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_hashes::hash160::Hash as Hash160;
18 use secp256k1::key::{SecretKey, PublicKey};
19 use secp256k1::{Secp256k1, Signature, Signing};
23 use util::logger::Logger;
24 use util::ser::{Writeable, Writer, Readable};
27 use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys};
31 use std::sync::atomic::{AtomicUsize, Ordering};
33 use ln::msgs::DecodeError;
35 /// When on-chain outputs are created by rust-lightning (which our counterparty is not able to
36 /// claim at any point in the future) an event is generated which you must track and be able to
37 /// spend on-chain. The information needed to do this is provided in this enum, including the
38 /// outpoint describing which txid and output index is available, the full output which exists at
39 /// that txid/index, and any keys or other information required to sign.
40 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> <one zero byte aka OP_0>
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 /// An output to a P2WPKH, spendable exclusively by the given private key.
77 /// The witness in the spending input, is, thus, simply:
78 /// <BIP 143 signature generated with the given key> <public key derived from the given key>
79 /// These are generally the result of our counterparty having broadcast the current state,
80 /// allowing us to claim the non-HTLC-encumbered outputs immediately.
82 /// The outpoint which is spendable
84 /// The secret key which must be used to sign the spending transaction
86 /// The output which is reference by the given outpoint
91 impl Writeable for SpendableOutputDescriptor {
92 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
94 &SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
96 outpoint.write(writer)?;
97 output.write(writer)?;
99 &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref key, ref witness_script, ref to_self_delay, ref output } => {
101 outpoint.write(writer)?;
103 witness_script.write(writer)?;
104 to_self_delay.write(writer)?;
105 output.write(writer)?;
107 &SpendableOutputDescriptor::DynamicOutputP2WPKH { ref outpoint, ref key, ref output } => {
109 outpoint.write(writer)?;
111 output.write(writer)?;
118 impl<R: ::std::io::Read> Readable<R> for SpendableOutputDescriptor {
119 fn read(reader: &mut R) -> Result<Self, DecodeError> {
120 match Readable::read(reader)? {
121 0u8 => Ok(SpendableOutputDescriptor::StaticOutput {
122 outpoint: Readable::read(reader)?,
123 output: Readable::read(reader)?,
125 1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH {
126 outpoint: Readable::read(reader)?,
127 key: Readable::read(reader)?,
128 witness_script: Readable::read(reader)?,
129 to_self_delay: Readable::read(reader)?,
130 output: Readable::read(reader)?,
132 2u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WPKH {
133 outpoint: Readable::read(reader)?,
134 key: Readable::read(reader)?,
135 output: Readable::read(reader)?,
137 _ => Err(DecodeError::InvalidValue),
142 /// A trait to describe an object which can get user secrets and key material.
143 pub trait KeysInterface: Send + Sync {
144 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
145 type ChanKeySigner : ChannelKeys;
147 /// Get node secret key (aka node_id or network_key)
148 fn get_node_secret(&self) -> SecretKey;
149 /// Get destination redeemScript to encumber static protocol exit points.
150 fn get_destination_script(&self) -> Script;
151 /// Get shutdown_pubkey to use as PublicKey at channel closure
152 fn get_shutdown_pubkey(&self) -> PublicKey;
153 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
154 /// restarted with some stale data!
155 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
156 /// Get a secret and PRNG seed for construting an onion packet
157 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
158 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
159 /// transaction is created, at which point they will use the outpoint in the funding
161 fn get_channel_id(&self) -> [u8; 32];
164 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
166 /// Signing services could be implemented on a hardware wallet. In this case,
167 /// the current ChannelKeys would be a front-end on top of a communication
168 /// channel connected to your secure device and lightning key material wouldn't
169 /// reside on a hot server. Nevertheless, a this deployment would still need
170 /// to trust the ChannelManager to avoid loss of funds as this latest component
171 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
173 /// A more secure iteration would be to use hashlock (or payment points) to pair
174 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
175 /// at the price of more state and computation on the hardware wallet side. In the future,
176 /// we are looking forward to design such interface.
