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::address::Address;
11 use bitcoin::util::bip143;
13 use bitcoin::hashes::{Hash, HashEngine};
14 use bitcoin::hashes::sha256::HashEngine as Sha256State;
15 use bitcoin::hashes::sha256::Hash as Sha256;
16 use bitcoin::hashes::sha256d::Hash as Sha256dHash;
17 use bitcoin::hash_types::WPubkeyHash;
19 use bitcoin::secp256k1::key::{SecretKey, PublicKey};
20 use bitcoin::secp256k1::{Secp256k1, Signature, Signing};
21 use bitcoin::secp256k1;
24 use util::ser::{Writeable, Writer, Readable};
27 use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, LocalCommitmentTransaction};
29 use ln::channelmanager::PaymentPreimage;
31 use std::sync::atomic::{AtomicUsize, Ordering};
33 use ln::msgs::DecodeError;
35 /// When on-chain outputs are created by rust-lightning (which our counterparty is not able to
36 /// claim at any point in the future) an event is generated which you must track and be able to
37 /// spend on-chain. The information needed to do this is provided in this enum, including the
38 /// outpoint describing which txid and output index is available, the full output which exists at
39 /// that txid/index, and any keys or other information required to sign.
40 #[derive(Clone, PartialEq)]
41 pub enum SpendableOutputDescriptor {
42 /// An output to a script which was provided via KeysInterface, thus you should already know
43 /// how to spend it. No keys are provided as rust-lightning was never given any keys - only the
44 /// script_pubkey as it appears in the output.
45 /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
46 /// on-chain using the payment preimage or after it has timed out.
48 /// The outpoint which is spendable
50 /// The output which is referenced by the given outpoint.
53 /// An output to a P2WSH script which can be spent with a single signature after a CSV delay.
55 /// The witness in the spending input should be:
56 /// <BIP 143 signature> <empty vector> (MINIMALIF standard rule) <provided witnessScript>
58 /// Note that the nSequence field in the spending input must be set to to_self_delay
59 /// (which means the transaction not being broadcastable until at least to_self_delay
60 /// blocks after the outpoint confirms).
62 /// These are generally the result of a "revocable" output to us, spendable only by us unless
63 /// it is an output from us having broadcast an old state (which should never happen).
65 /// WitnessScript may be regenerated by passing the revocation_pubkey, to_self_delay and
66 /// delayed_payment_pubkey to chan_utils::get_revokeable_redeemscript.
68 /// To derive the delayed_payment key corresponding to the channel state, you must pass the
69 /// channel's delayed_payment_key and the provided per_commitment_point to
70 /// chan_utils::derive_private_key. The resulting key should be used to sign the spending
73 /// The outpoint which is spendable
75 /// Per commitment point to derive delayed_payment_key by key holder
76 per_commitment_point: PublicKey,
77 /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in
78 /// the witness_script.
80 /// The output which is referenced by the given outpoint
82 /// The channel keys state used to proceed to derivation of signing key. Must
83 /// be pass to KeysInterface::derive_channel_keys.
84 key_derivation_params: (u64, u64),
85 /// The remote_revocation_pubkey used to derive witnessScript
86 remote_revocation_pubkey: PublicKey
88 // TODO: Note that because key is now static and exactly what is provided by us, we should drop
89 // this in favor of StaticOutput:
90 /// An output to a P2WPKH, spendable exclusively by the given private key.
91 /// The witness in the spending input, is, thus, simply:
92 /// <BIP 143 signature> <payment key>
94 /// These are generally the result of our counterparty having broadcast the current state,
95 /// allowing us to claim the non-HTLC-encumbered outputs immediately.
97 /// To derive the payment key corresponding to the channel state, you must pass the
98 /// channel's payment_base_key and the provided per_commitment_point to
99 /// chan_utils::derive_private_key. The resulting key should be used to sign the spending
101 DynamicOutputP2WPKH {
102 /// The outpoint which is spendable
104 /// The output which is reference by the given outpoint
106 /// The channel keys state used to proceed to derivation of signing key. Must
107 /// be pass to KeysInterface::derive_channel_keys.
