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, PreCalculatedTxCreationKeys};
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, 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::on_accept) 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 {
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 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
235 // making the callee generate it via some util function we expose)!
236 fn sign_counterparty_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u32, commitment_tx: &Transaction, keys: &PreCalculatedTxCreationKeys, htlcs: &[&HTLCOutputInCommitment], secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
238 /// Create a signature for a holder's commitment transaction. This will only ever be called with
239 /// the same holder_commitment_tx (or a copy thereof), though there are currently no guarantees
240 /// that it will not be called multiple times.
241 /// An external signer implementation should check that the commitment has not been revoked.
243 // TODO: Document the things someone using this interface should enforce before signing.
244 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
245 fn sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, holder_commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
247 /// Same as sign_holder_commitment, but exists only for tests to get access to holder commitment
248 /// transactions which will be broadcasted later, after the channel has moved on to a newer
249 /// state. Thus, needs its own method as sign_holder_commitment may enforce that we only ever
251 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
252 fn unsafe_sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, holder_commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
254 /// Create a signature for each HTLC transaction spending a holder's commitment transaction.
256 /// Unlike sign_holder_commitment, this may be called multiple times with *different*
257 /// holder_commitment_tx values. While this will never be called with a revoked
258 /// holder_commitment_tx, it is possible that it is called with the second-latest
259 /// holder_commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary
260 /// ChannelMonitor decided to broadcast before it had been updated to the latest.
262 /// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in
263 /// holder_commitment_tx. For those HTLCs which have transaction_output_index set to None
264 /// (implying they were considered dust at the time the commitment transaction was negotiated),
265 /// a corresponding None should be included in the return value. All other positions in the
266 /// return value must contain a signature.
267 fn sign_holder_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, holder_commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()>;
269 /// Create a signature for the given input in a transaction spending an HTLC or commitment
270 /// transaction output when our counterparty broadcasts an old state.
272 /// A justice transaction may claim multiples outputs at the same time if timelocks are
273 /// similar, but only a signature for the input at index `input` should be signed for here.
274 /// It may be called multiples time for same output(s) if a fee-bump is needed with regards
275 /// to an upcoming timelock expiration.
277 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
279 /// per_commitment_key is revocation secret which was provided by our counterparty when they
280 /// revoked the state which they eventually broadcast. It's not a _holder_ secret key and does
281 /// not allow the spending of any funds by itself (you need our holder revocation_secret to do
284 /// htlc holds HTLC elements (hash, timelock) if the output being spent is a HTLC output, thus
285 /// changing the format of the witness script (which is committed to in the BIP 143
287 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, ()>;
289 /// Create a signature for a claiming transaction for a HTLC output on a counterparty's commitment
290 /// transaction, either offered or received.
292 /// Such a transaction may claim multiples offered outputs at same time if we know the
293 /// preimage for each when we create it, but only the input at index `input` should be
294 /// signed for here. It may be called multiple times for same output(s) if a fee-bump is
295 /// needed with regards to an upcoming timelock expiration.
297 /// Witness_script is either a offered or received script as defined in BOLT3 for HTLC
300 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
302 /// Per_commitment_point is the dynamic point corresponding to the channel state
303 /// detected onchain. It has been generated by our counterparty and is used to derive
304 /// channel state keys, which are then included in the witness script and committed to in the
305 /// BIP 143 signature.
306 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, ()>;
308 /// Create a signature for a (proposed) closing transaction.
310 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
311 /// chosen to forgo their output as dust.
312 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
314 /// Signs a channel announcement message with our funding key, proving it comes from one
315 /// of the channel participants.
317 /// Note that if this fails or is rejected, the channel will not be publicly announced and
318 /// our counterparty may (though likely will not) close the channel on us for violating the
320 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
322 /// Set the counterparty channel basepoints and counterparty_selected/holder_selected_contest_delay.
323 /// This is done immediately on incoming channels and as soon as the channel is accepted on outgoing channels.
325 /// We bind holder_selected_contest_delay late here for API convenience.
327 /// Will be called before any signatures are applied.
328 fn on_accept(&mut self, channel_points: &ChannelPublicKeys, counterparty_selected_contest_delay: u16, holder_selected_contest_delay: u16);
331 /// A trait to describe an object which can get user secrets and key material.
332 pub trait KeysInterface: Send + Sync {
333 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
334 type ChanKeySigner : ChannelKeys;
336 /// Get node secret key (aka node_id or network_key)
337 fn get_node_secret(&self) -> SecretKey;
338 /// Get destination redeemScript to encumber static protocol exit points.
