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Merge pull request #2748 from TheBlueMatt/2023-11-2675-followups

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Doc and style followups from #2675
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Matt Corallo 2024-01-09 23:22:48 +00:00 • committed by GitHub
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2 changed files with 142 additions and 143 deletions
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2
lightning/src/ln/channel.rs
View file

@ -1833,8 +1833,6 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider {
/// will sign and send to our counterparty. /// will sign and send to our counterparty.
/// If an Err is returned, it is a ChannelError::Close (for get_funding_created) /// If an Err is returned, it is a ChannelError::Close (for get_funding_created)
fn build_remote_transaction_keys(&self) -> TxCreationKeys { fn build_remote_transaction_keys(&self) -> TxCreationKeys {
//TODO: Ensure that the payment_key derived here ends up in the library users' wallet as we
//may see payments to it!
let revocation_basepoint = &self.get_holder_pubkeys().revocation_basepoint; let revocation_basepoint = &self.get_holder_pubkeys().revocation_basepoint;
let htlc_basepoint = &self.get_holder_pubkeys().htlc_basepoint; let htlc_basepoint = &self.get_holder_pubkeys().htlc_basepoint;
let counterparty_pubkeys = self.get_counterparty_pubkeys(); let counterparty_pubkeys = self.get_counterparty_pubkeys();

101
lightning/src/ln/channel_keys.rs
View file

@ -50,18 +50,18 @@ macro_rules! basepoint_impl {
macro_rules! key_impl { macro_rules! key_impl {
($BasepointT:ty, $KeyName:expr) => { ($BasepointT:ty, $KeyName:expr) => {
doc_comment! { doc_comment! {
concat!("Generate ", $KeyName, " using per_commitment_point"), concat!("Derive a public ", $KeyName, " using one node's `per_commitment_point` and its countersignatory's `basepoint`"),
pub fn from_basepoint<T: secp256k1::Signing>( pub fn from_basepoint<T: secp256k1::Signing>(
secp_ctx: &Secp256k1<T>, secp_ctx: &Secp256k1<T>,
basepoint: &$BasepointT, countersignatory_basepoint: &$BasepointT,
per_commitment_point: &PublicKey, per_commitment_point: &PublicKey,
) -> Self { ) -> Self {
Self(derive_public_key(secp_ctx, per_commitment_point, &basepoint.0)) Self(derive_public_key(secp_ctx, per_commitment_point, &countersignatory_basepoint.0))
} }
} }
doc_comment! { doc_comment! {
concat!("Generate ", $KeyName, " from privkey"), concat!("Build a ", $KeyName, " directly from an already-derived private key"),
pub fn from_secret_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, sk: &SecretKey) -> Self { pub fn from_secret_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, sk: &SecretKey) -> Self {
Self(PublicKey::from_secret_key(&secp_ctx, &sk)) Self(PublicKey::from_secret_key(&secp_ctx, &sk))
} }
@ -92,17 +92,26 @@ macro_rules! key_read_write {
/// Master key used in conjunction with per_commitment_point to generate [`local_delayedpubkey`](https://github.com/lightning/bolts/blob/master/03-transactions.md#key-derivation) for the latest state of a channel. /// Base key used in conjunction with a `per_commitment_point` to generate a [`DelayedPaymentKey`].
/// A watcher can be given a [DelayedPaymentBasepoint] to generate per commitment [DelayedPaymentKey] to create justice transactions. ///
/// The delayed payment key is used to pay the commitment state broadcaster their
/// non-HTLC-encumbered funds after a delay to give their counterparty a chance to punish if the
/// state broadcasted was previously revoked.
#[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)] #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
pub struct DelayedPaymentBasepoint(pub PublicKey); pub struct DelayedPaymentBasepoint(pub PublicKey);
basepoint_impl!(DelayedPaymentBasepoint); basepoint_impl!(DelayedPaymentBasepoint);
key_read_write!(DelayedPaymentBasepoint); key_read_write!(DelayedPaymentBasepoint);
/// [delayedpubkey](https://github.com/lightning/bolts/blob/master/03-transactions.md#localpubkey-local_htlcpubkey-remote_htlcpubkey-local_delayedpubkey-and-remote_delayedpubkey-derivation)
/// To allow a counterparty to contest a channel state published by a node, Lightning protocol sets delays for some of the outputs, before can be spend. /// A derived key built from a [`DelayedPaymentBasepoint`] and `per_commitment_point`.
/// For example a commitment transaction has to_local output encumbered by a delay, negotiated at the channel establishment flow. ///
/// To spend from such output a node has to generate a script using, among others, a local delayed payment key. /// The delayed payment key is used to pay the commitment state broadcaster their
/// non-HTLC-encumbered funds after a delay. This delay gives their counterparty a chance to
/// punish and claim all the channel funds if the state broadcasted was previously revoked.
