1 //! keysinterface provides keys into rust-lightning and defines some useful enums which describe
2 //! spendable on-chain outputs which the user owns and is responsible for using just as any other
3 //! on-chain output which is theirs.
5 use bitcoin::blockdata::transaction::{Transaction, OutPoint, TxOut};
6 use bitcoin::blockdata::script::{Script, Builder};
7 use bitcoin::blockdata::opcodes;
8 use bitcoin::network::constants::Network;
9 use bitcoin::util::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber};
10 use bitcoin::util::bip143;
12 use bitcoin::hashes::{Hash, HashEngine};
13 use bitcoin::hashes::sha256::HashEngine as Sha256State;
14 use bitcoin::hashes::sha256::Hash as Sha256;
15 use bitcoin::hashes::sha256d::Hash as Sha256dHash;
16 use bitcoin::hash_types::WPubkeyHash;
18 use bitcoin::secp256k1::key::{SecretKey, PublicKey};
19 use bitcoin::secp256k1::{Secp256k1, Signature, Signing};
20 use bitcoin::secp256k1;
23 use util::ser::{Writeable, Writer, Readable};
26 use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, LocalCommitmentTransaction};
29 use std::sync::atomic::{AtomicUsize, Ordering};
31 use ln::msgs::DecodeError;
33 /// When on-chain outputs are created by rust-lightning (which our counterparty is not able to
34 /// claim at any point in the future) an event is generated which you must track and be able to
35 /// spend on-chain. The information needed to do this is provided in this enum, including the
36 /// outpoint describing which txid and output index is available, the full output which exists at
37 /// that txid/index, and any keys or other information required to sign.
38 #[derive(Clone, PartialEq)]
39 pub enum SpendableOutputDescriptor {
40 /// An output to a script which was provided via KeysInterface, thus you should already know
41 /// how to spend it. No keys are provided as rust-lightning was never given any keys - only the
42 /// script_pubkey as it appears in the output.
43 /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
44 /// on-chain using the payment preimage or after it has timed out.
46 /// The outpoint which is spendable
48 /// The output which is referenced by the given outpoint.
51 /// An output to a P2WSH script which can be spent with a single signature after a CSV delay.
53 /// The witness in the spending input should be:
54 /// <BIP 143 signature> <empty vector> (MINIMALIF standard rule) <provided witnessScript>
56 /// Note that the nSequence field in the spending input must be set to to_self_delay
57 /// (which means the transaction is not broadcastable until at least to_self_delay
58 /// blocks after the outpoint confirms).
60 /// These are generally the result of a "revocable" output to us, spendable only by us unless
61 /// it is an output from an old state which we broadcast (which should never happen).
63 /// To derive the delayed_payment key which is used to sign for this input, you must pass the
64 /// local delayed_payment_base_key (ie the private key which corresponds to the pubkey in
65 /// ChannelKeys::pubkeys().delayed_payment_basepoint) and the provided per_commitment_point to
66 /// chan_utils::derive_private_key. The public key can be generated without the secret key
67 /// using chan_utils::derive_public_key and only the delayed_payment_basepoint which appears in
68 /// ChannelKeys::pubkeys().
70 /// To derive the remote_revocation_pubkey provided here (which is used in the witness
71 /// script generation), you must pass the remote revocation_basepoint (which appears in the
72 /// call to ChannelKeys::set_remote_channel_pubkeys) and the provided per_commitment point
73 /// to chan_utils::derive_public_revocation_key.
75 /// The witness script which is hashed and included in the output script_pubkey may be
76 /// regenerated by passing the revocation_pubkey (derived as above), our delayed_payment pubkey
77 /// (derived as above), and the to_self_delay contained here to
78 /// chan_utils::get_revokeable_redeemscript.
80 // TODO: we need to expose utility methods in KeyManager to do all the relevant derivation.
