+//! Various utilities for building scripts and deriving keys related to channels. These are
+//! largely of interest for those implementing chain::keysinterface::ChannelKeys message signing
+//! by hand.
+
use bitcoin::blockdata::script::{Script,Builder};
use bitcoin::blockdata::opcodes;
-use bitcoin::blockdata::transaction::{TxIn,TxOut,OutPoint,Transaction};
+use bitcoin::blockdata::transaction::{TxIn,TxOut,OutPoint,Transaction, SigHashType};
+use bitcoin::consensus::encode::{self, Decodable, Encodable};
+use bitcoin::util::bip143;
use bitcoin_hashes::{Hash, HashEngine};
use bitcoin_hashes::sha256::Hash as Sha256;
use bitcoin_hashes::hash160::Hash as Hash160;
use bitcoin_hashes::sha256d::Hash as Sha256dHash;
-use ln::channelmanager::PaymentHash;
+use ln::channelmanager::{PaymentHash, PaymentPreimage};
+use ln::msgs::DecodeError;
+use util::ser::{Readable, Writeable, Writer, WriterWriteAdaptor};
-use secp256k1::key::{PublicKey,SecretKey};
-use secp256k1::Secp256k1;
+use secp256k1::key::{SecretKey, PublicKey};
+use secp256k1::{Secp256k1, Signature};
use secp256k1;
-pub const HTLC_SUCCESS_TX_WEIGHT: u64 = 703;
-pub const HTLC_TIMEOUT_TX_WEIGHT: u64 = 663;
+pub(super) const HTLC_SUCCESS_TX_WEIGHT: u64 = 703;
+pub(super) const HTLC_TIMEOUT_TX_WEIGHT: u64 = 663;
+
+#[derive(PartialEq)]
+pub(crate) enum HTLCType {
+ AcceptedHTLC,
+ OfferedHTLC
+}
+
+impl HTLCType {
+ /// Check if a given tx witnessScript len matchs one of a pre-signed HTLC
+ pub(crate) fn scriptlen_to_htlctype(witness_script_len: usize) -> Option<HTLCType> {
+ if witness_script_len == 133 {
+ Some(HTLCType::OfferedHTLC)
+ } else if witness_script_len >= 136 && witness_script_len <= 139 {
+ Some(HTLCType::AcceptedHTLC)
+ } else {
+ None
+ }
+ }
+}
// Various functions for key derivation and transaction creation for use within channels. Primarily
// used in Channel and ChannelMonitor.
-pub fn build_commitment_secret(commitment_seed: [u8; 32], idx: u64) -> [u8; 32] {
- let mut res: [u8; 32] = commitment_seed;
+pub(super) fn build_commitment_secret(commitment_seed: &[u8; 32], idx: u64) -> [u8; 32] {
+ let mut res: [u8; 32] = commitment_seed.clone();
for i in 0..48 {
let bitpos = 47 - i;
if idx & (1 << bitpos) == (1 << bitpos) {
res
}
+/// Derives a per-commitment-transaction private key (eg an htlc key or payment key) from the base
+/// private key for that type of key and the per_commitment_point (available in TxCreationKeys)
pub fn derive_private_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, base_secret: &SecretKey) -> Result<SecretKey, secp256k1::Error> {
let mut sha = Sha256::engine();
sha.input(&per_commitment_point.serialize());
Ok(key)
}
-pub fn derive_public_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, base_point: &PublicKey) -> Result<PublicKey, secp256k1::Error> {
+pub
(super) fn derive_public_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, base_point: &PublicKey) -> Result<PublicKey, secp256k1::Error> {
let mut sha = Sha256::engine();
sha.input(&per_commitment_point.serialize());
sha.input(&base_point.serialize());
base_point.combine(&hashkey)
}
-/// Derives a revocation key from its constituent parts
-pub fn derive_private_revocation_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_secret: &SecretKey, revocation_base_secret: &SecretKey) -> Result<SecretKey, secp256k1::Error> {
+/// Derives a revocation key from its constituent parts.
+/// Note that this is infallible iff we trust that at least one of the two input keys are randomly
+/// generated (ie our own).
+pub(super) fn derive_private_revocation_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_secret: &SecretKey, revocation_base_secret: &SecretKey) -> Result<SecretKey, secp256k1::Error> {
let revocation_base_point = PublicKey::from_secret_key(&secp_ctx, &revocation_base_secret);
let per_commitment_point = PublicKey::from_secret_key(&secp_ctx, &per_commitment_secret);
Ok(part_a)
}
-pub fn derive_public_revocation_key<T: secp256k1::Verification>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, revocation_base_point: &PublicKey) -> Result<PublicKey, secp256k1::Error> {
+pub
(super) fn derive_public_revocation_key<T: secp256k1::Verification>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, revocation_base_point: &PublicKey) -> Result<PublicKey, secp256k1::Error> {
let rev_append_commit_hash_key = {
let mut sha = Sha256::engine();
sha.input(&revocation_base_point.serialize());
part_a.combine(&part_b)
}
+/// The set of public keys which are used in the creation of one commitment transaction.
