X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fchain%2Fkeysinterface.rs;h=9d3b955861dbfca672fabf614ab4378f58aaa6a7;hb=ff00f6f8861419b73269e6c51d75ac9de75f1d1f;hp=73c22684c544459eb8bb2f10e24a405623db4d6a;hpb=92c0698865ffdfa2c603288ef1d7f23130243aae;p=rust-lightning diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs index 73c22684..9d3b9558 100644 --- a/lightning/src/chain/keysinterface.rs +++ b/lightning/src/chain/keysinterface.rs @@ -1,47 +1,108 @@ +// 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. + //! keysinterface provides keys into rust-lightning and defines some useful enums which describe //! spendable on-chain outputs which the user owns and is responsible for using just as any other //! on-chain output which is theirs. -use bitcoin::blockdata::transaction::{Transaction, OutPoint, TxOut}; +use bitcoin::blockdata::transaction::{Transaction, TxOut, TxIn, SigHashType}; use bitcoin::blockdata::script::{Script, Builder}; use bitcoin::blockdata::opcodes; use bitcoin::network::constants::Network; use bitcoin::util::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber}; use bitcoin::util::bip143; -use bitcoin_hashes::{Hash, HashEngine}; -use bitcoin_hashes::sha256::HashEngine as Sha256State; -use bitcoin_hashes::sha256::Hash as Sha256; -use bitcoin_hashes::sha256d::Hash as Sha256dHash; -use bitcoin_hashes::hash160::Hash as Hash160; +use bitcoin::hashes::{Hash, HashEngine}; +use bitcoin::hashes::sha256::HashEngine as Sha256State; +use bitcoin::hashes::sha256::Hash as Sha256; +use bitcoin::hashes::sha256d::Hash as Sha256dHash; +use bitcoin::hash_types::WPubkeyHash; -use secp256k1::key::{SecretKey, PublicKey}; -use secp256k1::{Secp256k1, Signature, Signing}; -use secp256k1; +use bitcoin::secp256k1::key::{SecretKey, PublicKey}; +use bitcoin::secp256k1::{Secp256k1, Signature, Signing}; +use bitcoin::secp256k1; -use util::byte_utils; -use util::logger::Logger; +use util::{byte_utils, transaction_utils}; use util::ser::{Writeable, Writer, Readable}; +use chain::transaction::OutPoint; use ln::chan_utils; -use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, LocalCommitmentTransaction}; -use ln::msgs; +use ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction}; +use ln::msgs::UnsignedChannelAnnouncement; -use std::sync::Arc; +use std::collections::HashSet; use std::sync::atomic::{AtomicUsize, Ordering}; use std::io::Error; -use ln::msgs::DecodeError; +use ln::msgs::{DecodeError, MAX_VALUE_MSAT}; + +/// Information about a spendable output to a P2WSH script. See +/// SpendableOutputDescriptor::DelayedPaymentOutput for more details on how to spend this. +#[derive(Clone, Debug, PartialEq)] +pub struct DelayedPaymentOutputDescriptor { + /// The outpoint which is spendable + pub outpoint: OutPoint, + /// Per commitment point to derive delayed_payment_key by key holder + pub per_commitment_point: PublicKey, + /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in + /// the witness_script. + pub to_self_delay: u16, + /// The output which is referenced by the given outpoint + pub output: TxOut, + /// The revocation point specific to the commitment transaction which was broadcast. Used to + /// derive the witnessScript for this output. + pub revocation_pubkey: PublicKey, + /// Arbitrary identification information returned by a call to + /// `Sign::channel_keys_id()`. This may be useful in re-deriving keys used in + /// the channel to spend the output. + pub channel_keys_id: [u8; 32], + /// The value of the channel which this output originated from, possibly indirectly. + pub channel_value_satoshis: u64, +} +impl DelayedPaymentOutputDescriptor { + /// The maximum length a well-formed witness spending one of these should have. + // Calculated as 1 byte length + 73 byte signature, 1 byte empty vec push, 1 byte length plus + // redeemscript push length. + pub const MAX_WITNESS_LENGTH: usize = 1 + 73 + 1 + chan_utils::REVOKEABLE_REDEEMSCRIPT_MAX_LENGTH + 1; +} + +/// Information about a spendable output to our "payment key". See +/// SpendableOutputDescriptor::StaticPaymentOutput for more details on how to spend this. +#[derive(Clone, Debug, PartialEq)] +pub struct StaticPaymentOutputDescriptor { + /// The outpoint which is spendable + pub outpoint: OutPoint, + /// The output which is referenced by the given outpoint + pub output: TxOut, + /// Arbitrary identification information returned by a call to + /// `Sign::channel_keys_id()`. This may be useful in re-deriving keys used in + /// the channel to spend the output. + pub channel_keys_id: [u8; 32], + /// The value of the channel which this transactions spends. + pub channel_value_satoshis: u64, +} +impl StaticPaymentOutputDescriptor { + /// The maximum length a well-formed witness spending one of these should have. + // Calculated as 1 byte legnth + 73 byte signature, 1 byte empty vec push, 1 byte length plus + // redeemscript push length. + pub const MAX_WITNESS_LENGTH: usize = 1 + 73 + 34; +} /// When on-chain outputs are created by rust-lightning (which our counterparty is not able to /// claim at any point in the future) an event is generated which you must track and be able to /// spend on-chain. The information needed to do this is provided in this enum, including the /// outpoint describing which txid and output index is available, the full output which exists at /// that txid/index, and any keys or other information required to sign. -#[derive(Clone, PartialEq)] +#[derive(Clone, Debug, PartialEq)] pub enum SpendableOutputDescriptor { - /// An output to a script which was provided via KeysInterface, thus you should already know - /// how to spend it. No keys are provided as rust-lightning was never given any keys - only the - /// script_pubkey as it appears in the output. + /// An output to a script which was provided via KeysInterface directly, either from + /// `get_destination_script()` or `get_shutdown_pubkey()`, thus you should already know how to + /// spend it. No secret keys are provided as rust-lightning was never given any key. /// These may include outputs from a transaction punishing our counterparty or claiming an HTLC /// on-chain using the payment preimage or after it has timed out. StaticOutput { @@ -51,42 +112,42 @@ pub enum SpendableOutputDescriptor { output: TxOut, }, /// An output to a P2WSH script which can be spent with a single signature after a CSV delay. - /// The private key which should be used to sign the transaction is provided, as well as the - /// full witness redeemScript which is hashed in the output script_pubkey. + /// /// The witness in the spending input should be: - /// (MINIMALIF standard rule) - /// - /// Note that the nSequence field in the input must be set to_self_delay (which corresponds to - /// the transaction not being broadcastable until at least to_self_delay blocks after the input - /// confirms). + /// (MINIMALIF standard rule) + /// + /// Note that the nSequence field in the spending input must be set to to_self_delay + /// (which means the transaction is not broadcastable until at least to_self_delay + /// blocks after the outpoint confirms). + /// /// These are generally the result of a "revocable" output to us, spendable only by us unless - /// it is an output from us having broadcast an old state (which should never happen). - DynamicOutputP2WSH { - /// The outpoint which is spendable - outpoint: OutPoint, - /// The secret key which must be used to sign the spending transaction - key: SecretKey, - /// The witness redeemScript which is hashed to create the script_pubkey in the given output - witness_script: Script, - /// The nSequence value which must be set in the spending input to satisfy the OP_CSV in - /// the witness_script. - to_self_delay: u16, - /// The output which is referenced by the given outpoint - output: TxOut, - }, - /// An output to a P2WPKH, spendable exclusively by the given private key. + /// it is an output from an old state which we broadcast (which should never happen). + /// + /// To derive the delayed_payment key which is used to sign for this input, you must pass the + /// holder delayed_payment_base_key (ie the private key which corresponds to the pubkey in + /// Sign::pubkeys().delayed_payment_basepoint) and the provided per_commitment_point to + /// chan_utils::derive_private_key. The public key can be generated without the secret key + /// using chan_utils::derive_public_key and only the delayed_payment_basepoint which appears in + /// Sign::pubkeys(). + /// + /// To derive the revocation_pubkey provided here (which is used in the witness + /// script generation), you must pass the counterparty revocation_basepoint (which appears in the + /// call to Sign::ready_channel) and the provided per_commitment point + /// to chan_utils::derive_public_revocation_key. + /// + /// The witness script which is hashed and included in the output script_pubkey may be + /// regenerated by passing the revocation_pubkey (derived as above), our delayed_payment pubkey + /// (derived as above), and the to_self_delay contained here to + /// chan_utils::get_revokeable_redeemscript. + DelayedPaymentOutput(DelayedPaymentOutputDescriptor), + /// An output to a P2WPKH, spendable exclusively by our payment key (ie the private key which + /// corresponds to the public key in Sign::pubkeys().payment_point). /// The witness in the spending input, is, thus, simply: - /// + /// + /// /// These are generally the result of our counterparty having broadcast the current state, /// allowing us to claim the non-HTLC-encumbered outputs immediately. - DynamicOutputP2WPKH { - /// The outpoint which is spendable - outpoint: OutPoint, - /// The secret key which must be used to sign the spending transaction - key: SecretKey, - /// The output which is reference by the given outpoint - output: TxOut, - } + StaticPaymentOutput(StaticPaymentOutputDescriptor), } impl Writeable for SpendableOutputDescriptor { @@ -97,19 +158,22 @@ impl Writeable for SpendableOutputDescriptor { outpoint.write(writer)?; output.write(writer)?; }, - &SpendableOutputDescriptor::DynamicOutputP2WSH { ref outpoint, ref key, ref witness_script, ref to_self_delay, ref output } => { + &SpendableOutputDescriptor::DelayedPaymentOutput(ref descriptor) => { 1u8.write(writer)?; - outpoint.write(writer)?; - key.write(writer)?; - witness_script.write(writer)?; - to_self_delay.write(writer)?; - output.write(writer)?; + descriptor.outpoint.write(writer)?; + descriptor.per_commitment_point.write(writer)?; + descriptor.to_self_delay.write(writer)?; + descriptor.output.write(writer)?; + descriptor.revocation_pubkey.write(writer)?; + descriptor.channel_keys_id.write(writer)?; + descriptor.channel_value_satoshis.write(writer)?; }, - &SpendableOutputDescriptor::DynamicOutputP2WPKH { ref outpoint, ref key, ref output } => { + &SpendableOutputDescriptor::StaticPaymentOutput(ref descriptor) => { 2u8.write(writer)?; - outpoint.write(writer)?; - key.write(writer)?; - output.write(writer)?; + descriptor.outpoint.write(writer)?; + descriptor.output.write(writer)?; + descriptor.channel_keys_id.write(writer)?; + descriptor.channel_value_satoshis.write(writer)?; }, } Ok(()) @@ -123,49 +187,30 @@ impl Readable for SpendableOutputDescriptor { outpoint: Readable::read(reader)?, output: Readable::read(reader)?, }), - 1u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WSH { + 1u8 => Ok(SpendableOutputDescriptor::DelayedPaymentOutput(DelayedPaymentOutputDescriptor { outpoint: Readable::read(reader)?, - key: Readable::read(reader)?, - witness_script: Readable::read(reader)?, + per_commitment_point: Readable::read(reader)?, to_self_delay: Readable::read(reader)?, output: Readable::read(reader)?, - }), - 2u8 => Ok(SpendableOutputDescriptor::DynamicOutputP2WPKH { + revocation_pubkey: Readable::read(reader)?, + channel_keys_id: Readable::read(reader)?, + channel_value_satoshis: Readable::read(reader)?, + })), + 2u8 => Ok(SpendableOutputDescriptor::StaticPaymentOutput(StaticPaymentOutputDescriptor { outpoint: Readable::read(reader)?, - key: Readable::read(reader)?, output: Readable::read(reader)?, - }), + channel_keys_id: Readable::read(reader)?, + channel_value_satoshis: Readable::read(reader)?, + })), _ => Err(DecodeError::InvalidValue), } } } -/// A trait to describe an object which can get user secrets and key material. -pub trait KeysInterface: Send + Sync { - /// A type which implements ChannelKeys which will be returned by get_channel_keys. - type ChanKeySigner : ChannelKeys; - - /// Get node secret key (aka node_id or network_key) - fn get_node_secret(&self) -> SecretKey; - /// Get destination redeemScript to encumber static protocol exit points. - fn get_destination_script(&self) -> Script; - /// Get shutdown_pubkey to use as PublicKey at channel closure - fn get_shutdown_pubkey(&self) -> PublicKey; - /// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you - /// restarted with some stale data! - fn get_channel_keys(&self, inbound: bool, channel_value_satoshis: u64) -> Self::ChanKeySigner; - /// Get a secret and PRNG seed for construting an onion packet - fn get_onion_rand(&self) -> (SecretKey, [u8; 32]); - /// Get a unique temporary channel id. Channels will be referred to by this until the funding - /// transaction is created, at which point they will use the outpoint in the funding - /// transaction. - fn get_channel_id(&self) -> [u8; 32]; -} - -/// Set of lightning keys needed to operate a channel as described in BOLT 3. +/// A trait to sign lightning channel transactions as described in BOLT 3. /// /// Signing services could be implemented on a hardware wallet. In this case, -/// the current ChannelKeys would be a front-end on top of a communication +/// the current Sign would be a front-end on top of a communication /// channel connected to your secure device and lightning key material wouldn't /// reside on a hot server. Nevertheless, a this deployment would still need /// to trust the ChannelManager to avoid loss of funds as this latest component @@ -179,71 +224,98 @@ pub trait KeysInterface: Send + Sync { /// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted /// to act, as liveness and breach reply correctness are always going to be hard requirements /// of LN security model, orthogonal of key management issues. -/// -/// If you're implementing a custom signer, you almost certainly want to implement -/// Readable/Writable to serialize out a unique reference to this set of keys so -/// that you can serialize the full ChannelManager object. -/// -// (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly -// to the possibility of reentrancy issues by calling the user's code during our deserialization -// routine). -// TODO: We should remove Clone by instead requesting a new ChannelKeys copy when we create +// TODO: We should remove Clone by instead requesting a new Sign copy when we create // ChannelMonitors instead of expecting to clone the one out of the Channel into the monitors. -pub trait ChannelKeys : Send+Clone { - /// Gets the private key for the anchor tx - fn funding_key<'a>(&'a self) -> &'a SecretKey; - /// Gets the local secret key for blinded