339 fn get_destination_script(&self) -> Script;
340 /// Get shutdown_pubkey to use as PublicKey at channel closure
341 fn get_shutdown_pubkey(&self) -> PublicKey;
342 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
343 /// restarted with some stale data!
344 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
345 /// Gets a unique, cryptographically-secure, random 32 byte value. This is used for encrypting
346 /// onion packets and for temporary channel IDs. There is no requirement that these be
347 /// persisted anywhere, though they must be unique across restarts.
348 fn get_secure_random_bytes(&self) -> [u8; 32];
352 /// Holds late-bound channel data.
353 /// This data is available after the channel is known to be accepted, either
354 /// when receiving an open_channel for an inbound channel or when
355 /// receiving accept_channel for an outbound channel.
356 struct AcceptedChannelData {
357 /// Counterparty public keys and base points
358 counterparty_channel_pubkeys: ChannelPublicKeys,
359 /// The contest_delay value specified by our counterparty and applied on holder-broadcastable
360 /// transactions, ie the amount of time that we have to wait to recover our funds if we
361 /// broadcast a transaction. You'll likely want to pass this to the
362 /// ln::chan_utils::build*_transaction functions when signing holder's transactions.
363 counterparty_selected_contest_delay: u16,
364 /// The contest_delay value specified by us and applied on transactions broadcastable
365 /// by our counterparty, ie the amount of time that they have to wait to recover their funds
366 /// if they broadcast a transaction.
367 holder_selected_contest_delay: u16,
371 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
372 pub struct InMemoryChannelKeys {
373 /// Private key of anchor tx
374 pub funding_key: SecretKey,
375 /// Holder secret key for blinded revocation pubkey
376 pub revocation_base_key: SecretKey,
377 /// Holder secret key used for our balance in counterparty-broadcasted commitment transactions
378 pub payment_key: SecretKey,
379 /// Holder secret key used in HTLC tx
380 pub delayed_payment_base_key: SecretKey,
381 /// Holder htlc secret key used in commitment tx htlc outputs
382 pub htlc_base_key: SecretKey,
384 pub commitment_seed: [u8; 32],
385 /// Holder public keys and basepoints
386 pub(crate) holder_channel_pubkeys: ChannelPublicKeys,
387 /// Counterparty public keys and counterparty/holder selected_contest_delay, populated on channel acceptance
388 accepted_channel_data: Option<AcceptedChannelData>,
389 /// The total value of this channel
390 channel_value_satoshis: u64,
391 /// Key derivation parameters
392 key_derivation_params: (u64, u64),
395 impl InMemoryChannelKeys {
396 /// Create a new InMemoryChannelKeys
397 pub fn new<C: Signing>(
398 secp_ctx: &Secp256k1<C>,
399 funding_key: SecretKey,
400 revocation_base_key: SecretKey,
401 payment_key: SecretKey,
402 delayed_payment_base_key: SecretKey,
403 htlc_base_key: SecretKey,
404 commitment_seed: [u8; 32],
405 channel_value_satoshis: u64,
406 key_derivation_params: (u64, u64)) -> InMemoryChannelKeys {
407 let holder_channel_pubkeys =
408 InMemoryChannelKeys::make_holder_keys(secp_ctx, &funding_key, &revocation_base_key,
409 &payment_key, &delayed_payment_base_key,
411 InMemoryChannelKeys {
415 delayed_payment_base_key,
418 channel_value_satoshis,
419 holder_channel_pubkeys,
420 accepted_channel_data: None,
421 key_derivation_params,
425 fn make_holder_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
426 funding_key: &SecretKey,
427 revocation_base_key: &SecretKey,
428 payment_key: &SecretKey,
429 delayed_payment_base_key: &SecretKey,
430 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
431 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
433 funding_pubkey: from_secret(&funding_key),
434 revocation_basepoint: from_secret(&revocation_base_key),
435 payment_point: from_secret(&payment_key),
436 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
437 htlc_basepoint: from_secret(&htlc_base_key),
441 /// Counterparty pubkeys.
442 /// Will panic if on_accept wasn't called.
443 pub fn counterparty_pubkeys(&self) -> &ChannelPublicKeys { &self.accepted_channel_data.as_ref().unwrap().counterparty_channel_pubkeys }
445 /// The contest_delay value specified by our counterparty and applied on holder-broadcastable
446 /// transactions, ie the amount of time that we have to wait to recover our funds if we
447 /// broadcast a transaction. You'll likely want to pass this to the
448 /// ln::chan_utils::build*_transaction functions when signing holder's transactions.
