//! spendable on-chain outputs which the user owns and is responsible for using just as any other
//! on-chain output which is theirs.
-use bitcoin::blockdata::transaction::{OutPoint, TxOut};
+use bitcoin::blockdata::transaction::{Transaction, OutPoint, TxOut};
use bitcoin::blockdata::script::{Script, Builder};
use bitcoin::blockdata::opcodes;
use bitcoin::network::constants::Network;
use bitcoin::util::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber};
+use bitcoin::util::bip143;
use bitcoin_hashes::{Hash, HashEngine};
use bitcoin_hashes::sha256::HashEngine as Sha256State;
use bitcoin_hashes::sha256::Hash as Sha256;
+use bitcoin_hashes::sha256d::Hash as Sha256dHash;
use bitcoin_hashes::hash160::Hash as Hash160;
use secp256k1::key::{SecretKey, PublicKey};
-use secp256k1::Secp256k1;
+use secp256k1::{Secp256k1, Signature, Signing};
use secp256k1;
use util::byte_utils;
use util::logger::Logger;
+use util::ser::{Writeable, Writer, Readable};
+
+use ln::chan_utils;
+use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys};
+use ln::msgs;
use std::sync::Arc;
use std::sync::atomic::{AtomicUsize, Ordering};
+use std::io::Error;
+use ln::msgs::DecodeError;
-/// When on-chain outputs are created by rust-lightning an event is generated which informs the
-/// user thereof. This enum describes the format of the output and provides the OutPoint.
+/// When on-chain outputs are created by rust-lightning (which our counterparty is not able to
+/// claim at any point in the future) an event is generated which you must track and be able to
+/// spend on-chain. The information needed to do this is provided in this enum, including the
+/// outpoint describing which txid and output index is available, the full output which exists at
+/// that txid/index, and any keys or other information required to sign.
pub enum SpendableOutputDescriptor {
- /// Outpoint with an output to a script which was provided via KeysInterface, thus you should
- /// have stored somewhere how to spend script_pubkey!
- /// Outputs from a justice tx, claim tx or preimage tx
+ /// An output to a script which was provided via KeysInterface, thus you should already know
+ /// how to spend it. No keys are provided as rust-lightning was never given any keys - only the
+ /// script_pubkey as it appears in the output.
+ /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC
+ /// on-chain using the payment preimage or after it has timed out.
StaticOutput {
- /// The outpoint spendable by user wallet
+ /// The outpoint which is spendable
outpoint: OutPoint,
- /// The output which is referenced by the given outpoint
+ /// The output which is referenced by the given outpoint.
output: TxOut,
},
- /// Outpoint commits to a P2WSH
- /// P2WSH should be spend by the following witness :
- /// <local_delayedsig> 0 <witnessScript>
- /// With input nSequence set to_self_delay.
- /// Outputs from a HTLC-Success/Timeout tx/commitment tx
+ /// An output to a P2WSH script which can be spent with a single signature after a CSV delay.
+ /// The private key which should be used to sign the transaction is provided, as well as the
+ /// full witness redeemScript which is hashed in the output script_pubkey.
+ /// The witness in the spending input should be:
+ /// <BIP 143 signature generated with the given key> <one zero byte aka OP_0>
+ /// <witness_script as provided>
+ /// Note that the nSequence field in the input must be set to_self_delay (which corresponds to
+ /// the transaction not being broadcastable until at least to_self_delay blocks after the input
+ /// confirms).
+ /// These are generally the result of a "revocable" output to us, spendable only by us unless
+ /// it is an output from us having broadcast an old state (which should never happen).
DynamicOutputP2WSH {
- /// Outpoint spendable by user wallet
+ /// The outpoint which is spendable
outpoint: OutPoint,
- /// local_delayedkey = delayed_payment_basepoint_secret + SHA256(per_commitment_point || delayed_payment_basepoint) OR
+ /// The secret key which must be used to sign the spending transaction
key: SecretKey,
- /// witness redeemScript encumbering output.
+ /// The witness redeemScript which is hashed to create the script_pubkey in the given output
witness_script: Script,
- /// nSequence input must commit to self_delay to satisfy script's OP_CSV
+ /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in
+ /// the witness_script.
to_self_delay: u16,
/// The output which is referenced by the given outpoint
output: TxOut,
},
- /// Outpoint commits to a P2WPKH
- /// P2WPKH should be spend by the following witness :
- /// <local_sig> <local_pubkey>
- /// Outputs to_remote from a commitment tx
+ /// An output to a P2WPKH, spendable exclusively by the given private key.
