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, OutPoint, TxOut};
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};
35 use ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, LocalCommitmentTransaction, PreCalculatedTxCreationKeys};
38 use std::sync::atomic::{AtomicUsize, Ordering};
40 use ln::msgs::DecodeError;
42 /// When on-chain outputs are created by rust-lightning (which our counterparty is not able to
43 /// claim at any point in the future) an event is generated which you must track and be able to
44 /// spend on-chain. The information needed to do this is provided in this enum, including the
45 /// outpoint describing which txid and output index is available, the full output which exists at
46 /// that txid/index, and any keys or other information required to sign.
47 #[derive(Clone, PartialEq)]
48 pub enum SpendableOutputDescriptor {
49 /// An output to a script which was provided via KeysInterface, thus you should already know
50 /// how to spend it. No keys are provided as rust-lightning was never given any keys - only the
51 /// script_pubkey as it appears in the output.
52 /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
53 /// on-chain using the payment preimage or after it has timed out.
55 /// The outpoint which is spendable
57 /// The output which is referenced by the given outpoint.
60 /// An output to a P2WSH script which can be spent with a single signature after a CSV delay.
62 /// The witness in the spending input should be:
63 /// <BIP 143 signature> <empty vector> (MINIMALIF standard rule) <provided witnessScript>
65 /// Note that the nSequence field in the spending input must be set to to_self_delay
66 /// (which means the transaction is not broadcastable until at least to_self_delay
67 /// blocks after the outpoint confirms).
69 /// These are generally the result of a "revocable" output to us, spendable only by us unless
70 /// it is an output from an old state which we broadcast (which should never happen).
72 /// To derive the delayed_payment key which is used to sign for this input, you must pass the
73 /// local delayed_payment_base_key (ie the private key which corresponds to the pubkey in
74 /// ChannelKeys::pubkeys().delayed_payment_basepoint) and the provided per_commitment_point to
75 /// chan_utils::derive_private_key. The public key can be generated without the secret key
76 /// using chan_utils::derive_public_key and only the delayed_payment_basepoint which appears in
77 /// ChannelKeys::pubkeys().
79 /// To derive the remote_revocation_pubkey provided here (which is used in the witness
80 /// script generation), you must pass the remote revocation_basepoint (which appears in the
81 /// call to ChannelKeys::on_accept) and the provided per_commitment point
82 /// to chan_utils::derive_public_revocation_key.
84 /// The witness script which is hashed and included in the output script_pubkey may be
85 /// regenerated by passing the revocation_pubkey (derived as above), our delayed_payment pubkey
86 /// (derived as above), and the to_self_delay contained here to
87 /// chan_utils::get_revokeable_redeemscript.
89 // TODO: we need to expose utility methods in KeyManager to do all the relevant derivation.
91 /// The outpoint which is spendable
93 /// Per commitment point to derive delayed_payment_key by key holder
94 per_commitment_point: PublicKey,
95 /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in
96 /// the witness_script.
98 /// The output which is referenced by the given outpoint
100 /// The channel keys state used to proceed to derivation of signing key. Must
101 /// be pass to KeysInterface::derive_channel_keys.
102 key_derivation_params: (u64, u64),
103 /// The remote_revocation_pubkey used to derive witnessScript
104 remote_revocation_pubkey: PublicKey
106 /// An output to a P2WPKH, spendable exclusively by our payment key (ie the private key which
107 /// corresponds to the public key in ChannelKeys::pubkeys().payment_point).
108 /// The witness in the spending input, is, thus, simply:
109 /// <BIP 143 signature> <payment key>
111 /// These are generally the result of our counterparty having broadcast the current state,
112 /// allowing us to claim the non-HTLC-encumbered outputs immediately.
113 StaticOutputRemotePayment {
114 /// The outpoint which is spendable
116 /// The output which is reference by the given outpoint
118 /// The channel keys state used to proceed to derivation of signing key. Must
119 /// be pass to KeysInterface::derive_channel_keys.
