X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Futil%2Fenforcing_trait_impls.rs;h=d7ddc38b3ddfee2641ba414108ca5b541878f503;hb=002a5db5b07fd317545d3aa4f1a217cd40b608e2;hp=5157c1a6c9469fa11ab78bc91cbbf51f47907ac2;hpb=bd2fa43acd54f9e0876d493178679dfcadf7d178;p=rust-lightning diff --git a/lightning/src/util/enforcing_trait_impls.rs b/lightning/src/util/enforcing_trait_impls.rs index 5157c1a6..d7ddc38b 100644 --- a/lightning/src/util/enforcing_trait_impls.rs +++ b/lightning/src/util/enforcing_trait_impls.rs @@ -1,11 +1,21 @@ -use ln::chan_utils::{HTLCOutputInCommitment, TxCreationKeys, ChannelPublicKeys, LocalCommitmentTransaction}; +// This file is Copyright its original authors, visible in version control +// history. +// +// This file is licensed under the Apache License, Version 2.0 or the MIT license +// , at your option. +// You may not use this file except in accordance with one or both of these +// licenses. + +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}; -use bitcoin::blockdata::transaction::Transaction; +use bitcoin::blockdata::transaction::{Transaction, SigHashType}; use bitcoin::util::bip143; use bitcoin::secp256k1; @@ -15,125 +25,184 @@ 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. +/// 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 They include: +/// +/// - When signing, the holder transaction has not been revoked +/// - When revoking, the holder transaction has not been signed +/// - The holder commitment number is monotonic and without gaps +/// - The counterparty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 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, u64)>>, +pub struct EnforcingSigner { + pub inner: InMemorySigner, + /// The last counterparty commitment number we signed, backwards counting + pub last_commitment_number: Arc>>, + /// The last holder commitment number we revoked, backwards counting + pub revoked_commitment: Arc>, + 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 { Self { inner, - commitment_number_obscure_and_last: Arc::new(Mutex::new((None, 0))), + last_commitment_number: Arc::new(Mutex::new(None)), + revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)), + 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 revocations. A pointer to this state is provided here, usually + /// by an implementation of KeysInterface. + pub fn new_with_revoked(inner: InMemorySigner, revoked_commitment: Arc>, disable_revocation_policy_check: bool) -> Self { + Self { + inner, + last_commitment_number: Arc::new(Mutex::new(None)), + revoked_commitment, + disable_revocation_policy_check } } } -impl EnforcingChannelKeys { - fn check_keys(&self, secp_ctx: &Secp256k1, - keys: &TxCreationKeys) { - let remote_points = self.inner.remote_channel_pubkeys.as_ref().unwrap(); +impl BaseSign for EnforcingSigner { + fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1) -> PublicKey { + self.inner.get_per_commitment_point(idx, secp_ctx) + } - let keys_expected = TxCreationKeys::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") } + fn release_commitment_secret(&self, idx: u64) -> [u8; 32] { + { + let mut revoked = self.revoked_commitment.lock().unwrap(); + assert!(idx == *revoked || idx == *revoked - 1, "can only revoke the current or next unrevoked commitment - trying {}, revoked {}", idx, *revoked); + *revoked = idx; + } + self.inner.release_commitment_secret(idx) } -} -impl ChannelKeys for EnforcingChannelKeys { - fn commitment_seed(&self) -> &[u8; 32] { self.inner.commitment_seed() } - fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { self.inner.pubkeys() } - fn key_derivation_params(&self) -> (u64, u64) { self.inner.key_derivation_params() } + fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() } + fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() } - fn sign_remote_commitment(&self, feerate_per_kw: u32, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { - if commitment_tx.input.len() != 1 { panic!("lightning commitment transactions have a single input"); } - self.check_keys(secp_ctx, keys); - 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) -> Result<(Signature, Vec), ()> { + 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 last_commitment_number_guard = self.last_commitment_number.lock().unwrap(); + let actual_commitment_number = commitment_tx.commitment_number(); + let last_commitment_number = last_commitment_number_guard.unwrap_or(actual_commitment_number); + // 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)) } - Ok(self.inner.sign_remote_commitment(feerate_per_kw, commitment_tx, keys, htlcs, to_self_delay, secp_ctx).unwrap()) + Ok(self.inner.sign_counterparty_commitment(commitment_tx, secp_ctx).unwrap()) } - fn sign_local_commitment(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1) -> Result { - Ok(self.inner.sign_local_commitment(local_commitment_tx, secp_ctx).unwrap()) - } + fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { + 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 revoked = self.revoked_commitment.lock().unwrap(); + let commitment_number = trusted_tx.commitment_number(); + if *revoked - 1 != commitment_number && *revoked - 2 != commitment_number { + if !self.disable_revocation_policy_check { + panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}", + *revoked, commitment_number, self.inner.commitment_seed[0]) + } + } - #[cfg(test)] - fn unsafe_sign_local_commitment(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1) -> Result { - Ok(self.inner.unsafe_sign_local_commitment(local_commitment_tx, secp_ctx).unwrap()) - } + 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); - fn sign_local_commitment_htlc_transactions(&self, local_commitment_tx: &LocalCommitmentTransaction, local_csv: u16, secp_ctx: &Secp256k1) -> Result>, ()> { - let commitment_txid = local_commitment_tx.txid(); + let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc, &keys); - for this_htlc in local_commitment_tx.per_htlc.iter() { - if this_htlc.0.transaction_output_index.is_some() { - let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, local_commitment_tx.feerate_per_kw, local_csv, &this_htlc.0, &local_commitment_tx.local_keys.a_delayed_payment_key, &local_commitment_tx.local_keys.revocation_key); + 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(); + } - let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&this_htlc.0, &local_commitment_tx.local_keys); + Ok(self.inner.sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap()) + } - let sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, this_htlc.0.amount_msat / 1000)[..]); - secp_ctx.verify(&sighash, this_htlc.1.as_ref().unwrap(), &local_commitment_tx.local_keys.b_htlc_key).unwrap(); - } - } + #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))] + fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { + Ok(self.inner.unsafe_sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap()) + } - Ok(self.inner.sign_local_commitment_htlc_transactions(local_commitment_tx, local_csv, secp_ctx).unwrap()) + fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1) -> Result { + Ok(self.inner.sign_justice_revoked_output(justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap()) } - fn sign_justice_transaction(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option, on_remote_tx_csv: u16, secp_ctx: &Secp256k1) -> Result { - Ok(self.inner.sign_justice_transaction(justice_tx, input, amount, per_commitment_key, htlc, on_remote_tx_csv, 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) -> Result { + Ok(self.inner.sign_justice_revoked_htlc(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap()) } - fn sign_remote_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1) -> Result { - Ok(self.inner.sign_remote_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap()) + fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1) -> Result { + Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap()) } - fn sign_closing_transaction(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1) -> Result { + fn sign_closing_transaction(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1) -> Result { Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap()) } - fn sign_channel_announcement(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1) -> Result { + fn sign_channel_announcement(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1) -> Result { self.inner.sign_channel_announcement(msg, secp_ctx) } - fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) { - self.inner.set_remote_channel_pubkeys(channel_pubkeys) + 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(&self, writer: &mut W) -> Result<(), Error> { self.inner.write(writer)?; - let (obscure, last) = *self.commitment_number_obscure_and_last.lock().unwrap(); - obscure.write(writer)?; + let last = *self.last_commitment_number.lock().unwrap(); last.write(writer)?; Ok(()) } } -impl Readable for EnforcingChannelKeys { +impl Readable for EnforcingSigner { fn read(reader: &mut R) -> Result { 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)) + let last_commitment_number = Readable::read(reader)?; + Ok(EnforcingSigner { + inner, + last_commitment_number: Arc::new(Mutex::new(last_commitment_number)), + revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)), + disable_revocation_policy_check: false, }) } } + +impl EnforcingSigner { + fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1) -> 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) -> 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") + } +}