X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fsign%2Fmod.rs;h=5912b7b84e16e393daffb3a144c6b12ee2e4331b;hb=9bd1cc76609e14c286477522cf2b56f17bd4346d;hp=04c4446e2c0c8c75bd4f2f7e3b415b8f35296cf2;hpb=89749eddec2ea178858bb5bc96c7d79e02944586;p=rust-lightning diff --git a/lightning/src/sign/mod.rs b/lightning/src/sign/mod.rs index 04c4446e..5912b7b8 100644 --- a/lightning/src/sign/mod.rs +++ b/lightning/src/sign/mod.rs @@ -30,13 +30,12 @@ use bitcoin::secp256k1::{KeyPair, PublicKey, Scalar, Secp256k1, SecretKey, Signi use bitcoin::secp256k1::ecdh::SharedSecret; use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature}; use bitcoin::secp256k1::schnorr; -use bitcoin::{PackedLockTime, secp256k1, Sequence, Witness}; +use bitcoin::{PackedLockTime, secp256k1, Sequence, Witness, Txid}; use crate::util::transaction_utils; use crate::util::crypto::{hkdf_extract_expand_twice, sign, sign_with_aux_rand}; use crate::util::ser::{Writeable, Writer, Readable, ReadableArgs}; use crate::chain::transaction::OutPoint; -use crate::events::bump_transaction::HTLCDescriptor; use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI; use crate::ln::{chan_utils, PaymentPreimage}; use crate::ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction, ClosingTransaction}; @@ -401,6 +400,151 @@ impl SpendableOutputDescriptor { } } +/// The parameters required to derive a channel signer via [`SignerProvider`]. +#[derive(Clone, Debug, PartialEq, Eq)] +pub struct ChannelDerivationParameters { + /// The value in satoshis of the channel we're attempting to spend the anchor output of. + pub value_satoshis: u64, + /// The unique identifier to re-derive the signer for the associated channel. + pub keys_id: [u8; 32], + /// The necessary channel parameters that need to be provided to the re-derived signer through + /// [`ChannelSigner::provide_channel_parameters`]. + pub transaction_parameters: ChannelTransactionParameters, +} + +impl_writeable_tlv_based!(ChannelDerivationParameters, { + (0, value_satoshis, required), + (2, keys_id, required), + (4, transaction_parameters, required), +}); + +/// A descriptor used to sign for a commitment transaction's HTLC output. +#[derive(Clone, Debug, PartialEq, Eq)] +pub struct HTLCDescriptor { + /// The parameters required to derive the signer for the HTLC input. + pub channel_derivation_parameters: ChannelDerivationParameters, + /// The txid of the commitment transaction in which the HTLC output lives. + pub commitment_txid: Txid, + /// The number of the commitment transaction in which the HTLC output lives. + pub per_commitment_number: u64, + /// The key tweak corresponding to the number of the commitment transaction in which the HTLC + /// output lives. This tweak is applied to all the basepoints for both parties in the channel to + /// arrive at unique keys per commitment. + /// + /// See for more info. + pub per_commitment_point: PublicKey, + /// The feerate to use on the HTLC claiming transaction. This is always `0` for HTLCs + /// originating from a channel supporting anchor outputs, otherwise it is the channel's + /// negotiated feerate at the time the commitment transaction was built. + pub feerate_per_kw: u32, + /// The details of the HTLC as it appears in the commitment transaction. + pub htlc: HTLCOutputInCommitment, + /// The preimage, if `Some`, to claim the HTLC output with. If `None`, the timeout path must be + /// taken. + pub preimage: Option, + /// The counterparty's signature required to spend the HTLC output. + pub counterparty_sig: Signature +} + +impl_writeable_tlv_based!(HTLCDescriptor, { + (0, channel_derivation_parameters, required), + (1, feerate_per_kw, (default_value, 0)), + (2, commitment_txid, required), + (4, per_commitment_number, required), + (6, per_commitment_point, required), + (8, htlc, required), + (10, preimage, option), + (12, counterparty_sig, required), +}); + +impl HTLCDescriptor { + /// Returns the outpoint of the HTLC output in the commitment transaction. This is the outpoint + /// being spent by the HTLC input in the HTLC transaction. + pub fn outpoint(&self) -> bitcoin::OutPoint { + bitcoin::OutPoint { + txid: self.commitment_txid, + vout: self.htlc.transaction_output_index.unwrap(), + } + } + + /// Returns the UTXO to be spent by the HTLC