revocation pubkey - fn revocation_base_key<'a>(&'a self) -> &'a SecretKey; - /// Gets the local secret key used in to_remote output of remote commitment tx - /// (and also as part of obscured commitment number) - fn payment_base_key<'a>(&'a self) -> &'a SecretKey; - /// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output - fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey; - /// Gets the local htlc secret key used in commitment tx htlc outputs - fn htlc_base_key<'a>(&'a self) -> &'a SecretKey; - /// Gets the commitment seed - fn commitment_seed<'a>(&'a self) -> &'a [u8; 32]; - /// Gets the local channel public keys and basepoints - fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys; - - /// Create a signature for a remote commitment transaction and associated HTLC transactions. +pub trait Sign : Send+Clone + Writeable { + /// Gets the per-commitment point for a specific commitment number + /// + /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards. + fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1) -> PublicKey; + /// Gets the commitment secret for a specific commitment number as part of the revocation process + /// + /// An external signer implementation should error here if the commitment was already signed + /// and should refuse to sign it in the future. + /// + /// May be called more than once for the same index. + /// + /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards. + // TODO: return a Result so we can signal a validation error + fn release_commitment_secret(&self, idx: u64) -> [u8; 32]; + /// Gets the holder's channel public keys and basepoints + fn pubkeys(&self) -> &ChannelPublicKeys; + /// Gets an arbitrary identifier describing the set of keys which are provided back to you in + /// some SpendableOutputDescriptor types. This should be sufficient to identify this + /// Sign object uniquely and lookup or re-derive its keys. + fn channel_keys_id(&self) -> [u8; 32]; + + /// Create a signature for a counterparty's commitment transaction and associated HTLC transactions. /// /// Note that if signing fails or is rejected, the channel will be force-closed. // // TODO: Document the things someone using this interface should enforce before signing. - // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and - // making the callee generate it via some util function we expose)! - fn sign_remote_commitment(&self, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()>; - - /// Create a signature for a local commitment transaction. This will only ever be called with - /// the same local_commitment_tx (or a copy thereof), though there are currently no guarantees - /// that it will not be called multiple times. + fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()>; + + /// Create a signatures for a holder's commitment transaction and its claiming HTLC transactions. + /// This will only ever be called with a non-revoked commitment_tx. This will be called with the + /// latest commitment_tx when we initiate a force-close. + /// This will be called with the previous latest, just to get claiming HTLC signatures, if we are + /// reacting to a ChannelMonitor replica that decided to broadcast before it had been updated to + /// the latest. + /// This may be called multiple times for the same transaction. + /// + /// An external signer implementation should check that the commitment has not been revoked. + /// + /// May return Err if key derivation fails. Callers, such as ChannelMonitor, will panic in such a case. // // TODO: Document the things someone using this interface should enforce before signing. - // TODO: Add more input vars to enable better checking (preferably removing commitment_tx and - fn sign_local_commitment(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1) -> Result; + // TODO: Key derivation failure should panic rather than Err + fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()>; - /// Same as sign_local_commitment, but exists only for tests to get access to local commitment + /// 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_local_commitment may enforce that we only ever + /// state. Thus, needs its own method as sign_holder_commitment may enforce that we only ever /// get called once. - #[cfg(test)] - fn unsafe_sign_local_commitment(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1) -> Result; + #[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), ()>; - /// Create a signature for each HTLC transaction spending a local commitment transaction. + /// Create a signature for the given input in a transaction spending an HTLC or commitment + /// transaction output when our counterparty broadcasts an old state. /// - /// Unlike sign_local_commitment, this may be called multiple times with *different* - /// local_commitment_tx values. While this will never be called with a revoked - /// local_commitment_tx, it is possible that it is called with the second-latest - /// local_commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary - /// ChannelMonitor decided to broadcast before it had been updated to the latest. + /// A justice transaction may claim multiples outputs at the same time if timelocks are + /// similar, but only a signature for the input at index `input` should be signed for here. + /// It may be called multiples time for same output(s) if a fee-bump is needed with regards + /// to an upcoming timelock expiration. /// - /// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in - /// local_commitment_tx. For those HTLCs which have transaction_output_index set to None - /// (implying they were considered dust at the time the commitment transaction was negotiated), - /// a corresponding None should be included in the return value. All other positions in the - /// return value must contain a signature. - fn sign_local_commitment_htlc_transactions(&self, local_commitment_tx: &LocalCommitmentTransaction, local_csv: u16, secp_ctx: &Secp256k1) -> Result>, ()>; + /// Amount is value of the output spent by this input, committed to in the BIP 143 signature. + /// + /// per_commitment_key is revocation secret which was provided by our counterparty when they + /// revoked the state which they eventually broadcast. It's not a _holder_ secret key and does + /// not allow the spending of any funds by itself (you need our holder revocation_secret to do + /// so). + /// + /// htlc holds HTLC elements (hash, timelock) if the output being spent is a HTLC output, thus + /// changing the format of the witness script (which is committed to in the BIP 143 + /// signatures). + fn sign_justice_transaction(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option, secp_ctx: &Secp256k1) -> Result; + + /// Create a signature for a claiming transaction for a HTLC output on a counterparty's commitment + /// transaction, either offered or received. + /// + /// Such a transaction may claim multiples offered outputs at same time if we know the + /// preimage for each when we create it, but only the input at index `input` should be + /// signed for here. It may be called multiple times for same output(s) if a fee-bump is + /// needed with regards to an upcoming timelock expiration. + /// + /// Witness_script is either a offered or received script as defined in BOLT3 for HTLC + /// outputs. + /// + /// Amount is value of the output spent by this input, committed to in the BIP 143 signature. + /// + /// Per_commitment_point is the dynamic point corresponding to the channel state + /// detected onchain. It has been generated by our counterparty and is