449 /// Will panic if on_accept wasn't called.
450 pub fn counterparty_selected_contest_delay(&self) -> u16 { self.accepted_channel_data.as_ref().unwrap().counterparty_selected_contest_delay }
452 /// The contest_delay value specified by us and applied on transactions broadcastable
453 /// by our counterparty, ie the amount of time that they have to wait to recover their funds
454 /// if they broadcast a transaction.
455 /// Will panic if on_accept wasn't called.
456 pub fn holder_selected_contest_delay(&self) -> u16 { self.accepted_channel_data.as_ref().unwrap().holder_selected_contest_delay }
459 impl ChannelKeys for InMemoryChannelKeys {
460 fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey {
461 let commitment_secret = SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx)).unwrap();
462 PublicKey::from_secret_key(secp_ctx, &commitment_secret)
465 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
466 chan_utils::build_commitment_secret(&self.commitment_seed, idx)
469 fn pubkeys(&self) -> &ChannelPublicKeys { &self.holder_channel_pubkeys }
470 fn key_derivation_params(&self) -> (u64, u64) { self.key_derivation_params }
472 fn sign_counterparty_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u32, commitment_tx: &Transaction, pre_keys: &PreCalculatedTxCreationKeys, htlcs: &[&HTLCOutputInCommitment], secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
473 if commitment_tx.input.len() != 1 { return Err(()); }
474 let keys = pre_keys.trust_key_derivation();
476 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
477 let accepted_data = self.accepted_channel_data.as_ref().expect("must accept before signing");
478 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &accepted_data.counterparty_channel_pubkeys.funding_pubkey);
480 let commitment_sighash = hash_to_message!(&bip143::SigHashCache::new(commitment_tx).signature_hash(0, &channel_funding_redeemscript, self.channel_value_satoshis, SigHashType::All)[..]);
481 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
483 let commitment_txid = commitment_tx.txid();
485 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
486 for ref htlc in htlcs {
487 if let Some(_) = htlc.transaction_output_index {
488 let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, feerate_per_kw, accepted_data.holder_selected_contest_delay, htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
489 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
490 let htlc_sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, SigHashType::All)[..]);
491 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
493 Err(_) => return Err(()),
495 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
499 Ok((commitment_sig, htlc_sigs))
502 fn sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, holder_commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
503 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
504 let counterparty_channel_data = self.accepted_channel_data.as_ref().expect("must accept before signing");
505 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_channel_data.counterparty_channel_pubkeys.funding_pubkey);
507 Ok(holder_commitment_tx.get_holder_sig(&self.funding_key, &channel_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, holder_commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
512 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
513 let counterparty_channel_pubkeys = &self.accepted_channel_data.as_ref().expect("must accept before signing").counterparty_channel_pubkeys;
514 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_channel_pubkeys.funding_pubkey);
516 Ok(holder_commitment_tx.get_holder_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
519 fn sign_holder_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, holder_commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()> {
520 let counterparty_selected_contest_delay = self.accepted_channel_data.as_ref().unwrap().counterparty_selected_contest_delay;
521 holder_commitment_tx.get_htlc_sigs(&self.htlc_base_key, counterparty_selected_contest_delay, secp_ctx)
524 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, ()> {
525 let revocation_key = match chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
526 Ok(revocation_key) => revocation_key,
527 Err(_) => return Err(())
529 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
530 let revocation_pubkey = match chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
531 Ok(revocation_pubkey) => revocation_pubkey,
532 Err(_) => return Err(())
534 let witness_script = if let &Some(ref htlc) = htlc {
535 let counterparty_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint) {
536 Ok(counterparty_htlcpubkey) => counterparty_htlcpubkey,
537 Err(_) => return Err(())
539 let holder_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
540 Ok(holder_htlcpubkey) => holder_htlcpubkey,
541 Err(_) => return Err(())
543 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
545 let counterparty_delayedpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().delayed_payment_basepoint) {