178 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
179 /// to act, as liveness and breach reply correctness are always going to be hard requirements
180 /// of LN security model, orthogonal of key management issues.
182 /// If you're implementing a custom signer, you almost certainly want to implement
183 /// Readable/Writable to serialize out a unique reference to this set of keys so
184 /// that you can serialize the full ChannelManager object.
186 /// (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
187 /// to the possibility of reentrancy issues by calling the user's code during our deserialization
189 /// TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
190 /// ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
191 pub trait ChannelKeys : Send+Clone {
192 /// Gets the private key for the anchor tx
193 fn funding_key<'a>(&'a self) -> &'a SecretKey;
194 /// Gets the local secret key for blinded revocation pubkey
195 fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
196 /// Gets the local secret key used in to_remote output of remote commitment tx
197 /// (and also as part of obscured commitment number)
198 fn payment_base_key<'a>(&'a self) -> &'a SecretKey;
199 /// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output
200 fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
201 /// Gets the local htlc secret key used in commitment tx htlc outputs
202 fn htlc_base_key<'a>(&'a self) -> &'a SecretKey;
203 /// Gets the commitment seed
204 fn commitment_seed<'a>(&'a self) -> &'a [u8; 32];
205 /// Gets the local channel public keys and basepoints
206 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys;
208 /// Create a signature for a remote commitment transaction and associated HTLC transactions.
210 /// Note that if signing fails or is rejected, the channel will be force-closed.
212 /// TODO: Document the things someone using this interface should enforce before signing.
213 /// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
214 /// making the callee generate it via some util function we expose)!
215 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>), ()>;
217 /// Create a signature for a (proposed) closing transaction.
219 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
220 /// chosen to forgo their output as dust.
221 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
223 /// Signs a channel announcement message with our funding key, proving it comes from one
224 /// of the channel participants.
226 /// Note that if this fails or is rejected, the channel will not be publicly announced and
227 /// our counterparty may (though likely will not) close the channel on us for violating the
229 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
231 /// Set the remote channel basepoints. This is done immediately on incoming channels
232 /// and as soon as the channel is accepted on outgoing channels.
234 /// Will be called before any signatures are applied.
235 fn set_remote_channel_pubkeys(&mut self, channel_points: &ChannelPublicKeys);
239 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
240 pub struct InMemoryChannelKeys {
241 /// Private key of anchor tx
242 funding_key: SecretKey,
243 /// Local secret key for blinded revocation pubkey
244 revocation_base_key: SecretKey,
245 /// Local secret key used in commitment tx htlc outputs
246 payment_base_key: SecretKey,
247 /// Local secret key used in HTLC tx
248 delayed_payment_base_key: SecretKey,
249 /// Local htlc secret key used in commitment tx htlc outputs
250 htlc_base_key: SecretKey,
252 commitment_seed: [u8; 32],
253 /// Local public keys and basepoints
254 pub(crate) local_channel_pubkeys: ChannelPublicKeys,
255 /// Remote public keys and base points
256 pub(crate) remote_channel_pubkeys: Option<ChannelPublicKeys>,
257 /// The total value of this channel
258 channel_value_satoshis: u64,
261 impl InMemoryChannelKeys {
262 /// Create a new InMemoryChannelKeys
263 pub fn new<C: Signing>(
264 secp_ctx: &Secp256k1<C>,
265 funding_key: SecretKey,
266 revocation_base_key: SecretKey,
267 payment_base_key: SecretKey,
268 delayed_payment_base_key: SecretKey,
269 htlc_base_key: SecretKey,
270 commitment_seed: [u8; 32],
271 channel_value_satoshis: u64) -> InMemoryChannelKeys {
272 let local_channel_pubkeys =
273 InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key,
274 &payment_base_key, &delayed_payment_base_key,
276 InMemoryChannelKeys {
280 delayed_payment_base_key,
283 channel_value_satoshis,
284 local_channel_pubkeys,
285 remote_channel_pubkeys: None,
289 fn make_local_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
290 funding_key: &SecretKey,
291 revocation_base_key: &SecretKey,
292 payment_base_key: &SecretKey,
293 delayed_payment_base_key: &SecretKey,
294 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
295 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
297 funding_pubkey: from_secret(&funding_key),
298 revocation_basepoint: from_secret(&revocation_base_key),
