X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fsign%2Fmod.rs;h=5912b7b84e16e393daffb3a144c6b12ee2e4331b;hb=9bd1cc76609e14c286477522cf2b56f17bd4346d;hp=6abf4bd254cb062250128280fd28c9c0a6367170;hpb=aae4e7c0cab7f30e38b06a2314eea505389eefe1;p=rust-lightning diff --git a/lightning/src/sign/mod.rs b/lightning/src/sign/mod.rs index 6abf4bd2..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 {