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::{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};
11 use bitcoin_hashes::{Hash, HashEngine};
12 use bitcoin_hashes::sha256::HashEngine as Sha256State;
13 use bitcoin_hashes::sha256::Hash as Sha256;
14 use bitcoin_hashes::hash160::Hash as Hash160;
16 use secp256k1::key::{SecretKey, PublicKey};
17 use secp256k1::Secp256k1;
21 use util::logger::Logger;
24 use std::sync::atomic::{AtomicUsize, Ordering};
26 /// When on-chain outputs are created by rust-lightning an event is generated which informs the
27 /// user thereof. This enum describes the format of the output and provides the OutPoint.
28 pub enum SpendableOutputDescriptor {
29 /// Outpoint with an output to a script which was provided via KeysInterface, thus you should
30 /// have stored somewhere how to spend script_pubkey!
31 /// Outputs from a justice tx, claim tx or preimage tx
33 /// The outpoint spendable by user wallet
35 /// The output which is referenced by the given outpoint
38 /// Outpoint commits to a P2WSH
39 /// P2WSH should be spend by the following witness :
40 /// <local_delayedsig> 0 <witnessScript>
41 /// With input nSequence set to_self_delay.
42 /// Outputs from a HTLC-Success/Timeout tx/commitment tx
44 /// Outpoint spendable by user wallet
46 /// local_delayedkey = delayed_payment_basepoint_secret + SHA256(per_commitment_point || delayed_payment_basepoint) OR
48 /// witness redeemScript encumbering output.
49 witness_script: Script,
50 /// nSequence input must commit to self_delay to satisfy script's OP_CSV
52 /// The output which is referenced by the given outpoint
55 /// Outpoint commits to a P2WPKH
56 /// P2WPKH should be spend by the following witness :
57 /// <local_sig> <local_pubkey>
58 /// Outputs to_remote from a commitment tx
60 /// Outpoint spendable by user wallet
62 /// localkey = payment_basepoint_secret + SHA256(per_commitment_point || payment_basepoint
64 /// The output which is reference by the given outpoint
69 /// A trait to describe an object which can get user secrets and key material.
70 pub trait KeysInterface: Send + Sync {
71 /// Get node secret key (aka node_id or network_key)
72 fn get_node_secret(&self) -> SecretKey;
73 /// Get destination redeemScript to encumber static protocol exit points.
74 fn get_destination_script(&self) -> Script;
75 /// Get shutdown_pubkey to use as PublicKey at channel closure
76 fn get_shutdown_pubkey(&self) -> PublicKey;
77 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
78 /// restarted with some stale data!
79 fn get_channel_keys(&self, inbound: bool) -> ChannelKeys;
80 /// Get a secret for construting an onion packet
81 fn get_session_key(&self) -> SecretKey;
82 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
83 /// transaction is created, at which point they will use the outpoint in the funding
85 fn get_channel_id(&self) -> [u8; 32];
88 /// Set of lightning keys needed to operate a channel as described in BOLT 3
90 pub struct ChannelKeys {
91 /// Private key of anchor tx
92 pub funding_key: SecretKey,
93 /// Local secret key for blinded revocation pubkey
94 pub revocation_base_key: SecretKey,
95 /// Local secret key used in commitment tx htlc outputs
96 pub payment_base_key: SecretKey,
97 /// Local secret key used in HTLC tx
98 pub delayed_payment_base_key: SecretKey,
99 /// Local htlc secret key used in commitment tx htlc outputs
100 pub htlc_base_key: SecretKey,
102 pub commitment_seed: [u8; 32],
105 impl_writeable!(ChannelKeys, 0, {
109 delayed_payment_base_key,
114 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
115 /// and derives keys from that.
117 /// Your node_id is seed/0'
118 /// ChannelMonitor closes may use seed/1'
119 /// Cooperative closes may use seed/2'
120 /// The two close keys may be needed to claim on-chain funds!