///
/// [See the BOLT specs]
/// (https://github.com/lightning/bolts/blob/master/03-transactions.md#localpubkey-local_htlcpubkey-remote_htlcpubkey-local_delayedpubkey-and-remote_delayedpubkey-derivation)
/// for more information on key derivation details.
#[derive(PartialEq, Eq, Clone, Copy, Debug)] #[derive(PartialEq, Eq, Clone, Copy, Debug)]
pub struct DelayedPaymentKey(pub PublicKey); pub struct DelayedPaymentKey(pub PublicKey);
@ -111,35 +120,25 @@ impl DelayedPaymentKey {
} }
key_read_write!(DelayedPaymentKey); key_read_write!(DelayedPaymentKey);
/// Master key used in conjunction with per_commitment_point to generate a [localpubkey](https://github.com/lightning/bolts/blob/master/03-transactions.md#key-derivation) for the latest state of a channel. /// Base key used in conjunction with a `per_commitment_point` to generate an [`HtlcKey`].
/// Also used to generate a commitment number in a commitment transaction or as a Payment Key for a remote node (not us) in an anchor output if `option_static_remotekey` is enabled. ///
/// Shared by both nodes in a channel establishment message flow. /// HTLC keys are used to ensure only the recipient of an HTLC can claim it on-chain with the HTLC
#[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)] /// preimage and that only the sender of an HTLC can claim it on-chain after it has timed out.
pub struct PaymentBasepoint(pub PublicKey); /// Thus, both channel counterparties' HTLC keys will appears in each HTLC output's script.
basepoint_impl!(PaymentBasepoint);
key_read_write!(PaymentBasepoint);
/// [localpubkey](https://github.com/lightning/bolts/blob/master/03-transactions.md#localpubkey-local_htlcpubkey-remote_htlcpubkey-local_delayedpubkey-and-remote_delayedpubkey-derivation) is a child key of a payment basepoint,
/// that enables a secure hash-lock for off-chain payments without risk of funds getting stuck or stolen. A payment key is normally shared with a counterparty so that it can generate
/// a commitment transaction's to_remote ouput, which our node can claim in case the counterparty force closes the channel.
#[derive(PartialEq, Eq, Clone, Copy, Debug)]
pub struct PaymentKey(pub PublicKey);
impl PaymentKey {
key_impl!(PaymentBasepoint, "localpubkey");
}
key_read_write!(PaymentKey);
/// Master key used in conjunction with per_commitment_point to generate [htlcpubkey](https://github.com/lightning/bolts/blob/master/03-transactions.md#key-derivation) for the latest state of a channel.
#[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)] #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
pub struct HtlcBasepoint(pub PublicKey); pub struct HtlcBasepoint(pub PublicKey);
basepoint_impl!(HtlcBasepoint); basepoint_impl!(HtlcBasepoint);
key_read_write!(HtlcBasepoint); key_read_write!(HtlcBasepoint);
/// A derived key built from a [`HtlcBasepoint`] and `per_commitment_point`.
/// [htlcpubkey](https://github.com/lightning/bolts/blob/master/03-transactions.md#localpubkey-local_htlcpubkey-remote_htlcpubkey-local_delayedpubkey-and-remote_delayedpubkey-derivation) is a child key of an htlc basepoint, ///
/// that enables secure routing of payments in onion scheme without a risk of them getting stuck or diverted. It is used to claim the funds in successful or timed out htlc outputs. /// HTLC keys are used to ensure only the recipient of an HTLC can claim it on-chain with the HTLC
/// preimage and that only the sender of an HTLC can claim it on-chain after it has timed out.
/// Thus, both channel counterparties' HTLC keys will appears in each HTLC output's script.
///
/// [See the BOLT specs]
/// (https://github.com/lightning/bolts/blob/master/03-transactions.md#localpubkey-local_htlcpubkey-remote_htlcpubkey-local_delayedpubkey-and-remote_delayedpubkey-derivation)
/// for more information on key derivation details.
#[derive(PartialEq, Eq, Clone, Copy, Debug)] #[derive(PartialEq, Eq, Clone, Copy, Debug)]
pub struct HtlcKey(pub PublicKey); pub struct HtlcKey(pub PublicKey);
@ -157,7 +156,6 @@ fn derive_public_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitm
sha.input(&base_point.serialize()); sha.input(&base_point.serialize());
let res = Sha256::from_engine(sha).to_byte_array(); let res = Sha256::from_engine(sha).to_byte_array();
let hashkey = PublicKey::from_secret_key(&secp_ctx, let hashkey = PublicKey::from_secret_key(&secp_ctx,
&SecretKey::from_slice(&res).expect("Hashes should always be valid keys unless SHA-256 is broken")); &SecretKey::from_slice(&res).expect("Hashes should always be valid keys unless SHA-256 is broken"));
base_point.combine(&hashkey) base_point.combine(&hashkey)
@ -172,31 +170,35 @@ basepoint_impl!(RevocationBasepoint);
key_read_write!(RevocationBasepoint); key_read_write!(RevocationBasepoint);
/// [htlcpubkey](https://github.com/lightning/bolts/blob/master/03-transactions.md#localpubkey-local_htlcpubkey-remote_htlcpubkey-local_delayedpubkey-and-remote_delayedpubkey-derivation) is a child key of a revocation basepoint, /// The revocation key is used to allow a channel party to revoke their state - giving their
/// that enables a node to create a justice transaction punishing a counterparty for an attempt to steal funds. Used to in generation of commitment and htlc outputs. /// counterparty the required material to claim all of their funds if they broadcast that state.