299 payment_basepoint: from_secret(&payment_base_key),
300 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
301 htlc_basepoint: from_secret(&htlc_base_key),
306 impl ChannelKeys for InMemoryChannelKeys {
307 fn funding_key(&self) -> &SecretKey { &self.funding_key }
308 fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
309 fn payment_base_key(&self) -> &SecretKey { &self.payment_base_key }
310 fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
311 fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
312 fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
313 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { &self.local_channel_pubkeys }
315 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>), ()> {
316 if commitment_tx.input.len() != 1 { return Err(()); }
318 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
319 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
320 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
322 let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
323 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
325 let commitment_txid = commitment_tx.txid();
327 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
328 for ref htlc in htlcs {
329 if let Some(_) = htlc.transaction_output_index {
330 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);
331 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
332 let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
333 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
335 Err(_) => return Err(()),
337 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
341 Ok((commitment_sig, htlc_sigs))
344 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
345 if closing_tx.input.len() != 1 { return Err(()); }
346 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
347 if closing_tx.output.len() > 2 { return Err(()); }
349 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
350 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
351 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
353 let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
354 .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
355 Ok(secp_ctx.sign(&sighash, &self.funding_key))
358 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
359 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
360 Ok(secp_ctx.sign(&msghash, &self.funding_key))
363 fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) {
364 assert!(self.remote_channel_pubkeys.is_none(), "Already set remote channel pubkeys");
365 self.remote_channel_pubkeys = Some(channel_pubkeys.clone());
369 impl Writeable for InMemoryChannelKeys {
370 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
371 self.funding_key.write(writer)?;
372 self.revocation_base_key.write(writer)?;
373 self.payment_base_key.write(writer)?;
374 self.delayed_payment_base_key.write(writer)?;
375 self.htlc_base_key.write(writer)?;
376 self.commitment_seed.write(writer)?;
377 self.remote_channel_pubkeys.write(writer)?;
378 self.channel_value_satoshis.write(writer)?;
384 impl<R: ::std::io::Read> Readable<R> for InMemoryChannelKeys {
385 fn read(reader: &mut R) -> Result<Self, DecodeError> {
386 let funding_key = Readable::read(reader)?;
387 let revocation_base_key = Readable::read(reader)?;
388 let payment_base_key = Readable::read(reader)?;
389 let delayed_payment_base_key = Readable::read(reader)?;
390 let htlc_base_key = Readable::read(reader)?;
391 let commitment_seed = Readable::read(reader)?;
392 let remote_channel_pubkeys = Readable::read(reader)?;
393 let channel_value_satoshis = Readable::read(reader)?;
394 let secp_ctx = Secp256k1::signing_only();
395 let local_channel_pubkeys =
396 InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key,
397 &payment_base_key, &delayed_payment_base_key,
400 Ok(InMemoryChannelKeys {
404 delayed_payment_base_key,
407 channel_value_satoshis,
408 local_channel_pubkeys,
409 remote_channel_pubkeys
414 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
415 /// and derives keys from that.
417 /// Your node_id is seed/0'
418 /// ChannelMonitor closes may use seed/1'
419 /// Cooperative closes may use seed/2'
420 /// The two close keys may be needed to claim on-chain funds!
421 pub struct KeysManager {
422 secp_ctx: Secp256k1<secp256k1::SignOnly>,
423 node_secret: SecretKey,
424 destination_script: Script,
425 shutdown_pubkey: PublicKey,
426 channel_master_key: ExtendedPrivKey,
427 channel_child_index: AtomicUsize,
428 session_master_key: ExtendedPrivKey,
429 session_child_index: AtomicUsize,
430 channel_id_master_key: ExtendedPrivKey,
431 channel_id_child_index: AtomicUsize,
433 unique_start: Sha256State,
438 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
439 /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
440 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
441 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
442 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
443 /// simply use the current time (with very high precision).
