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 not being 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 us having broadcast an old state (which should never happen).
63 /// WitnessScript may be regenerated by passing the revocation_pubkey, to_self_delay and
64 /// delayed_payment_pubkey to chan_utils::get_revokeable_redeemscript.
66 /// To derive the delayed_payment key corresponding to the channel state, you must pass the
67 /// channel's delayed_payment_key and the provided per_commitment_point to
68 /// chan_utils::derive_private_key. The resulting key should be used to sign the spending
71 /// The outpoint which is spendable
73 /// Per commitment point to derive delayed_payment_key by key holder
74 per_commitment_point: PublicKey,
75 /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in
76 /// the witness_script.
78 /// The output which is referenced by the given outpoint
80 /// The channel keys state used to proceed to derivation of signing key. Must
81 /// be pass to KeysInterface::derive_channel_keys.
82 key_derivation_params: (u64, u64),
83 /// The remote_revocation_pubkey used to derive witnessScript
84 remote_revocation_pubkey: PublicKey
86 // TODO: Note that because key is now static and exactly what is provided by us, we should drop
87 // this in favor of StaticOutput:
88 /// An output to a P2WPKH, spendable exclusively by the given private key.
89 /// The witness in the spending input, is, thus, simply:
90 /// <BIP 143 signature> <payment key>
92 /// These are generally the result of our counterparty having broadcast the current state,
93 /// allowing us to claim the non-HTLC-encumbered outputs immediately.
95 /// To derive the payment key corresponding to the channel state, you must pass the
96 /// channel's payment_base_key and the provided per_commitment_point to
97 /// chan_utils::derive_private_key. The resulting key should be used to sign the spending
100 /// The outpoint which is spendable
102 /// The output which is reference by the given outpoint
104 /// The channel keys state used to proceed to derivation of signing key. Must
105 /// be pass to KeysInterface::derive_channel_keys.
106 key_derivation_params: (u64, u64),
110 impl Writeable for SpendableOutputDescriptor {
111 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
113 &SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
115 outpoint.write(writer)?;
116 output.write(writer)?;
118 &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref per_commitment_point, ref to_self_delay, ref output, ref key_derivation_params, ref remote_revocation_pubkey } => {
120 outpoint.write(writer)?;
121 per_commitment_point.write(writer)?;
122 to_self_delay.write(writer)?;
123 output.write(writer)?;
124 key_derivation_params.0.write(writer)?;
125 key_derivation_params.1.write(writer)?;
126 remote_revocation_pubkey.write(writer)?;
128 &SpendableOutputDescriptor::DynamicOutputP2WPKH { ref outpoint, ref output, ref key_derivation_params } => {
130 outpoint.write(writer)?;
131 output.write(writer)?;
132 key_derivation_params.0.write(writer)?;
133 key_derivation_params.1.write(writer)?;
140 impl Readable for SpendableOutputDescriptor {
141 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
142 match Readable::read(reader)? {
143 0u8 => Ok(SpendableOutputDescriptor::StaticOutput {
144 outpoint: Readable::read(reader)?,
145 output: Readable::read(reader)?,
147 1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH {
148 outpoint: Readable::read(reader)?,
149 per_commitment_point: Readable::read(reader)?,
150 to_self_delay: Readable::read(reader)?,
151 output: Readable::read(reader)?,
152 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
153 remote_revocation_pubkey: Readable::read(reader)?,
155 2u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WPKH {
156 outpoint: Readable::read(reader)?,
157 output: Readable::read(reader)?,
158 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
160 _ => Err(DecodeError::InvalidValue),
165 /// A trait to describe an object which can get user secrets and key material.
166 pub trait KeysInterface: Send + Sync {
167 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
168 type ChanKeySigner : ChannelKeys;
170 /// Get node secret key (aka node_id or network_key)
171 fn get_node_secret(&self) -> SecretKey;
172 /// Get destination redeemScript to encumber static protocol exit points.
