_ Git - rust-lightning/blob - lightning/src/ln/chan_utils.rs

   1 //! Various utilities for building scripts and deriving keys related to channels. These are
   2 //! largely of interest for those implementing chain::keysinterface::ChannelKeys message signing
   3 //! by hand.
   4
   5 use bitcoin::blockdata::script::{Script,Builder};
   6 use bitcoin::blockdata::opcodes;
   7 use bitcoin::blockdata::transaction::{TxIn,TxOut,OutPoint,Transaction, SigHashType};
   8 use bitcoin::consensus::encode::{self, Decodable, Encodable};
   9 use bitcoin::util::bip143;
  10
  11 use bitcoin_hashes::{Hash, HashEngine};
  12 use bitcoin_hashes::sha256::Hash as Sha256;
  13 use bitcoin_hashes::ripemd160::Hash as Ripemd160;
  14 use bitcoin_hashes::hash160::Hash as Hash160;
  15 use bitcoin_hashes::sha256d::Hash as Sha256dHash;
  16
  17 use ln::channelmanager::{PaymentHash, PaymentPreimage};
  18 use ln::msgs::DecodeError;
  19 use util::ser::{Readable, Writeable, Writer, WriterWriteAdaptor};
  20
  21 use secp256k1::key::{SecretKey, PublicKey};
  22 use secp256k1::{Secp256k1, Signature};
  23 use secp256k1;
  24
  25 pub(super) const HTLC_SUCCESS_TX_WEIGHT: u64 = 703;
  26 pub(super) const HTLC_TIMEOUT_TX_WEIGHT: u64 = 663;
  27
  28 // Various functions for key derivation and transaction creation for use within channels. Primarily
  29 // used in Channel and ChannelMonitor.
  30
  31 pub(super) fn build_commitment_secret(commitment_seed: &[u8; 32], idx: u64) -> [u8; 32] {
  32         let mut res: [u8; 32] = commitment_seed.clone();
  33         for i in 0..48 {
  34                 let bitpos = 47 - i;
  35                 if idx & (1 << bitpos) == (1 << bitpos) {
  36                         res[bitpos / 8] ^= 1 << (bitpos & 7);
  37                         res = Sha256::hash(&res).into_inner();
  38                 }
  39         }
  40         res
  41 }
  42
  43 /// Derives a per-commitment-transaction private key (eg an htlc key or payment key) from the base
  44 /// private key for that type of key and the per_commitment_point (available in TxCreationKeys)
  45 pub fn derive_private_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, base_secret: &SecretKey) -> Result<SecretKey, secp256k1::Error> {
  46         let mut sha = Sha256::engine();
  47         sha.input(&per_commitment_point.serialize());
  48         sha.input(&PublicKey::from_secret_key(&secp_ctx, &base_secret).serialize());
  49         let res = Sha256::from_engine(sha).into_inner();
  50
  51         let mut key = base_secret.clone();
  52         key.add_assign(&res)?;
  53         Ok(key)
  54 }
  55
  56 pub(super) fn derive_public_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_commitment_point: &PublicKey, base_point: &PublicKey) -> Result<PublicKey, secp256k1::Error> {
  57         let mut sha = Sha256::engine();
  58         sha.input(&per_commitment_point.serialize());
  59         sha.input(&base_point.serialize());
  60         let res = Sha256::from_engine(sha).into_inner();
  61
  62         let hashkey = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&res)?);
  63         base_point.combine(&hashkey)
  64 }
  65
  66 /// Derives a revocation key from its constituent parts.
  67 /// Note that this is infallible iff we trust that at least one of the two input keys are randomly
  68 /// generated (ie our own).
