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::hash::Hash160;
10 use bitcoin::util::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber};
12 use secp256k1::key::{SecretKey, PublicKey};
13 use secp256k1::Secp256k1;
16 use crypto::hkdf::{hkdf_extract,hkdf_expand};
17 use crypto::digest::Digest;
19 use util::sha2::Sha256;
20 use util::logger::Logger;
24 use std::time::{SystemTime, UNIX_EPOCH};
26 use std::sync::atomic::{AtomicUsize, Ordering};
28 /// When on-chain outputs are created by rust-lightning an event is generated which informs the
29 /// user thereof. This enum describes the format of the output and provides the OutPoint.
30 pub enum SpendableOutputDescriptor {
31 /// Outpoint with an output to a script which was provided via KeysInterface, thus you should
32 /// have stored somewhere how to spend script_pubkey!
33 /// Outputs from a justice tx, claim tx or preimage tx
35 /// The outpoint spendable by user wallet
37 /// The output which is referenced by the given outpoint
40 /// Outpoint commits to a P2WSH
41 /// P2WSH should be spend by the following witness :
42 /// <local_delayedsig> 0 <witnessScript>
43 /// With input nSequence set to_self_delay.
44 /// Outputs from a HTLC-Success/Timeout tx/commitment tx
46 /// Outpoint spendable by user wallet
48 /// local_delayedkey = delayed_payment_basepoint_secret + SHA256(per_commitment_point || delayed_payment_basepoint) OR
50 /// witness redeemScript encumbering output.
51 witness_script: Script,
52 /// nSequence input must commit to self_delay to satisfy script's OP_CSV
54 /// The output which is referenced by the given outpoint
57 /// Outpoint commits to a P2WPKH
58 /// P2WPKH should be spend by the following witness :
59 /// <local_sig> <local_pubkey>
60 /// Outputs to_remote from a commitment tx
62 /// Outpoint spendable by user wallet
64 /// localkey = payment_basepoint_secret + SHA256(per_commitment_point || payment_basepoint
66 /// The output which is reference by the given outpoint
71 /// A trait to describe an object which can get user secrets and key material.
72 pub trait KeysInterface: Send + Sync {
73 /// Get node secret key (aka node_id or network_key)
74 fn get_node_secret(&self) -> SecretKey;
75 /// Get destination redeemScript to encumber static protocol exit points.
76 fn get_destination_script(&self) -> Script;
77 /// Get shutdown_pubkey to use as PublicKey at channel closure
78 fn get_shutdown_pubkey(&self) -> PublicKey;
79 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
80 /// restarted with some stale data!
81 fn get_channel_keys(&self, inbound: bool) -> ChannelKeys;
82 /// Get a secret for construting an onion packet
83 fn get_session_key(&self) -> SecretKey;
86 /// Set of lightning keys needed to operate a channel as described in BOLT 3
88 pub struct ChannelKeys {
89 /// Private key of anchor tx
90 pub funding_key: SecretKey,
91 /// Local secret key for blinded revocation pubkey
92 pub revocation_base_key: SecretKey,
93 /// Local secret key used in commitment tx htlc outputs
94 pub payment_base_key: SecretKey,
95 /// Local secret key used in HTLC tx
96 pub delayed_payment_base_key: SecretKey,
97 /// Local htlc secret key used in commitment tx htlc outputs
98 pub htlc_base_key: SecretKey,
100 pub commitment_seed: [u8; 32],
103 impl_writeable!(ChannelKeys, 0, {
107 delayed_payment_base_key,
113 /// Generate a set of lightning keys needed to operate a channel by HKDF-expanding a given
114 /// random 32-byte seed
115 pub fn new_from_seed(seed: &[u8; 32]) -> ChannelKeys {
116 let mut prk = [0; 32];
117 hkdf_extract(Sha256::new(), b"rust-lightning key gen salt", seed, &mut prk);
118 let secp_ctx = Secp256k1::without_caps();
120 let mut okm = [0; 32];
121 hkdf_expand(Sha256::new(), &prk, b"rust-lightning funding key info", &mut okm);
122 let funding_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
124 hkdf_expand(Sha256::new(), &prk, b"rust-lightning revocation base key info", &mut okm);
125 let revocation_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
127 hkdf_expand(Sha256::new(), &prk, b"rust-lightning payment base key info", &mut okm);
128 let payment_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
130 hkdf_expand(Sha256::new(), &prk, b"rust-lightning delayed payment base key info", &mut okm);
131 let delayed_payment_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
133 hkdf_expand(Sha256::new(), &prk, b"rust-lightning htlc base key info", &mut okm);
134 let htlc_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
136 hkdf_expand(Sha256::new(), &prk, b"rust-lightning local commitment seed info", &mut okm);
139 funding_key: funding_key,
140 revocation_base_key: revocation_base_key,
141 payment_base_key: payment_base_key,
142 delayed_payment_base_key: delayed_payment_base_key,
143 htlc_base_key: htlc_base_key,
149 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
150 /// and derives keys from that.
