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 /// An output to a P2WPKH, spendable exclusively by our payment key.
87 /// The witness in the spending input, is, thus, simply:
88 /// <BIP 143 signature> <payment key>
90 /// These are generally the result of our counterparty having broadcast the current state,
91 /// allowing us to claim the non-HTLC-encumbered outputs immediately.
92 StaticOutputRemotePayment {
93 /// The outpoint which is spendable
95 /// The output which is reference by the given outpoint
97 /// The channel keys state used to proceed to derivation of signing key. Must
98 /// be pass to KeysInterface::derive_channel_keys.
99 key_derivation_params: (u64, u64),
103 impl Writeable for SpendableOutputDescriptor {
104 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
106 &SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
108 outpoint.write(writer)?;
109 output.write(writer)?;
111 &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref per_commitment_point, ref to_self_delay, ref output, ref key_derivation_params, ref remote_revocation_pubkey } => {
113 outpoint.write(writer)?;
114 per_commitment_point.write(writer)?;
115 to_self_delay.write(writer)?;
116 output.write(writer)?;
117 key_derivation_params.0.write(writer)?;
118 key_derivation_params.1.write(writer)?;
119 remote_revocation_pubkey.write(writer)?;
121 &SpendableOutputDescriptor::StaticOutputRemotePayment { ref outpoint, ref output, ref key_derivation_params } => {
123 outpoint.write(writer)?;
124 output.write(writer)?;
125 key_derivation_params.0.write(writer)?;
126 key_derivation_params.1.write(writer)?;
133 impl Readable for SpendableOutputDescriptor {
134 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
135 match Readable::read(reader)? {
136 0u8 => Ok(SpendableOutputDescriptor::StaticOutput {
137 outpoint: Readable::read(reader)?,
138 output: Readable::read(reader)?,
140 1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH {
141 outpoint: Readable::read(reader)?,
142 per_commitment_point: Readable::read(reader)?,
143 to_self_delay: Readable::read(reader)?,
144 output: Readable::read(reader)?,
145 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
146 remote_revocation_pubkey: Readable::read(reader)?,
148 2u8 => Ok(SpendableOutputDescriptor::StaticOutputRemotePayment {
149 outpoint: Readable::read(reader)?,
150 output: Readable::read(reader)?,
151 key_derivation_params: (Readable::read(reader)?, Readable::read(reader)?),
153 _ => Err(DecodeError::InvalidValue),
158 /// A trait to describe an object which can get user secrets and key material.
159 pub trait KeysInterface: Send + Sync {
160 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
161 type ChanKeySigner : ChannelKeys;
163 /// Get node secret key (aka node_id or network_key)
164 fn get_node_secret(&self) -> SecretKey;
165 /// Get destination redeemScript to encumber static protocol exit points.
166 fn get_destination_script(&self) -> Script;
167 /// Get shutdown_pubkey to use as PublicKey at channel closure
168 fn get_shutdown_pubkey(&self) -> PublicKey;
169 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
170 /// restarted with some stale data!
171 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
172 /// Get a secret and PRNG seed for construting an onion packet
173 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
174 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
175 /// transaction is created, at which point they will use the outpoint in the funding
177 fn get_channel_id(&self) -> [u8; 32];
180 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
182 /// Signing services could be implemented on a hardware wallet. In this case,
183 /// the current ChannelKeys would be a front-end on top of a communication
184 /// channel connected to your secure device and lightning key material wouldn't
185 /// reside on a hot server. Nevertheless, a this deployment would still need
186 /// to trust the ChannelManager to avoid loss of funds as this latest component
187 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
189 /// A more secure iteration would be to use hashlock (or payment points) to pair
190 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
191 /// at the price of more state and computation on the hardware wallet side. In the future,
192 /// we are looking forward to design such interface.
194 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
195 /// to act, as liveness and breach reply correctness are always going to be hard requirements
196 /// of LN security model, orthogonal of key management issues.
198 /// If you're implementing a custom signer, you almost certainly want to implement
199 /// Readable/Writable to serialize out a unique reference to this set of keys so
200 /// that you can serialize the full ChannelManager object.
202 // (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
203 // to the possibility of reentrancy issues by calling the user's code during our deserialization
205 // TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
206 // ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
207 pub trait ChannelKeys : Send+Clone {
208 /// Gets the private key for the anchor tx
209 fn funding_key<'a>(&'a self) -> &'a SecretKey;
210 /// Gets the local secret key for blinded revocation pubkey
211 fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
212 /// Gets the local secret key used in the to_remote output of remote commitment tx (ie the
213 /// output to us in transactions our counterparty broadcasts).