+ /// The witness in the spending input, is, thus, simply:
+ /// <BIP 143 signature generated with the given key> <public key derived from the given key>
+ /// These are generally the result of our counterparty having broadcast the current state,
+ /// allowing us to claim the non-HTLC-encumbered outputs immediately.
DynamicOutputP2WPKH {
- /// Outpoint spendable by user wallet
+ /// The outpoint which is spendable
outpoint: OutPoint,
- /// localkey = payment_basepoint_secret + SHA256(per_commitment_point || payment_basepoint
+ /// The secret key which must be used to sign the spending transaction
key: SecretKey,
/// The output which is reference by the given outpoint
output: TxOut,
/// A trait to describe an object which can get user secrets and key material.
pub trait KeysInterface: Send + Sync {
+ /// A type which implements ChannelKeys which will be returned by get_channel_keys.
+ type ChanKeySigner : ChannelKeys;
+
/// Get node secret key (aka node_id or network_key)
fn get_node_secret(&self) -> SecretKey;
/// Get destination redeemScript to encumber static protocol exit points.
fn get_shutdown_pubkey(&self) -> PublicKey;
/// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
/// restarted with some stale data!
- fn get_channel_keys(&self, inbound: bool) -> ChannelKeys;
- /// Get a secret for construting an onion packet
- fn get_session_key(&self) -> SecretKey;
+ fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner;
+ /// Get a secret and PRNG seed for construting an onion packet
+ fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
/// Get a unique temporary channel id. Channels will be referred to by this until the funding
/// transaction is created, at which point they will use the outpoint in the funding
/// transaction.
fn get_channel_id(&self) -> [u8; 32];
}
-/// Set of lightning keys needed to operate a channel as described in BOLT 3
+/// Set of lightning keys needed to operate a channel as described in BOLT 3.
+///
+/// Signing services could be implemented on a hardware wallet. In this case,
+/// the current ChannelKeys would be a front-end on top of a communication
+/// channel connected to your secure device and lightning key material wouldn't
+/// reside on a hot server. Nevertheless, a this deployment would still need
+/// to trust the ChannelManager to avoid loss of funds as this latest component
+/// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
+///
+/// A more secure iteration would be to use hashlock (or payment points) to pair
+/// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
+/// at the price of more state and computation on the hardware wallet side. In the future,
+/// we are looking forward to design such interface.
+///
+/// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
+/// to act, as liveness and breach reply correctness are always going to be hard requirements
+/// of LN security model, orthogonal of key management issues.
+///
+/// If you're implementing a custom signer, you almost certainly want to implement
+/// Readable/Writable to serialize out a unique reference to this set of keys so
+/// that you can serialize the full ChannelManager object.
+///
+/// (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
+/// to the possibility of reentrancy issues by calling the user's code during our deserialization
+/// routine).
+/// TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create
+/// ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors.
+pub trait ChannelKeys : Send+Clone {
+ /// Gets the private key for the anchor tx
+ fn funding_key<'a>(&'a self) -> &'a SecretKey;
+ /// Gets the local secret key for blinded revocation pubkey
+ fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
+ /// Gets the local secret key used in to_remote output of remote commitment tx
+ /// (and also as part of obscured commitment number)
+ fn payment_base_key<'a>(&'a self) -> &'a SecretKey;
+ /// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output
+ fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
+ /// Gets the local htlc secret key used in commitment tx htlc outputs
+ fn htlc_base_key<'a>(&'a self) -> &'a SecretKey;
+ /// Gets the commitment seed
+ fn commitment_seed<'a>(&'a self) -> &'a [u8; 32];
+ /// Gets the local channel public keys and basepoints
+ fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys;
+
+ /// Create a signature for a remote commitment transaction and associated HTLC transactions.
+ ///
+ /// Note that if signing fails or is rejected, the channel will be force-closed.
+ ///
+ /// TODO: Document the things someone using this interface should enforce before signing.
+ /// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
+ /// making the callee generate it via some util function we expose)!
+ fn sign_remote_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
+
+ /// Create a signature for a (proposed) closing transaction.
+ ///
+ /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
+ /// chosen to forgo their output as dust.
+ fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
+
+ /// Signs a channel announcement message with our funding key, proving it comes from one
+ /// of the channel participants.
+ ///
+ /// Note that if this fails or is rejected, the channel will not be publicly announced and
+ /// our counterparty may (though likely will not) close the channel on us for violating the
+ /// protocol.
+ fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
+
+ /// Set the remote channel basepoints. This is done immediately on incoming channels
+ /// and as soon as the channel is accepted on outgoing channels.
+ ///
+ /// Will be called before any signatures are applied.
+ fn set_remote_channel_pubkeys(&mut self, channel_points: &ChannelPublicKeys);
+}
+
#[derive(Clone)]
-pub struct ChannelKeys {
+/// A simple implementation of ChannelKeys that just keeps the private keys in memory.
+pub struct InMemoryChannelKeys {
/// Private key of anchor tx
- pub funding_key: SecretKey,
+ funding_key: SecretKey,
/// Local secret key for blinded revocation pubkey
- pub revocation_base_key: SecretKey,
+ revocation_base_key: SecretKey,
/// Local secret key used in commitment tx htlc outputs
- pub payment_base_key: SecretKey,
+ payment_base_key: SecretKey,
/// Local secret key used in HTLC tx
- pub delayed_payment_base_key: SecretKey,
+ delayed_payment_base_key: SecretKey,
/// Local htlc secret key used in commitment tx htlc outputs
- pub htlc_base_key: SecretKey,
+ htlc_base_key: SecretKey,
/// Commitment seed
- pub commitment_seed: [u8; 32],
+ commitment_seed: [u8; 32],
+ /// Local public keys and basepoints
+ pub(crate) local_channel_pubkeys: ChannelPublicKeys,
+ /// Remote public keys and base points
+ pub(crate) remote_channel_pubkeys: Option<ChannelPublicKeys>,
+ /// The total value of this channel
+ channel_value_satoshis: u64,
+}
+
+impl InMemoryChannelKeys {
+ /// Create a new InMemoryChannelKeys
+ pub fn new<C: Signing>(
+ secp_ctx: &Secp256k1<C>,
+ funding_key: SecretKey,
+ revocation_base_key: SecretKey,
+ payment_base_key: SecretKey,
+ delayed_payment_base_key: SecretKey,
+ htlc_base_key: SecretKey,
+ commitment_seed: [u8; 32],
+ channel_value_satoshis: u64) -> InMemoryChannelKeys {
+ let local_channel_pubkeys =
+ InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key,
+ &payment_base_key, &delayed_payment_base_key,
+ &htlc_base_key);
+ InMemoryChannelKeys {
+ funding_key,
+ revocation_base_key,
+ payment_base_key,
+ delayed_payment_base_key,
+ htlc_base_key,
+ commitment_seed,
+ channel_value_satoshis,
+ local_channel_pubkeys,
+ remote_channel_pubkeys: None,
+ }
+ }
+
+ fn make_local_keys<C: Signing>(secp_ctx: &Secp256k1<C>,
+ funding_key: &SecretKey,
+ revocation_base_key: &SecretKey,
+ payment_base_key: &SecretKey,
+ delayed_payment_base_key: &SecretKey,
+ htlc_base_key: &SecretKey) -> ChannelPublicKeys {
+ let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s);
+ ChannelPublicKeys {
+ funding_pubkey: from_secret(&funding_key),
+ revocation_basepoint: from_secret(&revocation_base_key),
+ payment_basepoint: from_secret(&payment_base_key),
+ delayed_payment_basepoint: from_secret(&delayed_payment_base_key),
+ htlc_basepoint: from_secret(&htlc_base_key),
+ }
+ }
+}
+
+impl ChannelKeys for InMemoryChannelKeys {
+ fn funding_key(&self) -> &SecretKey { &self.funding_key }
+ fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
+ fn payment_base_key(&self) -> &SecretKey { &self.payment_base_key }
+ fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
+ fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
+ fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
+ fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { &self.local_channel_pubkeys }
+
+ fn sign_remote_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
+ if commitment_tx.input.len() != 1 { return Err(()); }
+
+ let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
+ let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
+ let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
+
+ let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
+ let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
+
+ let commitment_txid = commitment_tx.txid();
+
+ let mut htlc_sigs = Vec::with_capacity(htlcs.len());
+ for ref htlc in htlcs {
+ if let Some(_) = htlc.transaction_output_index {
+ 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);
+ let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
+ let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