445 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
446 /// obviously, starting_time should be unique every time you reload the library - it is only
447 /// used to generate new ephemeral key data (which will be stored by the individual channel if
450 /// Note that the seed is required to recover certain on-chain funds independent of
451 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
452 /// channel, and some on-chain during-closing funds.
454 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
455 /// versions. Once the library is more fully supported, the docs will be updated to include a
456 /// detailed description of the guarantee.
457 pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager {
458 let secp_ctx = Secp256k1::signing_only();
459 match ExtendedPrivKey::new_master(network.clone(), seed) {
461 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
462 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
463 Ok(destination_key) => {
464 let pubkey_hash160 = Hash160::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.key.serialize()[..]);
465 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
466 .push_slice(&pubkey_hash160.into_inner())
469 Err(_) => panic!("Your RNG is busted"),
471 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
472 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
473 Err(_) => panic!("Your RNG is busted"),
475 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
476 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
477 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
479 let mut unique_start = Sha256::engine();
480 unique_start.input(&byte_utils::be64_to_array(starting_time_secs));
481 unique_start.input(&byte_utils::be32_to_array(starting_time_nanos));
482 unique_start.input(seed);
490 channel_child_index: AtomicUsize::new(0),
492 session_child_index: AtomicUsize::new(0),
493 channel_id_master_key,
494 channel_id_child_index: AtomicUsize::new(0),
500 Err(_) => panic!("Your rng is busted"),
505 impl KeysInterface for KeysManager {
506 type ChanKeySigner = InMemoryChannelKeys;
508 fn get_node_secret(&self) -> SecretKey {
509 self.node_secret.clone()
512 fn get_destination_script(&self) -> Script {
513 self.destination_script.clone()
516 fn get_shutdown_pubkey(&self) -> PublicKey {
517 self.shutdown_pubkey.clone()
520 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys {
521 // We only seriously intend to rely on the channel_master_key for true secure
522 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
523 // starting_time provided in the constructor) to be unique.
524 let mut sha = self.unique_start.clone();
526 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
527 let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted");
528 sha.input(&child_privkey.private_key.key[..]);
530 let seed = Sha256::from_engine(sha).into_inner();
532 let commitment_seed = {
533 let mut sha = Sha256::engine();
535 sha.input(&b"commitment seed"[..]);
536 Sha256::from_engine(sha).into_inner()
538 macro_rules! key_step {
539 ($info: expr, $prev_key: expr) => {{
540 let mut sha = Sha256::engine();
542 sha.input(&$prev_key[..]);
543 sha.input(&$info[..]);
544 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
547 let funding_key = key_step!(b"funding key", commitment_seed);
548 let revocation_base_key = key_step!(b"revocation base key", funding_key);
549 let payment_base_key = key_step!(b"payment base key", revocation_base_key);
550 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key);
551 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
553 InMemoryChannelKeys::new(
558 delayed_payment_base_key,
561 channel_value_satoshis
565 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
566 let mut sha = self.unique_start.clone();
568 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
569 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");
570 sha.input(&child_privkey.private_key.key[..]);
572 let mut rng_seed = sha.clone();
573 // Not exactly the most ideal construction, but the second value will get fed into
574 // ChaCha so it is another step harder to break.
575 rng_seed.input(b"RNG Seed Salt");
576 sha.input(b"Session Key Salt");
577 (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
578 Sha256::from_engine(rng_seed).into_inner())
581 fn get_channel_id(&self) -> [u8; 32] {
582 let mut sha = self.unique_start.clone();
584 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
585 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");
586 sha.input(&child_privkey.private_key.key[..]);
588 (Sha256::from_engine(sha).into_inner())