173 fn get_destination_script(&self) -> Script;
174 /// Get shutdown_pubkey to use as PublicKey at channel closure
175 fn get_shutdown_pubkey(&self) -> PublicKey;
176 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
177 /// restarted with some stale data!
178 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
179 /// Get a secret and PRNG seed for construting an onion packet
180 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
181 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
182 /// transaction is created, at which point they will use the outpoint in the funding
184 fn get_channel_id(&self) -> [u8; 32];
187 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
189 /// Signing services could be implemented on a hardware wallet. In this case,
190 /// the current ChannelKeys would be a front-end on top of a communication
191 /// channel connected to your secure device and lightning key material wouldn't
192 /// reside on a hot server. Nevertheless, a this deployment would still need
193 /// to trust the ChannelManager to avoid loss of funds as this latest component
194 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
196 /// A more secure iteration would be to use hashlock (or payment points) to pair
197 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
198 /// at the price of more state and computation on the hardware wallet side. In the future,
199 /// we are looking forward to design such interface.
201 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
202 /// to act, as liveness and breach reply correctness are always going to be hard requirements
203 /// of LN security model, orthogonal of key management issues.
205 /// If you're implementing a custom signer, you almost certainly want to implement
206 /// Readable/Writable to serialize out a unique reference to this set of keys so
207 /// that you can serialize the full ChannelManager object.
209 // (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
210 // to the possibility of reentrancy issues by calling the user's code during our deserialization
212 // TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
213 // ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
214 pub trait ChannelKeys : Send+Clone {
215 /// Gets the private key for the anchor tx
216 fn funding_key<'a>(&'a self) -> &'a SecretKey;
217 /// Gets the local secret key for blinded revocation pubkey
218 fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
219 /// Gets the local secret key used in the to_remote output of remote commitment tx (ie the
220 /// output to us in transactions our counterparty broadcasts).
221 /// Also as part of obscured commitment number.
222 fn payment_key<'a>(&'a self) -> &'a SecretKey;
223 /// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output
224 fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
225 /// Gets the local htlc secret key used in commitment tx htlc outputs
226 fn htlc_base_key<'a>(&'a self) -> &'a SecretKey;
227 /// Gets the commitment seed
228 fn commitment_seed<'a>(&'a self) -> &'a [u8; 32];
229 /// Gets the local channel public keys and basepoints
230 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys;
231 /// Gets arbitrary identifiers describing the set of keys which are provided back to you in
232 /// some SpendableOutputDescriptor types. These should be sufficient to identify this
233 /// ChannelKeys object uniquely and lookup or re-derive its keys.
234 fn key_derivation_params(&self) -> (u64, u64);
236 /// Create a signature for a remote commitment transaction and associated HTLC transactions.
238 /// Note that if signing fails or is rejected, the channel will be force-closed.
240 // TODO: Document the things someone using this interface should enforce before signing.
241 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
242 // making the callee generate it via some util function we expose)!
243 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>), ()>;
245 /// Create a signature for a local commitment transaction. This will only ever be called with
246 /// the same local_commitment_tx (or a copy thereof), though there are currently no guarantees
247 /// that it will not be called multiple times.
249 // TODO: Document the things someone using this interface should enforce before signing.
250 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
251 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
253 /// Same as sign_local_commitment, but exists only for tests to get access to local commitment
254 /// transactions which will be broadcasted later, after the channel has moved on to a newer
255 /// state. Thus, needs its own method as sign_local_commitment may enforce that we only ever
258 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
260 /// Create a signature for each HTLC transaction spending a local commitment transaction.
262 /// Unlike sign_local_commitment, this may be called multiple times with *different*
263 /// local_commitment_tx values. While this will never be called with a revoked
264 /// local_commitment_tx, it is possible that it is called with the second-latest
265 /// local_commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary
266 /// ChannelMonitor decided to broadcast before it had been updated to the latest.
268 /// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in
269 /// local_commitment_tx. For those HTLCs which have transaction_output_index set to None
270 /// (implying they were considered dust at the time the commitment transaction was negotiated),
271 /// a corresponding None should be included in the return value. All other positions in the
272 /// return value must contain a signature.