120 key_derivation_params: (u64, u64),
124 impl Writeable for SpendableOutputDescriptor {
125 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
127 &SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
129 outpoint.write(writer)?;
130 output.write(writer)?;
132 &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref per_commitment_point, ref to_self_delay, ref output, ref key_derivation_params, ref remote_revocation_pubkey } => {
134 outpoint.write(writer)?;
135 per_commitment_point.write(writer)?;
136 to_self_delay.write(writer)?;
137 output.write(writer)?;
138 key_derivation_params.0.write(writer)?;
139 key_derivation_params.1.write(writer)?;
140 remote_revocation_pubkey.write(writer)?;
142 &SpendableOutputDescriptor::StaticOutputRemotePayment { ref outpoint, ref output, ref key_derivation_params } => {
144 outpoint.write(writer)?;
145 output.write(writer)?;
146 key_derivation_params.0.write(writer)?;
147 key_derivation_params.1.write(writer)?;
154 impl Readable for SpendableOutputDescriptor {
155 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
156 match Readable::read(reader)? {
157 0u8 => Ok(SpendableOutputDescriptor::StaticOutput {
158 outpoint: Readable::read(reader)?,
159 output: Readable::read(reader)?,
161 1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH {
162 outpoint: Readable::read(reader)?,
163 per_commitment_point: Readable::read(reader)?,
164 to_self_delay: Readable::read(reader)?,
165 output: Readable::read(reader)?,
166 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
167 remote_revocation_pubkey: Readable::read(reader)?,
169 2u8 => Ok(SpendableOutputDescriptor::StaticOutputRemotePayment {
170 outpoint: Readable::read(reader)?,
171 output: Readable::read(reader)?,
172 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
174 _ => Err(DecodeError::InvalidValue),
179 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
181 /// Signing services could be implemented on a hardware wallet. In this case,
182 /// the current ChannelKeys would be a front-end on top of a communication
183 /// channel connected to your secure device and lightning key material wouldn't
184 /// reside on a hot server. Nevertheless, a this deployment would still need
185 /// to trust the ChannelManager to avoid loss of funds as this latest component
186 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
188 /// A more secure iteration would be to use hashlock (or payment points) to pair
189 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
190 /// at the price of more state and computation on the hardware wallet side. In the future,
191 /// we are looking forward to design such interface.
193 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
194 /// to act, as liveness and breach reply correctness are always going to be hard requirements
195 /// of LN security model, orthogonal of key management issues.
197 /// If you're implementing a custom signer, you almost certainly want to implement
198 /// Readable/Writable to serialize out a unique reference to this set of keys so
199 /// that you can serialize the full ChannelManager object.
201 // (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
202 // to the possibility of reentrancy issues by calling the user's code during our deserialization
204 // TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
205 // ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
206 pub trait ChannelKeys : Send+Clone {
207 /// Gets the per-commitment point for a specific commitment number
209 /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards.
210 fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey;
211 /// Gets the commitment secret for a specific commitment number as part of the revocation process
213 /// An external signer implementation should error here if the commitment was already signed
214 /// and should refuse to sign it in the future.
216 /// May be called more than once for the same index.
218 /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards.
219 /// TODO: return a Result so we can signal a validation error
220 fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
221 /// Gets the local channel public keys and basepoints
222 fn pubkeys(&self) -> &ChannelPublicKeys;
223 /// Gets arbitrary identifiers describing the set of keys which are provided back to you in
224 /// some SpendableOutputDescriptor types. These should be sufficient to identify this
225 /// ChannelKeys object uniquely and lookup or re-derive its keys.
226 fn key_derivation_params(&self) -> (u64, u64);
228 /// Create a signature for a remote commitment transaction and associated HTLC transactions.
230 /// Note that if signing fails or is rejected, the channel will be force-closed.
232 // TODO: Document the things someone using this interface should enforce before signing.
233 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
234 // making the callee generate it via some util function we expose)!
235 fn sign_remote_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>), ()>;
237 /// Create a signature for a local commitment transaction. This will only ever be called with
238 /// the same local_commitment_tx (or a copy thereof), though there are currently no guarantees
239 /// that it will not be called multiple times.
240 /// An external signer implementation should check that the commitment has not been revoked.
242 // TODO: Document the things someone using this interface should enforce before signing.
