// You may not use this file except in accordance with one or both of these
// licenses.
-use ln::chan_utils::{HTLCOutputInCommitment, TxCreationKeys, ChannelPublicKeys, HolderCommitmentTransaction, PreCalculatedTxCreationKeys};
+use ln::chan_utils::{HTLCOutputInCommitment, ChannelPublicKeys, HolderCommitmentTransaction, CommitmentTransaction, ChannelTransactionParameters, TrustedCommitmentTransaction};
use ln::{chan_utils, msgs};
-use chain::keysinterface::{ChannelKeys, InMemoryChannelKeys};
+use chain::keysinterface::{Sign, InMemorySigner, BaseSign};
-use std::cmp;
-use std::sync::{Mutex, Arc};
+use prelude::*;
+use core::cmp;
+use sync::{Mutex, Arc};
+#[cfg(test)] use sync::MutexGuard;
use bitcoin::blockdata::transaction::{Transaction, SigHashType};
use bitcoin::util::bip143;
use bitcoin::secp256k1;
use bitcoin::secp256k1::key::{SecretKey, PublicKey};
use bitcoin::secp256k1::{Secp256k1, Signature};
-use util::ser::{Writeable, Writer, Readable};
-use std::io::Error;
-use ln::msgs::DecodeError;
-
-/// Enforces some rules on ChannelKeys calls. Eventually we will probably want to expose a variant
-/// of this which would essentially be what you'd want to run on a hardware wallet.
+use util::ser::{Writeable, Writer};
+use io::Error;
+
+/// Initial value for revoked commitment downward counter
+pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
+
+/// An implementation of Sign that enforces some policy checks. The current checks
+/// are an incomplete set. They include:
+///
+/// - When signing, the holder transaction has not been revoked
+/// - When revoking, the holder transaction has not been signed
+/// - The holder commitment number is monotonic and without gaps
+/// - The revoked holder commitment number is monotonic and without gaps
+/// - There is at least one unrevoked holder transaction at all times
+/// - The counterparty commitment number is monotonic and without gaps
+/// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
+///
+/// Eventually we will probably want to expose a variant of this which would essentially
+/// be what you'd want to run on a hardware wallet.
+///
+/// Note that counterparty signatures on the holder transaction are not checked, but it should
+/// be in a complete implementation.
+///
+/// Note that before we do so we should ensure its serialization format has backwards- and
+/// forwards-compatibility prefix/suffixes!
#[derive(Clone)]
-pub struct EnforcingChannelKeys {
- pub inner: InMemoryChannelKeys,
- commitment_number_obscure_and_last: Arc<Mutex<(Option<u64>, u64)>>,
+pub struct EnforcingSigner {
+ pub inner: InMemorySigner,
+ /// Channel state used for policy enforcement
+ pub state: Arc<Mutex<EnforcementState>>,
+ pub disable_revocation_policy_check: bool,
}
-impl EnforcingChannelKeys {
- pub fn new(inner: InMemoryChannelKeys) -> Self {
+impl EnforcingSigner {
+ /// Construct an EnforcingSigner
+ pub fn new(inner: InMemorySigner) -> Self {
+ let state = Arc::new(Mutex::new(EnforcementState::new()));
Self {
inner,
- commitment_number_obscure_and_last: Arc::new(Mutex::new((None, 0))),
+ state,
+ disable_revocation_policy_check: false
}
}
-}
-impl EnforcingChannelKeys {
- fn check_keys<T: secp256k1::Signing + secp256k1::Verification>(&self, secp_ctx: &Secp256k1<T>,
- keys: &TxCreationKeys) {
- let remote_points = self.inner.counterparty_pubkeys();
+ /// Construct an EnforcingSigner with externally managed storage
+ ///
+ /// Since there are multiple copies of this struct for each channel, some coordination is needed
+ /// so that all copies are aware of enforcement state. A pointer to this state is provided
+ /// here, usually by an implementation of KeysInterface.
+ pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
+ Self {
+ inner,
+ state,
+ disable_revocation_policy_check
+ }
+ }
- let keys_expected = TxCreationKeys::derive_new(secp_ctx,
- &keys.per_commitment_point,
- &remote_points.delayed_payment_basepoint,
- &remote_points.htlc_basepoint,
- &self.inner.pubkeys().revocation_basepoint,
- &self.inner.pubkeys().htlc_basepoint).unwrap();
- if keys != &keys_expected { panic!("derived different per-tx keys") }
+ #[cfg(test)]
+ pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
+ self.state.lock().unwrap()
}
}
-impl ChannelKeys for EnforcingChannelKeys {
- fn get_per_commitment_point<T: secp256k1::Signing + secp256k1::Verification>(&self, idx: u64, secp_ctx: &Secp256k1<T>) -> PublicKey {
+impl BaseSign for EnforcingSigner {
+ fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
self.inner.get_per_commitment_point(idx, secp_ctx)
}
fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
- // TODO: enforce the ChannelKeys contract - error here if we already signed this commitment
+ {
+ let mut state = self.state.lock().unwrap();
+ assert!(idx == state.last_holder_revoked_commitment || idx == state.last_holder_revoked_commitment - 1, "can only revoke the current or next unrevoked commitment - trying {}, last revoked {}", idx, state.last_holder_revoked_commitment);
+ assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
+ state.last_holder_revoked_commitment = idx;
+ }
self.inner.release_commitment_secret(idx)
}
+ fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction) {
+ let mut state = self.state.lock().unwrap();
+ let idx = holder_tx.commitment_number();
+ assert!(idx == state.last_holder_commitment || idx == state.last_holder_commitment - 1, "expecting to validate the current or next holder commitment - trying {}, current {}", idx, state.last_holder_commitment);
+ state.last_holder_commitment = idx;
+ }
+
fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
- fn key_derivation_params(&self) -> (u64, u64) { self.inner.key_derivation_params() }
+ fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
- fn sign_counterparty_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, feerate_per_kw: u32, commitment_tx: &Transaction, pre_keys: &PreCalculatedTxCreationKeys, htlcs: &[&HTLCOutputInCommitment], secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
- if commitment_tx.input.len() != 1 { panic!("lightning commitment transactions have a single input"); }
- self.check_keys(secp_ctx, pre_keys.trust_key_derivation());
- let obscured_commitment_transaction_number = (commitment_tx.lock_time & 0xffffff) as u64 | ((commitment_tx.input[0].sequence as u64 & 0xffffff) << 3*8);
+ fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
+ self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
{
- let mut commitment_data = self.commitment_number_obscure_and_last.lock().unwrap();
- if commitment_data.0.is_none() {
- commitment_data.0 = Some(obscured_commitment_transaction_number ^ commitment_data.1);
- }
- let commitment_number = obscured_commitment_transaction_number ^ commitment_data.0.unwrap();
- assert!(commitment_number == commitment_data.1 || commitment_number == commitment_data.1 + 1);
- commitment_data.1 = cmp::max(commitment_number, commitment_data.1)
+ let mut state = self.state.lock().unwrap();
+ let actual_commitment_number = commitment_tx.commitment_number();
+ let last_commitment_number = state.last_counterparty_commitment;
+ // These commitment numbers are backwards counting. We expect either the same as the previously encountered,
+ // or the next one.
+ assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
+ // Ensure that the counterparty doesn't get more than two broadcastable commitments -
+ // the last and the one we are trying to sign
+ assert!(actual_commitment_number >= state.last_counterparty_revoked_commitment - 2, "cannot sign a commitment if second to last wasn't revoked - signing {} revoked {}", actual_commitment_number, state.last_counterparty_revoked_commitment);
+ state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
}
- Ok(self.inner.sign_counterparty_commitment(feerate_per_kw, commitment_tx, pre_keys, htlcs, secp_ctx).unwrap())
- }
-
- fn sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, holder_commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
- // TODO: enforce the ChannelKeys contract - error if this commitment was already revoked
- // TODO: need the commitment number
- Ok(self.inner.sign_holder_commitment(holder_commitment_tx, secp_ctx).unwrap())
+ Ok(self.inner.sign_counterparty_commitment(commitment_tx, secp_ctx).unwrap())
}
- #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
- fn unsafe_sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, holder_commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
- Ok(self.inner.unsafe_sign_holder_commitment(holder_commitment_tx, secp_ctx).unwrap())
+ fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) {
+ let mut state = self.state.lock().unwrap();
+ assert!(idx == state.last_counterparty_revoked_commitment || idx == state.last_counterparty_revoked_commitment - 1, "expecting to validate the current or next counterparty revocation - trying {}, current {}", idx, state.last_counterparty_revoked_commitment);
+ state.last_counterparty_revoked_commitment = idx;
}
- fn sign_holder_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, holder_commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Vec<Option<Signature>>, ()> {
- let commitment_txid = holder_commitment_tx.txid();
+ fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
+ let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
+ let commitment_txid = trusted_tx.txid();
let holder_csv = self.inner.counterparty_selected_contest_delay();
- for this_htlc in holder_commitment_tx.per_htlc.iter() {
- if this_htlc.0.transaction_output_index.is_some() {
