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};
28 use ln::channelmanager::PaymentPreimage;
30 use std::sync::atomic::{AtomicUsize, Ordering};
32 use ln::msgs::DecodeError;
34 /// When on-chain outputs are created by rust-lightning (which our counterparty is not able to
35 /// claim at any point in the future) an event is generated which you must track and be able to
36 /// spend on-chain. The information needed to do this is provided in this enum, including the
37 /// outpoint describing which txid and output index is available, the full output which exists at
38 /// that txid/index, and any keys or other information required to sign.
39 #[derive(Clone, PartialEq)]
40 pub enum SpendableOutputDescriptor {
41 /// An output to a script which was provided via KeysInterface, thus you should already know
42 /// how to spend it. No keys are provided as rust-lightning was never given any keys - only the
43 /// script_pubkey as it appears in the output.
44 /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
45 /// on-chain using the payment preimage or after it has timed out.
47 /// The outpoint which is spendable
49 /// The output which is referenced by the given outpoint.
52 /// An output to a P2WSH script which can be spent with a single signature after a CSV delay.
53 /// The private key which should be used to sign the transaction is provided, as well as the
54 /// full witness redeemScript which is hashed in the output script_pubkey.
55 /// The witness in the spending input should be:
56 /// <BIP 143 signature generated with the given key> <empty vector> (MINIMALIF standard rule)
57 /// <witness_script as provided>
58 /// Note that the nSequence field in the input must be set to_self_delay (which corresponds to
59 /// the transaction not being broadcastable until at least to_self_delay blocks after the input
61 /// These are generally the result of a "revocable" output to us, spendable only by us unless
62 /// it is an output from us having broadcast an old state (which should never happen).
64 /// The outpoint which is spendable
66 /// The secret key which must be used to sign the spending transaction
68 /// The witness redeemScript which is hashed to create the script_pubkey in the given output
69 witness_script: Script,
70 /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in
71 /// the witness_script.
73 /// The output which is referenced by the given outpoint
76 // TODO: Note that because key is now static and exactly what is provided by us, we should drop
77 // this in favor of StaticOutput:
78 /// An output to a P2WPKH, spendable exclusively by the given private key.
79 /// The witness in the spending input, is, thus, simply:
80 /// <BIP 143 signature generated with the given key> <public key derived from the given key>
81 /// These are generally the result of our counterparty having broadcast the current state,
82 /// allowing us to claim the non-HTLC-encumbered outputs immediately.
84 /// The outpoint which is spendable
86 /// The secret key which must be used to sign the spending transaction
88 /// The output which is reference by the given outpoint
93 impl Writeable for SpendableOutputDescriptor {
94 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
96 &SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
98 outpoint.write(writer)?;
99 output.write(writer)?;
101 &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref key, ref witness_script, ref to_self_delay, ref output } => {
103 outpoint.write(writer)?;
105 witness_script.write(writer)?;
106 to_self_delay.write(writer)?;
107 output.write(writer)?;
109 &SpendableOutputDescriptor::DynamicOutputP2WPKH { ref outpoint, ref key, ref output } => {
111 outpoint.write(writer)?;
113 output.write(writer)?;
120 impl Readable for SpendableOutputDescriptor {
121 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
122 match Readable::read(reader)? {
123 0u8 => Ok(SpendableOutputDescriptor::StaticOutput {
124 outpoint: Readable::read(reader)?,
125 output: Readable::read(reader)?,
127 1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH {
128 outpoint: Readable::read(reader)?,
129 key: Readable::read(reader)?,
130 witness_script: Readable::read(reader)?,
131 to_self_delay: Readable::read(reader)?,
132 output: Readable::read(reader)?,
134 2u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WPKH {
135 outpoint: Readable::read(reader)?,
136 key: Readable::read(reader)?,
137 output: Readable::read(reader)?,
139 _ => Err(DecodeError::InvalidValue),
144 /// A trait to describe an object which can get user secrets and key material.
145 pub trait KeysInterface: Send + Sync {
146 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
147 type ChanKeySigner : ChannelKeys;
149 /// Get node secret key (aka node_id or network_key)
150 fn get_node_secret(&self) -> SecretKey;
151 /// Get destination redeemScript to encumber static protocol exit points.
152 fn get_destination_script(&self) -> Script;
153 /// Get shutdown_pubkey to use as PublicKey at channel closure
154 fn get_shutdown_pubkey(&self) -> PublicKey;
155 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
156 /// restarted with some stale data!