  69 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> {
  70         let revocation_base_point = PublicKey::from_secret_key(&secp_ctx, &revocation_base_secret);
  71         let per_commitment_point = PublicKey::from_secret_key(&secp_ctx, &per_commitment_secret);
  72
  73         let rev_append_commit_hash_key = {
  74                 let mut sha = Sha256::engine();
  75                 sha.input(&revocation_base_point.serialize());
  76                 sha.input(&per_commitment_point.serialize());
  77
  78                 Sha256::from_engine(sha).into_inner()
  79         };
  80         let commit_append_rev_hash_key = {
  81                 let mut sha = Sha256::engine();
  82                 sha.input(&per_commitment_point.serialize());
  83                 sha.input(&revocation_base_point.serialize());
  84
  85                 Sha256::from_engine(sha).into_inner()
  86         };
  87
  88         let mut part_a = revocation_base_secret.clone();
  89         part_a.mul_assign(&rev_append_commit_hash_key)?;
  90         let mut part_b = per_commitment_secret.clone();
  91         part_b.mul_assign(&commit_append_rev_hash_key)?;
  92         part_a.add_assign(&part_b[..])?;
  93         Ok(part_a)
  94 }
  95
  96 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> {
  97         let rev_append_commit_hash_key = {
  98                 let mut sha = Sha256::engine();
  99                 sha.input(&revocation_base_point.serialize());
 100                 sha.input(&per_commitment_point.serialize());
 101
 102                 Sha256::from_engine(sha).into_inner()
 103         };
 104         let commit_append_rev_hash_key = {
 105                 let mut sha = Sha256::engine();
 106                 sha.input(&per_commitment_point.serialize());
 107                 sha.input(&revocation_base_point.serialize());
 108
 109                 Sha256::from_engine(sha).into_inner()
 110         };
 111
 112         let mut part_a = revocation_base_point.clone();
 113         part_a.mul_assign(&secp_ctx, &rev_append_commit_hash_key)?;
 114         let mut part_b = per_commitment_point.clone();
 115         part_b.mul_assign(&secp_ctx, &commit_append_rev_hash_key)?;
 116         part_a.combine(&part_b)
 117 }
 118
 119 /// The set of public keys which are used in the creation of one commitment transaction.
 120 /// These are derived from the channel base keys and per-commitment data.
 121 #[derive(PartialEq)]
 122 pub struct TxCreationKeys {
 123         /// The per-commitment public key which was used to derive the other keys.
 124         pub per_commitment_point: PublicKey,
 125         /// The revocation key which is used to allow the owner of the commitment transaction to
 126         /// provide their counterparty the ability to punish them if they broadcast an old state.
 127         pub(crate) revocation_key: PublicKey,
 128         /// A's HTLC Key
 129         pub(crate) a_htlc_key: PublicKey,
 130         /// B's HTLC Key
 131         pub(crate) b_htlc_key: PublicKey,
 132         /// A's Payment Key (which isn't allowed to be spent from for some delay)
 133         pub(crate) a_delayed_payment_key: PublicKey,
 134         /// B's Payment Key
 135         pub(crate) b_payment_key: PublicKey,
 136 }
 137
 138 /// One counterparty's public keys which do not change over the life of a channel.
 139 #[derive(Clone)]
 140 pub struct ChannelPublicKeys {
 141         /// The public key which is used to sign all commitment transactions, as it appears in the
 142         /// on-chain channel lock-in 2-of-2 multisig output.
 143         pub funding_pubkey: PublicKey,
 144         /// The base point which is used (with derive_public_revocation_key) to derive per-commitment
 145         /// revocation keys. The per-commitment revocation private key is then revealed by the owner of
 146         /// a commitment transaction so that their counterparty can claim all available funds if they
 147         /// broadcast an old state.
 148         pub revocation_basepoint: PublicKey,
 149         /// The base point which is used (with derive_public_key) to derive a per-commitment payment
 150         /// public key which receives immediately-spendable non-HTLC-encumbered funds.
 151         pub payment_basepoint: PublicKey,
 152         /// The base point which is used (with derive_public_key) to derive a per-commitment payment
 153         /// public key which receives non-HTLC-encumbered funds which are only available for spending
 154         /// after some delay (or can be claimed via the revocation path).
 155         pub delayed_payment_basepoint: PublicKey,
 156         /// The base point which is used (with derive_public_key) to derive a per-commitment public key
 157         /// which is used to encumber HTLC-in-flight outputs.
