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::Hash as Sha256;
13 use bitcoin_hashes::hash160::Hash as Hash160;
15 use secp256k1::key::{SecretKey, PublicKey};
16 use secp256k1::Secp256k1;
19 use util::logger::Logger;
23 use std::time::{SystemTime, UNIX_EPOCH};
25 use std::sync::atomic::{AtomicUsize, Ordering};
27 /// When on-chain outputs are created by rust-lightning an event is generated which informs the
28 /// user thereof. This enum describes the format of the output and provides the OutPoint.
29 pub enum SpendableOutputDescriptor {
30 /// Outpoint with an output to a script which was provided via KeysInterface, thus you should
31 /// have stored somewhere how to spend script_pubkey!
32 /// Outputs from a justice tx, claim tx or preimage tx
34 /// The outpoint spendable by user wallet
36 /// The output which is referenced by the given outpoint
39 /// Outpoint commits to a P2WSH
40 /// P2WSH should be spend by the following witness :
41 /// <local_delayedsig> 0 <witnessScript>
42 /// With input nSequence set to_self_delay.
43 /// Outputs from a HTLC-Success/Timeout tx/commitment tx
45 /// Outpoint spendable by user wallet
47 /// local_delayedkey = delayed_payment_basepoint_secret + SHA256(per_commitment_point || delayed_payment_basepoint) OR
49 /// witness redeemScript encumbering output.
50 witness_script: Script,
51 /// nSequence input must commit to self_delay to satisfy script's OP_CSV
53 /// The output which is referenced by the given outpoint
56 /// Outpoint commits to a P2WPKH
57 /// P2WPKH should be spend by the following witness :
58 /// <local_sig> <local_pubkey>
59 /// Outputs to_remote from a commitment tx
61 /// Outpoint spendable by user wallet
63 /// localkey = payment_basepoint_secret + SHA256(per_commitment_point || payment_basepoint
65 /// The output which is reference by the given outpoint
70 /// A trait to describe an object which can get user secrets and key material.
71 pub trait KeysInterface: Send + Sync {
72 /// Get node secret key (aka node_id or network_key)
73 fn get_node_secret(&self) -> SecretKey;
74 /// Get destination redeemScript to encumber static protocol exit points.
75 fn get_destination_script(&self) -> Script;
76 /// Get shutdown_pubkey to use as PublicKey at channel closure
77 fn get_shutdown_pubkey(&self) -> PublicKey;
78 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
79 /// restarted with some stale data!
80 fn get_channel_keys(&self, inbound: bool) -> ChannelKeys;
81 /// Get a secret for construting an onion packet
82 fn get_session_key(&self) -> SecretKey;
83 /// Get a unique temporary channel id. Channels will be referred to by this until the funding
84 /// transaction is created, at which point they will use the outpoint in the funding
86 fn get_channel_id(&self) -> [u8; 32];
89 /// Set of lightning keys needed to operate a channel as described in BOLT 3
91 pub struct ChannelKeys {
92 /// Private key of anchor tx
93 pub funding_key: SecretKey,
94 /// Local secret key for blinded revocation pubkey
95 pub revocation_base_key: SecretKey,
96 /// Local secret key used in commitment tx htlc outputs
97 pub payment_base_key: SecretKey,
98 /// Local secret key used in HTLC tx
99 pub delayed_payment_base_key: SecretKey,
100 /// Local htlc secret key used in commitment tx htlc outputs
101 pub htlc_base_key: SecretKey,
103 pub commitment_seed: [u8; 32],
106 impl_writeable!(ChannelKeys, 0, {
110 delayed_payment_base_key,
115 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
116 /// and derives keys from that.
118 /// Your node_id is seed/0'
119 /// ChannelMonitor closes may use seed/1'
120 /// Cooperative closes may use seed/2'
121 /// The two close keys may be needed to claim on-chain funds!