82 /// The outpoint which is spendable
84 /// Per commitment point to derive delayed_payment_key by key holder
85 per_commitment_point: PublicKey,
86 /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in
87 /// the witness_script.
89 /// The output which is referenced by the given outpoint
91 /// The channel keys state used to proceed to derivation of signing key. Must
92 /// be pass to KeysInterface::derive_channel_keys.
93 key_derivation_params: (u64, u64),
94 /// The remote_revocation_pubkey used to derive witnessScript
95 remote_revocation_pubkey: PublicKey
97 /// An output to a P2WPKH, spendable exclusively by our payment key (ie the private key which
98 /// corresponds to the public key in ChannelKeys::pubkeys().payment_point).
99 /// The witness in the spending input, is, thus, simply:
100 /// <BIP 143 signature> <payment key>
102 /// These are generally the result of our counterparty having broadcast the current state,
103 /// allowing us to claim the non-HTLC-encumbered outputs immediately.
104 StaticOutputRemotePayment {
105 /// The outpoint which is spendable
107 /// The output which is reference by the given outpoint
109 /// The channel keys state used to proceed to derivation of signing key. Must
110 /// be pass to KeysInterface::derive_channel_keys.
111 key_derivation_params: (u64, u64),
115 impl Writeable for SpendableOutputDescriptor {
116 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
118 &SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
120 outpoint.write(writer)?;
121 output.write(writer)?;
123 &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref per_commitment_point, ref to_self_delay, ref output, ref key_derivation_params, ref remote_revocation_pubkey } => {
125 outpoint.write(writer)?;
126 per_commitment_point.write(writer)?;
127 to_self_delay.write(writer)?;
128 output.write(writer)?;
129 key_derivation_params.0.write(writer)?;
130 key_derivation_params.1.write(writer)?;
131 remote_revocation_pubkey.write(writer)?;
133 &SpendableOutputDescriptor::StaticOutputRemotePayment { ref outpoint, ref output, ref key_derivation_params } => {
135 outpoint.write(writer)?;
136 output.write(writer)?;
137 key_derivation_params.0.write(writer)?;
138 key_derivation_params.1.write(writer)?;
145 impl Readable for SpendableOutputDescriptor {
146 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
147 match Readable::read(reader)? {
148 0u8 => Ok(SpendableOutputDescriptor::StaticOutput {
149 outpoint: Readable::read(reader)?,
150 output: Readable::read(reader)?,
152 1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH {
153 outpoint: Readable::read(reader)?,
154 per_commitment_point: Readable::read(reader)?,
155 to_self_delay: Readable::read(reader)?,
156 output: Readable::read(reader)?,
157 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
158 remote_revocation_pubkey: Readable::read(reader)?,
160 2u8 => Ok(SpendableOutputDescriptor::StaticOutputRemotePayment {
161 outpoint: Readable::read(reader)?,
162 output: Readable::read(reader)?,
163 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
165 _ => Err(DecodeError::InvalidValue),
170 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
172 /// Signing services could be implemented on a hardware wallet. In this case,
173 /// the current ChannelKeys would be a front-end on top of a communication
174 /// channel connected to your secure device and lightning key material wouldn't
175 /// reside on a hot server. Nevertheless, a this deployment would still need
176 /// to trust the ChannelManager to avoid loss of funds as this latest component
177 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
179 /// A more secure iteration would be to use hashlock (or payment points) to pair
180 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
181 /// at the price of more state and computation on the hardware wallet side. In the future,
182 /// we are looking forward to design such interface.
184 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
185 /// to act, as liveness and breach reply correctness are always going to be hard requirements
186 /// of LN security model, orthogonal of key management issues.
188 /// If you're implementing a custom signer, you almost certainly want to implement
189 /// Readable/Writable to serialize out a unique reference to this set of keys so
190 /// that you can serialize the full ChannelManager object.