214 /// Also as part of obscured commitment number.
215 fn payment_key<'a>(&'a self) -> &'a SecretKey;
216 /// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output
217 fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
218 /// Gets the local htlc secret key used in commitment tx htlc outputs
219 fn htlc_base_key<'a>(&'a self) -> &'a SecretKey;
220 /// Gets the commitment seed
221 fn commitment_seed<'a>(&'a self) -> &'a [u8; 32];
222 /// Gets the local channel public keys and basepoints
223 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys;
224 /// Gets arbitrary identifiers describing the set of keys which are provided back to you in
225 /// some SpendableOutputDescriptor types. These should be sufficient to identify this
226 /// ChannelKeys object uniquely and lookup or re-derive its keys.
227 fn key_derivation_params(&self) -> (u64, u64);
229 /// Create a signature for a remote commitment transaction and associated HTLC transactions.
231 /// Note that if signing fails or is rejected, the channel will be force-closed.
233 // TODO: Document the things someone using this interface should enforce before signing.
234 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
235 // making the callee generate it via some util function we expose)!
236 fn sign_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>), ()>;
238 /// Create a signature for a local commitment transaction. This will only ever be called with
239 /// the same local_commitment_tx (or a copy thereof), though there are currently no guarantees
240 /// that it will not be called multiple times.
242 // TODO: Document the things someone using this interface should enforce before signing.
243 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
244 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
246 /// Same as sign_local_commitment, but exists only for tests to get access to local commitment
247 /// transactions which will be broadcasted later, after the channel has moved on to a newer
248 /// state. Thus, needs its own method as sign_local_commitment may enforce that we only ever
251 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
253 /// Create a signature for each HTLC transaction spending a local commitment transaction.
255 /// Unlike sign_local_commitment, this may be called multiple times with *different*
256 /// local_commitment_tx values. While this will never be called with a revoked
257 /// local_commitment_tx, it is possible that it is called with the second-latest
258 /// local_commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary
259 /// ChannelMonitor decided to broadcast before it had been updated to the latest.
261 /// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in
262 /// local_commitment_tx. For those HTLCs which have transaction_output_index set to None
263 /// (implying they were considered dust at the time the commitment transaction was negotiated),
264 /// a corresponding None should be included in the return value. All other positions in the
265 /// return value must contain a signature.
266 fn sign_local_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, local_csv: u16, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()>;
268 /// Create a signature for a transaction spending an HTLC or commitment transaction output
269 /// when our counterparty broadcast an old state.
271 /// Justice transaction may claim multiples outputs at same time if timelock are similar.
272 /// It may be called multiples time for same output(s) if a fee-bump is needed with regards
273 /// to an upcoming timelock expiration.
275 /// Input index is a pointer towards outpoint spent, commited by sigs (BIP 143).
277 /// Amount is value of the output spent by this input, committed by sigs (BIP 143).
279 /// Per_commitment key is revocation secret such as provided by remote party while
280 /// revocating detected onchain transaction. It's not a _local_ secret key, therefore
281 /// it may cross interfaces, a node compromise won't allow to spend revoked output without
282 /// also compromissing revocation key.
284 /// htlc holds HTLC elements (hash, timelock) if output spent is a HTLC one, committed as
285 /// part of witnessScript by sigs (BIP 143).
287 /// on_remote_tx_csv is the relative lock-time challenge if output spent is on remote
288 /// balance or 2nd-stage HTLC transactions, committed as part of witnessScript by sigs
290 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, ()>;
292 /// Create a signature for a claiming transaction for a HTLC output on a remote commitment
293 /// transaction, either offered or received.
295 /// HTLC transaction may claim multiples offered outputs at same time if we know preimage
296 /// for each at detection. It may be called multtiples time for same output(s) if a fee-bump
297 /// is needed with regards to an upcoming timelock expiration.
299 /// Witness_script is either a offered or received script as defined in BOLT3 for HTLC
302 /// Input index is a pointer towards outpoint spent, commited by sigs (BIP 143).
304 /// Amount is value of the output spent by this input, committed by sigs (BIP 143).
306 /// Per_commitment_point is the dynamic point corresponding to the channel state
307 /// detected onchain. It has been generated by remote party and is used to derive
308 /// channel state keys, committed as part of witnessScript by sigs (BIP 143).
309 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, ()>;
311 /// Create a signature for a (proposed) closing transaction.
313 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
314 /// chosen to forgo their output as dust.
315 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
317 /// Signs a channel announcement message with our funding key, proving it comes from one
318 /// of the channel participants.