243 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
244 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
246 /// Same as sign_local_commitment, but exists only for tests to get access to local commitment
247 /// transactions which will be broadcasted later, after the channel has moved on to a newer
248 /// state. Thus, needs its own method as sign_local_commitment may enforce that we only ever
250 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
251 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
253 /// Create a signature for each HTLC transaction spending a local commitment transaction.
255 /// Unlike sign_local_commitment, this may be called multiple times with *different*
256 /// local_commitment_tx values. While this will never be called with a revoked
257 /// local_commitment_tx, it is possible that it is called with the second-latest
258 /// local_commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary
259 /// ChannelMonitor decided to broadcast before it had been updated to the latest.
261 /// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in
262 /// local_commitment_tx. For those HTLCs which have transaction_output_index set to None
263 /// (implying they were considered dust at the time the commitment transaction was negotiated),
264 /// a corresponding None should be included in the return value. All other positions in the
265 /// return value must contain a signature.
266 fn sign_local_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()>;
268 /// Create a signature for the given input in a transaction spending an HTLC or commitment
269 /// transaction output when our counterparty broadcasts an old state.
271 /// A justice transaction may claim multiples outputs at the same time if timelocks are
272 /// similar, but only a signature for the input at index `input` should be signed for here.
273 /// It may be called multiples time for same output(s) if a fee-bump is needed with regards
274 /// to an upcoming timelock expiration.
276 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
278 /// per_commitment_key is revocation secret which was provided by our counterparty when they
279 /// revoked the state which they eventually broadcast. It's not a _local_ secret key and does
280 /// not allow the spending of any funds by itself (you need our local revocation_secret to do
283 /// htlc holds HTLC elements (hash, timelock) if the output being spent is a HTLC output, thus
284 /// changing the format of the witness script (which is committed to in the BIP 143
286 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, ()>;
288 /// Create a signature for a claiming transaction for a HTLC output on a remote commitment
289 /// transaction, either offered or received.
291 /// Such a transaction may claim multiples offered outputs at same time if we know the
292 /// preimage for each when we create it, but only the input at index `input` should be
293 /// signed for here. It may be called multiple times for same output(s) if a fee-bump is
294 /// needed with regards to an upcoming timelock expiration.
296 /// Witness_script is either a offered or received script as defined in BOLT3 for HTLC
299 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
301 /// Per_commitment_point is the dynamic point corresponding to the channel state
302 /// detected onchain. It has been generated by our counterparty and is used to derive
303 /// channel state keys, which are then included in the witness script and committed to in the
304 /// BIP 143 signature.
305 fn sign_remote_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, ()>;
307 /// Create a signature for a (proposed) closing transaction.
309 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
310 /// chosen to forgo their output as dust.
311 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
313 /// Signs a channel announcement message with our funding key, proving it comes from one
314 /// of the channel participants.
316 /// Note that if this fails or is rejected, the channel will not be publicly announced and
317 /// our counterparty may (though likely will not) close the channel on us for violating the
319 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
321 /// Set the remote channel basepoints and remote/local to_self_delay.
322 /// This is done immediately on incoming channels and as soon as the channel is accepted on outgoing channels.
324 /// We bind local_to_self_delay late here for API convenience.
326 /// Will be called before any signatures are applied.
327 fn on_accept(&mut self, channel_points: &ChannelPublicKeys, remote_to_self_delay: u16, local_to_self_delay: u16);
330 /// A trait to describe an object which can get user secrets and key material.
331 pub trait KeysInterface: Send + Sync {
332 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
333 type ChanKeySigner : ChannelKeys;
335 /// Get node secret key (aka node_id or network_key)
336 fn get_node_secret(&self) -> SecretKey;
337 /// Get destination redeemScript to encumber static protocol exit points.
338 fn get_destination_script(&self) -> Script;
339 /// Get shutdown_pubkey to use as PublicKey at channel closure
340 fn get_shutdown_pubkey(&self) -> PublicKey;
341 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
342 /// restarted with some stale data!
343 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
344 /// Get a secret and PRNG seed for constructing an onion packet
345 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
346 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
347 /// transaction is created, at which point they will use the outpoint in the funding
349 fn get_channel_id(&self) -> [u8; 32];
353 /// Holds late-bound channel data.