108 key_derivation_params: (u64, u64),
112 impl Writeable for SpendableOutputDescriptor {
113 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
115 &SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
117 outpoint.write(writer)?;
118 output.write(writer)?;
120 &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref per_commitment_point, ref to_self_delay, ref output, ref key_derivation_params, ref remote_revocation_pubkey } => {
122 outpoint.write(writer)?;
123 per_commitment_point.write(writer)?;
124 to_self_delay.write(writer)?;
125 output.write(writer)?;
126 key_derivation_params.0.write(writer)?;
127 key_derivation_params.1.write(writer)?;
128 remote_revocation_pubkey.write(writer)?;
130 &SpendableOutputDescriptor::DynamicOutputP2WPKH { ref outpoint, ref output, ref key_derivation_params } => {
132 outpoint.write(writer)?;
133 output.write(writer)?;
134 key_derivation_params.0.write(writer)?;
135 key_derivation_params.1.write(writer)?;
142 impl Readable for SpendableOutputDescriptor {
143 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
144 match Readable::read(reader)? {
145 0u8 => Ok(SpendableOutputDescriptor::StaticOutput {
146 outpoint: Readable::read(reader)?,
147 output: Readable::read(reader)?,
149 1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH {
150 outpoint: Readable::read(reader)?,
151 per_commitment_point: Readable::read(reader)?,
152 to_self_delay: Readable::read(reader)?,
153 output: Readable::read(reader)?,
154 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
155 remote_revocation_pubkey: Readable::read(reader)?,
157 2u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WPKH {
158 outpoint: Readable::read(reader)?,
159 output: Readable::read(reader)?,
160 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
162 _ => Err(DecodeError::InvalidValue),
167 /// A trait to describe an object which can get user secrets and key material.
168 pub trait KeysInterface: Send + Sync {
169 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
170 type ChanKeySigner : ChannelKeys;
172 /// Get node secret key (aka node_id or network_key)
173 fn get_node_secret(&self) -> SecretKey;
174 /// Get destination redeemScript to encumber static protocol exit points.
175 fn get_destination_script(&self) -> Script;
176 /// Get shutdown_pubkey to use as PublicKey at channel closure
177 fn get_shutdown_pubkey(&self) -> PublicKey;
178 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
179 /// restarted with some stale data!
180 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
181 /// Get a secret and PRNG seed for construting an onion packet
182 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
183 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
184 /// transaction is created, at which point they will use the outpoint in the funding
186 fn get_channel_id(&self) -> [u8; 32];
189 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
191 /// Signing services could be implemented on a hardware wallet. In this case,
192 /// the current ChannelKeys would be a front-end on top of a communication
193 /// channel connected to your secure device and lightning key material wouldn't
194 /// reside on a hot server. Nevertheless, a this deployment would still need
195 /// to trust the ChannelManager to avoid loss of funds as this latest component
196 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
198 /// A more secure iteration would be to use hashlock (or payment points) to pair
199 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
200 /// at the price of more state and computation on the hardware wallet side. In the future,
201 /// we are looking forward to design such interface.
203 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
204 /// to act, as liveness and breach reply correctness are always going to be hard requirements
205 /// of LN security model, orthogonal of key management issues.
207 /// If you're implementing a custom signer, you almost certainly want to implement
208 /// Readable/Writable to serialize out a unique reference to this set of keys so
209 /// that you can serialize the full ChannelManager object.
211 // (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
212 // to the possibility of reentrancy issues by calling the user's code during our deserialization
214 // TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
215 // ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
216 pub trait ChannelKeys : Send+Clone {
217 /// Gets the private key for the anchor tx
218 fn funding_key<'a>(&'a self) -> &'a SecretKey;
219 /// Gets the local secret key for blinded revocation pubkey
220 fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
221 /// Gets the local secret key used in the to_remote output of remote commitment tx (ie the
222 /// output to us in transactions our counterparty broadcasts).
223 /// Also as part of obscured commitment number.
224 fn payment_key<'a>(&'a self) -> &'a SecretKey;
225 /// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output
226 fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
227 /// Gets the local htlc secret key used in commitment tx htlc outputs
228 fn htlc_base_key<'a>(&'a self) -> &'a SecretKey;
229 /// Gets the commitment seed
230 fn commitment_seed<'a>(&'a self) -> &'a [u8; 32];
231 /// Gets the local channel public keys and basepoints
232 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys;
233 /// Gets arbitrary identifiers describing the set of keys which are provided back to you in
234 /// some SpendableOutputDescriptor types. These should be sufficient to identify this
235 /// ChannelKeys object uniquely and lookup or re-derive its keys.