152 /// Your node_id is seed/0'
153 /// ChannelMonitor closes may use seed/1'
154 /// Cooperative closes may use seed/2'
155 /// The two close keys may be needed to claim on-chain funds!
156 pub struct KeysManager {
157 secp_ctx: Secp256k1<secp256k1::All>,
158 node_secret: SecretKey,
159 destination_script: Script,
160 shutdown_pubkey: PublicKey,
161 channel_master_key: ExtendedPrivKey,
162 channel_child_index: AtomicUsize,
163 session_master_key: ExtendedPrivKey,
164 session_child_index: AtomicUsize,
170 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
171 /// RNG is busted) this may panic.
172 pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>) -> KeysManager {
173 let secp_ctx = Secp256k1::new();
174 match ExtendedPrivKey::new_master(&secp_ctx, network.clone(), seed) {
176 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0)).expect("Your RNG is busted").secret_key;
177 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1)) {
178 Ok(destination_key) => {
179 let pubkey_hash160 = Hash160::from_data(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.serialize()[..]);
180 Builder::new().push_opcode(opcodes::All::OP_PUSHBYTES_0)
181 .push_slice(pubkey_hash160.as_bytes())
184 Err(_) => panic!("Your RNG is busted"),
186 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2)) {
187 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key,
188 Err(_) => panic!("Your RNG is busted"),
190 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3)).expect("Your RNG is busted");
191 let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4)).expect("Your RNG is busted");
198 channel_child_index: AtomicUsize::new(0),
200 session_child_index: AtomicUsize::new(0),
205 Err(_) => panic!("Your rng is busted"),
210 impl KeysInterface for KeysManager {
211 fn get_node_secret(&self) -> SecretKey {
212 self.node_secret.clone()
215 fn get_destination_script(&self) -> Script {
216 self.destination_script.clone()
219 fn get_shutdown_pubkey(&self) -> PublicKey {
220 self.shutdown_pubkey.clone()
223 fn get_channel_keys(&self, _inbound: bool) -> ChannelKeys {
224 // We only seriously intend to rely on the channel_master_key for true secure
225 // entropy, everything else just ensures uniqueness. We generally don't expect
226 // all clients to have non-broken RNGs here, so we also include the current
227 // time as a fallback to get uniqueness.
228 let mut sha = Sha256::new();
230 let mut seed = [0u8; 32];
231 rng::fill_bytes(&mut seed[..]);
234 let now = SystemTime::now().duration_since(UNIX_EPOCH).expect("Time went backwards");
235 sha.input(&byte_utils::be32_to_array(now.subsec_nanos()));
236 sha.input(&byte_utils::be64_to_array(now.as_secs()));
238 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
239 let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32)).expect("Your RNG is busted");
240 sha.input(&child_privkey.secret_key[..]);
242 sha.result(&mut seed);
243 ChannelKeys::new_from_seed(&seed)
246 fn get_session_key(&self) -> SecretKey {
247 let mut sha = Sha256::new();
248 let mut res = [0u8; 32];
250 let now = SystemTime::now().duration_since(UNIX_EPOCH).expect("Time went backwards");
251 sha.input(&byte_utils::be32_to_array(now.subsec_nanos()));
252 sha.input(&byte_utils::be64_to_array(now.as_secs()));
254 let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
255 let child_privkey = self.session_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32)).expect("Your RNG is busted");
256 sha.input(&child_privkey.secret_key[..]);
257 sha.result(&mut res);
258 SecretKey::from_slice(&self.secp_ctx, &res).expect("Your RNG is busted")