 158         pub htlc_basepoint: PublicKey,
 159 }
 160
 161 impl_writeable!(ChannelPublicKeys, 33*5, {
 162         funding_pubkey,
 163         revocation_basepoint,
 164         payment_basepoint,
 165         delayed_payment_basepoint,
 166         htlc_basepoint
 167 });
 168
 169
 170 impl TxCreationKeys {
 171         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> {
 172                 Ok(TxCreationKeys {
 173                         per_commitment_point: per_commitment_point.clone(),
 174                         revocation_key: derive_public_revocation_key(&secp_ctx, &per_commitment_point, &b_revocation_base)?,
 175                         a_htlc_key: derive_public_key(&secp_ctx, &per_commitment_point, &a_htlc_base)?,
 176                         b_htlc_key: derive_public_key(&secp_ctx, &per_commitment_point, &b_htlc_base)?,
 177                         a_delayed_payment_key: derive_public_key(&secp_ctx, &per_commitment_point, &a_delayed_payment_base)?,
 178                         b_payment_key: derive_public_key(&secp_ctx, &per_commitment_point, &b_payment_base)?,
 179                 })
 180         }
 181 }
 182
 183 /// Gets the "to_local" output redeemscript, ie the script which is time-locked or spendable by
 184 /// the revocation key
 185 pub(super) fn get_revokeable_redeemscript(revocation_key: &PublicKey, to_self_delay: u16, delayed_payment_key: &PublicKey) -> Script {
 186         Builder::new().push_opcode(opcodes::all::OP_IF)
 187                       .push_slice(&revocation_key.serialize())
 188                       .push_opcode(opcodes::all::OP_ELSE)
 189                       .push_int(to_self_delay as i64)
 190                       .push_opcode(opcodes::all::OP_CSV)
 191                       .push_opcode(opcodes::all::OP_DROP)
 192                       .push_slice(&delayed_payment_key.serialize())
 193                       .push_opcode(opcodes::all::OP_ENDIF)
 194                       .push_opcode(opcodes::all::OP_CHECKSIG)
 195                       .into_script()
 196 }
 197
 198 #[derive(Clone, PartialEq)]
 199 /// Information about an HTLC as it appears in a commitment transaction
 200 pub struct HTLCOutputInCommitment {
 201         /// Whether the HTLC was "offered" (ie outbound in relation to this commitment transaction).
 202         /// Note that this is not the same as whether it is ountbound *from us*. To determine that you
 203         /// need to compare this value to whether the commitment transaction in question is that of
 204         /// the remote party or our own.
 205         pub offered: bool,
 206         /// The value, in msat, of the HTLC. The value as it appears in the commitment transaction is
 207         /// this divided by 1000.
 208         pub amount_msat: u64,
 209         /// The CLTV lock-time at which this HTLC expires.
 210         pub cltv_expiry: u32,
 211         /// The hash of the preimage which unlocks this HTLC.
 212         pub payment_hash: PaymentHash,
 213         /// The position within the commitment transactions' outputs. This may be None if the value is
 214         /// below the dust limit (in which case no output appears in the commitment transaction and the
 215         /// value is spent to additional transaction fees).
 216         pub transaction_output_index: Option<u32>,
 217 }
 218
 219 #[inline]
 220 pub(super) fn get_htlc_redeemscript_with_explicit_keys(htlc: &HTLCOutputInCommitment, a_htlc_key: &PublicKey, b_htlc_key: &PublicKey, revocation_key: &PublicKey) -> Script {
 221         let payment_hash160 = Ripemd160::hash(&htlc.payment_hash.0[..]).into_inner();
 222         if htlc.offered {
 223                 Builder::new().push_opcode(opcodes::all::OP_DUP)
 224                               .push_opcode(opcodes::all::OP_HASH160)
 225                               .push_slice(&Hash160::hash(&revocation_key.serialize())[..])
 226                               .push_opcode(opcodes::all::OP_EQUAL)
 227                               .push_opcode(opcodes::all::OP_IF)
 228                               .push_opcode(opcodes::all::OP_CHECKSIG)
 229                               .push_opcode(opcodes::all::OP_ELSE)
 230                               .push_slice(&b_htlc_key.serialize()[..])
 231                               .push_opcode(opcodes::all::OP_SWAP)
 232                               .push_opcode(opcodes::all::OP_SIZE)
 233                               .push_int(32)
 234                               .push_opcode(opcodes::all::OP_EQUAL)
 235                               .push_opcode(opcodes::all::OP_NOTIF)
 236                               .push_opcode(opcodes::all::OP_DROP)
 237                               .push_int(2)
 238                               .push_opcode(opcodes::all::OP_SWAP)
 239                               .push_slice(&a_htlc_key.serialize()[..])