354 /// This data is available after the channel is known to be accepted, either
355 /// when receiving an open_channel for an inbound channel or when
356 /// receiving accept_channel for an outbound channel.
357 struct AcceptedChannelData {
358 /// Remote public keys and base points
359 remote_channel_pubkeys: ChannelPublicKeys,
360 /// The to_self_delay value specified by our counterparty and applied on locally-broadcastable
361 /// transactions, ie the amount of time that we have to wait to recover our funds if we
362 /// broadcast a transaction. You'll likely want to pass this to the
363 /// ln::chan_utils::build*_transaction functions when signing local transactions.
364 remote_to_self_delay: u16,
365 /// The to_self_delay value specified by us and applied on transactions broadcastable
366 /// by our counterparty, ie the amount of time that they have to wait to recover their funds
367 /// if they broadcast a transaction.
368 local_to_self_delay: u16,
372 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
373 pub struct InMemoryChannelKeys {
374 /// Private key of anchor tx
375 pub funding_key: SecretKey,
376 /// Local secret key for blinded revocation pubkey
377 pub revocation_base_key: SecretKey,
378 /// Local secret key used for our balance in remote-broadcasted commitment transactions
379 pub payment_key: SecretKey,
380 /// Local secret key used in HTLC tx
381 pub delayed_payment_base_key: SecretKey,
382 /// Local htlc secret key used in commitment tx htlc outputs
383 pub htlc_base_key: SecretKey,
385 pub commitment_seed: [u8; 32],
386 /// Local public keys and basepoints
387 pub(crate) local_channel_pubkeys: ChannelPublicKeys,
388 /// Remote public keys and remote/local to_self_delay, populated on channel acceptance
389 accepted_channel_data: Option<AcceptedChannelData>,
390 /// The total value of this channel
391 channel_value_satoshis: u64,
392 /// Key derivation parameters
393 key_derivation_params: (u64, u64),
396 impl InMemoryChannelKeys {
397 /// Create a new InMemoryChannelKeys
398 pub fn new<C: Signing>(
399 secp_ctx: &Secp256k1<C>,
400 funding_key: SecretKey,
401 revocation_base_key: SecretKey,
402 payment_key: SecretKey,
403 delayed_payment_base_key: SecretKey,
404 htlc_base_key: SecretKey,
405 commitment_seed: [u8; 32],
406 channel_value_satoshis: u64,
407 key_derivation_params: (u64, u64)) -> InMemoryChannelKeys {
408 let local_channel_pubkeys =
409 InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key,
410 &payment_key, &delayed_payment_base_key,
412 InMemoryChannelKeys {
416 delayed_payment_base_key,
419 channel_value_satoshis,
420 local_channel_pubkeys,
421 accepted_channel_data: None,
422 key_derivation_params,
426 fn make_local_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
427 funding_key: &SecretKey,
428 revocation_base_key: &SecretKey,
429 payment_key: &SecretKey,
430 delayed_payment_base_key: &SecretKey,
431 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
432 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
434 funding_pubkey: from_secret(&funding_key),
435 revocation_basepoint: from_secret(&revocation_base_key),
436 payment_point: from_secret(&payment_key),
437 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
438 htlc_basepoint: from_secret(&htlc_base_key),
443 /// Will panic if on_accept wasn't called.
444 pub fn remote_pubkeys(&self) -> &ChannelPublicKeys { &self.accepted_channel_data.as_ref().unwrap().remote_channel_pubkeys }
446 /// The to_self_delay value specified by our counterparty and applied on locally-broadcastable
447 /// transactions, ie the amount of time that we have to wait to recover our funds if we
448 /// broadcast a transaction. You'll likely want to pass this to the
449 /// ln::chan_utils::build*_transaction functions when signing local transactions.
450 /// Will panic if on_accept wasn't called.
451 pub fn remote_to_self_delay(&self) -> u16 { self.accepted_channel_data.as_ref().unwrap().remote_to_self_delay }
453 /// The to_self_delay value specified by us and applied on transactions broadcastable
454 /// by our counterparty, ie the amount of time that they have to wait to recover their funds
455 /// if they broadcast a transaction.