546 Ok(counterparty_delayedpubkey) => counterparty_delayedpubkey,
547 Err(_) => return Err(())
549 chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.holder_selected_contest_delay(), &counterparty_delayedpubkey)
551 let mut sighash_parts = bip143::SigHashCache::new(justice_tx);
552 let sighash = hash_to_message!(&sighash_parts.signature_hash(input, &witness_script, amount, SigHashType::All)[..]);
553 return Ok(secp_ctx.sign(&sighash, &revocation_key))
556 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, ()> {
557 if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) {
558 let witness_script = if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
559 if let Ok(counterparty_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint) {
560 if let Ok(htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
561 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey)
562 } else { return Err(()) }
563 } else { return Err(()) }
564 } else { return Err(()) };
565 let mut sighash_parts = bip143::SigHashCache::new(htlc_tx);
566 let sighash = hash_to_message!(&sighash_parts.signature_hash(input, &witness_script, amount, SigHashType::All)[..]);
567 return Ok(secp_ctx.sign(&sighash, &htlc_key))
572 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
573 if closing_tx.input.len() != 1 { return Err(()); }
574 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
575 if closing_tx.output.len() > 2 { return Err(()); }
577 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
578 let counterparty_channel_data = self.accepted_channel_data.as_ref().expect("must accept before signing");
579 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_channel_data.counterparty_channel_pubkeys.funding_pubkey);
581 let sighash = hash_to_message!(&bip143::SigHashCache::new(closing_tx)
582 .signature_hash(0, &channel_funding_redeemscript, self.channel_value_satoshis, SigHashType::All)[..]);
583 Ok(secp_ctx.sign(&sighash, &self.funding_key))
586 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
587 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
588 Ok(secp_ctx.sign(&msghash, &self.funding_key))
591 fn on_accept(&mut self, channel_pubkeys: &ChannelPublicKeys, counterparty_selected_contest_delay: u16, holder_selected_contest_delay: u16) {
592 assert!(self.accepted_channel_data.is_none(), "Already accepted");
593 self.accepted_channel_data = Some(AcceptedChannelData {
594 counterparty_channel_pubkeys: channel_pubkeys.clone(),
595 counterparty_selected_contest_delay,
596 holder_selected_contest_delay,
601 impl_writeable!(AcceptedChannelData, 0,
602 { counterparty_channel_pubkeys, counterparty_selected_contest_delay, holder_selected_contest_delay });
604 impl Writeable for InMemoryChannelKeys {
605 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
606 self.funding_key.write(writer)?;
607 self.revocation_base_key.write(writer)?;
608 self.payment_key.write(writer)?;
609 self.delayed_payment_base_key.write(writer)?;
610 self.htlc_base_key.write(writer)?;
611 self.commitment_seed.write(writer)?;
612 self.accepted_channel_data.write(writer)?;
613 self.channel_value_satoshis.write(writer)?;
614 self.key_derivation_params.0.write(writer)?;
615 self.key_derivation_params.1.write(writer)?;
621 impl Readable for InMemoryChannelKeys {
622 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
623 let funding_key = Readable::read(reader)?;
624 let revocation_base_key = Readable::read(reader)?;
625 let payment_key = Readable::read(reader)?;
626 let delayed_payment_base_key = Readable::read(reader)?;
627 let htlc_base_key = Readable::read(reader)?;
628 let commitment_seed = Readable::read(reader)?;
629 let counterparty_channel_data = Readable::read(reader)?;
630 let channel_value_satoshis = Readable::read(reader)?;
631 let secp_ctx = Secp256k1::signing_only();
632 let holder_channel_pubkeys =
633 InMemoryChannelKeys::make_holder_keys(&secp_ctx, &funding_key, &revocation_base_key,
634 &payment_key, &delayed_payment_base_key,
636 let params_1 = Readable::read(reader)?;
637 let params_2 = Readable::read(reader)?;
639 Ok(InMemoryChannelKeys {
643 delayed_payment_base_key,
646 channel_value_satoshis,
647 holder_channel_pubkeys,
648 accepted_channel_data: counterparty_channel_data,
649 key_derivation_params: (params_1, params_2),
654 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
655 /// and derives keys from that.
657 /// Your node_id is seed/0'
658 /// ChannelMonitor closes may use seed/1'
659 /// Cooperative closes may use seed/2'
660 /// The two close keys may be needed to claim on-chain funds!
661 pub struct KeysManager {
662 secp_ctx: Secp256k1<secp256k1::SignOnly>,
663 node_secret: SecretKey,
664 destination_script: Script,
665 shutdown_pubkey: PublicKey,
666 channel_master_key: ExtendedPrivKey,
667 channel_child_index: AtomicUsize,
668 rand_bytes_master_key: ExtendedPrivKey,
669 rand_bytes_child_index: AtomicUsize,
672 starting_time_secs: u64,
673 starting_time_nanos: u32,
677 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
678 /// CSRNG is busted) this may panic (but more importantly, you will possibly lose funds).