192 // (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
193 // to the possibility of reentrancy issues by calling the user's code during our deserialization
195 // TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
196 // ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
197 pub trait ChannelKeys : Send+Clone {
198 /// Gets the per-commitment point for a specific commitment number
200 /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards.
201 fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey;
202 /// Gets the commitment secret for a specific commitment number as part of the revocation process
204 /// An external signer implementation should error here if the commitment was already signed
205 /// and should refuse to sign it in the future.
207 /// May be called more than once for the same index.
209 /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards.
210 /// TODO: return a Result so we can signal a validation error
211 fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
212 /// Gets the local channel public keys and basepoints
213 fn pubkeys(&self) -> &ChannelPublicKeys;
214 /// Gets arbitrary identifiers describing the set of keys which are provided back to you in
215 /// some SpendableOutputDescriptor types. These should be sufficient to identify this
216 /// ChannelKeys object uniquely and lookup or re-derive its keys.
217 fn key_derivation_params(&self) -> (u64, u64);
219 /// Create a signature for a remote commitment transaction and associated HTLC transactions.
221 /// Note that if signing fails or is rejected, the channel will be force-closed.
223 // TODO: Document the things someone using this interface should enforce before signing.
224 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
225 // making the callee generate it via some util function we expose)!
226 fn sign_remote_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u32, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
228 /// Create a signature for a local commitment transaction. This will only ever be called with
229 /// the same local_commitment_tx (or a copy thereof), though there are currently no guarantees
230 /// that it will not be called multiple times.
231 /// An external signer implementation should check that the commitment has not been revoked.
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 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
237 /// Same as sign_local_commitment, but exists only for tests to get access to local commitment
238 /// transactions which will be broadcasted later, after the channel has moved on to a newer
239 /// state. Thus, needs its own method as sign_local_commitment may enforce that we only ever
242 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
244 /// Create a signature for each HTLC transaction spending a local commitment transaction.
246 /// Unlike sign_local_commitment, this may be called multiple times with *different*
247 /// local_commitment_tx values. While this will never be called with a revoked
248 /// local_commitment_tx, it is possible that it is called with the second-latest
249 /// local_commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary
250 /// ChannelMonitor decided to broadcast before it had been updated to the latest.
252 /// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in
253 /// local_commitment_tx. For those HTLCs which have transaction_output_index set to None
254 /// (implying they were considered dust at the time the commitment transaction was negotiated),
255 /// a corresponding None should be included in the return value. All other positions in the
256 /// return value must contain a signature.
257 fn sign_local_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, local_csv: u16, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()>;
259 /// Create a signature for the given input in a transaction spending an HTLC or commitment
260 /// transaction output when our counterparty broadcasts an old state.
262 /// A justice transaction may claim multiples outputs at the same time if timelocks are
263 /// similar, but only a signature for the input at index `input` should be signed for here.
264 /// It may be called multiples time for same output(s) if a fee-bump is needed with regards
265 /// to an upcoming timelock expiration.
267 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
269 /// per_commitment_key is revocation secret which was provided by our counterparty when they
270 /// revoked the state which they eventually broadcast. It's not a _local_ secret key and does
271 /// not allow the spending of any funds by itself (you need our local revocation_secret to do
274 /// htlc holds HTLC elements (hash, timelock) if the output being spent is a HTLC output, thus
275 /// changing the format of the witness script (which is committed to in the BIP 143
278 /// on_remote_tx_csv is the relative lock-time that that our counterparty would have to set on
279 /// their transaction were they to spend the same output. It is included in the witness script
280 /// and thus committed to in the BIP 143 signature.
281 fn sign_justice_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option<HTLCOutputInCommitment>, on_remote_tx_csv: u16, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
283 /// Create a signature for a claiming transaction for a HTLC output on a remote commitment
284 /// transaction, either offered or received.
286 /// Such a transaction may claim multiples offered outputs at same time if we know the
287 /// preimage for each when we create it, but only the input at index `input` should be
288 /// signed for here. It may be called multiple times for same output(s) if a fee-bump is
289 /// needed with regards to an upcoming timelock expiration.