used to derive + /// channel state keys, which are then included in the witness script and committed to in the + /// BIP 143 signature. + fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1) -> Result; /// Create a signature for a (proposed) closing transaction. /// @@ -257,140 +329,332 @@ pub trait ChannelKeys : Send+Clone { /// Note that if this fails or is rejected, the channel will not be publicly announced and /// our counterparty may (though likely will not) close the channel on us for violating the /// protocol. - fn sign_channel_announcement(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1) -> Result; + fn sign_channel_announcement(&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1) -> Result; - /// Set the remote channel basepoints. This is done immediately on incoming channels - /// and as soon as the channel is accepted on outgoing channels. + /// Set the counterparty static channel data, including basepoints, + /// counterparty_selected/holder_selected_contest_delay and funding outpoint. + /// This is done as soon as the funding outpoint is known. Since these are static channel data, + /// they MUST NOT be allowed to change to different values once set. + /// + /// channel_parameters.is_populated() MUST be true. + /// + /// We bind holder_selected_contest_delay late here for API convenience. /// /// Will be called before any signatures are applied. - fn set_remote_channel_pubkeys(&mut self, channel_points: &ChannelPublicKeys); + fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters); +} + +/// A trait to describe an object which can get user secrets and key material. +pub trait KeysInterface: Send + Sync { + /// A type which implements Sign which will be returned by get_channel_signer. + type Signer : Sign; + + /// Get node secret key (aka node_id or network_key). + /// + /// This method must return the same value each time it is called. + fn get_node_secret(&self) -> SecretKey; + /// Get a script pubkey which we send funds to when claiming on-chain contestable outputs. + /// + /// This method should return a different value each time it is called, to avoid linking + /// on-chain funds across channels as controlled to the same user. + fn get_destination_script(&self) -> Script; + /// Get a public key which we will send funds to (in the form of a P2WPKH output) when closing + /// a channel. + /// + /// This method should return a different value each time it is called, to avoid linking + /// on-chain funds across channels as controlled to the same user. + fn get_shutdown_pubkey(&self) -> PublicKey; + /// Get a new set of Sign for per-channel secrets. These MUST be unique even if you + /// restarted with some stale data! + /// + /// This method must return a different value each time it is called. + fn get_channel_signer(&self, inbound: bool, channel_value_satoshis: u64) -> Self::Signer; + /// Gets a unique, cryptographically-secure, random 32 byte value. This is used for encrypting + /// onion packets and for temporary channel IDs. There is no requirement that these be + /// persisted anywhere, though they must be unique across restarts. + /// + /// This method must return a different value each time it is called. + fn get_secure_random_bytes(&self) -> [u8; 32]; + + /// Reads a `Signer` for this `KeysInterface` from the given input stream. + /// This is only called during deserialization of other objects which contain + /// `Sign`-implementing objects (ie `ChannelMonitor`s and `ChannelManager`s). + /// The bytes are exactly those which `::write()` writes, and + /// contain no versioning scheme. You may wish to include your own version prefix and ensure + /// you've read all of the provided bytes to ensure no corruption occurred. + fn read_chan_signer(&self, reader: &[u8]) -> Result; } #[derive(Clone)] -/// A simple implementation of ChannelKeys that just keeps the private keys in memory. -pub struct InMemoryChannelKeys { +/// A simple implementation of Sign that just keeps the private keys in memory. +/// +/// This implementation performs no policy checks and is insufficient by itself as +/// a secure external signer. +pub struct InMemorySigner { /// Private key of anchor tx - funding_key: SecretKey, - /// Local secret key for blinded revocation pubkey - revocation_base_key: SecretKey, - /// Local secret key used in commitment tx htlc outputs - payment_base_key: SecretKey, - /// Local secret key used in HTLC tx - delayed_payment_base_key: SecretKey, - /// Local htlc secret key used in commitment tx htlc outputs - htlc_base_key: SecretKey, + pub funding_key: SecretKey, + /// Holder secret key for blinded revocation pubkey + pub revocation_base_key: SecretKey, + /// Holder secret key used for our balance in counterparty-broadcasted commitment transactions + pub payment_key: SecretKey, + /// Holder secret key used in HTLC tx + pub delayed_payment_base_key: SecretKey, + /// Holder htlc secret key used in commitment tx htlc outputs + pub htlc_base_key: SecretKey, /// Commitment seed - commitment_seed: [u8; 32], - /// Local public keys and basepoints - pub(crate) local_channel_pubkeys: ChannelPublicKeys, - /// Remote public keys and base points - pub(crate) remote_channel_pubkeys: Option, + pub commitment_seed: [u8; 32], + /// Holder public keys and basepoints + pub(crate) holder_channel_pubkeys: ChannelPublicKeys, + /// Counterparty public keys and counterparty/holder selected_contest_delay, populated on channel acceptance + channel_parameters: Option, /// The total value of this channel channel_value_satoshis: u64, + /// Key derivation parameters + channel_keys_id: [u8; 32], } -impl InMemoryChannelKeys { - /// Create a new InMemoryChannelKeys +impl InMemorySigner { + /// Create a new InMemorySigner pub fn new( secp_ctx: &Secp256k1, funding_key: SecretKey, revocation_base_key: SecretKey, - payment_base_key: SecretKey, + payment_key: SecretKey, delayed_payment_base_key: SecretKey, htlc_base_key: SecretKey, commitment_seed: [u8; 32], - channel_value_satoshis: u64) -> InMemoryChannelKeys { - let local_channel_pubkeys = - InMemoryChannelKeys::make_local_keys(secp_ctx, &funding_key, &revocation_base_key, - &payment_base_key, &delayed_payment_base_key, + channel_value_satoshis: u64, + channel_keys_id: [u8; 32]) -> InMemorySigner { + let holder_channel_pubkeys = + InMemorySigner::make_holder_keys(secp_ctx, &funding_key, &revocation_base_key, + &payment_key, &delayed_payment_base_key, &htlc_base_key); - InMemoryChannelKeys { + InMemorySigner { funding_key, revocation_base_key, - payment_base_key, + payment_key, delayed_payment_base_key, htlc_base_key, commitment_seed, channel_value_satoshis, - local_channel_pubkeys, - remote_channel_pubkeys: None, + holder_channel_pubkeys, + channel_parameters: None, + channel_keys_id, } } - fn make_local_keys(secp_ctx: &Secp256k1, + fn make_holder_keys(secp_ctx: &Secp256k1, funding_key: &SecretKey, revocation_base_key: &SecretKey, - payment_base_key: &SecretKey, + payment_key: &SecretKey, delayed_payment_base_key: &SecretKey, htlc_base_key: &SecretKey) -> ChannelPublicKeys { let from_secret = |s: &SecretKey| PublicKey::from_secret_key(secp_ctx, s); ChannelPublicKeys { funding_pubkey: from_secret(&funding_key), revocation_basepoint: from_secret(&revocation_base_key), - payment_basepoint: from_secret(&payment_base_key), + payment_point: from_secret(&payment_key), delayed_payment_basepoint: from_secret(&delayed_payment_base_key), htlc_basepoint: from_secret(&htlc_base_key), } } + + /// Counterparty pubkeys. + /// Will panic if ready_channel wasn't called. + pub fn