157 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
158 /// Get a secret and PRNG seed for construting an onion packet
159 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
160 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
161 /// transaction is created, at which point they will use the outpoint in the funding
163 fn get_channel_id(&self) -> [u8; 32];
166 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
168 /// Signing services could be implemented on a hardware wallet. In this case,
169 /// the current ChannelKeys would be a front-end on top of a communication
170 /// channel connected to your secure device and lightning key material wouldn't
171 /// reside on a hot server. Nevertheless, a this deployment would still need
172 /// to trust the ChannelManager to avoid loss of funds as this latest component
173 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
175 /// A more secure iteration would be to use hashlock (or payment points) to pair
176 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
177 /// at the price of more state and computation on the hardware wallet side. In the future,
178 /// we are looking forward to design such interface.
180 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
181 /// to act, as liveness and breach reply correctness are always going to be hard requirements
182 /// of LN security model, orthogonal of key management issues.
184 /// If you're implementing a custom signer, you almost certainly want to implement
185 /// Readable/Writable to serialize out a unique reference to this set of keys so
186 /// that you can serialize the full ChannelManager object.
188 // (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
189 // to the possibility of reentrancy issues by calling the user's code during our deserialization
191 // TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
192 // ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
193 pub trait ChannelKeys : Send+Clone {
194 /// Gets the private key for the anchor tx
195 fn funding_key<'a>(&'a self) -> &'a SecretKey;
196 /// Gets the local secret key for blinded revocation pubkey
197 fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
198 /// Gets the local secret key used in the to_remote output of remote commitment tx (ie the
199 /// output to us in transactions our counterparty broadcasts).
200 /// Also as part of obscured commitment number.
201 fn payment_key<'a>(&'a self) -> &'a SecretKey;
202 /// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output
203 fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
204 /// Gets the local htlc secret key used in commitment tx htlc outputs
205 fn htlc_base_key<'a>(&'a self) -> &'a SecretKey;
206 /// Gets the commitment seed
207 fn commitment_seed<'a>(&'a self) -> &'a [u8; 32];
208 /// Gets the local channel public keys and basepoints
209 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys;
210 /// Gets arbitrary identifiers describing the set of keys which are provided back to you in
211 /// some SpendableOutputDescriptor types. These should be sufficient to identify this
212 /// ChannelKeys object uniquely and lookup or re-derive its keys.
213 fn key_derivation_params(&self) -> (u64, u64);
215 /// Create a signature for a remote commitment transaction and associated HTLC transactions.
217 /// Note that if signing fails or is rejected, the channel will be force-closed.
219 // TODO: Document the things someone using this interface should enforce before signing.
220 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
221 // making the callee generate it via some util function we expose)!
222 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>), ()>;
224 /// Create a signature for a local commitment transaction. This will only ever be called with
225 /// the same local_commitment_tx (or a copy thereof), though there are currently no guarantees
226 /// that it will not be called multiple times.
228 // TODO: Document the things someone using this interface should enforce before signing.
229 // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
230 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
232 /// Same as sign_local_commitment, but exists only for tests to get access to local commitment
233 /// transactions which will be broadcasted later, after the channel has moved on to a newer
234 /// state. Thus, needs its own method as sign_local_commitment may enforce that we only ever
237 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
239 /// Create a signature for each HTLC transaction spending a local commitment transaction.
241 /// Unlike sign_local_commitment, this may be called multiple times with *different*
242 /// local_commitment_tx values. While this will never be called with a revoked
243 /// local_commitment_tx, it is possible that it is called with the second-latest
244 /// local_commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary
245 /// ChannelMonitor decided to broadcast before it had been updated to the latest.
247 /// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in
248 /// local_commitment_tx. For those HTLCs which have transaction_output_index set to None
249 /// (implying they were considered dust at the time the commitment transaction was negotiated),
250 /// a corresponding None should be included in the return value. All other positions in the
251 /// return value must contain a signature.
252 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>>, ()>;
254 /// Create a signature for a transaction spending an HTLC or commitment transaction output
255 /// when our counterparty broadcast an old state.
257 /// Justice transaction may claim multiples outputs at same time if timelock are similar.
258 /// It may be called multiples time for same output(s) if a fee-bump is needed with regards
259 /// to an upcoming timelock expiration.
261 /// Witness_script is a revokable witness script as defined in BOLT3 for `to_local`/HTLC
264 /// Input index is a pointer towards outpoint spent, commited by sigs (BIP 143).
266 /// Amount is value of the output spent by this input, committed by sigs (BIP 143).
