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, 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
45 /// Outpoint spendable by user wallet
47 /// local_delayedkey = delayed_payment_basepoint_secret + SHA256(per_commitment_point || delayed_payment_basepoint)
48 local_delayedkey: SecretKey,
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
58 /// A trait to describe an object which can get user secrets and key material.
59 pub trait KeysInterface: Send + Sync {
60 /// Get node secret key (aka node_id or network_key)
61 fn get_node_secret(&self) -> SecretKey;
62 /// Get destination redeemScript to encumber static protocol exit points.
63 fn get_destination_script(&self) -> Script;
64 /// Get shutdown_pubkey to use as PublicKey at channel closure
65 fn get_shutdown_pubkey(&self) -> PublicKey;
66 /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
67 /// restarted with some stale data!
68 fn get_channel_keys(&self, inbound: bool) -> ChannelKeys;
71 /// Set of lightning keys needed to operate a channel as described in BOLT 3
73 pub struct ChannelKeys {
74 /// Private key of anchor tx
75 pub funding_key: SecretKey,
76 /// Local secret key for blinded revocation pubkey
77 pub revocation_base_key: SecretKey,
78 /// Local secret key used in commitment tx htlc outputs
79 pub payment_base_key: SecretKey,
80 /// Local secret key used in HTLC tx
81 pub delayed_payment_base_key: SecretKey,
82 /// Local htlc secret key used in commitment tx htlc outputs
83 pub htlc_base_key: SecretKey,
85 pub commitment_seed: [u8; 32],
88 impl_writeable!(ChannelKeys, 0, {
92 delayed_payment_base_key,
98 /// Generate a set of lightning keys needed to operate a channel by HKDF-expanding a given
99 /// random 32-byte seed
100 pub fn new_from_seed(seed: &[u8; 32]) -> ChannelKeys {
101 let mut prk = [0; 32];
102 hkdf_extract(Sha256::new(), b"rust-lightning key gen salt", seed, &mut prk);
103 let secp_ctx = Secp256k1::without_caps();
105 let mut okm = [0; 32];
106 hkdf_expand(Sha256::new(), &prk, b"rust-lightning funding key info", &mut okm);
107 let funding_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
109 hkdf_expand(Sha256::new(), &prk, b"rust-lightning revocation base key info", &mut okm);
110 let revocation_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
112 hkdf_expand(Sha256::new(), &prk, b"rust-lightning payment base key info", &mut okm);
113 let payment_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
115 hkdf_expand(Sha256::new(), &prk, b"rust-lightning delayed payment base key info", &mut okm);
116 let delayed_payment_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
118 hkdf_expand(Sha256::new(), &prk, b"rust-lightning htlc base key info", &mut okm);
119 let htlc_base_key = SecretKey::from_slice(&secp_ctx, &okm).expect("Sha256 is broken");
121 hkdf_expand(Sha256::new(), &prk, b"rust-lightning local commitment seed info", &mut okm);
124 funding_key: funding_key,
125 revocation_base_key: revocation_base_key,
126 payment_base_key: payment_base_key,
127 delayed_payment_base_key: delayed_payment_base_key,
128 htlc_base_key: htlc_base_key,
134 /// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
135 /// and derives keys from that.
137 /// Your node_id is seed/0'
138 /// ChannelMonitor closes may use seed/1'
139 /// Cooperative closes may use seed/2'
140 /// The two close keys may be needed to claim on-chain funds!
141 pub struct KeysManager {
142 secp_ctx: Secp256k1<secp256k1::All>,
143 node_secret: SecretKey,
144 destination_script: Script,
145 shutdown_pubkey: PublicKey,
146 channel_master_key: ExtendedPrivKey,
147 channel_child_index: AtomicUsize,
153 /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your
154 /// RNG is busted) this may panic.
155 pub fn new(seed: &[u8; 32], network: Network, logger: Arc<Logger>) -> KeysManager {
156 let secp_ctx = Secp256k1::new();
157 match ExtendedPrivKey::new_master(&secp_ctx, network.clone(), seed) {
159 let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0)).expect("Your RNG is busted").secret_key;
160 let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1)) {
161 Ok(destination_key) => {
162 let pubkey_hash160 = Hash160::from_data(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.serialize()[..]);
163 Builder::new().push_opcode(opcodes::All::OP_PUSHBYTES_0)
164 .push_slice(pubkey_hash160.as_bytes())
167 Err(_) => panic!("Your RNG is busted"),
169 let shutdown_pubkey = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(2)) {
170 Ok(shutdown_key) => ExtendedPubKey::from_private(&secp_ctx, &shutdown_key).public_key,
171 Err(_) => panic!("Your RNG is busted"),
173 let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3)).expect("Your RNG is busted");
180 channel_child_index: AtomicUsize::new(0),
185 Err(_) => panic!("Your rng is busted"),
190 impl KeysInterface for KeysManager {
191 fn get_node_secret(&self) -> SecretKey {
192 self.node_secret.clone()
195 fn get_destination_script(&self) -> Script {
196 self.destination_script.clone()
199 fn get_shutdown_pubkey(&self) -> PublicKey {
200 self.shutdown_pubkey.clone()
203 fn get_channel_keys(&self, _inbound: bool) -> ChannelKeys {
204 // We only seriously intend to rely on the channel_master_key for true secure
205 // entropy, everything else just ensures uniqueness. We generally don't expect
206 // all clients to have non-broken RNGs here, so we also include the current
207 // time as a fallback to get uniqueness.
208 let mut sha = Sha256::new();
210 let mut seed = [0u8; 32];
211 rng::fill_bytes(&mut seed[..]);
214 let now = SystemTime::now().duration_since(UNIX_EPOCH).expect("Time went backwards");
215 sha.input(&byte_utils::be32_to_array(now.subsec_nanos()));
216 sha.input(&byte_utils::be64_to_array(now.as_secs()));
218 let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
219 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");
220 sha.input(&child_privkey.secret_key[..]);
222 sha.result(&mut seed);
223 ChannelKeys::new_from_seed(&seed)