 240                               .push_int(2)
 241                               .push_opcode(opcodes::all::OP_CHECKMULTISIG)
 242                               .push_opcode(opcodes::all::OP_ELSE)
 243                               .push_opcode(opcodes::all::OP_HASH160)
 244                               .push_slice(&payment_hash160)
 245                               .push_opcode(opcodes::all::OP_EQUALVERIFY)
 246                               .push_opcode(opcodes::all::OP_CHECKSIG)
 247                               .push_opcode(opcodes::all::OP_ENDIF)
 248                               .push_opcode(opcodes::all::OP_ENDIF)
 249                               .into_script()
 250         } else {
 251                 Builder::new().push_opcode(opcodes::all::OP_DUP)
 252                               .push_opcode(opcodes::all::OP_HASH160)
 253                               .push_slice(&Hash160::hash(&revocation_key.serialize())[..])
 254                               .push_opcode(opcodes::all::OP_EQUAL)
 255                               .push_opcode(opcodes::all::OP_IF)
 256                               .push_opcode(opcodes::all::OP_CHECKSIG)
 257                               .push_opcode(opcodes::all::OP_ELSE)
 258                               .push_slice(&b_htlc_key.serialize()[..])
 259                               .push_opcode(opcodes::all::OP_SWAP)
 260                               .push_opcode(opcodes::all::OP_SIZE)
 261                               .push_int(32)
 262                               .push_opcode(opcodes::all::OP_EQUAL)
 263                               .push_opcode(opcodes::all::OP_IF)
 264                               .push_opcode(opcodes::all::OP_HASH160)
 265                               .push_slice(&payment_hash160)
 266                               .push_opcode(opcodes::all::OP_EQUALVERIFY)
 267                               .push_int(2)
 268                               .push_opcode(opcodes::all::OP_SWAP)
 269                               .push_slice(&a_htlc_key.serialize()[..])
 270                               .push_int(2)
 271                               .push_opcode(opcodes::all::OP_CHECKMULTISIG)
 272                               .push_opcode(opcodes::all::OP_ELSE)
 273                               .push_opcode(opcodes::all::OP_DROP)
 274                               .push_int(htlc.cltv_expiry as i64)
 275                               .push_opcode(opcodes::all::OP_CLTV)
 276                               .push_opcode(opcodes::all::OP_DROP)
 277                               .push_opcode(opcodes::all::OP_CHECKSIG)
 278                               .push_opcode(opcodes::all::OP_ENDIF)
 279                               .push_opcode(opcodes::all::OP_ENDIF)
 280                               .into_script()
 281         }
 282 }
 283
 284 /// note here that 'a_revocation_key' is generated using b_revocation_basepoint and a's
 285 /// commitment secret. 'htlc' does *not* need to have its previous_output_index filled.
 286 #[inline]
 287 pub fn get_htlc_redeemscript(htlc: &HTLCOutputInCommitment, keys: &TxCreationKeys) -> Script {
 288         get_htlc_redeemscript_with_explicit_keys(htlc, &keys.a_htlc_key, &keys.b_htlc_key, &keys.revocation_key)
 289 }
 290
 291 /// Gets the redeemscript for a funding output from the two funding public keys.
 292 /// Note that the order of funding public keys does not matter.
 293 pub fn make_funding_redeemscript(a: &PublicKey, b: &PublicKey) -> Script {
 294         let our_funding_key = a.serialize();
 295         let their_funding_key = b.serialize();
 296
 297         let builder = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2);
 298         if our_funding_key[..] < their_funding_key[..] {
 299                 builder.push_slice(&our_funding_key)
 300                         .push_slice(&their_funding_key)
 301         } else {
 302                 builder.push_slice(&their_funding_key)
 303                         .push_slice(&our_funding_key)
 304         }.push_opcode(opcodes::all::OP_PUSHNUM_2).push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script()
 305 }
 306
 307 /// panics if htlc.transaction_output_index.is_none()!