122 pub struct KeysManager {
123 secp_ctx: Secp256k1<secp256k1::SignOnly>,
124 node_secret: SecretKey,
125 destination_script: Script,
126 shutdown_pubkey: PublicKey,
127 channel_master_key: ExtendedPrivKey,
128 channel_child_index: AtomicUsize,
129 session_master_key: ExtendedPrivKey,
130 session_child_index: AtomicUsize,
131 channel_id_master_key: ExtendedPrivKey,
132 channel_id_child_index: AtomicUsize,
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.
140 pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>) -> KeysManager {
141 let secp_ctx = Secp256k1::signing_only();
142 match ExtendedPrivKey::new_master(network.clone(), seed) {
144 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key;
145 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) {
146 Ok(destination_key) => {
147 let pubkey_hash160 = Hash160::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.key.serialize()[..]);
148 Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
149 .push_slice(&pubkey_hash160.into_inner())
152 Err(_) => panic!("Your RNG is busted"),
154 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2).unwrap()) {
155 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key.key,
156 Err(_) => panic!("Your RNG is busted"),
158 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted");
159 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted");
160 let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted");
167 channel_child_index: AtomicUsize::new(0),
169 session_child_index: AtomicUsize::new(0),
170 channel_id_master_key,
171 channel_id_child_index: AtomicUsize::new(0),
176 Err(_) => panic!("Your rng is busted"),
181 impl KeysInterface for KeysManager {
182 fn get_node_secret(&self) -> SecretKey {
183 self.node_secret.clone()
186 fn get_destination_script(&self) -> Script {
187 self.destination_script.clone()
190 fn get_shutdown_pubkey(&self) -> PublicKey {
191 self.shutdown_pubkey.clone()
194 fn get_channel_keys(&self, _inbound: bool) -> ChannelKeys {
195 // We only seriously intend to rely on the channel_master_key for true secure
196 // entropy, everything else just ensures uniqueness. We generally don't expect
197 // all clients to have non-broken RNGs here, so we also include the current
198 // time as a fallback to get uniqueness.
199 let mut sha = Sha256::engine();
201 let mut seed = [0u8; 32];
202 rng::fill_bytes(&mut seed[..]);
205 let now = SystemTime::now().duration_since(UNIX_EPOCH).expect("Time went backwards");
206 sha.input(&byte_utils::be32_to_array(now.subsec_nanos()));
207 sha.input(&byte_utils::be64_to_array(now.as_secs()));
209 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
210 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");
211 sha.input(&child_privkey.private_key.key[..]);
213 seed = Sha256::from_engine(sha).into_inner();
215 let commitment_seed = {
216 let mut sha = Sha256::engine();
218 sha.input(&b"commitment seed"[..]);
219 Sha256::from_engine(sha).into_inner()
221 macro_rules! key_step {
222 ($info: expr, $prev_key: expr) => {{
223 let mut sha = Sha256::engine();
225 sha.input(&$prev_key[..]);
226 sha.input(&$info[..]);
227 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("SHA-256 is busted")
230 let funding_key = key_step!(b"funding key", commitment_seed);
231 let revocation_base_key = key_step!(b"revocation base key", funding_key);
232 let payment_base_key = key_step!(b"payment base key", revocation_base_key);
233 let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key);
234 let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
240 delayed_payment_base_key,
246 fn get_session_key(&self) -> SecretKey {
247 let mut sha = Sha256::engine();
249 let now = SystemTime::now().duration_since(UNIX_EPOCH).expect("Time went backwards");
250 sha.input(&byte_utils::be32_to_array(now.subsec_nanos()));
251 sha.input(&byte_utils::be64_to_array(now.as_secs()));
253 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
254 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");
255 sha.input(&child_privkey.private_key.key[..]);
256 SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted")
259 fn get_channel_id(&self) -> [u8; 32] {
260 let mut sha = Sha256::engine();
262 let now = SystemTime::now().duration_since(UNIX_EPOCH).expect("Time went backwards");
263 sha.input(&byte_utils::be32_to_array(now.subsec_nanos()));
264 sha.input(&byte_utils::be64_to_array(now.as_secs()));
266 let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel);
267 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");
268 sha.input(&child_privkey.private_key.key[..]);
270 (Sha256::from_engine(sha).into_inner())