320 /// Note that if this fails or is rejected, the channel will not be publicly announced and
321 /// our counterparty may (though likely will not) close the channel on us for violating the
323 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
325 /// Set the remote channel basepoints. This is done immediately on incoming channels
326 /// and as soon as the channel is accepted on outgoing channels.
328 /// Will be called before any signatures are applied.
329 fn set_remote_channel_pubkeys(&mut self, channel_points: &ChannelPublicKeys);
333 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
334 pub struct InMemoryChannelKeys {
335 /// Private key of anchor tx
336 funding_key: SecretKey,
337 /// Local secret key for blinded revocation pubkey
338 revocation_base_key: SecretKey,
339 /// Local secret key used for our balance in remote-broadcasted commitment transactions
340 payment_key: SecretKey,
341 /// Local secret key used in HTLC tx
342 delayed_payment_base_key: SecretKey,
343 /// Local htlc secret key used in commitment tx htlc outputs
344 htlc_base_key: SecretKey,
346 commitment_seed: [u8; 32],
347 /// Local public keys and basepoints
348 pub(crate) local_channel_pubkeys: ChannelPublicKeys,
349 /// Remote public keys and base points
350 pub(crate) remote_channel_pubkeys: Option<ChannelPublicKeys>,
351 /// The total value of this channel
352 channel_value_satoshis: u64,
353 /// Key derivation parameters
354 key_derivation_params: (u64, u64),
357 impl InMemoryChannelKeys {
358 /// Create a new InMemoryChannelKeys
359 pub fn new<C: Signing>(
360 secp_ctx: &Secp256k1<C>,
361 funding_key: SecretKey,
362 revocation_base_key: SecretKey,
363 payment_key: SecretKey,
364 delayed_payment_base_key: SecretKey,
365 htlc_base_key: SecretKey,
366 commitment_seed: [u8; 32],
367 channel_value_satoshis: u64,
368 key_derivation_params: (u64, u64)) -> InMemoryChannelKeys {
369 let local_channel_pubkeys =
370 InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key,
371 &payment_key, &delayed_payment_base_key,
373 InMemoryChannelKeys {
377 delayed_payment_base_key,
380 channel_value_satoshis,
381 local_channel_pubkeys,
382 remote_channel_pubkeys: None,
383 key_derivation_params,
387 fn make_local_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
388 funding_key: &SecretKey,
389 revocation_base_key: &SecretKey,
390 payment_key: &SecretKey,
391 delayed_payment_base_key: &SecretKey,
392 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
393 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
395 funding_pubkey: from_secret(&funding_key),
396 revocation_basepoint: from_secret(&revocation_base_key),
397 payment_point: from_secret(&payment_key),
398 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
399 htlc_basepoint: from_secret(&htlc_base_key),
403 fn remote_pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { self.remote_channel_pubkeys.as_ref().unwrap() }
406 impl ChannelKeys for InMemoryChannelKeys {
407 fn funding_key(&self) -> &SecretKey { &self.funding_key }
408 fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
409 fn payment_key(&self) -> &SecretKey { &self.payment_key }
410 fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
411 fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
412 fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
413 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { &self.local_channel_pubkeys }
414 fn key_derivation_params(&self) -> (u64, u64) { self.key_derivation_params }
416 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>), ()> {
417 if commitment_tx.input.len() != 1 { return Err(()); }
419 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
420 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
421 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
423 let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
424 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
426 let commitment_txid = commitment_tx.txid();
428 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
429 for ref htlc in htlcs {
430 if let Some(_) = htlc.transaction_output_index {
431 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);
432 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
433 let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
434 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
436 Err(_) => return Err(()),
438 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
442 Ok((commitment_sig, htlc_sigs))
445 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
446 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
447 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
448 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
450 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
454 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
455 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
456 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
457 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
459 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
462 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>>, ()> {
463 local_commitment_tx.get_htlc_sigs(&self.htlc_base_key, local_csv, secp_ctx)
466 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, ()> {
467 let revocation_key = match chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
468 Ok(revocation_key) => revocation_key,
469 Err(_) => return Err(())
471 let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key);
472 let revocation_pubkey = match chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