+ let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
+ Ok(s) => s,
+ Err(_) => return Err(()),
+ };
+ htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
+ }
+ }
+
+ Ok((commitment_sig, htlc_sigs))
+ }
+
+ fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
+ if closing_tx.input.len() != 1 { return Err(()); }
+ if closing_tx.input[0].witness.len() != 0 { return Err(()); }
+ if closing_tx.output.len() > 2 { return Err(()); }
+
+ let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing");
+ let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
+ let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey);
+
+ let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
+ .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]);
+ Ok(secp_ctx.sign(&sighash, &self.funding_key))
+ }
+
+ fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
+ let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]);
+ Ok(secp_ctx.sign(&msghash, &self.funding_key))
+ }
+
+ fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) {
+ assert!(self.remote_channel_pubkeys.is_none(), "Already set remote channel pubkeys");
+ self.remote_channel_pubkeys = Some(channel_pubkeys.clone());
+ }
}
-impl_writeable!(ChannelKeys, 0, {
- funding_key,
- revocation_base_key,
- payment_base_key,
- delayed_payment_base_key,
- htlc_base_key,
- commitment_seed
-});
+impl Writeable for InMemoryChannelKeys {
+ fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
+ self.funding_key.write(writer)?;
+ self.revocation_base_key.write(writer)?;
+ self.payment_base_key.write(writer)?;
+ self.delayed_payment_base_key.write(writer)?;
+ self.htlc_base_key.write(writer)?;
+ self.commitment_seed.write(writer)?;
+ self.remote_channel_pubkeys.write(writer)?;
+ self.channel_value_satoshis.write(writer)?;
+
+ Ok(())
+ }
+}
+
+impl<R: ::std::io::Read> Readable<R> for InMemoryChannelKeys {
+ fn read(reader: &mut R) -> Result<Self, DecodeError> {
+ let funding_key = Readable::read(reader)?;
+ let revocation_base_key = Readable::read(reader)?;
+ let payment_base_key = Readable::read(reader)?;
+ let delayed_payment_base_key = Readable::read(reader)?;
+ let htlc_base_key = Readable::read(reader)?;
+ let commitment_seed = Readable::read(reader)?;
+ let remote_channel_pubkeys = Readable::read(reader)?;
+ let channel_value_satoshis = Readable::read(reader)?;
+ let secp_ctx = Secp256k1::signing_only();
+ let local_channel_pubkeys =
+ InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key,
+ &payment_base_key, &delayed_payment_base_key,
+ &htlc_base_key);
+
+ Ok(InMemoryChannelKeys {
+ funding_key,
+ revocation_base_key,
+ payment_base_key,
+ delayed_payment_base_key,
+ htlc_base_key,
+ commitment_seed,
+ channel_value_satoshis,
+ local_channel_pubkeys,
+ remote_channel_pubkeys
+ })
+ }
+}
/// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
/// and derives keys from that.
}
impl KeysInterface for KeysManager {
+ type ChanKeySigner = InMemoryChannelKeys;
+
fn get_node_secret(&self) -> SecretKey {
self.node_secret.clone()
}
self.shutdown_pubkey.clone()
}
- fn get_channel_keys(&self, _inbound: bool) -> ChannelKeys {
+ fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys {
// We only seriously intend to rely on the channel_master_key for true secure
// entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
// starting_time provided in the constructor) to be unique.
let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key);
let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
- ChannelKeys {
+ InMemoryChannelKeys::new(
+ &self.secp_ctx,
funding_key,
revocation_base_key,
payment_base_key,
delayed_payment_base_key,
htlc_base_key,
commitment_seed,
- }
+ channel_value_satoshis
+ )
}
- fn get_session_key(&self) -> SecretKey {
+ fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
let mut sha = self.unique_start.clone();
let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
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");
sha.input(&child_privkey.private_key.key[..]);
- SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted")
+
+ let mut rng_seed = sha.clone();
+ // Not exactly the most ideal construction, but the second value will get fed into
+ // ChaCha so it is another step harder to break.
+ rng_seed.input(b"RNG Seed Salt");
+ sha.input(b"Session Key Salt");
+ (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
+ Sha256::from_engine(rng_seed).into_inner())
}
fn get_channel_id(&self) -> [u8; 32] {