679 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
680 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
681 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
682 /// simply use the current time (with very high precision).
684 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
685 /// obviously, starting_time should be unique every time you reload the library - it is only
686 /// used to generate new ephemeral key data (which will be stored by the individual channel if
689 /// Note that the seed is required to recover certain on-chain funds independent of
690 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
691 /// channel, and some on-chain during-closing funds.
693 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
694 /// versions. Once the library is more fully supported, the docs will be updated to include a
695 /// detailed description of the guarantee.
696 pub fn new(seed: &[u8; 32], network: Network, starting_time_secs: u64, starting_time_nanos: u32) -> Self {
697 let secp_ctx = Secp256k1::signing_only();
698 match ExtendedPrivKey::new_master(network.clone(), seed) {
700 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
701 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
702 Ok(destination_key) => {
703 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
704 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
705 .push_slice(&wpubkey_hash.into_inner())
708 Err(_) => panic!("Your RNG is busted"),
710 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
711 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
712 Err(_) => panic!("Your RNG is busted"),
714 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
715 let rand_bytes_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
723 channel_child_index: AtomicUsize::new(0),
724 rand_bytes_master_key,
725 rand_bytes_child_index: AtomicUsize::new(0),
732 Err(_) => panic!("Your rng is busted"),
735 fn derive_unique_start(&self) -> Sha256State {
736 let mut unique_start = Sha256::engine();
737 unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs));
738 unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos));
739 unique_start.input(&self.seed);
742 /// Derive an old set of ChannelKeys for per-channel secrets based on a key derivation
744 /// Key derivation parameters are accessible through a per-channel secrets
745 /// ChannelKeys::key_derivation_params and is provided inside DynamicOuputP2WSH in case of
746 /// onchain output detection for which a corresponding delayed_payment_key must be derived.
747 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params_1: u64, params_2: u64) -> InMemoryChannelKeys {
748 let chan_id = ((params_1 & 0xFFFF_FFFF_0000_0000) >> 32) as u32;
749 let mut unique_start = Sha256::engine();
750 unique_start.input(&byte_utils::be64_to_array(params_2));
751 unique_start.input(&byte_utils::be32_to_array(params_1 as u32));
752 unique_start.input(&self.seed);
754 // We only seriously intend to rely on the channel_master_key for true secure
755 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
756 // starting_time provided in the constructor) to be unique.
757 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");
758 unique_start.input(&child_privkey.private_key.key[..]);
760 let seed = Sha256::from_engine(unique_start).into_inner();
762 let commitment_seed = {
763 let mut sha = Sha256::engine();
765 sha.input(&b"commitment seed"[..]);
766 Sha256::from_engine(sha).into_inner()
768 macro_rules! key_step {
769 ($info: expr, $prev_key: expr) => {{
770 let mut sha = Sha256::engine();
772 sha.input(&$prev_key[..]);
773 sha.input(&$info[..]);
774 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
777 let funding_key = key_step!(b"funding key", commitment_seed);
778 let revocation_base_key = key_step!(b"revocation base key", funding_key);
779 let payment_key = key_step!(b"payment key", revocation_base_key);
780 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
781 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
783 InMemoryChannelKeys::new(
788 delayed_payment_base_key,
791 channel_value_satoshis,
792 (params_1, params_2),
797 impl KeysInterface for KeysManager {
798 type ChanKeySigner = InMemoryChannelKeys;
800 fn get_node_secret(&self) -> SecretKey {
801 self.node_secret.clone()
804 fn get_destination_script(&self) -> Script {
805 self.destination_script.clone()
808 fn get_shutdown_pubkey(&self) -> PublicKey {
809 self.shutdown_pubkey.clone()
812 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner {
813 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
814 let ix_and_nanos: u64 = (child_ix as u64) << 32 | (self.starting_time_nanos as u64);
815 self.derive_channel_keys(channel_value_satoshis, ix_and_nanos, self.starting_time_secs)
818 fn get_secure_random_bytes(&self) -> [u8; 32] {
819 let mut sha = self.derive_unique_start();
821 let child_ix = self.rand_bytes_child_index.fetch_add(1, Ordering::AcqRel);
822 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");
823 sha.input(&child_privkey.private_key.key[..]);
825 sha.input(b"Unique Secure Random Bytes Salt");
826 Sha256::from_engine(sha).into_inner()