291 /// Witness_script is either a offered or received script as defined in BOLT3 for HTLC
294 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
296 /// Per_commitment_point is the dynamic point corresponding to the channel state
297 /// detected onchain. It has been generated by our counterparty and is used to derive
298 /// channel state keys, which are then included in the witness script and committed to in the
299 /// BIP 143 signature.
300 fn sign_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, ()>;
302 /// Create a signature for a (proposed) closing transaction.
304 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
305 /// chosen to forgo their output as dust.
306 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
308 /// Signs a channel announcement message with our funding key, proving it comes from one
309 /// of the channel participants.
311 /// Note that if this fails or is rejected, the channel will not be publicly announced and
312 /// our counterparty may (though likely will not) close the channel on us for violating the
314 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
316 /// Set the remote channel basepoints. This is done immediately on incoming channels
317 /// and as soon as the channel is accepted on outgoing channels.
319 /// Will be called before any signatures are applied.
320 fn set_remote_channel_pubkeys(&mut self, channel_points: &ChannelPublicKeys);
323 /// A trait to describe an object which can get user secrets and key material.
324 pub trait KeysInterface: Send + Sync {
325 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
326 type ChanKeySigner : ChannelKeys;
328 /// Get node secret key (aka node_id or network_key)
329 fn get_node_secret(&self) -> SecretKey;
330 /// Get destination redeemScript to encumber static protocol exit points.
331 fn get_destination_script(&self) -> Script;
332 /// Get shutdown_pubkey to use as PublicKey at channel closure
333 fn get_shutdown_pubkey(&self) -> PublicKey;
334 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
335 /// restarted with some stale data!
336 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
337 /// Get a secret and PRNG seed for constructing an onion packet
338 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
339 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
340 /// transaction is created, at which point they will use the outpoint in the funding
342 fn get_channel_id(&self) -> [u8; 32];
346 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
347 pub struct InMemoryChannelKeys {
348 /// Private key of anchor tx
349 pub funding_key: SecretKey,
350 /// Local secret key for blinded revocation pubkey
351 pub revocation_base_key: SecretKey,
352 /// Local secret key used for our balance in remote-broadcasted commitment transactions
353 pub payment_key: SecretKey,
354 /// Local secret key used in HTLC tx
355 pub delayed_payment_base_key: SecretKey,
356 /// Local htlc secret key used in commitment tx htlc outputs
357 pub htlc_base_key: SecretKey,
359 pub commitment_seed: [u8; 32],
360 /// Local public keys and basepoints
361 pub(crate) local_channel_pubkeys: ChannelPublicKeys,
362 /// Remote public keys and base points
363 pub(crate) remote_channel_pubkeys: Option<ChannelPublicKeys>,
364 /// The total value of this channel
365 channel_value_satoshis: u64,
366 /// Key derivation parameters
367 key_derivation_params: (u64, u64),
370 impl InMemoryChannelKeys {
371 /// Create a new InMemoryChannelKeys
372 pub fn new<C: Signing>(
373 secp_ctx: &Secp256k1<C>,
374 funding_key: SecretKey,
375 revocation_base_key: SecretKey,
376 payment_key: SecretKey,
377 delayed_payment_base_key: SecretKey,
378 htlc_base_key: SecretKey,
379 commitment_seed: [u8; 32],
380 channel_value_satoshis: u64,
381 key_derivation_params: (u64, u64)) -> InMemoryChannelKeys {
382 let local_channel_pubkeys =
383 InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key,
384 &payment_key, &delayed_payment_base_key,
386 InMemoryChannelKeys {
390 delayed_payment_base_key,
393 channel_value_satoshis,
394 local_channel_pubkeys,
395 remote_channel_pubkeys: None,
396 key_derivation_params,
400 fn make_local_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
401 funding_key: &SecretKey,
402 revocation_base_key: &SecretKey,
403 payment_key: &SecretKey,
404 delayed_payment_base_key: &SecretKey,
405 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
406 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
408 funding_pubkey: from_secret(&funding_key),
409 revocation_basepoint: from_secret(&revocation_base_key),
410 payment_point: from_secret(&payment_key),
411 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
