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 /// A trait to describe an object which can get user secrets and key material.
92 pub trait KeysInterface: Send + Sync {
93 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
94 type ChanKeySigner : ChannelKeys;
96 /// Get node secret key (aka node_id or network_key)
97 fn get_node_secret(&self) -> SecretKey;
98 /// Get destination redeemScript to encumber static protocol exit points.
99 fn get_destination_script(&self) -> Script;
100 /// Get shutdown_pubkey to use as PublicKey at channel closure
101 fn get_shutdown_pubkey(&self) -> PublicKey;
102 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
103 /// restarted with some stale data!
104 fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
105 /// Get a secret and PRNG seed for construting an onion packet
106 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
107 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
108 /// transaction is created, at which point they will use the outpoint in the funding
110 fn get_channel_id(&self) -> [u8; 32];
113 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
115 /// Signing services could be implemented on a hardware wallet. In this case,
116 /// the current ChannelKeys would be a front-end on top of a communication
117 /// channel connected to your secure device and lightning key material wouldn't
118 /// reside on a hot server. Nevertheless, a this deployment would still need
119 /// to trust the ChannelManager to avoid loss of funds as this latest component
120 /// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
122 /// A more secure iteration would be to use hashlock (or payment points) to pair
123 /// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
124 /// at the price of more state and computation on the hardware wallet side. In the future,
125 /// we are looking forward to design such interface.
127 /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
128 /// to act, as liveness and breach reply correctness are always going to be hard requirements
129 /// of LN security model, orthogonal of key management issues.
131 /// If you're implementing a custom signer, you almost certainly want to implement
132 /// Readable/Writable to serialize out a unique reference to this set of keys so
133 /// that you can serialize the full ChannelManager object.
135 /// (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
136 /// to the possibility of reentrancy issues by calling the user's code during our deserialization
138 /// TODO: remove Clone once we start returning ChannelUpdate objects instead of copying ChannelMonitor
139 pub trait ChannelKeys : Send+Clone {
140 /// Gets the private key for the anchor tx
141 fn funding_key<'a>(&'a self) -> &'a SecretKey;
142 /// Gets the local secret key for blinded revocation pubkey
143 fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
144 /// Gets the local secret key used in to_remote output of remote commitment tx
145 /// (and also as part of obscured commitment number)
146 fn payment_base_key<'a>(&'a self) -> &'a SecretKey;
147 /// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output
148 fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
149 /// Gets the local htlc secret key used in commitment tx htlc outputs
150 fn htlc_base_key<'a>(&'a self) -> &'a SecretKey;
151 /// Gets the commitment seed
152 fn commitment_seed<'a>(&'a self) -> &'a [u8; 32];
153 /// Gets the local channel public keys and basepoints
154 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys;
156 /// Create a signature for a remote commitment transaction and associated HTLC transactions.
158 /// Note that if signing fails or is rejected, the channel will be force-closed.
160 /// TODO: Document the things someone using this interface should enforce before signing.
161 /// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
162 /// making the callee generate it via some util function we expose)!
163 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>), ()>;
165 /// Create a signature for a (proposed) closing transaction.
167 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
168 /// chosen to forgo their output as dust.
169 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
171 /// Signs a channel announcement message with our funding key, proving it comes from one
172 /// of the channel participants.
174 /// Note that if this fails or is rejected, the channel will not be publicly announced and
175 /// our counterparty may (though likely will not) close the channel on us for violating the
177 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
179 /// Set the remote channel basepoints. This is done immediately on incoming channels
180 /// and as soon as the channel is accepted on outgoing channels.
182 /// Will be called before any signatures are applied.