273 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>>, ()>;
275 /// Create a signature for a transaction spending an HTLC or commitment transaction output
276 /// when our counterparty broadcast an old state.
278 /// Justice transaction may claim multiples outputs at same time if timelock are similar.
279 /// It may be called multiples time for same output(s) if a fee-bump is needed with regards
280 /// to an upcoming timelock expiration.
282 /// Input index is a pointer towards outpoint spent, commited by sigs (BIP 143).
284 /// Amount is value of the output spent by this input, committed by sigs (BIP 143).
286 /// Per_commitment key is revocation secret such as provided by remote party while
287 /// revocating detected onchain transaction. It's not a _local_ secret key, therefore
288 /// it may cross interfaces, a node compromise won't allow to spend revoked output without
289 /// also compromissing revocation key.
291 /// htlc holds HTLC elements (hash, timelock) if output spent is a HTLC one, committed as
292 /// part of witnessScript by sigs (BIP 143).
294 /// on_remote_tx_csv is the relative lock-time challenge if output spent is on remote
295 /// balance or 2nd-stage HTLC transactions, committed as part of witnessScript by sigs
297 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, ()>;
299 /// Create a signature for a claiming transaction for a HTLC output on a remote commitment
300 /// transaction, either offered or received.
302 /// HTLC transaction may claim multiples offered outputs at same time if we know preimage
303 /// for each at detection. It may be called multtiples time for same output(s) if a fee-bump
304 /// is needed with regards to an upcoming timelock expiration.
306 /// Witness_script is either a offered or received script as defined in BOLT3 for HTLC
309 /// Input index is a pointer towards outpoint spent, commited by sigs (BIP 143).
311 /// Amount is value of the output spent by this input, committed by sigs (BIP 143).
313 /// Per_commitment_point is the dynamic point corresponding to the channel state
314 /// detected onchain. It has been generated by remote party and is used to derive
315 /// channel state keys, committed as part of witnessScript by sigs (BIP 143).
316 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, ()>;
318 /// Create a signature for a (proposed) closing transaction.
320 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
321 /// chosen to forgo their output as dust.
322 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
324 /// Signs a channel announcement message with our funding key, proving it comes from one
325 /// of the channel participants.
327 /// Note that if this fails or is rejected, the channel will not be publicly announced and
328 /// our counterparty may (though likely will not) close the channel on us for violating the
330 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
332 /// Set the remote channel basepoints. This is done immediately on incoming channels
333 /// and as soon as the channel is accepted on outgoing channels.
335 /// Will be called before any signatures are applied.
336 fn set_remote_channel_pubkeys(&mut self, channel_points: &ChannelPublicKeys);
340 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
341 pub struct InMemoryChannelKeys {
342 /// Private key of anchor tx
343 funding_key: SecretKey,
344 /// Local secret key for blinded revocation pubkey
345 revocation_base_key: SecretKey,
346 /// Local secret key used for our balance in remote-broadcasted commitment transactions
347 payment_key: SecretKey,
348 /// Local secret key used in HTLC tx
349 delayed_payment_base_key: SecretKey,
350 /// Local htlc secret key used in commitment tx htlc outputs
351 htlc_base_key: SecretKey,
353 commitment_seed: [u8; 32],
354 /// Local public keys and basepoints
355 pub(crate) local_channel_pubkeys: ChannelPublicKeys,
356 /// Remote public keys and base points
357 pub(crate) remote_channel_pubkeys: Option<ChannelPublicKeys>,
358 /// The total value of this channel
359 channel_value_satoshis: u64,
360 /// Key derivation parameters
361 key_derivation_params: (u64, u64),
364 impl InMemoryChannelKeys {
365 /// Create a new InMemoryChannelKeys
366 pub fn new<C: Signing>(
367 secp_ctx: &Secp256k1<C>,
368 funding_key: SecretKey,
369 revocation_base_key: SecretKey,
370 payment_key: SecretKey,
371 delayed_payment_base_key: SecretKey,
372 htlc_base_key: SecretKey,
373 commitment_seed: [u8; 32],
374 channel_value_satoshis: u64,
375 key_derivation_params: (u64, u64)) -> InMemoryChannelKeys {
376 let local_channel_pubkeys =
377 InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key,
378 &payment_key, &delayed_payment_base_key,
380 InMemoryChannelKeys {
