//! 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};
use secp256k1;
use util::byte_utils;
use util::logger::Logger;
+use util::ser::Writeable;
+
+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};
-/// 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,
/// 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.
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 commitment tx htlc outputs
+ /// 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 tx
+ /// 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];
+
+ /// 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, channel_value_satoshis: u64, 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, channel_value_satoshis: u64, channel_funding_redeemscript: &Script, 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 htlc_base_key: SecretKey,
/// Commitment seed
pub commitment_seed: [u8; 32],
+ /// Remote funding pubkey
+ pub remote_channel_pubkeys: Option<ChannelPublicKeys>,
}
impl ChannelKeys for InMemoryChannelKeys {
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 sign_remote_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, channel_value_satoshis: u64, 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, 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, channel_value_satoshis: u64, channel_funding_redeemscript: &Script, 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 sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx)
+ .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, 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!(InMemoryChannelKeys, 0, {
payment_base_key,
delayed_payment_base_key,
htlc_base_key,
- commitment_seed
+ commitment_seed,
+ remote_channel_pubkeys
});
/// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key
delayed_payment_base_key,
htlc_base_key,
commitment_seed,
+ remote_channel_pubkeys: None,
}
}
projects / rust-lightning / blobdiff