counterparty_pubkeys(&self) -> &ChannelPublicKeys { &self.get_channel_parameters().counterparty_parameters.as_ref().unwrap().pubkeys } + + /// The contest_delay value specified by our counterparty and applied on holder-broadcastable + /// transactions, ie the amount of time that we have to wait to recover our funds if we + /// broadcast a transaction. + /// Will panic if ready_channel wasn't called. + pub fn counterparty_selected_contest_delay(&self) -> u16 { self.get_channel_parameters().counterparty_parameters.as_ref().unwrap().selected_contest_delay } + + /// The contest_delay value specified by us and applied on transactions broadcastable + /// by our counterparty, ie the amount of time that they have to wait to recover their funds + /// if they broadcast a transaction. + /// Will panic if ready_channel wasn't called. + pub fn holder_selected_contest_delay(&self) -> u16 { self.get_channel_parameters().holder_selected_contest_delay } + + /// Whether the holder is the initiator + /// Will panic if ready_channel wasn't called. + pub fn is_outbound(&self) -> bool { self.get_channel_parameters().is_outbound_from_holder } + + /// Funding outpoint + /// Will panic if ready_channel wasn't called. + pub fn funding_outpoint(&self) -> &OutPoint { self.get_channel_parameters().funding_outpoint.as_ref().unwrap() } + + /// Obtain a ChannelTransactionParameters for this channel, to be used when verifying or + /// building transactions. + /// + /// Will panic if ready_channel wasn't called. + pub fn get_channel_parameters(&self) -> &ChannelTransactionParameters { + self.channel_parameters.as_ref().unwrap() + } + + /// Sign the single input of spend_tx at index `input_idx` which spends the output + /// described by descriptor, returning the witness stack for the input. + /// + /// Returns an Err if the input at input_idx does not exist, has a non-empty script_sig, + /// or is not spending the outpoint described by `descriptor.outpoint`. + pub fn sign_counterparty_payment_input(&self, spend_tx: &Transaction, input_idx: usize, descriptor: &StaticPaymentOutputDescriptor, secp_ctx: &Secp256k1) -> Result>, ()> { + // TODO: We really should be taking the SigHashCache as a parameter here instead of + // spend_tx, but ideally the SigHashCache would expose the transaction's inputs read-only + // so that we can check them. This requires upstream rust-bitcoin changes (as well as + // bindings updates to support SigHashCache objects). + if spend_tx.input.len() <= input_idx { return Err(()); } + if !spend_tx.input[input_idx].script_sig.is_empty() { return Err(()); } + if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint() { return Err(()); } + + let remotepubkey = self.pubkeys().payment_point; + let witness_script = bitcoin::Address::p2pkh(&::bitcoin::PublicKey{compressed: true, key: remotepubkey}, Network::Testnet).script_pubkey(); + let sighash = hash_to_message!(&bip143::SigHashCache::new(spend_tx).signature_hash(input_idx, &witness_script, descriptor.output.value, SigHashType::All)[..]); + let remotesig = secp_ctx.sign(&sighash, &self.payment_key); + + let mut witness = Vec::with_capacity(2); + witness.push(remotesig.serialize_der().to_vec()); + witness[0].push(SigHashType::All as u8); + witness.push(remotepubkey.serialize().to_vec()); + Ok(witness) + } + + /// Sign the single input of spend_tx at index `input_idx` which spends the output + /// described by descriptor, returning the witness stack for the input. + /// + /// Returns an Err if the input at input_idx does not exist, has a non-empty script_sig, + /// is not spending the outpoint described by `descriptor.outpoint`, or does not have a + /// sequence set to `descriptor.to_self_delay`. + pub fn sign_dynamic_p2wsh_input(&self, spend_tx: &Transaction, input_idx: usize, descriptor: &DelayedPaymentOutputDescriptor, secp_ctx: &Secp256k1) -> Result>, ()> { + // TODO: We really should be taking the SigHashCache as a parameter here instead of + // spend_tx, but ideally the SigHashCache would expose the transaction's inputs read-only + // so that we can check them. This requires upstream rust-bitcoin changes (as well as + // bindings updates to support SigHashCache objects). + if spend_tx.input.len() <= input_idx { return Err(()); } + if !spend_tx.input[input_idx].script_sig.is_empty() { return Err(()); } + if spend_tx.input[input_idx].previous_output != descriptor.outpoint.into_bitcoin_outpoint() { return Err(()); } + if spend_tx.input[input_idx].sequence != descriptor.to_self_delay as u32 { return Err(()); } + + let delayed_payment_key = chan_utils::derive_private_key(&secp_ctx, &descriptor.per_commitment_point, &self.delayed_payment_base_key) + .expect("We constructed the payment_base_key, so we can only fail here if the RNG is busted."); + let delayed_payment_pubkey = PublicKey::from_secret_key(&secp_ctx, &delayed_payment_key); + let witness_script = chan_utils::get_revokeable_redeemscript(&descriptor.revocation_pubkey, descriptor.to_self_delay, &delayed_payment_pubkey); + let sighash = hash_to_message!(&bip143::SigHashCache::new(spend_tx).signature_hash(input_idx, &witness_script, descriptor.output.value, SigHashType::All)[..]); + let local_delayedsig = secp_ctx.sign(&sighash, &delayed_payment_key); + + let mut witness = Vec::with_capacity(3); + witness.push(local_delayedsig.serialize_der().to_vec()); + witness[0].push(SigHashType::All as u8); + witness.push(vec!()); //MINIMALIF + witness.push(witness_script.clone().into_bytes()); + Ok(witness) + } } -impl ChannelKeys for InMemoryChannelKeys { - fn funding_key(&self) -> &SecretKey { &self.funding_key } - fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key } - fn payment_base_key(&self) -> &SecretKey { &self.payment_base_key } - fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key } - fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key } - fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed } - fn pubkeys<'a>(&'a self) -> &'a ChannelPublicKeys { &self.local_channel_pubkeys } +impl Sign for InMemorySigner { + fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1) -> PublicKey { + let commitment_secret = SecretKey::from_slice(&chan_utils::build_commitment_secret(&self.commitment_seed, idx)).unwrap(); + PublicKey::from_secret_key(secp_ctx, &commitment_secret) + } - fn sign_remote_commitment(&self, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { - if commitment_tx.input.len() != 1 { return Err(()); } + fn release_commitment_secret(&self, idx: u64) -> [u8; 32] { + chan_utils::build_commitment_secret(&self.commitment_seed, idx) + } + + fn pubkeys(&self) -> &ChannelPublicKeys { &self.holder_channel_pubkeys } + fn channel_keys_id(&self) -> [u8; 32] { self.channel_keys_id } + + fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { + let trusted_tx = commitment_tx.trust(); + let keys = trusted_tx.keys(); let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key); - let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing"); - let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey); - - let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]); - let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key); - - let commitment_txid = commitment_tx.txid(); - - let mut htlc_sigs = Vec::with_capacity(htlcs.len()); - for ref htlc in htlcs { - if let Some(_) = htlc.transaction_output_index { - let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, feerate_per_kw, to_self_delay, htlc, &keys.a_delayed_payment_key, &keys.revocation_key); - let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys); - let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]); - let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) { - Ok(s) => s, - Err(_) => return