183 fn set_remote_channel_pubkeys(&mut self, channel_points: &ChannelPublicKeys);
187 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
188 pub struct InMemoryChannelKeys {
189 /// Private key of anchor tx
190 funding_key: SecretKey,
191 /// Local secret key for blinded revocation pubkey
192 revocation_base_key: SecretKey,
193 /// Local secret key used in commitment tx htlc outputs
194 payment_base_key: SecretKey,
195 /// Local secret key used in HTLC tx
196 delayed_payment_base_key: SecretKey,
197 /// Local htlc secret key used in commitment tx htlc outputs
198 htlc_base_key: SecretKey,
200 commitment_seed: [u8; 32],
201 /// Local public keys and basepoints
202 pub(crate) local_channel_pubkeys: ChannelPublicKeys,
203 /// Remote public keys and base points
204 pub(crate) remote_channel_pubkeys: Option<ChannelPublicKeys>,
205 /// The total value of this channel
206 channel_value_satoshis: u64,
209 impl InMemoryChannelKeys {
210 /// Create a new InMemoryChannelKeys
211 pub fn new<C: Signing>(
212 secp_ctx: &Secp256k1<C>,
213 funding_key: SecretKey,
214 revocation_base_key: SecretKey,
215 payment_base_key: SecretKey,
216 delayed_payment_base_key: SecretKey,
217 htlc_base_key: SecretKey,
218 commitment_seed: [u8; 32],
219 channel_value_satoshis: u64) -> InMemoryChannelKeys {
220 let local_channel_pubkeys =
221 InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key,
222 &payment_base_key, &delayed_payment_base_key,
224 InMemoryChannelKeys {
228 delayed_payment_base_key,
231 channel_value_satoshis,
232 local_channel_pubkeys,
233 remote_channel_pubkeys: None,
237 fn make_local_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
238 funding_key: &SecretKey,
239 revocation_base_key: &SecretKey,
240 payment_base_key: &SecretKey,
241 delayed_payment_base_key: &SecretKey,
242 htlc_base_key: &SecretKey) -> ChannelPublicKeys {
243 let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
245 funding_pubkey: from_secret(&funding_key),
246 revocation_basepoint: from_secret(&revocation_base_key),
247 payment_basepoint: from_secret(&payment_base_key),
248 delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
249 htlc_basepoint: from_secret(&htlc_base_key),
254 impl ChannelKeys for InMemoryChannelKeys {
255 fn funding_key(&self) -> &SecretKey { &self.funding_key }
256 fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
257 fn payment_base_key(&self) -> &SecretKey { &self.payment_base_key }
258 fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
259 fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
260 fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
261 fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { &self.local_channel_pubkeys }
263 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>), ()> {
264 if commitment_tx.input.len() != 1 { return Err(()); }
266 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
267 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
268 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
270 let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
271 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
273 let commitment_txid = commitment_tx.txid();
275 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
276 for ref htlc in htlcs {
277 if let Some(_) = htlc.transaction_output_index {
278 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);
279 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
280 let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
281 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
283 Err(_) => return Err(()),
285 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
289 Ok((commitment_sig, htlc_sigs))
292 fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
293 if closing_tx.input.len() != 1 { return Err(()); }
294 if closing_tx.input[0].witness.len() != 0 { return Err(()); }
295 if closing_tx.output.len() > 2 { return Err(()); }
297 let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
298 let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
299 let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
301 let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
302 .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
303 Ok(secp_ctx.sign(&sighash, &self.funding_key))
306 fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
307 let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
308 Ok(secp_ctx.sign(&msghash, &self.funding_key))
311 fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) {
312 assert!(self.remote_channel_pubkeys.is_none(), "Already set remote channel pubkeys");
313 self.remote_channel_pubkeys = Some(channel_pubkeys.clone());
317 impl Writeable for InMemoryChannelKeys {
318 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
319 self.funding_key.write(writer)?;
320 self.revocation_base_key.write(writer)?;
321 self.payment_base_key.write(writer)?;
322 self.delayed_payment_base_key.write(writer)?;
323 self.htlc_base_key.write(writer)?;
324 self.commitment_seed.write(writer)?;
325 self.remote_channel_pubkeys.write(writer)?;
326 self.channel_value_satoshis.write(writer)?;
332 impl<R: ::std::io::Read> Readable<R> for InMemoryChannelKeys {
333 fn read(reader: &mut R) -> Result<Self, DecodeError> {
334 let funding_key = Readable::read(reader)?;
335 let revocation_base_key = Readable::read(reader)?;
336 let payment_base_key = Readable::read(reader)?;
337 let delayed_payment_base_key = Readable::read(reader)?;
338 let htlc_base_key = Readable::read(reader)?;
339 let commitment_seed = Readable::read(reader)?;
340 let remote_channel_pubkeys = Readable::read(reader)?;
341 let channel_value_satoshis = Readable::read(reader)?;
342 let secp_ctx = Secp256k1::signing_only();
343 let local_channel_pubkeys =
344 InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key,
345 &payment_base_key, &delayed_payment_base_key,
348 Ok(InMemoryChannelKeys {
352 delayed_payment_base_key,
355 channel_value_satoshis,
356 local_channel_pubkeys,
357 remote_channel_pubkeys
362 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
363 /// and derives keys from that.