+/// These are derived from the channel base keys and per-commitment data.
+#[derive(PartialEq)]
pub struct TxCreationKeys {
+ /// The per-commitment public key which was used to derive the other keys.
pub per_commitment_point: PublicKey,
- pub revocation_key: PublicKey,
- pub a_htlc_key: PublicKey,
- pub b_htlc_key: PublicKey,
- pub a_delayed_payment_key: PublicKey,
- pub b_payment_key: PublicKey,
+ /// The revocation key which is used to allow the owner of the commitment transaction to
+ /// provide their counterparty the ability to punish them if they broadcast an old state.
+ pub(crate) revocation_key: PublicKey,
+ /// A's HTLC Key
+ pub(crate) a_htlc_key: PublicKey,
+ /// B's HTLC Key
+ pub(crate) b_htlc_key: PublicKey,
+ /// A's Payment Key (which isn't allowed to be spent from for some delay)
+ pub(crate) a_delayed_payment_key: PublicKey,
+ /// B's Payment Key
+ pub(crate) b_payment_key: PublicKey,
}
+/// One counterparty's public keys which do not change over the life of a channel.
+#[derive(Clone, PartialEq)]
+pub struct ChannelPublicKeys {
+ /// The public key which is used to sign all commitment transactions, as it appears in the
+ /// on-chain channel lock-in 2-of-2 multisig output.
+ pub funding_pubkey: PublicKey,
+ /// The base point which is used (with derive_public_revocation_key) to derive per-commitment
+ /// revocation keys. The per-commitment revocation private key is then revealed by the owner of
+ /// a commitment transaction so that their counterparty can claim all available funds if they
+ /// broadcast an old state.
+ pub revocation_basepoint: PublicKey,
+ /// The base point which is used (with derive_public_key) to derive a per-commitment payment
+ /// public key which receives immediately-spendable non-HTLC-encumbered funds.
+ pub payment_basepoint: PublicKey,
+ /// The base point which is used (with derive_public_key) to derive a per-commitment payment
+ /// public key which receives non-HTLC-encumbered funds which are only available for spending
+ /// after some delay (or can be claimed via the revocation path).
+ pub delayed_payment_basepoint: PublicKey,
+ /// The base point which is used (with derive_public_key) to derive a per-commitment public key
+ /// which is used to encumber HTLC-in-flight outputs.
+ pub htlc_basepoint: PublicKey,
+}
+
+impl_writeable!(ChannelPublicKeys, 33*5, {
+ funding_pubkey,
+ revocation_basepoint,
+ payment_basepoint,
+ delayed_payment_basepoint,
+ htlc_basepoint
+});
+
+
impl TxCreationKeys {
- pub fn new<T: secp256k1::Signing + secp256k1::Verification>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, a_delayed_payment_base: &PublicKey, a_htlc_base: &PublicKey, b_revocation_base: &PublicKey, b_payment_base: &PublicKey, b_htlc_base: &PublicKey) -> Result<TxCreationKeys, secp256k1::Error> {
+ pub(crate) fn new<T: secp256k1::Signing + secp256k1::Verification>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, a_delayed_payment_base: &PublicKey, a_htlc_base: &PublicKey, b_revocation_base: &PublicKey, b_payment_base: &PublicKey, b_htlc_base: &PublicKey) -> Result<TxCreationKeys, secp256k1::Error> {
Ok(TxCreationKeys {
per_commitment_point: per_commitment_point.clone(),
revocation_key: derive_public_revocation_key(&secp_ctx, &per_commitment_point, &b_revocation_base)?,
/// Gets the "to_local" output redeemscript, ie the script which is time-locked or spendable by
/// the revocation key
-pub fn get_revokeable_redeemscript(revocation_key: &PublicKey, to_self_delay: u16, delayed_payment_key: &PublicKey) -> Script {
+pub(super) fn get_revokeable_redeemscript(revocation_key: &PublicKey, to_self_delay: u16, delayed_payment_key: &PublicKey) -> Script {
Builder::new().push_opcode(opcodes::all::OP_IF)
.push_slice(&revocation_key.serialize())
.push_opcode(opcodes::all::OP_ELSE)
}
#[derive(Clone, PartialEq)]
+/// Information about an HTLC as it appears in a commitment transaction
pub struct HTLCOutputInCommitment {
+ /// Whether the HTLC was "offered" (ie outbound in relation to this commitment transaction).