236 fn key_derivation_params(&self) -> (u64, u64);
238 /// Create a signature for a remote commitment transaction and associated HTLC transactions.
240 /// Note that if signing fails or is rejected, the channel will be force-closed.
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 // making the callee generate it via some util function we expose)!
245 fn sign_remote_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
247 /// Create a signature for a local commitment transaction. This will only ever be called with
248 /// the same local_commitment_tx (or a copy thereof), though there are currently no guarantees
249 /// that it will not be called multiple times.
251 // TODO: Document the things someone using this interface should enforce before signing.
252 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
253 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
255 /// Same as sign_local_commitment, but exists only for tests to get access to local commitment
256 /// transactions which will be broadcasted later, after the channel has moved on to a newer
257 /// state. Thus, needs its own method as sign_local_commitment may enforce that we only ever
260 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
262 /// Create a signature for each HTLC transaction spending a local commitment transaction.
264 /// Unlike sign_local_commitment, this may be called multiple times with *different*
265 /// local_commitment_tx values. While this will never be called with a revoked
266 /// local_commitment_tx, it is possible that it is called with the second-latest
267 /// local_commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary
268 /// ChannelMonitor decided to broadcast before it had been updated to the latest.
270 /// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in
271 /// local_commitment_tx. For those HTLCs which have transaction_output_index set to None
272 /// (implying they were considered dust at the time the commitment transaction was negotiated),
273 /// a corresponding None should be included in the return value. All other positions in the
274 /// return value must contain a signature.
275 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>>, ()>;
277 /// Create a signature for a transaction spending an HTLC or commitment transaction output
278 /// when our counterparty broadcast an old state.
280 /// Justice transaction may claim multiples outputs at same time if timelock are similar.
281 /// It may be called multiples time for same output(s) if a fee-bump is needed with regards
282 /// to an upcoming timelock expiration.
284 /// Witness_script is a revokable witness script as defined in BOLT3 for `to_local`/HTLC
287 /// Input index is a pointer towards outpoint spent, commited by sigs (BIP 143).
289 /// Amount is value of the output spent by this input, committed by sigs (BIP 143).
291 /// Per_commitment key is revocation secret such as provided by remote party while
292 /// revocating detected onchain transaction. It's not a _local_ secret key, therefore
293 /// it may cross interfaces, a node compromise won't allow to spend revoked output without
294 /// also compromissing revocation key.
295 //TODO: dry-up witness_script and pass pubkeys
296 fn sign_justice_transaction<T: secp256k1::Signing>(&self, justice_tx: &Transaction, input: usize, witness_script: &Script, amount: u64, per_commitment_key: &SecretKey, revocation_pubkey: &PublicKey, is_htlc: bool, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
298 /// Create a signature for a claiming transaction for a HTLC output on a remote commitment
299 /// transaction, either offered or received.
301 /// HTLC transaction may claim multiples offered outputs at same time if we know preimage
302 /// for each at detection. It may be called multtiples time for same output(s) if a fee-bump
303 /// is needed with regards to an upcoming timelock expiration.
305 /// Witness_script is either a offered or received script as defined in BOLT3 for HTLC
308 /// Input index is a pointer towards outpoint spent, commited by sigs (BIP 143).
310 /// Amount is value of the output spent by this input, committed by sigs (BIP 143).
312 /// Preimage is solution for an offered HTLC haslock. A preimage sets to None hints this
313 /// htlc_tx as timing-out funds back to us on a received output.
314 //TODO: dry-up witness_script and pass pubkeys
315 fn sign_remote_htlc_transaction<T: secp256k1::Signing>(&self, htlc_tx: &Transaction, input: usize, witness_script: &Script, amount: u64, per_commitment_point: &PublicKey, preimage: &Option<PaymentPreimage>, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
317 /// Create a signature for a (proposed) closing transaction.
319 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
320 /// chosen to forgo their output as dust.
321 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
323 /// Signs a channel announcement message with our funding key, proving it comes from one
324 /// of the channel participants.