365 /// Your node_id is seed/0'
366 /// ChannelMonitor closes may use seed/1'
367 /// Cooperative closes may use seed/2'
368 /// The two close keys may be needed to claim on-chain funds!
369 pub struct KeysManager {
370 secp_ctx: Secp256k1<secp256k1::SignOnly>,
371 node_secret: SecretKey,
372 destination_script: Script,
373 shutdown_pubkey: PublicKey,
374 channel_master_key: ExtendedPrivKey,
375 channel_child_index: AtomicUsize,
376 session_master_key: ExtendedPrivKey,
377 session_child_index: AtomicUsize,
378 channel_id_master_key: ExtendedPrivKey,
379 channel_id_child_index: AtomicUsize,
381 unique_start: Sha256State,
386 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
387 /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
388 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
389 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
390 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
391 /// simply use the current time (with very high precision).
393 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
394 /// obviously, starting_time should be unique every time you reload the library - it is only
395 /// used to generate new ephemeral key data (which will be stored by the individual channel if
398 /// Note that the seed is required to recover certain on-chain funds independent of
399 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
400 /// channel, and some on-chain during-closing funds.
402 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
403 /// versions. Once the library is more fully supported, the docs will be updated to include a
404 /// detailed description of the guarantee.
405 pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager {
406 let secp_ctx = Secp256k1::signing_only();
407 match ExtendedPrivKey::new_master(network.clone(), seed) {
409 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
410 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
411 Ok(destination_key) => {
412 let pubkey_hash160 = Hash160::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.key.serialize()[..]);
413 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
414 .push_slice(&pubkey_hash160.into_inner())
417 Err(_) => panic!("Your RNG is busted"),
419 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
420 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
421 Err(_) => panic!("Your RNG is busted"),
423 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
424 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
425 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
427 let mut unique_start = Sha256::engine();
428 unique_start.input(&byte_utils::be64_to_array(starting_time_secs));
429 unique_start.input(&byte_utils::be32_to_array(starting_time_nanos));
430 unique_start.input(seed);
438 channel_child_index: AtomicUsize::new(0),
440 session_child_index: AtomicUsize::new(0),
441 channel_id_master_key,
442 channel_id_child_index: AtomicUsize::new(0),
448 Err(_) => panic!("Your rng is busted"),
453 impl KeysInterface for KeysManager {
454 type ChanKeySigner = InMemoryChannelKeys;
456 fn get_node_secret(&self) -> SecretKey {
457 self.node_secret.clone()
460 fn get_destination_script(&self) -> Script {
461 self.destination_script.clone()
464 fn get_shutdown_pubkey(&self) -> PublicKey {
465 self.shutdown_pubkey.clone()
468 fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys {
469 // We only seriously intend to rely on the channel_master_key for true secure
470 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
471 // starting_time provided in the constructor) to be unique.
472 let mut sha = self.unique_start.clone();
474 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
475 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");
476 sha.input(&child_privkey.private_key.key[..]);
478 let seed = Sha256::from_engine(sha).into_inner();
480 let commitment_seed = {
481 let mut sha = Sha256::engine();
483 sha.input(&b"commitment seed"[..]);
484 Sha256::from_engine(sha).into_inner()
486 macro_rules! key_step {
487 ($info: expr, $prev_key: expr) => {{
488 let mut sha = Sha256::engine();
490 sha.input(&$prev_key[..]);
491 sha.input(&$info[..]);
492 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
495 let funding_key = key_step!(b"funding key", commitment_seed);
496 let revocation_base_key = key_step!(b"revocation base key", funding_key);
497 let payment_base_key = key_step!(b"payment base key", revocation_base_key);
498 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key);
499 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
501 InMemoryChannelKeys::new(
506 delayed_payment_base_key,
509 channel_value_satoshis
513 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
514 let mut sha = self.unique_start.clone();
516 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
517 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");
518 sha.input(&child_privkey.private_key.key[..]);
520 let mut rng_seed = sha.clone();
521 // Not exactly the most ideal construction, but the second value will get fed into
522 // ChaCha so it is another step harder to break.
523 rng_seed.input(b"RNG Seed Salt");
524 sha.input(b"Session Key Salt");
525 (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
526 Sha256::from_engine(rng_seed).into_inner())
529 fn get_channel_id(&self) -> [u8; 32] {
530 let mut sha = self.unique_start.clone();
532 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
533 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");
534 sha.input(&child_privkey.private_key.key[..]);
536 (Sha256::from_engine(sha).into_inner())