Err(()), - }; - htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key)); - } + let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey); + + let built_tx = trusted_tx.built_transaction(); + let commitment_sig = built_tx.sign(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx); + let commitment_txid = built_tx.txid; + + let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len()); + for htlc in commitment_tx.htlcs() { + let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), self.holder_selected_contest_delay(), htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key); + let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys); + let htlc_sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, SigHashType::All)[..]); + let holder_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) { + Ok(s) => s, + Err(_) => return Err(()), + }; + htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &holder_htlc_key)); } Ok((commitment_sig, htlc_sigs)) } - fn sign_local_commitment(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1) -> Result { + fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key); - let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing"); - let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey); - - Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx)) + let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey); + let trusted_tx = commitment_tx.trust(); + let sig = trusted_tx.built_transaction().sign(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, secp_ctx); + let channel_parameters = self.get_channel_parameters(); + let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), secp_ctx)?; + Ok((sig, htlc_sigs)) } - #[cfg(test)] - fn unsafe_sign_local_commitment(&self, local_commitment_tx: &LocalCommitmentTransaction, secp_ctx: &Secp256k1) -> Result { + #[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), ()> { let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key); - let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing"); - let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey); + let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey); + let trusted_tx = commitment_tx.trust(); + let sig = trusted_tx.built_transaction().sign(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, secp_ctx); + let channel_parameters = self.get_channel_parameters(); + let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), secp_ctx)?; + Ok((sig, htlc_sigs)) + } - Ok(local_commitment_tx.get_local_sig(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx)) + fn sign_justice_transaction(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option, secp_ctx: &Secp256k1) -> Result { + let revocation_key = match chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) { + Ok(revocation_key) => revocation_key, + Err(_) => return Err(()) + }; + let per_commitment_point = PublicKey::from_secret_key(secp_ctx, &per_commitment_key); + let revocation_pubkey = match chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) { + Ok(revocation_pubkey) => revocation_pubkey, + Err(_) => return Err(()) + }; + let witness_script = if let &Some(ref htlc) = htlc { + let counterparty_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint) { + Ok(counterparty_htlcpubkey) => counterparty_htlcpubkey, + Err(_) => return Err(()) + }; + let holder_htlcpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) { + Ok(holder_htlcpubkey) => holder_htlcpubkey, + Err(_) => return Err(()) + }; + chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey) + } else { + let counterparty_delayedpubkey = match chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().delayed_payment_basepoint) { + Ok(counterparty_delayedpubkey) => counterparty_delayedpubkey, + Err(_) => return Err(()) + }; + chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.holder_selected_contest_delay(), &counterparty_delayedpubkey) + }; + let mut sighash_parts = bip143::SigHashCache::new(justice_tx); + let sighash = hash_to_message!(&sighash_parts.signature_hash(input, &witness_script, amount, SigHashType::All)[..]); + return Ok(secp_ctx.sign(&sighash, &revocation_key)) } - fn sign_local_commitment_htlc_transactions(&self, local_commitment_tx: &LocalCommitmentTransaction, local_csv: u16, secp_ctx: &Secp256k1) -> Result>, ()> { - local_commitment_tx.get_htlc_sigs(&self.htlc_base_key, local_csv, secp_ctx) + fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1) -> Result { + if let Ok(htlc_key) = chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &self.htlc_base_key) { + let witness_script = if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) { + if let Ok(counterparty_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint) { + if let Ok(htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) { + chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey) + } else { return Err(()) } + } else { return Err(()) } + } else { return Err(()) }; + let mut sighash_parts = bip143::SigHashCache::new(htlc_tx); + let sighash = hash_to_message!(&sighash_parts.signature_hash(input, &witness_script, amount, SigHashType::All)[..]); + return Ok(secp_ctx.sign(&sighash, &htlc_key)) + } + Err(()) } fn sign_closing_transaction(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1) -> Result { @@ -398,67 +662,70 @@ impl ChannelKeys for InMemoryChannelKeys { if closing_tx.input[0].witness.len() != 0 { return Err(()); } if closing_tx.output.len() > 2 { return Err(()); } - let remote_channel_pubkeys = self.remote_channel_pubkeys.as_ref().expect("must set remote channel pubkeys before signing"); let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key); - let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &remote_channel_pubkeys.funding_pubkey); + let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey); - let sighash = hash_to_message!(&bip143::SighashComponents::new(closing_tx) - .sighash_all(&closing_tx.input[0], &channel_funding_redeemscript, self.channel_value_satoshis)[..]); + let sighash = hash_to_message!(&bip143::SigHashCache::new(closing_tx) + .signature_hash(0, &channel_funding_redeemscript, self.channel_value_satoshis, SigHashType::All)[..]); Ok(secp_ctx.sign(&sighash, &self.funding_key)) } - fn sign_channel_announcement(&self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1) -> Result { + fn sign_channel_announcement(&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1) -> Result { let msghash = hash_to_message!(&Sha256dHash::hash(&msg.encode()[..])[..]); Ok(secp_ctx.sign(&msghash, &self.funding_key)) } - fn set_remote_channel_pubkeys(&mut self, channel_pubkeys: &ChannelPublicKeys) { - assert!(self.remote_channel_pubkeys.is_none(), "Already set remote channel pubkeys"); - self.remote_channel_pubkeys = Some(channel_pubkeys.clone()); + fn ready_channel(&mut self, channel_parameters: &ChannelTransactionParameters) { + assert!(self.channel_parameters.is_none(), "Acceptance already noted"); + assert!