326 /// Note that if this fails or is rejected, the channel will not be publicly announced and
327 /// our counterparty may (though likely will not) close the channel on us for violating the
329 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
331 /// Set the remote channel basepoints. This is done immediately on incoming channels
332 /// and as soon as the channel is accepted on outgoing channels.
334 /// Will be called before any signatures are applied.
335 fn set_remote_channel_pubkeys(&mut self, channel_points: &ChannelPublicKeys);
339 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
340 pub struct InMemoryChannelKeys {
341 /// Private key of anchor tx
342 funding_key: SecretKey,
343 /// Local secret key for blinded revocation pubkey
344 revocation_base_key: SecretKey,
345 /// Local secret key used for our balance in remote-broadcasted commitment transactions
346 payment_key: SecretKey,
347 /// Local secret key used in HTLC tx
348 delayed_payment_base_key: SecretKey,
349 /// Local htlc secret key used in commitment tx htlc outputs
350 htlc_base_key: SecretKey,
352 commitment_seed: [u8; 32],
353 /// Local public keys and basepoints
354 pub(crate) local_channel_pubkeys: ChannelPublicKeys,
355 /// Remote public keys and base points
356 pub(crate) remote_channel_pubkeys: Option<ChannelPublicKeys>,
357 /// The total value of this channel
358 channel_value_satoshis: u64,
359 /// Key derivation parameters
360 key_derivation_params: (u64, u64),
363 impl InMemoryChannelKeys {
364 /// Create a new InMemoryChannelKeys
365 pub fn new<C: Signing>(
366 secp_ctx: &Secp256k1<C>,
367 funding_key: SecretKey,
368 revocation_base_key: SecretKey,
369 payment_key: SecretKey,
370 delayed_payment_base_key: SecretKey,
371 htlc_base_key: SecretKey,
372 commitment_seed: [u8; 32],
373 channel_value_satoshis: u64,
374 key_derivation_params: (u64, u64)) -> InMemoryChannelKeys {
375 let local_channel_pubkeys =
376 InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key,
377 &payment_key, &delayed_payment_base_key,
379 InMemoryChannelKeys {
383 delayed_payment_base_key,
386 channel_value_satoshis,
387 local_channel_pubkeys,
388 remote_channel_pubkeys: None,
389 key_derivation_params,
393 fn make_local_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
394 funding_key: &SecretKey,
395 revocation_base_key: &SecretKey,
396 payment_key: &SecretKey,
397 delayed_payment_base_key: &SecretKey,
398 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
399 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
401 funding_pubkey: from_secret(&funding_key),
402 revocation_basepoint: from_secret(&revocation_base_key),
403 payment_point: from_secret(&payment_key),
404 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
405 htlc_basepoint: from_secret(&htlc_base_key),
409 fn remote_pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { self.remote_channel_pubkeys.as_ref().unwrap() }
412 impl ChannelKeys for InMemoryChannelKeys {
413 fn funding_key(&self) -> &SecretKey { &self.funding_key }
414 fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
415 fn payment_key(&self) -> &SecretKey { &self.payment_key }
416 fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
417 fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
418 fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
419 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { &self.local_channel_pubkeys }
420 fn key_derivation_params(&self) -> (u64, u64) { self.key_derivation_params }
422 fn sign_remote_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
423 if commitment_tx.input.len() != 1 { return Err(()); }
425 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
426 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
427 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
429 let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
430 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
432 let commitment_txid = commitment_tx.txid();
434 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
435 for ref htlc in htlcs {
436 if let Some(_) = htlc.transaction_output_index {
437 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);
438 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
439 let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
440 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
442 Err(_) => return Err(()),
444 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
448 Ok((commitment_sig, htlc_sigs))
451 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
452 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
453 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
454 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
456 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
460 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
461 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
462 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
463 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
465 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
468 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>>, ()> {
469 local_commitment_tx.get_htlc_sigs(&self.htlc_base_key, local_csv, secp_ctx)
