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;
+use util::ser::{Writeable, Writer};
+use io::Error;
-/// An implementation of ChannelKeys that enforces some policy checks.
+/// 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+/// - When signing, the holder transaction has not been revoked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,
- last_commitment_number: Arc<Mutex<Option<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,
+ state,
+ disable_revocation_policy_check: false
+ }
+ }
+
+ /// 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,
- last_commitment_number: Arc::new(Mutex::new(None)),
+ state,
+ disable_revocation_policy_check
}
}
+
+ #[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) -> Result<(), ()> {
+ 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;
+ Ok(())
+ }
+
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, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
+ 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 last_commitment_number_guard = self.last_commitment_number.lock().unwrap();
+ let mut state = self.state.lock().unwrap();
let actual_commitment_number = commitment_tx.commitment_number();
- let last_commitment_number = last_commitment_number_guard.unwrap_or(actual_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);
- *last_commitment_number_guard = Some(cmp::min(last_commitment_number, actual_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(commitment_tx, secp_ctx).unwrap())
}
- fn sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
+ fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
+ 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;
+ Ok(())
+ }
+
+ 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();
+ 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])
+ }
+ }
+
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();
secp_ctx.verify(&sighash, sig, &keys.countersignatory_htlc_key).unwrap();
}
- // TODO: enforce the ChannelKeys contract - error if this commitment was already revoked
- // TODO: need the commitment number
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<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
- Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
+ 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)
}
}
}
+impl Sign for EnforcingSigner {}
-impl Writeable for EnforcingChannelKeys {
+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 last = *self.last_commitment_number.lock().unwrap();
- 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 last_commitment_number = Readable::read(reader)?;
- Ok(EnforcingChannelKeys {
- inner,
- last_commitment_number: Arc::new(Mutex::new(last_commitment_number))
- })
- }
-}
-
-impl EnforcingChannelKeys {
+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")
}
}
+
+/// 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