(channel_parameters.is_populated(), "Channel parameters must be fully populated"); + self.channel_parameters = Some(channel_parameters.clone()); } } -impl Writeable for InMemoryChannelKeys { +impl Writeable for InMemorySigner { fn write(&self, writer: &mut W) -> Result<(), Error> { self.funding_key.write(writer)?; self.revocation_base_key.write(writer)?; - self.payment_base_key.write(writer)?; + self.payment_key.write(writer)?; self.delayed_payment_base_key.write(writer)?; self.htlc_base_key.write(writer)?; self.commitment_seed.write(writer)?; - self.remote_channel_pubkeys.write(writer)?; + self.channel_parameters.write(writer)?; self.channel_value_satoshis.write(writer)?; + self.channel_keys_id.write(writer)?; Ok(()) } } -impl Readable for InMemoryChannelKeys { +impl Readable for InMemorySigner { fn read(reader: &mut R) -> Result { let funding_key = Readable::read(reader)?; let revocation_base_key = Readable::read(reader)?; - let payment_base_key = Readable::read(reader)?; + let payment_key = Readable::read(reader)?; let delayed_payment_base_key = Readable::read(reader)?; let htlc_base_key = Readable::read(reader)?; let commitment_seed = Readable::read(reader)?; - let remote_channel_pubkeys = Readable::read(reader)?; + let counterparty_channel_data = Readable::read(reader)?; let channel_value_satoshis = Readable::read(reader)?; let secp_ctx = Secp256k1::signing_only(); - let local_channel_pubkeys = - InMemoryChannelKeys::make_local_keys(&secp_ctx, &funding_key, &revocation_base_key, - &payment_base_key, &delayed_payment_base_key, + let holder_channel_pubkeys = + InMemorySigner::make_holder_keys(&secp_ctx, &funding_key, &revocation_base_key, + &payment_key, &delayed_payment_base_key, &htlc_base_key); + let keys_id = Readable::read(reader)?; - Ok(InMemoryChannelKeys { + Ok(InMemorySigner { funding_key, revocation_base_key, - payment_base_key, + payment_key, delayed_payment_base_key, htlc_base_key, commitment_seed, channel_value_satoshis, - local_channel_pubkeys, - remote_channel_pubkeys + holder_channel_pubkeys, + channel_parameters: counterparty_channel_data, + channel_keys_id: keys_id, }) } } @@ -477,18 +744,17 @@ pub struct KeysManager { shutdown_pubkey: PublicKey, channel_master_key: ExtendedPrivKey, channel_child_index: AtomicUsize, - session_master_key: ExtendedPrivKey, - session_child_index: AtomicUsize, - channel_id_master_key: ExtendedPrivKey, - channel_id_child_index: AtomicUsize, + rand_bytes_master_key: ExtendedPrivKey, + rand_bytes_child_index: AtomicUsize, - unique_start: Sha256State, - logger: Arc, + seed: [u8; 32], + starting_time_secs: u64, + starting_time_nanos: u32, } impl KeysManager { /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your - /// RNG is busted) this may panic (but more importantly, you will possibly lose funds). + /// CSRNG is busted) this may panic (but more importantly, you will possibly lose funds). /// starting_time isn't strictly required to actually be a time, but it must absolutely, /// without a doubt, be unique to this instance. ie if you start multiple times with the same /// seed, starting_time must be unique to each run. Thus, the easiest way to achieve this is to @@ -506,16 +772,17 @@ impl KeysManager { /// Note that until the 0.1 release there is no guarantee of backward compatibility between /// versions. Once the library is more fully supported, the docs will be updated to include a /// detailed description of the guarantee. - pub fn new(seed: &[u8; 32], network: Network, logger: Arc, starting_time_secs: u64, starting_time_nanos: u32) -> KeysManager { + pub fn new(seed: &[u8; 32], starting_time_secs: u64, starting_time_nanos: u32) -> Self { let secp_ctx = Secp256k1::signing_only(); - match ExtendedPrivKey::new_master(network.clone(), seed) { + // Note that when we aren't serializing the key, network doesn't matter + match ExtendedPrivKey::new_master(Network::Testnet, seed) { Ok(master_key) => { let node_secret = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(0).unwrap()).expect("Your RNG is busted").private_key.key; let destination_script = match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(1).unwrap()) { Ok(destination_key) => { - let pubkey_hash160 = Hash160::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.key.serialize()[..]); + let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_private(&secp_ctx, &destination_key).public_key.to_bytes()); Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0) - .push_slice(&pubkey_hash160.into_inner()) + .push_slice(&wpubkey_hash.into_inner()) .into_script() }, Err(_) => panic!("Your RNG is busted"), @@ -525,13 +792,7 @@ impl KeysManager { Err(_) => panic!("Your RNG is busted"), }; let channel_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(3).unwrap()).expect("Your RNG is busted"); - let session_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted"); - let channel_id_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(5).unwrap()).expect("Your RNG is busted"); - - let mut unique_start = Sha256::engine(); - unique_start.input(&byte_utils::be64_to_array(starting_time_secs)); - unique_start.input(&byte_utils::be32_to_array(starting_time_nanos)); - unique_start.input(seed); + let rand_bytes_master_key = master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(4).unwrap()).expect("Your RNG is busted"); KeysManager { secp_ctx, @@ -540,46 +801,43 @@ impl KeysManager { shutdown_pubkey, channel_master_key, channel_child_index: AtomicUsize::new(0), - session_master_key, - session_child_index: AtomicUsize::new(0), - channel_id_master_key, - channel_id_child_index: AtomicUsize::new(0), + rand_bytes_master_key, + rand_bytes_child_index: AtomicUsize::new(0), - unique_start, - logger, + seed: *seed, + starting_time_secs, + starting_time_nanos, } }, Err(_) => panic!("Your rng is busted"), } } -} - -impl KeysInterface for KeysManager { - type ChanKeySigner = InMemoryChannelKeys; - - fn get_node_secret(&self) -> SecretKey { - self.node_secret.clone() - } - - fn get_destination_script(&self) -> Script { - self.destination_script.clone() + fn derive_unique_start(&self) -> Sha256State { + let mut unique_start = Sha256::engine(); + unique_start.input(&byte_utils::be64_to_array(self.starting_time_secs)); + unique_start.input(&byte_utils::be32_to_array(self.starting_time_nanos)); + unique_start.input(&self.seed); + unique_start } + /// Derive an old set of Sign for per-channel secrets based on a key derivation + /// parameters. + /// Key derivation parameters are accessible through a per-channel secrets + /// Sign::channel_keys_id and is provided inside DynamicOuputP2WSH in case of + /// onchain output detection for which a corresponding delayed_payment_key must be derived. + pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params: &[u8; 32]) -> InMemorySigner { + let chan_id = byte_utils::slice_to_be64(¶ms[0..8]); + assert!(chan_id <= std::u32::MAX as u64); // Otherwise the params field wasn't created by us + let mut unique_start = Sha256::engine(); + unique_start.input(params); + unique_start.input(&self.seed); - fn get_shutdown_pubkey(&self) -> PublicKey { - self.shutdown_pubkey.clone() - } - - fn get_channel_keys(&self, _inbound: bool, channel_value_satoshis: u64) -> InMemoryChannelKeys { // We only seriously intend to rely on the channel_master_key for true secure // entropy, everything else just ensures uniqueness. We rely on the unique_start (ie // starting_time provided in the constructor) to be unique. - let mut sha = self.unique_start.clone(); + let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(chan_id as u32).expect("key space exhausted")).expect("Your RNG is busted"); + unique_start.input(&child_privkey.private_key.key[..]); - let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel); - let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted"); - sha.input(&child_privkey.private_key.key[..]); - - let seed = Sha256::from_engine(sha).into_inner(); + let seed = Sha256::from_engine(unique_start).into_inner(); let commitment_seed = { let mut sha = Sha256::engine(); @@ -598,45 +856,178 @@ impl KeysInterface for KeysManager { } let funding_key = key_step!