121 pub struct KeysManager {
122 secp_ctx: Secp256k1<secp256k1::SignOnly>,
123 node_secret: SecretKey,
124 destination_script: Script,
125 shutdown_pubkey: PublicKey,
126 channel_master_key: ExtendedPrivKey,
127 channel_child_index: AtomicUsize,
128 session_master_key: ExtendedPrivKey,
129 session_child_index: AtomicUsize,
130 channel_id_master_key: ExtendedPrivKey,
131 channel_id_child_index: AtomicUsize,
133 unique_start: Sha256State,
138 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
139 /// RNG is busted) this may panic (but more importantly, you will possibly lose funds).
140 /// starting_time isn't strictly required to actually be a time, but it must absolutely,
141 /// without a doubt, be unique to this instance. ie if you start multiple times with the same
142 /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to
143 /// simply use the current time (with very high precision).
145 /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however,
146 /// obviously, starting_time should be unique every time you reload the library - it is only
147 /// used to generate new ephemeral key data (which will be stored by the individual channel if
150 /// Note that the seed is required to recover certain on-chain funds independent of
151 /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any
152 /// channel, and some on-chain during-closing funds.
154 /// Note that until the 0.1 release there is no guarantee of backward compatibility between
155 /// versions. Once the library is more fully supported, the docs will be updated to include a
156 /// detailed description of the guarantee.
157 pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager {
158 let secp_ctx = Secp256k1::signing_only();
159 match ExtendedPrivKey::new_master(network.clone(), seed) {
161 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
162 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
163 Ok(destination_key) => {
164 let pubkey_hash160 = Hash160::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.key.serialize()[..]);
165 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
166 .push_slice(&pubkey_hash160.into_inner())
169 Err(_) => panic!("Your RNG is busted"),
171 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
172 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
173 Err(_) => panic!("Your RNG is busted"),
175 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
176 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
177 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
179 let mut unique_start = Sha256::engine();
180 unique_start.input(&byte_utils::be64_to_array(starting_time_secs));
181 unique_start.input(&byte_utils::be32_to_array(starting_time_nanos));
182 unique_start.input(seed);
190 channel_child_index: AtomicUsize::new(0),
192 session_child_index: AtomicUsize::new(0),
193 channel_id_master_key,
194 channel_id_child_index: AtomicUsize::new(0),
200 Err(_) => panic!("Your rng is busted"),
205 impl KeysInterface for KeysManager {
206 fn get_node_secret(&self) -> SecretKey {
207 self.node_secret.clone()
210 fn get_destination_script(&self) -> Script {
211 self.destination_script.clone()
214 fn get_shutdown_pubkey(&self) -> PublicKey {
215 self.shutdown_pubkey.clone()
218 fn get_channel_keys(&self, _inbound: bool) -> ChannelKeys {
219 // We only seriously intend to rely on the channel_master_key for true secure
220 // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
221 // starting_time provided in the constructor) to be unique.
222 let mut sha = self.unique_start.clone();
224 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
225 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");
226 sha.input(&child_privkey.private_key.key[..]);
228 let seed = Sha256::from_engine(sha).into_inner();
230 let commitment_seed = {
231 let mut sha = Sha256::engine();
233 sha.input(&b"commitment seed"[..]);
234 Sha256::from_engine(sha).into_inner()
236 macro_rules! key_step {
237 ($info: expr, $prev_key: expr) => {{
238 let mut sha = Sha256::engine();
240 sha.input(&$prev_key[..]);
241 sha.input(&$info[..]);
242 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
245 let funding_key = key_step!(b"funding key", commitment_seed);
246 let revocation_base_key = key_step!(b"revocation base key", funding_key);
247 let payment_base_key = key_step!(b"payment base key", revocation_base_key);
248 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key);
249 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
255 delayed_payment_base_key,
261 fn get_session_key(&self) -> SecretKey {
262 let mut sha = self.unique_start.clone();
264 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
265 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");
266 sha.input(&child_privkey.private_key.key[..]);
267 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted")
270 fn get_channel_id(&self) -> [u8; 32] {
271 let mut sha = self.unique_start.clone();
273 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
274 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");
275 sha.input(&child_privkey.private_key.key[..]);
277 (Sha256::from_engine(sha).into_inner())