412 htlc_basepoint: from_secret(&htlc_base_key),
416 fn remote_pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { self.remote_channel_pubkeys.as_ref().unwrap() }
419 impl ChannelKeys for InMemoryChannelKeys {
420 fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey {
421 let commitment_secret = SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx)).unwrap();
422 PublicKey::from_secret_key(secp_ctx, &commitment_secret)
425 fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
426 chan_utils::build_commitment_secret(&self.commitment_seed, idx)
429 fn pubkeys(&self) -> &ChannelPublicKeys { &self.local_channel_pubkeys }
430 fn key_derivation_params(&self) -> (u64, u64) { self.key_derivation_params }
432 fn sign_remote_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u32, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
433 if commitment_tx.input.len() != 1 { return Err(()); }
435 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
436 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
437 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
439 let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
440 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
442 let commitment_txid = commitment_tx.txid();
444 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
445 for ref htlc in htlcs {
446 if let Some(_) = htlc.transaction_output_index {
447 let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, feerate_per_kw, to_self_delay, htlc, &keys.a_delayed_payment_key, &keys.revocation_key);
448 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
449 let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
450 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
452 Err(_) => return Err(()),
454 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
458 Ok((commitment_sig, htlc_sigs))
461 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
462 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
463 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
464 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
466 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
470 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
471 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
472 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
473 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
475 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
478 fn sign_local_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, local_csv: u16, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()> {
479 local_commitment_tx.get_htlc_sigs(&self.htlc_base_key, local_csv, secp_ctx)
482 fn sign_justice_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option<HTLCOutputInCommitment>, on_remote_tx_csv: u16, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
483 let revocation_key = match chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
484 Ok(revocation_key) => revocation_key,
485 Err(_) => return Err(())
487 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
488 let revocation_pubkey = match chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
489 Ok(revocation_pubkey) => revocation_pubkey,
490 Err(_) => return Err(())
492 let witness_script = if let &Some(ref htlc) = htlc {
493 let remote_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().htlc_basepoint) {
494 Ok(remote_htlcpubkey) => remote_htlcpubkey,
495 Err(_) => return Err(())
497 let local_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
498 Ok(local_htlcpubkey) => local_htlcpubkey,
499 Err(_) => return Err(())
501 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &remote_htlcpubkey, &local_htlcpubkey, &revocation_pubkey)
503 let remote_delayedpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().delayed_payment_basepoint) {
504 Ok(remote_delayedpubkey) => remote_delayedpubkey,
505 Err(_) => return Err(())
507 chan_utils::get_revokeable_redeemscript(&revocation_pubkey, on_remote_tx_csv, &remote_delayedpubkey)
509 let sighash_parts = bip143::SighashComponents::new(&justice_tx);
510 let sighash = hash_to_message!(&sighash_parts.sighash_all(&justice_tx.input[input], &witness_script, amount)[..]);
511 return Ok(secp_ctx.sign(&sighash, &revocation_key))
514 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, ()> {
515 if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) {
516 let witness_script = if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
517 if let Ok(remote_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().htlc_basepoint) {
518 if let Ok(local_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