///
/// Each commitment transaction has a revocation key based on the basepoint and
/// per_commitment_point which is used in both commitment and HTLC transactions.
///
/// See [the BOLT spec for derivation details]
/// (https://github.com/lightning/bolts/blob/master/03-transactions.md#revocationpubkey-derivation)
#[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)] #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
pub struct RevocationKey(pub PublicKey); pub struct RevocationKey(pub PublicKey);
impl RevocationKey { impl RevocationKey {
/// Derives a per-commitment-transaction revocation public key from its constituent parts. This is /// Derives a per-commitment-transaction revocation public key from one party's per-commitment
/// the public equivalend of derive_private_revocation_key - using only public keys to derive a /// point and the other party's [`RevocationBasepoint`]. This is the public equivalent of
/// public key instead of private keys. /// [`chan_utils::derive_private_revocation_key`] - using only public keys to derive a public
/// /// key instead of private keys.
/// Only the cheating participant owns a valid witness to propagate a revoked
/// commitment transaction, thus per_commitment_point always come from cheater
/// and revocation_base_point always come from punisher, which is the broadcaster
/// of the transaction spending with this key knowledge.
/// ///
/// Note that this is infallible iff we trust that at least one of the two input keys are randomly /// Note that this is infallible iff we trust that at least one of the two input keys are randomly
/// generated (ie our own). /// generated (ie our own).
///
/// [`chan_utils::derive_private_revocation_key`]: crate::ln::chan_utils::derive_private_revocation_key
pub fn from_basepoint<T: secp256k1::Verification>( pub fn from_basepoint<T: secp256k1::Verification>(
secp_ctx: &Secp256k1<T>, secp_ctx: &Secp256k1<T>,
basepoint: &RevocationBasepoint, countersignatory_basepoint: &RevocationBasepoint,
per_commitment_point: &PublicKey, per_commitment_point: &PublicKey,
) -> Self { ) -> Self {
let rev_append_commit_hash_key = { let rev_append_commit_hash_key = {
let mut sha = Sha256::engine(); let mut sha = Sha256::engine();
sha.input(&basepoint.to_public_key().serialize()); sha.input(&countersignatory_basepoint.to_public_key().serialize());
sha.input(&per_commitment_point.serialize()); sha.input(&per_commitment_point.serialize());
Sha256::from_engine(sha).to_byte_array() Sha256::from_engine(sha).to_byte_array()
@ -204,12 +206,12 @@ impl RevocationKey {
let commit_append_rev_hash_key = { let commit_append_rev_hash_key = {
let mut sha = Sha256::engine(); let mut sha = Sha256::engine();
sha.input(&per_commitment_point.serialize()); sha.input(&per_commitment_point.serialize());
sha.input(&basepoint.to_public_key().serialize()); sha.input(&countersignatory_basepoint.to_public_key().serialize());
Sha256::from_engine(sha).to_byte_array() Sha256::from_engine(sha).to_byte_array()
}; };
let countersignatory_contrib = basepoint.to_public_key().mul_tweak(&secp_ctx, &Scalar::from_be_bytes(rev_append_commit_hash_key).unwrap()) let countersignatory_contrib = countersignatory_basepoint.to_public_key().mul_tweak(&secp_ctx, &Scalar::from_be_bytes(rev_append_commit_hash_key).unwrap())
.expect("Multiplying a valid public key by a hash is expected to never fail per secp256k1 docs"); .expect("Multiplying a valid public key by a hash is expected to never fail per secp256k1 docs");
let broadcaster_contrib = (&per_commitment_point).mul_tweak(&secp_ctx, &Scalar::from_be_bytes(commit_append_rev_hash_key).unwrap()) let broadcaster_contrib = (&per_commitment_point).mul_tweak(&secp_ctx, &Scalar::from_be_bytes(commit_append_rev_hash_key).unwrap())
.expect("Multiplying a valid public key by a hash is expected to never fail per secp256k1 docs"); .expect("Multiplying a valid public key by a hash is expected to never fail per secp256k1 docs");
@ -226,7 +228,6 @@ impl RevocationKey {
key_read_write!(RevocationKey); key_read_write!(RevocationKey);
#[cfg(test)] #[cfg(test)]
mod test { mod test {
use bitcoin::secp256k1::{Secp256k1, SecretKey, PublicKey}; use bitcoin::secp256k1::{Secp256k1, SecretKey, PublicKey};