384 delayed_payment_base_key,
387 channel_value_satoshis,
388 local_channel_pubkeys,
389 remote_channel_pubkeys: None,
390 key_derivation_params,
394 fn make_local_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
395 funding_key: &SecretKey,
396 revocation_base_key: &SecretKey,
397 payment_key: &SecretKey,
398 delayed_payment_base_key: &SecretKey,
399 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
400 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
402 funding_pubkey: from_secret(&funding_key),
403 revocation_basepoint: from_secret(&revocation_base_key),
404 payment_point: from_secret(&payment_key),
405 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
406 htlc_basepoint: from_secret(&htlc_base_key),
410 fn remote_pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { self.remote_channel_pubkeys.as_ref().unwrap() }
413 impl ChannelKeys for InMemoryChannelKeys {
414 fn funding_key(&self) -> &SecretKey { &self.funding_key }
415 fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
416 fn payment_key(&self) -> &SecretKey { &self.payment_key }
417 fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
418 fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
419 fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
420 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { &self.local_channel_pubkeys }
421 fn key_derivation_params(&self) -> (u64, u64) { self.key_derivation_params }
423 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>), ()> {
424 if commitment_tx.input.len() != 1 { return Err(()); }
426 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
427 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
428 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
430 let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
431 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
433 let commitment_txid = commitment_tx.txid();
435 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
436 for ref htlc in htlcs {
437 if let Some(_) = htlc.transaction_output_index {
438 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);
439 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
440 let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
441 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
443 Err(_) => return Err(()),
445 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
449 Ok((commitment_sig, htlc_sigs))
452 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
453 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
454 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
455 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
457 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
461 fn unsafe_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))
469 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>>, ()> {
470 local_commitment_tx.get_htlc_sigs(&self.htlc_base_key, local_csv, secp_ctx)
473 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, ()> {
474 let revocation_key = match chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
475 Ok(revocation_key) => revocation_key,
476 Err(_) => return Err(())
478 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
479 let revocation_pubkey = match chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
480 Ok(revocation_pubkey) => revocation_pubkey,
481 Err(_) => return Err(())
483 let witness_script = if let &Some(ref htlc) = htlc {
484 let remote_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().htlc_basepoint) {
485 Ok(remote_htlcpubkey) => remote_htlcpubkey,
486 Err(_) => return Err(())
488 let local_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
489 Ok(local_htlcpubkey) => local_htlcpubkey,
490 Err(_) => return Err(())
492 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &remote_htlcpubkey, &local_htlcpubkey, &revocation_pubkey)
494 let remote_delayedpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().delayed_payment_basepoint) {
495 Ok(remote_delayedpubkey) => remote_delayedpubkey,
496 Err(_) => return Err(())
498 chan_utils::get_revokeable_redeemscript(&revocation_pubkey, on_remote_tx_csv, &remote_delayedpubkey)
500 let sighash_parts = bip143::SighashComponents::new(&justice_tx);
501 let sighash = hash_to_message!(&sighash_parts.sighash_all(&justice_tx.input[input], &witness_script, amount)[..]);
502 return Ok(secp_ctx.sign(&sighash, &revocation_key))
505 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, ()> {
506 if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) {
507 let witness_script = if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
508 if let Ok(remote_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().htlc_basepoint) {
509 if let Ok(local_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