+ /// Note that this is not the same as whether it is ountbound *from us*. To determine that you
+ /// need to compare this value to whether the commitment transaction in question is that of
+ /// the remote party or our own.
pub offered: bool,
+ /// The value, in msat, of the HTLC. The value as it appears in the commitment transaction is
+ /// this divided by 1000.
pub amount_msat: u64,
+ /// The CLTV lock-time at which this HTLC expires.
pub cltv_expiry: u32,
+ /// The hash of the preimage which unlocks this HTLC.
pub payment_hash: PaymentHash,
+ /// The position within the commitment transactions' outputs. This may be None if the value is
+ /// below the dust limit (in which case no output appears in the commitment transaction and the
+ /// value is spent to additional transaction fees).
pub transaction_output_index: Option<u32>,
}
#[inline]
-pub fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommitment, a_htlc_key: &PublicKey, b_htlc_key: &PublicKey, revocation_key: &PublicKey) -> Script {
+pub(super) fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommitment, a_htlc_key: &PublicKey, b_htlc_key: &PublicKey, revocation_key: &PublicKey) -> Script {
let payment_hash160 = Ripemd160::hash(&htlc.payment_hash.0[..]).into_inner();
if htlc.offered {
Builder::new().push_opcode(opcodes::all::OP_DUP)
get_htlc_redeemscript_with_explicit_keys(htlc, &keys.a_htlc_key, &keys.b_htlc_key, &keys.revocation_key)
}
+/// Gets the redeemscript for a funding output from the two funding public keys.
+/// Note that the order of funding public keys does not matter.
+pub fn make_funding_redeemscript(a: &PublicKey, b: &PublicKey) -> Script {
+ let our_funding_key = a.serialize();
+ let their_funding_key = b.serialize();
+
+ let builder = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2);
+ if our_funding_key[..] < their_funding_key[..] {
+ builder.push_slice(&our_funding_key)
+ .push_slice(&their_funding_key)
+ } else {
+ builder.push_slice(&their_funding_key)
+ .push_slice(&our_funding_key)
+ }.push_opcode(opcodes::all::OP_PUSHNUM_2).push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script()
+}
+
/// panics if htlc.transaction_output_index.is_none()!
pub fn build_htlc_transaction(prev_hash: &Sha256dHash, feerate_per_kw: u64, to_self_delay: u16, htlc: &HTLCOutputInCommitment, a_delayed_payment_key: &PublicKey, revocation_key: &PublicKey) -> Transaction {
let mut txins: Vec<TxIn> = Vec::new();
output: txouts,
}
}
+
+/// Signs a transaction created by build_htlc_transaction. If the transaction is an
+/// HTLC-Success transaction (ie htlc.offered is false), preimage must be set!
+pub(crate) fn sign_htlc_transaction<T: secp256k1::Signing>(tx: &mut Transaction, their_sig: &Signature, preimage: &Option<PaymentPreimage>, htlc: &HTLCOutputInCommitment, a_htlc_key: &PublicKey, b_htlc_key: &PublicKey, revocation_key: &PublicKey, per_commitment_point: &PublicKey, htlc_base_key: &SecretKey, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Script), ()> {
+ if tx.input.len() != 1 { return Err(()); }
+ if tx.input[0].witness.len() != 0 { return Err(()); }
+
+ let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&htlc, a_htlc_key, b_htlc_key, revocation_key);
+
+ let our_htlc_key = derive_private_key(secp_ctx, per_commitment_point, htlc_base_key).map_err(|_| ())?;
+ let sighash = hash_to_message!(&bip143::SighashComponents::new(&tx).sighash_all(&tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
+ let local_tx = PublicKey::from_secret_key(&secp_ctx, &our_htlc_key) == *a_htlc_key;
+ let our_sig = secp_ctx.sign(&sighash, &our_htlc_key);
+
+ tx.input[0].witness.push(Vec::new()); // First is the multisig dummy
+
+ if local_tx { // b, then a
+ tx.input[0].witness.push(their_sig.serialize_der().to_vec());
+ tx.input[0].witness.push(our_sig.serialize_der().to_vec());
+ } else {
+ tx.input[0].witness.push(our_sig.serialize_der().to_vec());
+ tx.input[0].witness.push(their_sig.serialize_der().to_vec());
+ }
+ tx.input[0].witness[1].push(SigHashType::All as u8);
+ tx.input[0].witness[2].push(SigHashType::All as u8);
+
+ if htlc.offered {
+ tx.input[0].witness.push(Vec::new());
+ assert!(preimage.is_none());
+ } else {
+ tx.input[0].witness.push(preimage.unwrap().0.to_vec());
+ }
+
+ tx.input[0].witness.push(htlc_redeemscript.as_bytes().to_vec());
+
+ Ok((our_sig, htlc_redeemscript))
+}
+
+#[derive(Clone)]
+/// We use this to track local commitment transactions and put off signing them until we are ready
+/// to broadcast. Eventually this will require a signer which is possibly external, but for now we
+/// just pass in the SecretKeys required.