input, which can be obtained via + /// [`Self::unsigned_tx_input`]. + pub fn previous_utxo(&self, secp: &Secp256k1) -> TxOut { + TxOut { + script_pubkey: self.witness_script(secp).to_v0_p2wsh(), + value: self.htlc.amount_msat / 1000, + } + } + + /// Returns the unsigned transaction input spending the HTLC output in the commitment + /// transaction. + pub fn unsigned_tx_input(&self) -> TxIn { + chan_utils::build_htlc_input( + &self.commitment_txid, &self.htlc, &self.channel_derivation_parameters.transaction_parameters.channel_type_features + ) + } + + /// Returns the delayed output created as a result of spending the HTLC output in the commitment + /// transaction. + pub fn tx_output(&self, secp: &Secp256k1) -> TxOut { + let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable(); + let broadcaster_keys = channel_params.broadcaster_pubkeys(); + let counterparty_keys = channel_params.countersignatory_pubkeys(); + let broadcaster_delayed_key = chan_utils::derive_public_key( + secp, &self.per_commitment_point, &broadcaster_keys.delayed_payment_basepoint + ); + let counterparty_revocation_key = chan_utils::derive_public_revocation_key( + secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint + ); + chan_utils::build_htlc_output( + self.feerate_per_kw, channel_params.contest_delay(), &self.htlc, + channel_params.channel_type_features(), &broadcaster_delayed_key, &counterparty_revocation_key + ) + } + + /// Returns the witness script of the HTLC output in the commitment transaction. + pub fn witness_script(&self, secp: &Secp256k1) -> Script { + let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable(); + let broadcaster_keys = channel_params.broadcaster_pubkeys(); + let counterparty_keys = channel_params.countersignatory_pubkeys(); + let broadcaster_htlc_key = chan_utils::derive_public_key( + secp, &self.per_commitment_point, &broadcaster_keys.htlc_basepoint + ); + let counterparty_htlc_key = chan_utils::derive_public_key( + secp, &self.per_commitment_point, &counterparty_keys.htlc_basepoint + ); + let counterparty_revocation_key = chan_utils::derive_public_revocation_key( + secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint + ); + chan_utils::get_htlc_redeemscript_with_explicit_keys( + &self.htlc, channel_params.channel_type_features(), &broadcaster_htlc_key, &counterparty_htlc_key, + &counterparty_revocation_key, + ) + } + + /// Returns the fully signed witness required to spend the HTLC output in the commitment + /// transaction. + pub fn tx_input_witness(&self, signature: &Signature, witness_script: &Script) -> Witness { + chan_utils::build_htlc_input_witness( + signature, &self.counterparty_sig, &self.preimage, witness_script, + &self.channel_derivation_parameters.transaction_parameters.channel_type_features + ) + } + + /// Derives the channel signer required to sign the HTLC input. + pub fn derive_channel_signer(&self, signer_provider: &SP) -> S + where + SP::Target: SignerProvider + { + let mut signer = signer_provider.derive_channel_signer( + self.channel_derivation_parameters.value_satoshis, + self.channel_derivation_parameters.keys_id, + ); + signer.provide_channel_parameters(&self.channel_derivation_parameters.transaction_parameters); + signer + } +} + /// A trait to handle Lightning channel key material without concretizing the channel type or /// the signature mechanism. pub trait ChannelSigner { @@ -487,31 +631,26 @@ pub trait EcdsaChannelSigner: ChannelSigner { /// This is required in order for the signer to make sure that the state has moved /// forward and it is safe to sign the next counterparty commitment. fn validate_counterparty_revocation(&self, idx: u64, secret: &SecretKey) -> Result<(), ()>; - /// Creates a signature for a holder's commitment transaction and its claiming HTLC transactions. + /// Creates a signature for a holder's commitment transaction. /// /// This will be called /// - with a non-revoked `commitment_tx`. /// - with the latest `commitment_tx` when we initiate a force-close. - /// - with the previous `commitment_tx`, just to get claiming HTLC - /// signatures, if we are reacting to a [`ChannelMonitor`] - /// [replica](https://github.com/lightningdevkit/rust-lightning/blob/main/GLOSSARY.md#monitor-replicas) - /// that decided to broadcast before it