456 /// Will panic if on_accept wasn't called.
457 pub fn local_to_self_delay(&self) -> u16 { self.accepted_channel_data.as_ref().unwrap().local_to_self_delay }
460 impl ChannelKeys for InMemoryChannelKeys {
461 fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey {
462 let commitment_secret = SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx)).unwrap();
463 PublicKey::from_secret_key(secp_ctx, &commitment_secret)
466 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
467 chan_utils::build_commitment_secret(&self.commitment_seed, idx)
470 fn pubkeys(&self) -> &ChannelPublicKeys { &self.local_channel_pubkeys }
471 fn key_derivation_params(&self) -> (u64, u64) { self.key_derivation_params }
473 fn sign_remote_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>), ()> {
474 if commitment_tx.input.len() != 1 { return Err(()); }
475 let keys = pre_keys.trust_key_derivation();
477 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
478 let accepted_data = self.accepted_channel_data.as_ref().expect("must accept before signing");
479 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &accepted_data.remote_channel_pubkeys.funding_pubkey);
481 let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
482 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
484 let commitment_txid = commitment_tx.txid();
486 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
487 for ref htlc in htlcs {
488 if let Some(_) = htlc.transaction_output_index {
489 let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, feerate_per_kw, accepted_data.local_to_self_delay, htlc, &keys.a_delayed_payment_key, &keys.revocation_key);
490 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
491 let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
492 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
494 Err(_) => return Err(()),
496 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
500 Ok((commitment_sig, htlc_sigs))
503 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
504 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
505 let remote_channel_data = self.accepted_channel_data.as_ref().expect("must accept before signing");
506 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_data.remote_channel_pubkeys.funding_pubkey);
508 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
511 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
512 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
513 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
514 let remote_channel_pubkeys = &self.accepted_channel_data.as_ref().expect("must accept before signing").remote_channel_pubkeys;
515 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
517 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
520 fn sign_local_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()> {
521 let local_csv = self.accepted_channel_data.as_ref().unwrap().remote_to_self_delay;
522 local_commitment_tx.get_htlc_sigs(&self.htlc_base_key, local_csv, secp_ctx)
525 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, ()> {
526 let revocation_key = match chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
527 Ok(revocation_key) => revocation_key,
528 Err(_) => return Err(())
530 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
531 let revocation_pubkey = match chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
532 Ok(revocation_pubkey) => revocation_pubkey,
533 Err(_) => return Err(())
535 let witness_script = if let &Some(ref htlc) = htlc {
536 let remote_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().htlc_basepoint) {
537 Ok(remote_htlcpubkey) => remote_htlcpubkey,
538 Err(_) => return Err(())
540 let local_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
541 Ok(local_htlcpubkey) => local_htlcpubkey,
542 Err(_) => return Err(())
544 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &remote_htlcpubkey, &local_htlcpubkey, &revocation_pubkey)
546 let remote_delayedpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().delayed_payment_basepoint) {
547 Ok(remote_delayedpubkey) => remote_delayedpubkey,
548 Err(_) => return Err(())
550 chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.local_to_self_delay(), &remote_delayedpubkey)
552 let sighash_parts = bip143::SighashComponents::new(&justice_tx);
553 let sighash = hash_to_message!(&sighash_parts.sighash_all(&justice_tx.input[input], &witness_script, amount)[..]);
554 return Ok(secp_ctx.sign(&sighash, &revocation_key))
557 fn sign_remote_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, ()> {
558 if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) {
559 let witness_script = if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
560 if let Ok(remote_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().htlc_basepoint) {
561 if let Ok(local_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
562 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &remote_htlcpubkey, &local_htlcpubkey, &revocation_pubkey)