473 Ok(revocation_pubkey) => revocation_pubkey,
474 Err(_) => return Err(())
476 let witness_script = if let &Some(ref htlc) = htlc {
477 let remote_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().htlc_basepoint) {
478 Ok(remote_htlcpubkey) => remote_htlcpubkey,
479 Err(_) => return Err(())
481 let local_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
482 Ok(local_htlcpubkey) => local_htlcpubkey,
483 Err(_) => return Err(())
485 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &remote_htlcpubkey, &local_htlcpubkey, &revocation_pubkey)
487 let remote_delayedpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().delayed_payment_basepoint) {
488 Ok(remote_delayedpubkey) => remote_delayedpubkey,
489 Err(_) => return Err(())
491 chan_utils::get_revokeable_redeemscript(&revocation_pubkey, on_remote_tx_csv, &remote_delayedpubkey)
493 let sighash_parts = bip143::SighashComponents::new(&justice_tx);
494 let sighash = hash_to_message!(&sighash_parts.sighash_all(&justice_tx.input[input], &witness_script, amount)[..]);
495 return Ok(secp_ctx.sign(&sighash, &revocation_key))
498 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, ()> {
499 if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) {
500 let witness_script = if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
501 if let Ok(remote_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.remote_pubkeys().htlc_basepoint) {
502 if let Ok(local_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
503 chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &remote_htlcpubkey, &local_htlcpubkey, &revocation_pubkey)
504 } else { return Err(()) }
505 } else { return Err(()) }
506 } else { return Err(()) };
507 let sighash_parts = bip143::SighashComponents::new(&htlc_tx);
508 let sighash = hash_to_message!(&sighash_parts.sighash_all(&htlc_tx.input[input], &witness_script, amount)[..]);
509 return Ok(secp_ctx.sign(&sighash, &htlc_key))
514 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
515 if closing_tx.input.len() != 1 { return Err(()); }
516 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
517 if closing_tx.output.len() > 2 { return Err(()); }
519 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
520 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
521 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
523 let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
524 .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
525 Ok(secp_ctx.sign(&sighash, &self.funding_key))
528 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
529 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
530 Ok(secp_ctx.sign(&msghash, &self.funding_key))
533 fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) {
534 assert!(self.remote_channel_pubkeys.is_none(), "Already set remote channel pubkeys");
535 self.remote_channel_pubkeys = Some(channel_pubkeys.clone());
539 impl Writeable for InMemoryChannelKeys {
540 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
541 self.funding_key.write(writer)?;
542 self.revocation_base_key.write(writer)?;
543 self.payment_key.write(writer)?;
544 self.delayed_payment_base_key.write(writer)?;
545 self.htlc_base_key.write(writer)?;
546 self.commitment_seed.write(writer)?;
547 self.remote_channel_pubkeys.write(writer)?;
548 self.channel_value_satoshis.write(writer)?;
549 self.key_derivation_params.0.write(writer)?;
550 self.key_derivation_params.1.write(writer)?;
556 impl Readable for InMemoryChannelKeys {
557 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
558 let funding_key = Readable::read(reader)?;
559 let revocation_base_key = Readable::read(reader)?;
560 let payment_key = Readable::read(reader)?;
561 let delayed_payment_base_key = Readable::read(reader)?;
562 let htlc_base_key = Readable::read(reader)?;
563 let commitment_seed = Readable::read(reader)?;
564 let remote_channel_pubkeys = Readable::read(reader)?;
565 let channel_value_satoshis = Readable::read(reader)?;
566 let secp_ctx = Secp256k1::signing_only();
567 let local_channel_pubkeys =
568 InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key,
569 &payment_key, &delayed_payment_base_key,
571 let params_1 = Readable::read(reader)?;
572 let params_2 = Readable::read(reader)?;
574 Ok(InMemoryChannelKeys {
578 delayed_payment_base_key,
581 channel_value_satoshis,
582 local_channel_pubkeys,
583 remote_channel_pubkeys,
584 key_derivation_params: (params_1, params_2),
589 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
590 /// and derives keys from that.
592 /// Your node_id is seed/0'
593 /// ChannelMonitor closes may use seed/1'
594 /// Cooperative closes may use seed/2'
595 /// The two close keys may be needed to claim on-chain funds!
596 pub struct KeysManager {
597 secp_ctx: Secp256k1<secp256k1::SignOnly>,
598 node_secret: SecretKey,
599 destination_script: Script,
600 shutdown_pubkey: PublicKey,
601 channel_master_key: ExtendedPrivKey,
602 channel_child_index: AtomicUsize,
603 session_master_key: ExtendedPrivKey,
604 session_child_index: AtomicUsize,
605 channel_id_master_key: ExtendedPrivKey,
606 channel_id_child_index: AtomicUsize,
609 starting_time_secs: u64,
610 starting_time_nanos: u32,
614 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
615 /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
616 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
617 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
618 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
619 /// simply use the current time (with very high precision).