had been updated to the latest `commitment_tx`. /// /// This may be called multiple times for the same transaction. /// /// An external signer implementation should check that the commitment has not been revoked. - /// - /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor + // // TODO: Document the things someone using this interface should enforce before signing. - fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, - secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()>; - /// Same as [`sign_holder_commitment_and_htlcs`], but exists only for tests to get access to - /// holder commitment transactions which will be broadcasted later, after the channel has moved - /// on to a newer state. Thus, needs its own method as [`sign_holder_commitment_and_htlcs`] may - /// enforce that we only ever get called once. + fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, + secp_ctx: &Secp256k1) -> Result; + /// Same as [`sign_holder_commitment`], but exists only for tests to get access to holder + /// commitment transactions which will be broadcasted later, after the channel has moved on to a + /// newer state. Thus, needs its own method as [`sign_holder_commitment`] may enforce that we + /// only ever get called once. #[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), ()>; + fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, + secp_ctx: &Secp256k1) -> Result; /// Create a signature for the given input in a transaction spending an HTLC transaction output /// or a commitment transaction `to_local` output when our counterparty broadcasts an old state. /// @@ -552,11 +691,14 @@ pub trait EcdsaChannelSigner: ChannelSigner { secp_ctx: &Secp256k1) -> Result; /// Computes the signature for a commitment transaction's HTLC output used as an input within /// `htlc_tx`, which spends the commitment transaction at index `input`. The signature returned - /// must be be computed using [`EcdsaSighashType::All`]. Note that this should only be used to - /// sign HTLC transactions from channels supporting anchor outputs after all additional - /// inputs/outputs have been added to the transaction. + /// must be be computed using [`EcdsaSighashType::All`]. + /// + /// Note that this may be called for HTLCs in the penultimate commitment transaction if a + /// [`ChannelMonitor`] [replica](https://github.com/lightningdevkit/rust-lightning/blob/main/GLOSSARY.md#monitor-replicas) + /// broadcasts it before receiving the update for the latest commitment transaction. /// /// [`EcdsaSighashType::All`]: bitcoin::blockdata::transaction::EcdsaSighashType::All + /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1 ) -> Result; @@ -1120,27 +1262,21 @@ impl EcdsaChannelSigner for InMemorySigner { Ok(()) } - fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { + fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result { let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key); let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR); let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey); let trusted_tx = commitment_tx.trust(); - let sig = trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx); - let channel_parameters = self.get_channel_parameters().expect(MISSING_PARAMS_ERR); - let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), &self, secp_ctx)?; - Ok((sig, htlc_sigs)) + Ok(trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx)) } #[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), ()> { + fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result { let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key); let counterparty_keys = self.counterparty_pubkeys().expect(MISSING_PARAMS_ERR); let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &counterparty_keys.funding_pubkey); let trusted_tx = commitment_tx.trust(); - let sig = trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx); - let channel_parameters = self.get_channel_parameters().expect(MISSING_PARAMS_ERR); - let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), &self, secp_ctx)?; - Ok((sig, htlc_sigs)) + Ok(trusted_tx.built_transaction().sign_holder_commitment(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, &self, secp_ctx)) } fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1) -> Result {