510 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &remote_htlcpubkey, &local_htlcpubkey, &revocation_pubkey)
511 } else { return Err(()) }
512 } else { return Err(()) }
513 } else { return Err(()) };
514 let sighash_parts = bip143::SighashComponents::new(&htlc_tx);
515 let sighash = hash_to_message!(&sighash_parts.sighash_all(&htlc_tx.input[input], &witness_script, amount)[..]);
516 return Ok(secp_ctx.sign(&sighash, &htlc_key))
521 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
522 if closing_tx.input.len() != 1 { return Err(()); }
523 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
524 if closing_tx.output.len() > 2 { return Err(()); }
526 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
527 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
528 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
530 let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
531 .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
532 Ok(secp_ctx.sign(&sighash, &self.funding_key))
535 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
536 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
537 Ok(secp_ctx.sign(&msghash, &self.funding_key))
540 fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) {
541 assert!(self.remote_channel_pubkeys.is_none(), "Already set remote channel pubkeys");
542 self.remote_channel_pubkeys = Some(channel_pubkeys.clone());
546 impl Writeable for InMemoryChannelKeys {
547 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
548 self.funding_key.write(writer)?;
549 self.revocation_base_key.write(writer)?;
550 self.payment_key.write(writer)?;
551 self.delayed_payment_base_key.write(writer)?;
552 self.htlc_base_key.write(writer)?;
553 self.commitment_seed.write(writer)?;
554 self.remote_channel_pubkeys.write(writer)?;
555 self.channel_value_satoshis.write(writer)?;
556 self.key_derivation_params.0.write(writer)?;
557 self.key_derivation_params.1.write(writer)?;
563 impl Readable for InMemoryChannelKeys {
564 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
565 let funding_key = Readable::read(reader)?;
566 let revocation_base_key = Readable::read(reader)?;
567 let payment_key = Readable::read(reader)?;
568 let delayed_payment_base_key = Readable::read(reader)?;
569 let htlc_base_key = Readable::read(reader)?;
570 let commitment_seed = Readable::read(reader)?;
571 let remote_channel_pubkeys = Readable::read(reader)?;
572 let channel_value_satoshis = Readable::read(reader)?;
573 let secp_ctx = Secp256k1::signing_only();
574 let local_channel_pubkeys =
575 InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key,
576 &payment_key, &delayed_payment_base_key,
578 let params_1 = Readable::read(reader)?;
579 let params_2 = Readable::read(reader)?;
581 Ok(InMemoryChannelKeys {
585 delayed_payment_base_key,
588 channel_value_satoshis,
589 local_channel_pubkeys,
590 remote_channel_pubkeys,
591 key_derivation_params: (params_1, params_2),
596 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
597 /// and derives keys from that.
599 /// Your node_id is seed/0'
600 /// ChannelMonitor closes may use seed/1'
601 /// Cooperative closes may use seed/2'
602 /// The two close keys may be needed to claim on-chain funds!
603 pub struct KeysManager {
604 secp_ctx: Secp256k1<secp256k1::SignOnly>,
605 node_secret: SecretKey,
606 destination_script: Script,
607 shutdown_pubkey: PublicKey,
608 channel_master_key: ExtendedPrivKey,
609 channel_child_index: AtomicUsize,
610 session_master_key: ExtendedPrivKey,
611 session_child_index: AtomicUsize,
612 channel_id_master_key: ExtendedPrivKey,
613 channel_id_child_index: AtomicUsize,
616 starting_time_secs: u64,
617 starting_time_nanos: u32,
621 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
622 /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
623 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
624 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
625 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
626 /// simply use the current time (with very high precision).
628 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
629 /// obviously, starting_time should be unique every time you reload the library - it is only
630 /// used to generate new ephemeral key data (which will be stored by the individual channel if
633 /// Note that the seed is required to recover certain on-chain funds independent of
634 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
635 /// channel, and some on-chain during-closing funds.
637 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
638 /// versions. Once the library is more fully supported, the docs will be updated to include a
639 /// detailed description of the guarantee.