472 fn sign_justice_transaction<T: secp256k1::Signing>(&self, justice_tx: &Transaction, input: usize, witness_script: &Script, amount: u64, per_commitment_key: &SecretKey, revocation_pubkey: &PublicKey, is_htlc: bool, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
473 if let Ok(revocation_key) = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
474 let sighash_parts = bip143::SighashComponents::new(&justice_tx);
475 let sighash = hash_to_message!(&sighash_parts.sighash_all(&justice_tx.input[input], &witness_script, amount)[..]);
476 return Ok(secp_ctx.sign(&sighash, &revocation_key))
481 fn sign_remote_htlc_transaction<T: secp256k1::Signing>(&self, htlc_tx: &Transaction, input: usize, witness_script: &Script, amount: u64, per_commitment_point: &PublicKey, preimage: &Option<PaymentPreimage>, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
482 if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) {
483 let sighash_parts = bip143::SighashComponents::new(&htlc_tx);
484 let sighash = hash_to_message!(&sighash_parts.sighash_all(&htlc_tx.input[input], &witness_script, amount)[..]);
485 return Ok(secp_ctx.sign(&sighash, &htlc_key))
490 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
491 if closing_tx.input.len() != 1 { return Err(()); }
492 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
493 if closing_tx.output.len() > 2 { return Err(()); }
495 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
496 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
497 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
499 let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
500 .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
501 Ok(secp_ctx.sign(&sighash, &self.funding_key))
504 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
505 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
506 Ok(secp_ctx.sign(&msghash, &self.funding_key))
509 fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) {
510 assert!(self.remote_channel_pubkeys.is_none(), "Already set remote channel pubkeys");
511 self.remote_channel_pubkeys = Some(channel_pubkeys.clone());
515 impl Writeable for InMemoryChannelKeys {
516 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
517 self.funding_key.write(writer)?;
518 self.revocation_base_key.write(writer)?;
519 self.payment_key.write(writer)?;
520 self.delayed_payment_base_key.write(writer)?;
521 self.htlc_base_key.write(writer)?;
522 self.commitment_seed.write(writer)?;
523 self.remote_channel_pubkeys.write(writer)?;
524 self.channel_value_satoshis.write(writer)?;
525 self.key_derivation_params.0.write(writer)?;
526 self.key_derivation_params.1.write(writer)?;
532 impl Readable for InMemoryChannelKeys {
533 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
534 let funding_key = Readable::read(reader)?;
535 let revocation_base_key = Readable::read(reader)?;
536 let payment_key = Readable::read(reader)?;
537 let delayed_payment_base_key = Readable::read(reader)?;
538 let htlc_base_key = Readable::read(reader)?;
539 let commitment_seed = Readable::read(reader)?;
540 let remote_channel_pubkeys = Readable::read(reader)?;
541 let channel_value_satoshis = Readable::read(reader)?;
542 let secp_ctx = Secp256k1::signing_only();
543 let local_channel_pubkeys =
544 InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key,
545 &payment_key, &delayed_payment_base_key,
547 let params_1 = Readable::read(reader)?;
548 let params_2 = Readable::read(reader)?;
550 Ok(InMemoryChannelKeys {
554 delayed_payment_base_key,
557 channel_value_satoshis,
558 local_channel_pubkeys,
559 remote_channel_pubkeys,
560 key_derivation_params: (params_1, params_2),
565 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
566 /// and derives keys from that.
568 /// Your node_id is seed/0'
569 /// ChannelMonitor closes may use seed/1'
570 /// Cooperative closes may use seed/2'
571 /// The two close keys may be needed to claim on-chain funds!
572 pub struct KeysManager {
573 secp_ctx: Secp256k1<secp256k1::SignOnly>,
574 node_secret: SecretKey,
575 destination_script: Script,
576 shutdown_pubkey: PublicKey,
577 channel_master_key: ExtendedPrivKey,
578 channel_child_index: AtomicUsize,
579 session_master_key: ExtendedPrivKey,
580 session_child_index: AtomicUsize,
581 channel_id_master_key: ExtendedPrivKey,
582 channel_id_child_index: AtomicUsize,
585 starting_time_secs: u64,
586 starting_time_nanos: u32,
590 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
591 /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
592 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
593 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
594 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
595 /// simply use the current time (with very high precision).
597 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
598 /// obviously, starting_time should be unique every time you reload the library - it is only
599 /// used to generate new ephemeral key data (which will be stored by the individual channel if
602 /// Note that the seed is required to recover certain on-chain funds independent of
603 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
604 /// channel, and some on-chain during-closing funds.
