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::hash160::Hash as Hash160;
17 use secp256k1::key::{SecretKey, PublicKey};
18 use secp256k1::{Secp256k1, Signature};
22 use util::logger::Logger;
25 use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment};
28 use std::sync::atomic::{AtomicUsize, Ordering};
30 /// When on-chain outputs are created by rust-lightning an event is generated which informs the
31 /// user thereof. This enum describes the format of the output and provides the OutPoint.
32 pub enum SpendableOutputDescriptor {
33 /// Outpoint with an output to a script which was provided via KeysInterface, thus you should
34 /// have stored somewhere how to spend script_pubkey!
35 /// Outputs from a justice tx, claim tx or preimage tx
37 /// The outpoint spendable by user wallet
39 /// The output which is referenced by the given outpoint
42 /// Outpoint commits to a P2WSH
43 /// P2WSH should be spend by the following witness :
44 /// <local_delayedsig> 0 <witnessScript>
45 /// With input nSequence set to_self_delay.
46 /// Outputs from a HTLC-Success/Timeout tx/commitment tx
48 /// Outpoint spendable by user wallet
50 /// local_delayedkey = delayed_payment_basepoint_secret + SHA256(per_commitment_point || delayed_payment_basepoint) OR
52 /// witness redeemScript encumbering output.
53 witness_script: Script,
54 /// nSequence input must commit to self_delay to satisfy script's OP_CSV
56 /// The output which is referenced by the given outpoint
59 /// Outpoint commits to a P2WPKH
60 /// P2WPKH should be spend by the following witness :
61 /// <local_sig> <local_pubkey>
62 /// Outputs to_remote from a commitment tx
64 /// Outpoint spendable by user wallet
66 /// localkey = payment_basepoint_secret + SHA256(per_commitment_point || payment_basepoint
68 /// The output which is reference by the given outpoint
73 /// A trait to describe an object which can get user secrets and key material.
74 pub trait KeysInterface: Send + Sync {
75 /// A type which implements ChannelKeys which will be returned by get_channel_keys.
76 type ChanKeySigner : ChannelKeys;
78 /// Get node secret key (aka node_id or network_key)
79 fn get_node_secret(&self) -> SecretKey;
80 /// Get destination redeemScript to encumber static protocol exit points.
81 fn get_destination_script(&self) -> Script;
82 /// Get shutdown_pubkey to use as PublicKey at channel closure
83 fn get_shutdown_pubkey(&self) -> PublicKey;
84 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
85 /// restarted with some stale data!
86 fn get_channel_keys(&self, inbound: bool) -> Self::ChanKeySigner;
87 /// Get a secret and PRNG seed for construting an onion packet
88 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
89 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
90 /// transaction is created, at which point they will use the outpoint in the funding
92 fn get_channel_id(&self) -> [u8; 32];
95 /// Set of lightning keys needed to operate a channel as described in BOLT 3.
97 /// If you're implementing a custom signer, you almost certainly want to implement
98 /// Readable/Writable to serialize out a unique reference to this set of keys so
99 /// that you can serialize the full ChannelManager object.
101 /// (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
102 /// to the possibility of reentrancy issues by calling the user's code during our deserialization
104 pub trait ChannelKeys : Send {
105 /// Gets the private key for the anchor tx
106 fn funding_key<'a>(&'a self) -> &'a SecretKey;
107 /// Gets the local secret key for blinded revocation pubkey
108 fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
109 /// Gets the local secret key used in commitment tx htlc outputs
110 fn payment_base_key<'a>(&'a self) -> &'a SecretKey;
111 /// Gets the local secret key used in HTLC tx
112 fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
113 /// Gets the local htlc secret key used in commitment tx htlc outputs
114 fn htlc_base_key<'a>(&'a self) -> &'a SecretKey;
115 /// Gets the commitment seed
116 fn commitment_seed<'a>(&'a self) -> &'a [u8; 32];
118 /// Create a signature for a remote commitment transaction and associated HTLC transactions.
120 /// Note that if signing fails or is rejected, the channel will be force-closed.
122 /// TODO: Document the things someone using this interface should enforce before signing.
123 /// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
124 /// making the callee generate it via some util function we expose)!
125 fn sign_remote_commitment<T: secp256k1::Signing>(&self, channel_value_satoshis: u64, channel_funding_script: &Script, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
129 /// A simple implementation of ChannelKeys that just keeps the private keys in memory.
130 pub struct InMemoryChannelKeys {
131 /// Private key of anchor tx
132 pub funding_key: SecretKey,
133 /// Local secret key for blinded revocation pubkey
134 pub revocation_base_key: SecretKey,
135 /// Local secret key used in commitment tx htlc outputs
136 pub payment_base_key: SecretKey,
137 /// Local secret key used in HTLC tx
138 pub delayed_payment_base_key: SecretKey,
139 /// Local htlc secret key used in commitment tx htlc outputs
140 pub htlc_base_key: SecretKey,
142 pub commitment_seed: [u8; 32],
145 impl ChannelKeys for InMemoryChannelKeys {
146 fn funding_key(&self) -> &SecretKey { &self.funding_key }
147 fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
148 fn payment_base_key(&self) -> &SecretKey { &self.payment_base_key }
149 fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
150 fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
151 fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
154 fn sign_remote_commitment<T: secp256k1::Signing>(&self, channel_value_satoshis: u64, channel_funding_script: &Script, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
155 if commitment_tx.input.len() != 1 { return Err(()); }
156 let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_script, channel_value_satoshis)[..]);
157 let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
159 let commitment_txid = commitment_tx.txid();
161 let mut htlc_sigs = Vec::with_capacity(htlcs.len());
162 for ref htlc in htlcs {
163 if let Some(_) = htlc.transaction_output_index {
164 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);
165 let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
166 let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
167 let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
169 Err(_) => return Err(()),
171 htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
175 Ok((commitment_sig, htlc_sigs))
179 impl_writeable!(InMemoryChannelKeys, 0, {
183 delayed_payment_base_key,
188 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
189 /// and derives keys from that.