640 pub fn new(seed: &[u8; 32], network: Network, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager {
641 let secp_ctx = Secp256k1::signing_only();
642 match ExtendedPrivKey::new_master(network.clone(), seed) {
644 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
645 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
646 Ok(destination_key) => {
647 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
648 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
649 .push_slice(&wpubkey_hash.into_inner())
652 Err(_) => panic!("Your RNG is busted"),
654 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
655 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
656 Err(_) => panic!("Your RNG is busted"),
658 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
659 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
660 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
668 channel_child_index: AtomicUsize::new(0),
670 session_child_index: AtomicUsize::new(0),
671 channel_id_master_key,
672 channel_id_child_index: AtomicUsize::new(0),
679 Err(_) => panic!("Your rng is busted"),
682 fn derive_unique_start(&self) -> Sha256State {
683 let mut unique_start = Sha256::engine();
684 unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs));
685 unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos));
686 unique_start.input(&self.seed);
689 /// Derive an old set of ChannelKeys for per-channel secrets based on a key derivation
691 /// Key derivation parameters are accessible through a per-channel secrets
692 /// ChannelKeys::key_derivation_params and is provided inside DynamicOuputP2WSH in case of
693 /// onchain output detection for which a corresponding delayed_payment_key must be derived.
694 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params_1: u64, params_2: u64) -> InMemoryChannelKeys {
695 let chan_id = ((params_1 & 0xFFFF_FFFF_0000_0000) >> 32) as u32;
696 let mut unique_start = Sha256::engine();
697 unique_start.input(&byte_utils::be64_to_array(params_2));
698 unique_start.input(&byte_utils::be32_to_array(params_1 as u32));
699 unique_start.input(&self.seed);
701 // We only seriously intend to rely on the channel_master_key for true secure
702 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
703 // starting_time provided in the constructor) to be unique.
704 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");
705 unique_start.input(&child_privkey.private_key.key[..]);
707 let seed = Sha256::from_engine(unique_start).into_inner();
709 let commitment_seed = {
710 let mut sha = Sha256::engine();
712 sha.input(&b"commitment seed"[..]);
713 Sha256::from_engine(sha).into_inner()
715 macro_rules! key_step {
716 ($info: expr, $prev_key: expr) => {{
717 let mut sha = Sha256::engine();
719 sha.input(&$prev_key[..]);
720 sha.input(&$info[..]);
721 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
724 let funding_key = key_step!(b"funding key", commitment_seed);
725 let revocation_base_key = key_step!(b"revocation base key", funding_key);
726 let payment_key = key_step!(b"payment key", revocation_base_key);
727 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
728 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
730 InMemoryChannelKeys::new(
735 delayed_payment_base_key,
738 channel_value_satoshis,
739 (params_1, params_2),
744 impl KeysInterface for KeysManager {
745 type ChanKeySigner = InMemoryChannelKeys;
747 fn get_node_secret(&self) -> SecretKey {
748 self.node_secret.clone()
751 fn get_destination_script(&self) -> Script {
752 self.destination_script.clone()
755 fn get_shutdown_pubkey(&self) -> PublicKey {
756 self.shutdown_pubkey.clone()
759 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys {
760 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
761 let ix_and_nanos: u64 = (child_ix as u64) << 32 | (self.starting_time_nanos as u64);
762 self.derive_channel_keys(channel_value_satoshis, ix_and_nanos, self.starting_time_secs)
765 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
766 let mut sha = self.derive_unique_start();
768 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
769 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");
770 sha.input(&child_privkey.private_key.key[..]);
772 let mut rng_seed = sha.clone();
773 // Not exactly the most ideal construction, but the second value will get fed into
774 // ChaCha so it is another step harder to break.
775 rng_seed.input(b"RNG Seed Salt");
776 sha.input(b"Session Key Salt");
777 (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
778 Sha256::from_engine(rng_seed).into_inner())
781 fn get_channel_id(&self) -> [u8; 32] {
782 let mut sha = self.derive_unique_start();
784 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
785 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");
786 sha.input(&child_privkey.private_key.key[..]);
788 Sha256::from_engine(sha).into_inner()