268 /// Per_commitment key is revocation secret such as provided by remote party while
269 /// revocating detected onchain transaction. It's not a _local_ secret key, therefore
270 /// it may cross interfaces, a node compromise won't allow to spend revoked output without
271 /// also compromissing revocation key.
272 //TODO: dry-up witness_script and pass pubkeys
273 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, ()>;
275 /// Create a signature for a claiming transaction for a HTLC output on a remote commitment
276 /// transaction, either offered or received.
278 /// HTLC transaction may claim multiples offered outputs at same time if we know preimage
279 /// for each at detection. It may be called multtiples time for same output(s) if a fee-bump
280 /// is needed with regards to an upcoming timelock expiration.
282 /// Witness_script is either a offered or received script as defined in BOLT3 for HTLC
285 /// Input index is a pointer towards outpoint spent, commited by sigs (BIP 143).
287 /// Amount is value of the output spent by this input, committed by sigs (BIP 143).
289 /// Preimage is solution for an offered HTLC haslock. A preimage sets to None hints this
290 /// htlc_tx as timing-out funds back to us on a received output.
291 //TODO: dry-up witness_script and pass pubkeys
292 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, ()>;
294 /// Create a signature for a (proposed) closing transaction.
296 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
297 /// chosen to forgo their output as dust.
298 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
300 /// Signs a channel announcement message with our funding key, proving it comes from one
301 /// of the channel participants.
303 /// Note that if this fails or is rejected, the channel will not be publicly announced and
304 /// our counterparty may (though likely will not) close the channel on us for violating the
306 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
308 /// Set the remote channel basepoints. This is done immediately on incoming channels
309 /// and as soon as the channel is accepted on outgoing channels.
311 /// Will be called before any signatures are applied.
312 fn set_remote_channel_pubkeys(&mut self, channel_points: &ChannelPublicKeys);
316 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
317 pub struct InMemoryChannelKeys {
318 /// Private key of anchor tx
319 funding_key: SecretKey,
320 /// Local secret key for blinded revocation pubkey
321 revocation_base_key: SecretKey,
322 /// Local secret key used for our balance in remote-broadcasted commitment transactions
323 payment_key: SecretKey,
324 /// Local secret key used in HTLC tx
325 delayed_payment_base_key: SecretKey,
326 /// Local htlc secret key used in commitment tx htlc outputs
327 htlc_base_key: SecretKey,
329 commitment_seed: [u8; 32],
330 /// Local public keys and basepoints
331 pub(crate) local_channel_pubkeys: ChannelPublicKeys,
332 /// Remote public keys and base points
333 pub(crate) remote_channel_pubkeys: Option<ChannelPublicKeys>,
334 /// The total value of this channel
335 channel_value_satoshis: u64,
336 /// Key derivation parameters
337 key_derivation_params: (u64, u64),
340 impl InMemoryChannelKeys {
341 /// Create a new InMemoryChannelKeys
342 pub fn new<C: Signing>(
343 secp_ctx: &Secp256k1<C>,
344 funding_key: SecretKey,
345 revocation_base_key: SecretKey,
346 payment_key: SecretKey,
347 delayed_payment_base_key: SecretKey,
348 htlc_base_key: SecretKey,
349 commitment_seed: [u8; 32],
350 channel_value_satoshis: u64,
351 key_derivation_params: (u64, u64)) -> InMemoryChannelKeys {
352 let local_channel_pubkeys =
353 InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key,
354 &payment_key, &delayed_payment_base_key,
356 InMemoryChannelKeys {
360 delayed_payment_base_key,
363 channel_value_satoshis,
364 local_channel_pubkeys,
365 remote_channel_pubkeys: None,
366 key_derivation_params,
370 fn make_local_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
371 funding_key: &SecretKey,
372 revocation_base_key: &SecretKey,
373 payment_key: &SecretKey,
374 delayed_payment_base_key: &SecretKey,
375 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
376 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
378 funding_pubkey: from_secret(&funding_key),
379 revocation_basepoint: from_secret(&revocation_base_key),
380 payment_point: from_secret(&payment_key),
381 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
382 htlc_basepoint: from_secret(&htlc_base_key),
387 impl ChannelKeys for InMemoryChannelKeys {
388 fn funding_key(&self) -> &SecretKey { &self.funding_key }
389 fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
390 fn payment_key(&self) -> &SecretKey { &self.payment_key }
391 fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
392 fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
393 fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
394 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { &self.local_channel_pubkeys }
395 fn key_derivation_params(&self) -> (u64, u64) { self.key_derivation_params }
397 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>), ()> {
398 if commitment_tx.input.len() != 1 { return Err(()); }
400 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
401 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
402 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
404 let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
405 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
407 let commitment_txid = commitment_tx.txid();