563 } else { return Err(()) }
564 } else { return Err(()) }
565 } else { return Err(()) };
566 let sighash_parts = bip143::SighashComponents::new(&htlc_tx);
567 let sighash = hash_to_message!(&sighash_parts.sighash_all(&htlc_tx.input[input], &witness_script, amount)[..]);
568 return Ok(secp_ctx.sign(&sighash, &htlc_key))
573 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
574 if closing_tx.input.len() != 1 { return Err(()); }
575 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
576 if closing_tx.output.len() > 2 { return Err(()); }
578 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
579 let remote_channel_data = self.accepted_channel_data.as_ref().expect("must accept before signing");
580 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_data.remote_channel_pubkeys.funding_pubkey);
582 let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
583 .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
584 Ok(secp_ctx.sign(&sighash, &self.funding_key))
587 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
588 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
589 Ok(secp_ctx.sign(&msghash, &self.funding_key))
592 fn on_accept(&mut self, channel_pubkeys: &ChannelPublicKeys, remote_to_self_delay: u16, local_to_self_delay: u16) {
593 assert!(self.accepted_channel_data.is_none(), "Already accepted");
594 self.accepted_channel_data = Some(AcceptedChannelData {
595 remote_channel_pubkeys: channel_pubkeys.clone(),
596 remote_to_self_delay,
602 impl_writeable!(AcceptedChannelData, 0,
603 { remote_channel_pubkeys, remote_to_self_delay, local_to_self_delay });
605 impl Writeable for InMemoryChannelKeys {
606 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
607 self.funding_key.write(writer)?;
608 self.revocation_base_key.write(writer)?;
609 self.payment_key.write(writer)?;
610 self.delayed_payment_base_key.write(writer)?;
611 self.htlc_base_key.write(writer)?;
612 self.commitment_seed.write(writer)?;
613 self.accepted_channel_data.write(writer)?;
614 self.channel_value_satoshis.write(writer)?;
615 self.key_derivation_params.0.write(writer)?;
616 self.key_derivation_params.1.write(writer)?;
622 impl Readable for InMemoryChannelKeys {
623 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
624 let funding_key = Readable::read(reader)?;
625 let revocation_base_key = Readable::read(reader)?;
626 let payment_key = Readable::read(reader)?;
627 let delayed_payment_base_key = Readable::read(reader)?;
628 let htlc_base_key = Readable::read(reader)?;
629 let commitment_seed = Readable::read(reader)?;
630 let remote_channel_data = Readable::read(reader)?;
631 let channel_value_satoshis = Readable::read(reader)?;
632 let secp_ctx = Secp256k1::signing_only();
633 let local_channel_pubkeys =
634 InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key,
635 &payment_key, &delayed_payment_base_key,
637 let params_1 = Readable::read(reader)?;
638 let params_2 = Readable::read(reader)?;
640 Ok(InMemoryChannelKeys {
644 delayed_payment_base_key,
647 channel_value_satoshis,
648 local_channel_pubkeys,
649 accepted_channel_data: remote_channel_data,
650 key_derivation_params: (params_1, params_2),
655 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
656 /// and derives keys from that.
658 /// Your node_id is seed/0'
659 /// ChannelMonitor closes may use seed/1'
660 /// Cooperative closes may use seed/2'
661 /// The two close keys may be needed to claim on-chain funds!
662 pub struct KeysManager {
663 secp_ctx: Secp256k1<secp256k1::SignOnly>,
664 node_secret: SecretKey,
665 destination_script: Script,
666 shutdown_pubkey: PublicKey,
667 channel_master_key: ExtendedPrivKey,
668 channel_child_index: AtomicUsize,
669 session_master_key: ExtendedPrivKey,
670 session_child_index: AtomicUsize,
671 channel_id_master_key: ExtendedPrivKey,
672 channel_id_child_index: AtomicUsize,
675 starting_time_secs: u64,
676 starting_time_nanos: u32,
680 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
681 /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
682 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
683 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
684 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
685 /// simply use the current time (with very high precision).
687 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
688 /// obviously, starting_time should be unique every time you reload the library - it is only
689 /// used to generate new ephemeral key data (which will be stored by the individual channel if
692 /// Note that the seed is required to recover certain on-chain funds independent of
693 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
694 /// channel, and some on-chain during-closing funds.
696 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
697 /// versions. Once the library is more fully supported, the docs will be updated to include a
698 /// detailed description of the guarantee.