191 /// Your node_id is seed/0'
192 /// ChannelMonitor closes may use seed/1'
193 /// Cooperative closes may use seed/2'
194 /// The two close keys may be needed to claim on-chain funds!
195 pub struct KeysManager {
196 secp_ctx: Secp256k1<secp256k1::SignOnly>,
197 node_secret: SecretKey,
198 destination_script: Script,
199 shutdown_pubkey: PublicKey,
200 channel_master_key: ExtendedPrivKey,
201 channel_child_index: AtomicUsize,
202 session_master_key: ExtendedPrivKey,
203 session_child_index: AtomicUsize,
204 channel_id_master_key: ExtendedPrivKey,
205 channel_id_child_index: AtomicUsize,
207 unique_start: Sha256State,
212 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
213 /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
214 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
215 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
216 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
217 /// simply use the current time (with very high precision).
219 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
220 /// obviously, starting_time should be unique every time you reload the library - it is only
221 /// used to generate new ephemeral key data (which will be stored by the individual channel if
224 /// Note that the seed is required to recover certain on-chain funds independent of
225 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
226 /// channel, and some on-chain during-closing funds.
228 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
229 /// versions. Once the library is more fully supported, the docs will be updated to include a
230 /// detailed description of the guarantee.
231 pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager {
232 let secp_ctx = Secp256k1::signing_only();
233 match ExtendedPrivKey::new_master(network.clone(), seed) {
235 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
236 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
237 Ok(destination_key) => {
238 let pubkey_hash160 = Hash160::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.key.serialize()[..]);
239 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
240 .push_slice(&pubkey_hash160.into_inner())
243 Err(_) => panic!("Your RNG is busted"),
245 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
246 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
247 Err(_) => panic!("Your RNG is busted"),
249 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
250 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
251 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
253 let mut unique_start = Sha256::engine();
254 unique_start.input(&byte_utils::be64_to_array(starting_time_secs));
255 unique_start.input(&byte_utils::be32_to_array(starting_time_nanos));
256 unique_start.input(seed);
264 channel_child_index: AtomicUsize::new(0),
266 session_child_index: AtomicUsize::new(0),
267 channel_id_master_key,
268 channel_id_child_index: AtomicUsize::new(0),
274 Err(_) => panic!("Your rng is busted"),
279 impl KeysInterface for KeysManager {
280 type ChanKeySigner = InMemoryChannelKeys;
282 fn get_node_secret(&self) -> SecretKey {
283 self.node_secret.clone()
286 fn get_destination_script(&self) -> Script {
287 self.destination_script.clone()
290 fn get_shutdown_pubkey(&self) -> PublicKey {
291 self.shutdown_pubkey.clone()
294 fn get_channel_keys(&self, _inbound: bool) -> InMemoryChannelKeys {
295 // We only seriously intend to rely on the channel_master_key for true secure
296 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
297 // starting_time provided in the constructor) to be unique.
298 let mut sha = self.unique_start.clone();
300 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
301 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");
302 sha.input(&child_privkey.private_key.key[..]);
304 let seed = Sha256::from_engine(sha).into_inner();
306 let commitment_seed = {
307 let mut sha = Sha256::engine();
309 sha.input(&b"commitment seed"[..]);
310 Sha256::from_engine(sha).into_inner()
312 macro_rules! key_step {
313 ($info: expr, $prev_key: expr) => {{
314 let mut sha = Sha256::engine();
316 sha.input(&$prev_key[..]);
317 sha.input(&$info[..]);
318 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
321 let funding_key = key_step!(b"funding key", commitment_seed);
322 let revocation_base_key = key_step!(b"revocation base key", funding_key);
323 let payment_base_key = key_step!(b"payment base key", revocation_base_key);
324 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key);
325 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
327 InMemoryChannelKeys {
331 delayed_payment_base_key,
337 fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
338 let mut sha = self.unique_start.clone();
340 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
341 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");
342 sha.input(&child_privkey.private_key.key[..]);
344 let mut rng_seed = sha.clone();
345 // Not exactly the most ideal construction, but the second value will get fed into
346 // ChaCha so it is another step harder to break.
347 rng_seed.input(b"RNG Seed Salt");
348 sha.input(b"Session Key Salt");
349 (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
350 Sha256::from_engine(rng_seed).into_inner())
353 fn get_channel_id(&self) -> [u8; 32] {
354 let mut sha = self.unique_start.clone();
356 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
357 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");
358 sha.input(&child_privkey.private_key.key[..]);
360 (Sha256::from_engine(sha).into_inner())