- let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, holder_commitment_tx.feerate_per_kw, holder_csv, &this_htlc.0, &holder_commitment_tx.keys.broadcaster_delayed_payment_key, &holder_commitment_tx.keys.revocation_key);
+ let state = self.state.lock().unwrap();
+ let commitment_number = trusted_tx.commitment_number();
+ if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
+ if !self.disable_revocation_policy_check {
+ panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
+ state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
+ }
+ }
- let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc.0, &holder_commitment_tx.keys);
+ for (this_htlc, sig) in trusted_tx.htlcs().iter().zip(&commitment_tx.counterparty_htlc_sigs) {
+ assert!(this_htlc.transaction_output_index.is_some());
+ let keys = trusted_tx.keys();
+ let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, trusted_tx.feerate_per_kw(), holder_csv, &this_htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
- let sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, this_htlc.0.amount_msat / 1000, SigHashType::All)[..]);
- secp_ctx.verify(&sighash, this_htlc.1.as_ref().unwrap(), &holder_commitment_tx.keys.countersignatory_htlc_key).unwrap();
- }
+ let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc, &keys);
+
+ let sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, this_htlc.amount_msat / 1000, SigHashType::All)[..]);
+ secp_ctx.verify(&sighash, sig, &keys.countersignatory_htlc_key).unwrap();
}
- Ok(self.inner.sign_holder_commitment_htlc_transactions(holder_commitment_tx, secp_ctx).unwrap())
+ Ok(self.inner.sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
+ }
+
+ #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
+ fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
+ Ok(self.inner.unsafe_sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
+ }
+
+ fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
+ Ok(self.inner.sign_justice_revoked_output(justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
}
- fn sign_justice_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option<HTLCOutputInCommitment>, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
- Ok(self.inner.sign_justice_transaction(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
+ fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
+ Ok(self.inner.sign_justice_revoked_htlc(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
}
- fn sign_counterparty_htlc_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
+ fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
}
- fn sign_closing_transaction<T: secp256k1::Signing>(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
+ fn sign_closing_transaction(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
}
- fn sign_channel_announcement<T: secp256k1::Signing>(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
+ fn sign_channel_announcement(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
self.inner.sign_channel_announcement(msg, secp_ctx)
}
- fn on_accept(&mut self, channel_pubkeys: &ChannelPublicKeys, remote_locally_selected_delay: u16, locally_selected_delay: u16) {
- self.inner.on_accept(channel_pubkeys, remote_locally_selected_delay, locally_selected_delay)
+ fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters) {
+ self.inner.ready_channel(channel_parameters)
}
}
-impl Writeable for EnforcingChannelKeys {
+impl Sign for EnforcingSigner {}
+
+impl Writeable for EnforcingSigner {
fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
+ // EnforcingSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
+ // ([`EnforcementState`]). `inner` is serialized here and deserialized by
+ // [`KeysInterface::read_chan_signer`]. `state` is managed by [`KeysInterface`]
+ // and will be serialized as needed by the implementation of that trait.
self.inner.write(writer)?;
- let (obscure, last) = *self.commitment_number_obscure_and_last.lock().unwrap();
- obscure.write(writer)?;
- last.write(writer)?;
Ok(())
}
}
-impl Readable for EnforcingChannelKeys {
- fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
- let inner = Readable::read(reader)?;
- let obscure_and_last = Readable::read(reader)?;
- Ok(EnforcingChannelKeys {
- inner: inner,
- commitment_number_obscure_and_last: Arc::new(Mutex::new(obscure_and_last))
- })
+impl EnforcingSigner {
+ fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
+ commitment_tx.verify(&self.inner.get_channel_parameters().as_counterparty_broadcastable(),
+ self.inner.counterparty_pubkeys(), self.inner.pubkeys(), secp_ctx)
+ .expect("derived different per-tx keys or built transaction")
+ }
+
+ fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
+ commitment_tx.verify(&self.inner.get_channel_parameters().as_holder_broadcastable(),
+ self.inner.pubkeys(), self.inner.counterparty_pubkeys(), secp_ctx)
+ .expect("derived different per-tx keys or built transaction")
+ }
+}
+
+/// The state used by [`EnforcingSigner`] in order to enforce policy checks
+///
+/// This structure is maintained by KeysInterface since we may have multiple copies of
+/// the signer and they must coordinate their state.
+#[derive(Clone)]
+pub struct EnforcementState {
+ /// The last counterparty commitment number we signed, backwards counting
+ pub last_counterparty_commitment: u64,
+ /// The last counterparty commitment they revoked, backwards counting
+ pub last_counterparty_revoked_commitment: u64,
+ /// The last holder commitment number we revoked, backwards counting
+ pub last_holder_revoked_commitment: u64,
+ /// The last validated holder commitment number, backwards counting
+ pub last_holder_commitment: u64,
+}
+
+impl EnforcementState {
+ /// Enforcement state for a new channel
+ pub fn new() -> Self {
+ EnforcementState {
+ last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
+ last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
+ last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
+ last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
+ }
}
}
projects / rust-lightning / blobdiff