699 pub fn new(seed: &[u8; 32], network: Network, starting_time_secs: u64, starting_time_nanos: u32) -> Self {
700 let secp_ctx = Secp256k1::signing_only();
701 match ExtendedPrivKey::new_master(network.clone(), seed) {
703 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
704 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
705 Ok(destination_key) => {
706 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
707 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
708 .push_slice(&wpubkey_hash.into_inner())
711 Err(_) => panic!("Your RNG is busted"),
713 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
714 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
715 Err(_) => panic!("Your RNG is busted"),
717 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
718 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
719 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
727 channel_child_index: AtomicUsize::new(0),
729 session_child_index: AtomicUsize::new(0),
730 channel_id_master_key,
731 channel_id_child_index: AtomicUsize::new(0),
738 Err(_) => panic!("Your rng is busted"),
741 fn derive_unique_start(&self) -> Sha256State {
742 let mut unique_start = Sha256::engine();
743 unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs));
744 unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos));
745 unique_start.input(&self.seed);
748 /// Derive an old set of ChannelKeys for per-channel secrets based on a key derivation
750 /// Key derivation parameters are accessible through a per-channel secrets
751 /// ChannelKeys::key_derivation_params and is provided inside DynamicOuputP2WSH in case of
752 /// onchain output detection for which a corresponding delayed_payment_key must be derived.
753 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params_1: u64, params_2: u64) -> InMemoryChannelKeys {
754 let chan_id = ((params_1 & 0xFFFF_FFFF_0000_0000) >> 32) as u32;
755 let mut unique_start = Sha256::engine();
756 unique_start.input(&byte_utils::be64_to_array(params_2));
757 unique_start.input(&byte_utils::be32_to_array(params_1 as u32));
758 unique_start.input(&self.seed);
760 // We only seriously intend to rely on the channel_master_key for true secure
761 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
762 // starting_time provided in the constructor) to be unique.
763 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");
764 unique_start.input(&child_privkey.private_key.key[..]);
766 let seed = Sha256::from_engine(unique_start).into_inner();
768 let commitment_seed = {
769 let mut sha = Sha256::engine();
771 sha.input(&b"commitment seed"[..]);
772 Sha256::from_engine(sha).into_inner()
774 macro_rules! key_step {
775 ($info: expr, $prev_key: expr) => {{
776 let mut sha = Sha256::engine();
778 sha.input(&$prev_key[..]);
779 sha.input(&$info[..]);
780 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
783 let funding_key = key_step!(b"funding key", commitment_seed);
784 let revocation_base_key = key_step!(b"revocation base key", funding_key);
785 let payment_key = key_step!(b"payment key", revocation_base_key);
786 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
787 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
789 InMemoryChannelKeys::new(
794 delayed_payment_base_key,
797 channel_value_satoshis,
798 (params_1, params_2),
803 impl KeysInterface for KeysManager {
804 type ChanKeySigner = InMemoryChannelKeys;
806 fn get_node_secret(&self) -> SecretKey {
807 self.node_secret.clone()
810 fn get_destination_script(&self) -> Script {
811 self.destination_script.clone()
814 fn get_shutdown_pubkey(&self) -> PublicKey {
815 self.shutdown_pubkey.clone()
818 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys {
819 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
820 let ix_and_nanos: u64 = (child_ix as u64) << 32 | (self.starting_time_nanos as u64);
821 self.derive_channel_keys(channel_value_satoshis, ix_and_nanos, self.starting_time_secs)
824 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
825 let mut sha = self.derive_unique_start();
827 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
828 let child_privkey = self.session_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted");
829 sha.input(&child_privkey.private_key.key[..]);
831 let mut rng_seed = sha.clone();
832 // Not exactly the most ideal construction, but the second value will get fed into
833 // ChaCha so it is another step harder to break.
834 rng_seed.input(b"RNG Seed Salt");
835 sha.input(b"Session Key Salt");
836 (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
837 Sha256::from_engine(rng_seed).into_inner())
840 fn get_channel_id(&self) -> [u8; 32] {
841 let mut sha = self.derive_unique_start();
843 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
844 let child_privkey = self.channel_id_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted");
845 sha.input(&child_privkey.private_key.key[..]);
847 Sha256::from_engine(sha).into_inner()