 308 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 {
 309         let mut txins: Vec<TxIn> = Vec::new();
 310         txins.push(TxIn {
 311                 previous_output: OutPoint {
 312                         txid: prev_hash.clone(),
 313                         vout: htlc.transaction_output_index.expect("Can't build an HTLC transaction for a dust output"),
 314                 },
 315                 script_sig: Script::new(),
 316                 sequence: 0,
 317                 witness: Vec::new(),
 318         });
 319
 320         let total_fee = if htlc.offered {
 321                         feerate_per_kw * HTLC_TIMEOUT_TX_WEIGHT / 1000
 322                 } else {
 323                         feerate_per_kw * HTLC_SUCCESS_TX_WEIGHT / 1000
 324                 };
 325
 326         let mut txouts: Vec<TxOut> = Vec::new();
 327         txouts.push(TxOut {
 328                 script_pubkey: get_revokeable_redeemscript(revocation_key, to_self_delay, a_delayed_payment_key).to_v0_p2wsh(),
 329                 value: htlc.amount_msat / 1000 - total_fee //TODO: BOLT 3 does not specify if we should add amount_msat before dividing or if we should divide by 1000 before subtracting (as we do here)
 330         });
 331
 332         Transaction {
 333                 version: 2,
 334                 lock_time: if htlc.offered { htlc.cltv_expiry } else { 0 },
 335                 input: txins,
 336                 output: txouts,
 337         }
 338 }
 339
 340 /// Signs a transaction created by build_htlc_transaction. If the transaction is an
 341 /// HTLC-Success transaction (ie htlc.offered is false), preimage must be set!
 342 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), ()> {
 343         if tx.input.len() != 1 { return Err(()); }
 344         if tx.input[0].witness.len() != 0 { return Err(()); }
 345
 346         let htlc_redeemscript = get_htlc_redeemscript_with_explicit_keys(&htlc, a_htlc_key, b_htlc_key, revocation_key);
 347
 348         let our_htlc_key = derive_private_key(secp_ctx, per_commitment_point, htlc_base_key).map_err(|_| ())?;
 349         let sighash = hash_to_message!(&bip143::SighashComponents::new(&tx).sighash_all(&tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
 350         let local_tx = PublicKey::from_secret_key(&secp_ctx, &our_htlc_key) == *a_htlc_key;
 351         let our_sig = secp_ctx.sign(&sighash, &our_htlc_key);
 352
 353         tx.input[0].witness.push(Vec::new()); // First is the multisig dummy
 354
 355         if local_tx { // b, then a
 356                 tx.input[0].witness.push(their_sig.serialize_der().to_vec());
 357                 tx.input[0].witness.push(our_sig.serialize_der().to_vec());
 358         } else {
 359                 tx.input[0].witness.push(our_sig.serialize_der().to_vec());
 360                 tx.input[0].witness.push(their_sig.serialize_der().to_vec());
 361         }
 362         tx.input[0].witness[1].push(SigHashType::All as u8);
 363         tx.input[0].witness[2].push(SigHashType::All as u8);
 364
 365         if htlc.offered {
 366                 tx.input[0].witness.push(Vec::new());
 367                 assert!(preimage.is_none());
 368         } else {
 369                 tx.input[0].witness.push(preimage.unwrap().0.to_vec());
 370         }
 371
 372         tx.input[0].witness.push(htlc_redeemscript.as_bytes().to_vec());
 373
 374         Ok((our_sig, htlc_redeemscript))
 375 }
 376
 377 #[derive(Clone)]
 378 /// We use this to track local commitment transactions and put off signing them until we are ready
 379 /// to broadcast. Eventually this will require a signer which is possibly external, but for now we
 380 /// just pass in the SecretKeys required.