621 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
622 /// obviously, starting_time should be unique every time you reload the library - it is only
623 /// used to generate new ephemeral key data (which will be stored by the individual channel if
626 /// Note that the seed is required to recover certain on-chain funds independent of
627 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
628 /// channel, and some on-chain during-closing funds.
630 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
631 /// versions. Once the library is more fully supported, the docs will be updated to include a
632 /// detailed description of the guarantee.
633 pub fn new(seed: &[u8; 32], network: Network, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager {
634 let secp_ctx = Secp256k1::signing_only();
635 match ExtendedPrivKey::new_master(network.clone(), seed) {
637 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
638 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
639 Ok(destination_key) => {
640 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
641 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
642 .push_slice(&wpubkey_hash.into_inner())
645 Err(_) => panic!("Your RNG is busted"),
647 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
648 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
649 Err(_) => panic!("Your RNG is busted"),
651 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
652 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
653 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
661 channel_child_index: AtomicUsize::new(0),
663 session_child_index: AtomicUsize::new(0),
664 channel_id_master_key,
665 channel_id_child_index: AtomicUsize::new(0),
672 Err(_) => panic!("Your rng is busted"),
675 fn derive_unique_start(&self) -> Sha256State {
676 let mut unique_start = Sha256::engine();
677 unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs));
678 unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos));
679 unique_start.input(&self.seed);
682 /// Derive an old set of ChannelKeys for per-channel secrets based on a key derivation
684 /// Key derivation parameters are accessible through a per-channel secrets
685 /// ChannelKeys::key_derivation_params and is provided inside DynamicOuputP2WSH in case of
686 /// onchain output detection for which a corresponding delayed_payment_key must be derived.
687 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params_1: u64, params_2: u64) -> InMemoryChannelKeys {
688 let chan_id = ((params_1 & 0xFFFF_FFFF_0000_0000) >> 32) as u32;
689 let mut unique_start = Sha256::engine();
690 unique_start.input(&byte_utils::be64_to_array(params_2));
691 unique_start.input(&byte_utils::be32_to_array(params_1 as u32));
692 unique_start.input(&self.seed);
694 // We only seriously intend to rely on the channel_master_key for true secure
695 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
696 // starting_time provided in the constructor) to be unique.
697 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");
698 unique_start.input(&child_privkey.private_key.key[..]);
700 let seed = Sha256::from_engine(unique_start).into_inner();
702 let commitment_seed = {
703 let mut sha = Sha256::engine();
705 sha.input(&b"commitment seed"[..]);
706 Sha256::from_engine(sha).into_inner()
708 macro_rules! key_step {
709 ($info: expr, $prev_key: expr) => {{
710 let mut sha = Sha256::engine();
712 sha.input(&$prev_key[..]);
713 sha.input(&$info[..]);
714 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
717 let funding_key = key_step!(b"funding key", commitment_seed);
718 let revocation_base_key = key_step!(b"revocation base key", funding_key);
719 let payment_key = key_step!(b"payment key", revocation_base_key);
720 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
721 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
723 InMemoryChannelKeys::new(
728 delayed_payment_base_key,
731 channel_value_satoshis,
732 (params_1, params_2),
737 impl KeysInterface for KeysManager {
738 type ChanKeySigner = InMemoryChannelKeys;
740 fn get_node_secret(&self) -> SecretKey {
741 self.node_secret.clone()
744 fn get_destination_script(&self) -> Script {
745 self.destination_script.clone()
748 fn get_shutdown_pubkey(&self) -> PublicKey {
749 self.shutdown_pubkey.clone()
752 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys {
753 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
754 let ix_and_nanos: u64 = (child_ix as u64) << 32 | (self.starting_time_nanos as u64);
755 self.derive_channel_keys(channel_value_satoshis, ix_and_nanos, self.starting_time_secs)
758 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
759 let mut sha = self.derive_unique_start();
761 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
762 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");
763 sha.input(&child_privkey.private_key.key[..]);
765 let mut rng_seed = sha.clone();
766 // Not exactly the most ideal construction, but the second value will get fed into
767 // ChaCha so it is another step harder to break.
768 rng_seed.input(b"RNG Seed Salt");
769 sha.input(b"Session Key Salt");
770 (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
771 Sha256::from_engine(rng_seed).into_inner())
774 fn get_channel_id(&self) -> [u8; 32] {
775 let mut sha = self.derive_unique_start();
777 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
778 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");
779 sha.input(&child_privkey.private_key.key[..]);
781 Sha256::from_engine(sha).into_inner()