated");
610 self.channel_parameters = Some(channel_parameters.clone());
614 impl Writeable for InMemoryChannelKeys {
615 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
616 self.funding_key.write(writer)?;
617 self.revocation_base_key.write(writer)?;
618 self.payment_key.write(writer)?;
619 self.delayed_payment_base_key.write(writer)?;
620 self.htlc_base_key.write(writer)?;
621 self.commitment_seed.write(writer)?;
622 self.channel_parameters.write(writer)?;
623 self.channel_value_satoshis.write(writer)?;
624 self.channel_keys_id.write(writer)?;
630 impl Readable for InMemoryChannelKeys {
631 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
632 let funding_key = Readable::read(reader)?;
633 let revocation_base_key = Readable::read(reader)?;
634 let payment_key = Readable::read(reader)?;
635 let delayed_payment_base_key = Readable::read(reader)?;
636 let htlc_base_key = Readable::read(reader)?;
637 let commitment_seed = Readable::read(reader)?;
638 let counterparty_channel_data = Readable::read(reader)?;
639 let channel_value_satoshis = Readable::read(reader)?;
640 let secp_ctx = Secp256k1::signing_only();
641 let holder_channel_pubkeys =
642 InMemoryChannelKeys::make_holder_keys(&secp_ctx, &funding_key, &revocation_base_key,
643 &payment_key, &delayed_payment_base_key,
645 let keys_id = Readable::read(reader)?;
647 Ok(InMemoryChannelKeys {
651 delayed_payment_base_key,
654 channel_value_satoshis,
655 holder_channel_pubkeys,
656 channel_parameters: counterparty_channel_data,
657 channel_keys_id: keys_id,
662 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
663 /// and derives keys from that.
665 /// Your node_id is seed/0'
666 /// ChannelMonitor closes may use seed/1'
667 /// Cooperative closes may use seed/2'
668 /// The two close keys may be needed to claim on-chain funds!
669 pub struct KeysManager {
670 secp_ctx: Secp256k1<secp256k1::SignOnly>,
671 node_secret: SecretKey,
672 destination_script: Script,
673 shutdown_pubkey: PublicKey,
674 channel_master_key: ExtendedPrivKey,
675 channel_child_index: AtomicUsize,
676 rand_bytes_master_key: ExtendedPrivKey,
677 rand_bytes_child_index: AtomicUsize,
680 starting_time_secs: u64,
681 starting_time_nanos: u32,
685 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
686 /// CSRNG is busted) this may panic (but more importantly, you will possibly lose funds).
687 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
688 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
689 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
690 /// simply use the current time (with very high precision).
692 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
693 /// obviously, starting_time should be unique every time you reload the library - it is only
694 /// used to generate new ephemeral key data (which will be stored by the individual channel if
697 /// Note that the seed is required to recover certain on-chain funds independent of
698 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
699 /// channel, and some on-chain during-closing funds.
701 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
702 /// versions. Once the library is more fully supported, the docs will be updated to include a
703 /// detailed description of the guarantee.
704 pub fn new(seed: &[u8; 32], network: Network, starting_time_secs: u64, starting_time_nanos: u32) -> Self {
705 let secp_ctx = Secp256k1::signing_only();
706 match ExtendedPrivKey::new_master(network.clone(), seed) {
708 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
709 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
710 Ok(destination_key) => {
711 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
712 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
713 .push_slice(&wpubkey_hash.into_inner())
716 Err(_) => panic!("Your RNG is busted"),
718 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
719 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
720 Err(_) => panic!("Your RNG is busted"),
722 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
723 let rand_bytes_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
731 channel_child_index: AtomicUsize::new(0),
732 rand_bytes_master_key,
733 rand_bytes_child_index: AtomicUsize::new(0),
740 Err(_) => panic!("Your rng is busted"),
743 fn derive_unique_start(&self) -> Sha256State {
744 let mut unique_start = Sha256::engine();
745 unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs));
746 unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos));
747 unique_start.input(&self.seed);
750 /// Derive an old set of ChannelKeys for per-channel secrets based on a key derivation
752 /// Key derivation parameters are accessible through a per-channel secrets
753 /// ChannelKeys::channel_keys_id and is provided inside DynamicOuputP2WSH in case of
754 /// onchain output detection for which a corresponding delayed_payment_key must be derived.
755 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params: &[u8; 32]) -> InMemoryChannelKeys {
756 let chan_id = byte_utils::slice_to_be64(¶ms[0..8]);
757 assert!(chan_id <= std::u32::MAX as u64); // Otherwise the params field wasn't created by us
758 let mut unique_start = Sha256::engine();
759 unique_start.input(params);
760 unique_start.input(&self.seed);
762 // We only seriously intend to rely on the channel_master_key for true secure
763 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
764 // starting_time provided in the constructor) to be unique.
765 let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(chan_id as u32).expect("key space exhausted")).expect("Your RNG is busted");
766 unique_start.input(&child_privkey.private_key.key[..]);
768 let seed = Sha256::from_engine(unique_start).into_inner();
770 let commitment_seed = {
771 let mut sha = Sha256::engine();
773 sha.input(&b"commitment seed"[..]);
774 Sha256::from_engine(sha).into_inner()
776 macro_rules! key_step {
777 ($info: expr, $prev_key: expr) => {{
778 let mut sha = Sha256::engine();
780 sha.input(&$prev_key[..]);
781 sha.input(&$info[..]);
782 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
785 let funding_key = key_step!(b"funding key", commitment_seed);
786 let revocation_base_key = key_step!(b"revocation base key", funding_key);
787 let payment_key = key_step!(b"payment key", revocation_base_key);
788 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
789 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
791 InMemoryChannelKeys::new(
796 delayed_payment_base_key,
799 channel_value_satoshis,
805 impl KeysInterface for KeysManager {
806 type ChanKeySigner = InMemoryChannelKeys;
808 fn get_node_secret(&self) -> SecretKey {
809 self.node_secret.clone()
812 fn get_destination_script(&self) -> Script {
813 self.destination_script.clone()
816 fn get_shutdown_pubkey(&self) -> PublicKey {
817 self.shutdown_pubkey.clone()
820 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner {
821 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
822 assert!(child_ix <= std::u32::MAX as usize);
823 let mut id = [0; 32];
824 id[0..8].copy_from_slice(&byte_utils::be64_to_array(child_ix as u64));
825 id[8..16].copy_from_slice(&byte_utils::be64_to_array(self.starting_time_nanos as u64));
826 id[16..24].copy_from_slice(&byte_utils::be64_to_array(self.starting_time_secs));
827 self.derive_channel_keys(channel_value_satoshis, &id)
830 fn get_secure_random_bytes(&self) -> [u8; 32] {
831 let mut sha = self.derive_unique_start();
833 let child_ix = self.rand_bytes_child_index.fetch_add(1, Ordering::AcqRel);
834 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");
835 sha.input(&child_privkey.private_key.key[..]);
837 sha.input(b"Unique Secure Random Bytes Salt");
838 Sha256::from_engine(sha).into_inner()
841 fn read_chan_signer(&self, reader: &[u8]) -> Result<Self::ChanKeySigner, DecodeError> {
842 InMemoryChannelKeys::read(&mut std::io::Cursor::new(reader))