 381 pub(crate) struct LocalCommitmentTransaction {
 382         tx: Transaction
 383 }
 384 impl LocalCommitmentTransaction {
 385         #[cfg(test)]
 386         pub fn dummy() -> Self {
 387                 Self { tx: Transaction {
 388                         version: 2,
 389                         input: Vec::new(),
 390                         output: Vec::new(),
 391                         lock_time: 0,
 392                 } }
 393         }
 394
 395         pub fn new_missing_local_sig(mut tx: Transaction, their_sig: &Signature, our_funding_key: &PublicKey, their_funding_key: &PublicKey) -> LocalCommitmentTransaction {
 396                 if tx.input.len() != 1 { panic!("Tried to store a commitment transaction that had input count != 1!"); }
 397                 if tx.input[0].witness.len() != 0 { panic!("Tried to store a signed commitment transaction?"); }
 398
 399                 tx.input[0].witness.push(Vec::new()); // First is the multisig dummy
 400
 401                 if our_funding_key.serialize()[..] < their_funding_key.serialize()[..] {
 402                         tx.input[0].witness.push(Vec::new());
 403                         tx.input[0].witness.push(their_sig.serialize_der().to_vec());
 404                         tx.input[0].witness[2].push(SigHashType::All as u8);
 405                 } else {
 406                         tx.input[0].witness.push(their_sig.serialize_der().to_vec());
 407                         tx.input[0].witness[1].push(SigHashType::All as u8);
 408                         tx.input[0].witness.push(Vec::new());
 409                 }
 410
 411                 Self { tx }
 412         }
 413
 414         pub fn txid(&self) -> Sha256dHash {
 415                 self.tx.txid()
 416         }
 417
 418         pub fn has_local_sig(&self) -> bool {
 419                 if self.tx.input.len() != 1 { panic!("Commitment transactions must have input count == 1!"); }
 420                 if self.tx.input[0].witness.len() == 4 {
 421                         assert!(!self.tx.input[0].witness[1].is_empty());
 422                         assert!(!self.tx.input[0].witness[2].is_empty());
 423                         true
 424                 } else {
 425                         assert_eq!(self.tx.input[0].witness.len(), 3);
 426                         assert!(self.tx.input[0].witness[0].is_empty());
 427                         assert!(self.tx.input[0].witness[1].is_empty() || self.tx.input[0].witness[2].is_empty());
 428                         false
 429                 }
 430         }
 431
 432         pub fn add_local_sig<T: secp256k1::Signing>(&mut self, funding_key: &SecretKey, funding_redeemscript: &Script, channel_value_satoshis: u64, secp_ctx: &Secp256k1<T>) {
 433                 if self.has_local_sig() { return; }
 434                 let sighash = hash_to_message!(&bip143::SighashComponents::new(&self.tx)
 435                         .sighash_all(&self.tx.input[0], funding_redeemscript, channel_value_satoshis)[..]);
 436                 let our_sig = secp_ctx.sign(&sighash, funding_key);
 437
 438                 if self.tx.input[0].witness[1].is_empty() {
 439                         self.tx.input[0].witness[1] = our_sig.serialize_der().to_vec();
 440                         self.tx.input[0].witness[1].push(SigHashType::All as u8);
 441                 } else {
 442                         self.tx.input[0].witness[2] = our_sig.serialize_der().to_vec();
 443                         self.tx.input[0].witness[2].push(SigHashType::All as u8);
 444                 }
 445
 446                 self.tx.input[0].witness.push(funding_redeemscript.as_bytes().to_vec());
 447         }
 448
 449         pub fn without_valid_witness(&self) -> &Transaction { &self.tx }
 450         pub fn with_valid_witness(&self) -> &Transaction {
 451                 assert!(self.has_local_sig());
 452                 &self.tx
 453         }
 454 }
 455 impl PartialEq for LocalCommitmentTransaction {
 456         // We dont care whether we are signed in equality comparison
 457         fn eq(&self, o: &Self) -> bool {
 458                 self.txid() == o.txid()
 459         }
 460 }
 461 impl Writeable for LocalCommitmentTransaction {
 462         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
 463                 if let Err(e) = self.tx.consensus_encode(&mut WriterWriteAdaptor(writer)) {
 464                         match e {
 465                                 encode::Error::Io(e) => return Err(e),
 466                                 _ => panic!("local tx must have been well-formed!"),
 467                         }
 468                 }
 469                 Ok(())
 470         }
 471 }
 472 impl<R: ::std::io::Read> Readable<R> for LocalCommitmentTransaction {
 473         fn read(reader: &mut R) -> Result<Self, DecodeError> {
 474                 let tx = match Transaction::consensus_decode(reader.by_ref()) {
 475                         Ok(tx) => tx,
 476                         Err(e) => match e {
 477                                 encode::Error::Io(ioe) => return Err(DecodeError::Io(ioe)),
 478                                 _ => return Err(DecodeError::InvalidValue),
 479                         },
 480                 };
 481
 482                 if tx.input.len() != 1 {
 483                         // Ensure tx didn't hit the 0-input ambiguity case.
 484                         return Err(DecodeError::InvalidValue);
 485                 }
 486                 Ok(Self { tx })
 487         }
 488 }