+pub(crate) struct LocalCommitmentTransaction {
+ tx: Transaction
+}
+impl LocalCommitmentTransaction {
+ #[cfg(test)]
+ pub fn dummy() -> Self {
+ Self { tx: Transaction {
+ version: 2,
+ input: Vec::new(),
+ output: Vec::new(),
+ lock_time: 0,
+ } }
+ }
+
+ pub fn new_missing_local_sig(mut tx: Transaction, their_sig: &Signature, our_funding_key: &PublicKey, their_funding_key: &PublicKey) -> LocalCommitmentTransaction {
+ if tx.input.len() != 1 { panic!("Tried to store a commitment transaction that had input count != 1!"); }
+ if tx.input[0].witness.len() != 0 { panic!("Tried to store a signed commitment transaction?"); }
+
+ tx.input[0].witness.push(Vec::new()); // First is the multisig dummy
+
+ if our_funding_key.serialize()[..] < their_funding_key.serialize()[..] {
+ tx.input[0].witness.push(Vec::new());
+ tx.input[0].witness.push(their_sig.serialize_der().to_vec());
+ tx.input[0].witness[2].push(SigHashType::All as u8);
+ } else {
+ tx.input[0].witness.push(their_sig.serialize_der().to_vec());
+ tx.input[0].witness[1].push(SigHashType::All as u8);
+ tx.input[0].witness.push(Vec::new());
+ }
+
+ Self { tx }
+ }
+
+ pub fn txid(&self) -> Sha256dHash {
+ self.tx.txid()
+ }
+
+ pub fn has_local_sig(&self) -> bool {
+ if self.tx.input.len() != 1 { panic!("Commitment transactions must have input count == 1!"); }
+ if self.tx.input[0].witness.len() == 4 {
+ assert!(!self.tx.input[0].witness[1].is_empty());
+ assert!(!self.tx.input[0].witness[2].is_empty());
+ true
+ } else {
+ assert_eq!(self.tx.input[0].witness.len(), 3);
+ assert!(self.tx.input[0].witness[0].is_empty());
+ assert!(self.tx.input[0].witness[1].is_empty() || self.tx.input[0].witness[2].is_empty());
+ false
+ }
+ }
+
+ pub fn add_local_sig<T: secp256k1::Signing>(&mut self, funding_key: &SecretKey, funding_redeemscript: &Script, channel_value_satoshis: u64, secp_ctx: &Secp256k1<T>) {
+ if self.has_local_sig() { return; }
+ let sighash = hash_to_message!(&bip143::SighashComponents::new(&self.tx)
+ .sighash_all(&self.tx.input[0], funding_redeemscript, channel_value_satoshis)[..]);
+ let our_sig = secp_ctx.sign(&sighash, funding_key);
+
+ if self.tx.input[0].witness[1].is_empty() {
+ self.tx.input[0].witness[1] = our_sig.serialize_der().to_vec();
+ self.tx.input[0].witness[1].push(SigHashType::All as u8);
+ } else {
+ self.tx.input[0].witness[2] = our_sig.serialize_der().to_vec();
+ self.tx.input[0].witness[2].push(SigHashType::All as u8);
+ }
+
+ self.tx.input[0].witness.push(funding_redeemscript.as_bytes().to_vec());
+ }
+
+ pub fn without_valid_witness(&self) -> &Transaction { &self.tx }
+ pub fn with_valid_witness(&self) -> &Transaction {
+ assert!(self.has_local_sig());
+ &self.tx
+ }
+}
+impl PartialEq for LocalCommitmentTransaction {
+ // We dont care whether we are signed in equality comparison
+ fn eq(&self, o: &Self) -> bool {
+ self.txid() == o.txid()
+ }
+}
+impl Writeable for LocalCommitmentTransaction {
+ fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
+ if let Err(e) = self.tx.consensus_encode(&mut WriterWriteAdaptor(writer)) {
+ match e {
+ encode::Error::Io(e) => return Err(e),
+ _ => panic!("local tx must have been well-formed!"),
+ }
+ }
+ Ok(())
+ }
+}
+impl<R: ::std::io::Read> Readable<R> for LocalCommitmentTransaction {
+ fn read(reader: &mut R) -> Result<Self, DecodeError> {
+ let tx = match Transaction::consensus_decode(reader.by_ref()) {
+ Ok(tx) => tx,
+ Err(e) => match e {
+ encode::Error::Io(ioe) => return Err(DecodeError::Io(ioe)),
+ _ => return Err(DecodeError::InvalidValue),
+ },
+ };
+
+ if tx.input.len() != 1 {
+ // Ensure tx didn't hit the 0-input ambiguity case.
+ return Err(DecodeError::InvalidValue);
+ }
+ Ok(Self { tx })
+ }
+}
projects / rust-lightning / blobdiff