409 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
410 for ref htlc in htlcs {
411 if let Some(_) = htlc.transaction_output_index {
412 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);
413 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
414 let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
415 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
417 Err(_) => return Err(()),
419 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
423 Ok((commitment_sig, htlc_sigs))
426 fn sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
427 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
428 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
429 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
431 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
435 fn unsafe_sign_local_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
436 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
437 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
438 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
440 Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
443 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>>, ()> {
444 local_commitment_tx.get_htlc_sigs(&self.htlc_base_key, local_csv, secp_ctx)
447 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, ()> {
448 if let Ok(revocation_key) = chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
449 let sighash_parts = bip143::SighashComponents::new(&justice_tx);
450 let sighash = hash_to_message!(&sighash_parts.sighash_all(&justice_tx.input[input], &witness_script, amount)[..]);
451 return Ok(secp_ctx.sign(&sighash, &revocation_key))
456 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, ()> {
457 if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) {
458 let sighash_parts = bip143::SighashComponents::new(&htlc_tx);
459 let sighash = hash_to_message!(&sighash_parts.sighash_all(&htlc_tx.input[input], &witness_script, amount)[..]);
460 return Ok(secp_ctx.sign(&sighash, &htlc_key))
465 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
466 if closing_tx.input.len() != 1 { return Err(()); }
467 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
468 if closing_tx.output.len() > 2 { return Err(()); }
470 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
471 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
472 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
474 let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
475 .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
476 Ok(secp_ctx.sign(&sighash, &self.funding_key))
479 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
480 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
481 Ok(secp_ctx.sign(&msghash, &self.funding_key))
484 fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) {
485 assert!(self.remote_channel_pubkeys.is_none(), "Already set remote channel pubkeys");
486 self.remote_channel_pubkeys = Some(channel_pubkeys.clone());
490 impl Writeable for InMemoryChannelKeys {
491 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
492 self.funding_key.write(writer)?;
493 self.revocation_base_key.write(writer)?;
494 self.payment_key.write(writer)?;
495 self.delayed_payment_base_key.write(writer)?;
496 self.htlc_base_key.write(writer)?;
497 self.commitment_seed.write(writer)?;
498 self.remote_channel_pubkeys.write(writer)?;
499 self.channel_value_satoshis.write(writer)?;
500 self.key_derivation_params.0.write(writer)?;
501 self.key_derivation_params.1.write(writer)?;
507 impl Readable for InMemoryChannelKeys {
508 fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
509 let funding_key = Readable::read(reader)?;
510 let revocation_base_key = Readable::read(reader)?;
511 let payment_key = Readable::read(reader)?;
512 let delayed_payment_base_key = Readable::read(reader)?;
513 let htlc_base_key = Readable::read(reader)?;
514 let commitment_seed = Readable::read(reader)?;
515 let remote_channel_pubkeys = Readable::read(reader)?;
516 let channel_value_satoshis = Readable::read(reader)?;
517 let secp_ctx = Secp256k1::signing_only();
518 let local_channel_pubkeys =
519 InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key,
520 &payment_key, &delayed_payment_base_key,
522 let params_1 = Readable::read(reader)?;
523 let params_2 = Readable::read(reader)?;
525 Ok(InMemoryChannelKeys {
529 delayed_payment_base_key,
532 channel_value_satoshis,
533 local_channel_pubkeys,
534 remote_channel_pubkeys,
535 key_derivation_params: (params_1, params_2),
540 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
541 /// and derives keys from that.
543 /// Your node_id is seed/0'
544 /// ChannelMonitor closes may use seed/1'
545 /// Cooperative closes may use seed/2'
546 /// The two close keys may be needed to claim on-chain funds!
547 pub struct KeysManager {
548 secp_ctx: Secp256k1<secp256k1::SignOnly>,
549 node_secret: SecretKey,
550 destination_script: Script,
551 shutdown_pubkey: PublicKey,
552 channel_master_key: ExtendedPrivKey,
553 channel_child_index: AtomicUsize,
554 session_master_key: ExtendedPrivKey,
555 session_child_index: AtomicUsize,
556 channel_id_master_key: ExtendedPrivKey,
557 channel_id_child_index: AtomicUsize,
560 starting_time_secs: u64,
561 starting_time_nanos: u32,
565 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
566 /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
567 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
568 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
569 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
570 /// simply use the current time (with very high precision).