606 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
607 /// versions. Once the library is more fully supported, the docs will be updated to include a
608 /// detailed description of the guarantee.
609 pub fn new(seed: &[u8; 32], network: Network, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager {
610 let secp_ctx = Secp256k1::signing_only();
611 match ExtendedPrivKey::new_master(network.clone(), seed) {
613 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
614 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
615 Ok(destination_key) => {
616 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
617 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
618 .push_slice(&wpubkey_hash.into_inner())
621 Err(_) => panic!("Your RNG is busted"),
623 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
624 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
625 Err(_) => panic!("Your RNG is busted"),
627 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
628 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
629 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
637 channel_child_index: AtomicUsize::new(0),
639 session_child_index: AtomicUsize::new(0),
640 channel_id_master_key,
641 channel_id_child_index: AtomicUsize::new(0),
648 Err(_) => panic!("Your rng is busted"),
651 fn derive_unique_start(&self) -> Sha256State {
652 let mut unique_start = Sha256::engine();
653 unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs));
654 unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos));
655 unique_start.input(&self.seed);
658 /// Derive an old set of ChannelKeys for per-channel secrets based on a key derivation
660 /// Key derivation parameters are accessible through a per-channel secrets
661 /// ChannelKeys::key_derivation_params and is provided inside DynamicOuputP2WSH in case of
662 /// onchain output detection for which a corresponding delayed_payment_key must be derived.
663 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params_1: u64, params_2: u64) -> InMemoryChannelKeys {
664 let chan_id = ((params_1 & 0xFFFF_FFFF_0000_0000) >> 32) as u32;
665 let mut unique_start = Sha256::engine();
666 unique_start.input(&byte_utils::be64_to_array(params_2));
667 unique_start.input(&byte_utils::be32_to_array(params_1 as u32));
668 unique_start.input(&self.seed);
670 // We only seriously intend to rely on the channel_master_key for true secure
671 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
672 // starting_time provided in the constructor) to be unique.
673 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");
674 unique_start.input(&child_privkey.private_key.key[..]);
676 let seed = Sha256::from_engine(unique_start).into_inner();
678 let commitment_seed = {
679 let mut sha = Sha256::engine();
681 sha.input(&b"commitment seed"[..]);
682 Sha256::from_engine(sha).into_inner()
684 macro_rules! key_step {
685 ($info: expr, $prev_key: expr) => {{
686 let mut sha = Sha256::engine();
688 sha.input(&$prev_key[..]);
689 sha.input(&$info[..]);
690 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
693 let funding_key = key_step!(b"funding key", commitment_seed);
694 let revocation_base_key = key_step!(b"revocation base key", funding_key);
695 let payment_key = key_step!(b"payment key", revocation_base_key);
696 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
697 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
699 InMemoryChannelKeys::new(
704 delayed_payment_base_key,
707 channel_value_satoshis,
708 (params_1, params_2),
713 impl KeysInterface for KeysManager {
714 type ChanKeySigner = InMemoryChannelKeys;
716 fn get_node_secret(&self) -> SecretKey {
717 self.node_secret.clone()
720 fn get_destination_script(&self) -> Script {
721 self.destination_script.clone()
724 fn get_shutdown_pubkey(&self) -> PublicKey {
725 self.shutdown_pubkey.clone()
728 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys {
729 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
730 let ix_and_nanos: u64 = (child_ix as u64) << 32 | (self.starting_time_nanos as u64);
731 self.derive_channel_keys(channel_value_satoshis, ix_and_nanos, self.starting_time_secs)
734 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
735 let mut sha = self.derive_unique_start();
737 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
738 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");
739 sha.input(&child_privkey.private_key.key[..]);
741 let mut rng_seed = sha.clone();
742 // Not exactly the most ideal construction, but the second value will get fed into
743 // ChaCha so it is another step harder to break.
744 rng_seed.input(b"RNG Seed Salt");
745 sha.input(b"Session Key Salt");
746 (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
747 Sha256::from_engine(rng_seed).into_inner())
750 fn get_channel_id(&self) -> [u8; 32] {
751 let mut sha = self.derive_unique_start();
753 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
754 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");
755 sha.input(&child_privkey.private_key.key[..]);
757 Sha256::from_engine(sha).into_inner()