519 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &remote_htlcpubkey, &local_htlcpubkey, &revocation_pubkey)
520 } else { return Err(()) }
521 } else { return Err(()) }
522 } else { return Err(()) };
523 let sighash_parts = bip143::SighashComponents::new(&htlc_tx);
524 let sighash = hash_to_message!(&sighash_parts.sighash_all(&htlc_tx.input[input], &witness_script, amount)[..]);
525 return Ok(secp_ctx.sign(&sighash, &htlc_key))
530 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
531 if closing_tx.input.len() != 1 { return Err(()); }
532 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
533 if closing_tx.output.len() > 2 { return Err(()); }
535 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
536 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
537 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
539 let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
540 .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
541 Ok(secp_ctx.sign(&sighash, &self.funding_key))
544 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
545 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
546 Ok(secp_ctx.sign(&msghash, &self.funding_key))
549 fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) {
550 assert!(self.remote_channel_pubkeys.is_none(), "Already set remote channel pubkeys");
551 self.remote_channel_pubkeys = Some(channel_pubkeys.clone());
555 impl Writeable for InMemoryChannelKeys {
556 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
557 self.funding_key.write(writer)?;
558 self.revocation_base_key.write(writer)?;
559 self.payment_key.write(writer)?;
560 self.delayed_payment_base_key.write(writer)?;
561 self.htlc_base_key.write(writer)?;
562 self.commitment_seed.write(writer)?;
563 self.remote_channel_pubkeys.write(writer)?;
564 self.channel_value_satoshis.write(writer)?;
565 self.key_derivation_params.0.write(writer)?;
566 self.key_derivation_params.1.write(writer)?;
572 impl Readable for InMemoryChannelKeys {
573 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
574 let funding_key = Readable::read(reader)?;
575 let revocation_base_key = Readable::read(reader)?;
576 let payment_key = Readable::read(reader)?;
577 let delayed_payment_base_key = Readable::read(reader)?;
578 let htlc_base_key = Readable::read(reader)?;
579 let commitment_seed = Readable::read(reader)?;
580 let remote_channel_pubkeys = Readable::read(reader)?;
581 let channel_value_satoshis = Readable::read(reader)?;
582 let secp_ctx = Secp256k1::signing_only();
583 let local_channel_pubkeys =
584 InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key,
585 &payment_key, &delayed_payment_base_key,
587 let params_1 = Readable::read(reader)?;
588 let params_2 = Readable::read(reader)?;
590 Ok(InMemoryChannelKeys {
594 delayed_payment_base_key,
597 channel_value_satoshis,
598 local_channel_pubkeys,
599 remote_channel_pubkeys,
600 key_derivation_params: (params_1, params_2),
605 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
606 /// and derives keys from that.
608 /// Your node_id is seed/0'
609 /// ChannelMonitor closes may use seed/1'
610 /// Cooperative closes may use seed/2'
611 /// The two close keys may be needed to claim on-chain funds!
612 pub struct KeysManager {
613 secp_ctx: Secp256k1<secp256k1::SignOnly>,
614 node_secret: SecretKey,
615 destination_script: Script,
616 shutdown_pubkey: PublicKey,
617 channel_master_key: ExtendedPrivKey,
618 channel_child_index: AtomicUsize,
619 session_master_key: ExtendedPrivKey,
620 session_child_index: AtomicUsize,
621 channel_id_master_key: ExtendedPrivKey,
622 channel_id_child_index: AtomicUsize,
625 starting_time_secs: u64,
626 starting_time_nanos: u32,
630 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
631 /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
632 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
633 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
634 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
635 /// simply use the current time (with very high precision).
637 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
638 /// obviously, starting_time should be unique every time you reload the library - it is only
639 /// used to generate new ephemeral key data (which will be stored by the individual channel if
642 /// Note that the seed is required to recover certain on-chain funds independent of
643 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
644 /// channel, and some on-chain during-closing funds.
646 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
647 /// versions. Once the library is more fully supported, the docs will be updated to include a
648 /// detailed description of the guarantee.