572 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
573 /// obviously, starting_time should be unique every time you reload the library - it is only
574 /// used to generate new ephemeral key data (which will be stored by the individual channel if
577 /// Note that the seed is required to recover certain on-chain funds independent of
578 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
579 /// channel, and some on-chain during-closing funds.
581 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
582 /// versions. Once the library is more fully supported, the docs will be updated to include a
583 /// detailed description of the guarantee.
584 pub fn new(seed: &[u8; 32], network: Network, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager {
585 let secp_ctx = Secp256k1::signing_only();
586 match ExtendedPrivKey::new_master(network.clone(), seed) {
588 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
589 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
590 Ok(destination_key) => {
591 let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes());
592 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
593 .push_slice(&wpubkey_hash.into_inner())
596 Err(_) => panic!("Your RNG is busted"),
598 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
599 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
600 Err(_) => panic!("Your RNG is busted"),
602 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
603 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
604 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
612 channel_child_index: AtomicUsize::new(0),
614 session_child_index: AtomicUsize::new(0),
615 channel_id_master_key,
616 channel_id_child_index: AtomicUsize::new(0),
623 Err(_) => panic!("Your rng is busted"),
626 fn derive_unique_start(&self) -> Sha256State {
627 let mut unique_start = Sha256::engine();
628 unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs));
629 unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos));
630 unique_start.input(&self.seed);
633 /// Derive an old set of ChannelKeys for per-channel secrets based on a key derivation
635 /// Key derivation parameters are accessible through a per-channel secrets
636 /// ChannelKeys::key_derivation_params and is provided inside DynamicOuputP2WSH in case of
637 /// onchain output detection for which a corresponding delayed_payment_key must be derived.
638 pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params_1: u64, params_2: u64) -> InMemoryChannelKeys {
639 let chan_id = ((params_1 & 0xFFFF_FFFF_0000_0000) >> 32) as u32;
640 let mut unique_start = Sha256::engine();
641 unique_start.input(&byte_utils::be64_to_array(params_2));
642 unique_start.input(&byte_utils::be32_to_array(params_1 as u32));
643 unique_start.input(&self.seed);
645 // We only seriously intend to rely on the channel_master_key for true secure
646 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
647 // starting_time provided in the constructor) to be unique.
648 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");
649 unique_start.input(&child_privkey.private_key.key[..]);
651 let seed = Sha256::from_engine(unique_start).into_inner();
653 let commitment_seed = {
654 let mut sha = Sha256::engine();
656 sha.input(&b"commitment seed"[..]);
657 Sha256::from_engine(sha).into_inner()
659 macro_rules! key_step {
660 ($info: expr, $prev_key: expr) => {{
661 let mut sha = Sha256::engine();
663 sha.input(&$prev_key[..]);
664 sha.input(&$info[..]);
665 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
668 let funding_key = key_step!(b"funding key", commitment_seed);
669 let revocation_base_key = key_step!(b"revocation base key", funding_key);
670 let payment_key = key_step!(b"payment key", revocation_base_key);
671 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key);
672 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
674 InMemoryChannelKeys::new(
679 delayed_payment_base_key,
682 channel_value_satoshis,
683 (params_1, params_2),
688 impl KeysInterface for KeysManager {
689 type ChanKeySigner = InMemoryChannelKeys;
691 fn get_node_secret(&self) -> SecretKey {
692 self.node_secret.clone()
695 fn get_destination_script(&self) -> Script {
696 self.destination_script.clone()
699 fn get_shutdown_pubkey(&self) -> PublicKey {
700 self.shutdown_pubkey.clone()
703 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys {
704 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
705 let ix_and_nanos: u64 = (child_ix as u64) << 32 | (self.starting_time_nanos as u64);
706 self.derive_channel_keys(channel_value_satoshis, ix_and_nanos, self.starting_time_secs)
709 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
710 let mut sha = self.derive_unique_start();
712 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
713 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");
714 sha.input(&child_privkey.private_key.key[..]);
716 let mut rng_seed = sha.clone();
717 // Not exactly the most ideal construction, but the second value will get fed into
718 // ChaCha so it is another step harder to break.
719 rng_seed.input(b"RNG Seed Salt");
720 sha.input(b"Session Key Salt");
721 (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
722 Sha256::from_engine(rng_seed).into_inner())
725 fn get_channel_id(&self) -> [u8; 32] {
726 let mut sha = self.derive_unique_start();
728 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
729 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");
730 sha.input(&child_privkey.private_key.key[..]);
732 Sha256::from_engine(sha).into_inner()