649 pub fn new(seed: &[u8; 32], network: Network, starting_time_secs: u64, starting_time_nanos: u32) -> Self {
650 let secp_ctx = Secp256k1::signing_only();
651 match ExtendedPrivKey::new_master(network.clone(), seed) {
653 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
654 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
655 Ok(destination_key) => {
656 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
657 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
658 .push_slice(&wpubkey_hash.into_inner())
661 Err(_) => panic!("Your RNG is busted"),
663 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
664 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
665 Err(_) => panic!("Your RNG is busted"),
667 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
668 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
669 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
677 channel_child_index: AtomicUsize::new(0),
679 session_child_index: AtomicUsize::new(0),
680 channel_id_master_key,
681 channel_id_child_index: AtomicUsize::new(0),
688 Err(_) => panic!("Your rng is busted"),
691 fn derive_unique_start(&self) -> Sha256State {
692 let mut unique_start = Sha256::engine();
693 unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs));
694 unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos));
695 unique_start.input(&self.seed);
698 /// Derive an old set of ChannelKeys for per-channel secrets based on a key derivation
700 /// Key derivation parameters are accessible through a per-channel secrets
701 /// ChannelKeys::key_derivation_params and is provided inside DynamicOuputP2WSH in case of
702 /// onchain output detection for which a corresponding delayed_payment_key must be derived.
703 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params_1: u64, params_2: u64) -> InMemoryChannelKeys {
704 let chan_id = ((params_1 & 0xFFFF_FFFF_0000_0000) >> 32) as u32;
705 let mut unique_start = Sha256::engine();
706 unique_start.input(&byte_utils::be64_to_array(params_2));
707 unique_start.input(&byte_utils::be32_to_array(params_1 as u32));
708 unique_start.input(&self.seed);
710 // We only seriously intend to rely on the channel_master_key for true secure
711 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
712 // starting_time provided in the constructor) to be unique.
713 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");
714 unique_start.input(&child_privkey.private_key.key[..]);
716 let seed = Sha256::from_engine(unique_start).into_inner();
718 let commitment_seed = {
719 let mut sha = Sha256::engine();
721 sha.input(&b"commitment seed"[..]);
722 Sha256::from_engine(sha).into_inner()
724 macro_rules! key_step {
725 ($info: expr, $prev_key: expr) => {{
726 let mut sha = Sha256::engine();
728 sha.input(&$prev_key[..]);
729 sha.input(&$info[..]);
730 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
733 let funding_key = key_step!(b"funding key", commitment_seed);
734 let revocation_base_key = key_step!(b"revocation base key", funding_key);
735 let payment_key = key_step!(b"payment key", revocation_base_key);
736 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
737 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
739 InMemoryChannelKeys::new(
744 delayed_payment_base_key,
747 channel_value_satoshis,
748 (params_1, params_2),
753 impl KeysInterface for KeysManager {
754 type ChanKeySigner = InMemoryChannelKeys;
756 fn get_node_secret(&self) -> SecretKey {
757 self.node_secret.clone()
760 fn get_destination_script(&self) -> Script {
761 self.destination_script.clone()
764 fn get_shutdown_pubkey(&self) -> PublicKey {
765 self.shutdown_pubkey.clone()
768 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys {
769 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
770 let ix_and_nanos: u64 = (child_ix as u64) << 32 | (self.starting_time_nanos as u64);
771 self.derive_channel_keys(channel_value_satoshis, ix_and_nanos, self.starting_time_secs)
774 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
775 let mut sha = self.derive_unique_start();
777 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
778 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");
779 sha.input(&child_privkey.private_key.key[..]);
781 let mut rng_seed = sha.clone();
782 // Not exactly the most ideal construction, but the second value will get fed into
783 // ChaCha so it is another step harder to break.
784 rng_seed.input(b"RNG Seed Salt");
785 sha.input(b"Session Key Salt");
786 (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
787 Sha256::from_engine(rng_seed).into_inner())
790 fn get_channel_id(&self) -> [u8; 32] {
791 let mut sha = self.derive_unique_start();
793 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
794 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");
795 sha.input(&child_privkey.private_key.key[..]);
797 Sha256::from_engine(sha).into_inner()