(b"funding key", commitment_seed); let revocation_base_key = key_step!(b"revocation base key", funding_key); - let payment_base_key = key_step!(b"payment base key", revocation_base_key); - let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key); + let payment_key = key_step!(b"payment key", revocation_base_key); + let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_key); let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key); - InMemoryChannelKeys::new( + InMemorySigner::new( &self.secp_ctx, funding_key, revocation_base_key, - payment_base_key, + payment_key, delayed_payment_base_key, htlc_base_key, commitment_seed, - channel_value_satoshis + channel_value_satoshis, + params.clone() ) } - fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) { - let mut sha = self.unique_start.clone(); + /// Creates a Transaction which spends the given descriptors to the given outputs, plus an + /// output to the given change destination (if sufficient change value remains). The + /// transaction will have a feerate, at least, of the given value. + /// + /// Returns `Err(())` if the output value is greater than the input value minus required fee or + /// if a descriptor was duplicated. + /// + /// We do not enforce that outputs meet the dust limit or that any output scripts are standard. + /// + /// May panic if the `SpendableOutputDescriptor`s were not generated by Channels which used + /// this KeysManager or one of the `InMemorySigner` created by this KeysManager. + pub fn spend_spendable_outputs(&self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec, change_destination_script: Script, feerate_sat_per_1000_weight: u32, secp_ctx: &Secp256k1) -> Result { + let mut input = Vec::new(); + let mut input_value = 0; + let mut witness_weight = 0; + let mut output_set = HashSet::with_capacity(descriptors.len()); + for outp in descriptors { + match outp { + SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => { + input.push(TxIn { + previous_output: descriptor.outpoint.into_bitcoin_outpoint(), + script_sig: Script::new(), + sequence: 0, + witness: Vec::new(), + }); + witness_weight += StaticPaymentOutputDescriptor::MAX_WITNESS_LENGTH; + input_value += descriptor.output.value; + if !output_set.insert(descriptor.outpoint) { return Err(()); } + }, + SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => { + input.push(TxIn { + previous_output: descriptor.outpoint.into_bitcoin_outpoint(), + script_sig: Script::new(), + sequence: descriptor.to_self_delay as u32, + witness: Vec::new(), + }); + witness_weight += DelayedPaymentOutputDescriptor::MAX_WITNESS_LENGTH; + input_value += descriptor.output.value; + if !output_set.insert(descriptor.outpoint) { return Err(()); } + }, + SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => { + input.push(TxIn { + previous_output: outpoint.into_bitcoin_outpoint(), + script_sig: Script::new(), + sequence: 0, + witness: Vec::new(), + }); + witness_weight += 1 + 73 + 34; + input_value += output.value; + if !output_set.insert(*outpoint) { return Err(()); } + } + } + if input_value > MAX_VALUE_MSAT / 1000 { return Err(()); } + } + let mut spend_tx = Transaction { + version: 2, + lock_time: 0, + input, + output: outputs, + }; + transaction_utils::maybe_add_change_output(&mut spend_tx, input_value, witness_weight, feerate_sat_per_1000_weight, change_destination_script)?; + + let mut keys_cache: Option<(InMemorySigner, [u8; 32])> = None; + let mut input_idx = 0; + for outp in descriptors { + match outp { + SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => { + if keys_cache.is_none() || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id { + keys_cache = Some(( + self.derive_channel_keys(descriptor.channel_value_satoshis, &descriptor.channel_keys_id), + descriptor.channel_keys_id)); + } + spend_tx.input[input_idx].witness = keys_cache.as_ref().unwrap().0.sign_counterparty_payment_input(&spend_tx, input_idx, &descriptor, &secp_ctx).unwrap(); + }, + SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => { + if keys_cache.is_none() || keys_cache.as_ref().unwrap().1 != descriptor.channel_keys_id { + keys_cache = Some(( + self.derive_channel_keys(descriptor.channel_value_satoshis, &descriptor.channel_keys_id), + descriptor.channel_keys_id)); + } + spend_tx.input[input_idx].witness = keys_cache.as_ref().unwrap().0.sign_dynamic_p2wsh_input(&spend_tx, input_idx, &descriptor, &secp_ctx).unwrap(); + }, + SpendableOutputDescriptor::StaticOutput { ref output, .. } => { + let derivation_idx = if output.script_pubkey == self.destination_script { + 1 + } else { + 2 + }; + let secret = { + // Note that when we aren't serializing the key, network doesn't matter + match ExtendedPrivKey::new_master(Network::Testnet, &self.seed) { + Ok(master_key) => { + match master_key.ckd_priv(&secp_ctx, ChildNumber::from_hardened_idx(derivation_idx).expect("key space exhausted")) { + Ok(key) => key, + Err(_) => panic!("Your RNG is busted"), + } + } + Err(_) => panic!("Your rng is busted"), + } + }; + let pubkey = ExtendedPubKey::from_private(&secp_ctx, &secret).public_key; + if derivation_idx == 2 { + assert_eq!(pubkey.key, self.shutdown_pubkey); + } + let witness_script = bitcoin::Address::p2pkh(&pubkey, Network::Testnet).script_pubkey(); + let sighash = hash_to_message!(&bip143::SigHashCache::new(&spend_tx).signature_hash(input_idx, &witness_script, output.value, SigHashType::All)[..]); + let sig = secp_ctx.sign(&sighash, &secret.private_key.key); + spend_tx.input[input_idx].witness.push(sig.serialize_der().to_vec()); + spend_tx.input[input_idx].witness[0].push(SigHashType::All as u8); + spend_tx.input[input_idx].witness.push(pubkey.key.serialize().to_vec()); + }, + } + input_idx += 1; + } + Ok(spend_tx) + } +} - let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel); - let child_privkey = self.session_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted"); - sha.input(&child_privkey.private_key.key[..]); +impl KeysInterface for KeysManager { + type Signer = InMemorySigner; - let mut rng_seed = sha.clone(); - // Not exactly the most ideal construction, but the second value will get fed into - // ChaCha so it is another step harder to break. - rng_seed.input(b"RNG Seed Salt"); - sha.input(b"Session Key Salt"); - (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"), - Sha256::from_engine(rng_seed).into_inner()) + fn get_node_secret(&self) -> SecretKey { + self.node_secret.clone() } - fn get_channel_id(&self) -> [u8; 32] { - let mut sha = self.unique_start.clone(); + fn get_destination_script(&self) -> Script { + self.destination_script.clone() + } - let child_ix = self.channel_id_child_index.fetch_add(1, Ordering::AcqRel); - let child_privkey = self.channel_id_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted"); + fn get_shutdown_pubkey(&self) -> PublicKey { + self.shutdown_pubkey.clone() + } + + fn get_channel_signer(&self, _inbound: bool, channel_value_satoshis: u64) -> Self::Signer { + let child_ix = self.channel_child_index.fetch_add(1, Ordering::AcqRel); + assert!(child_ix <= std::u32::MAX as usize); + let mut id = [0; 32]; + id[0..8].copy_from_slice(&byte_utils::be64_to_array(child_ix as u64)); + id[8..16].copy_from_slice(&byte_utils::be64_to_array(self.starting_time_nanos as u64)); + id[16..24].copy_from_slice(&byte_utils::be64_to_array(self.starting_time_secs)); + self.derive_channel_keys(channel_value_satoshis, &id) + } + + fn get_secure_random_bytes(&self) -> [u8; 32] { + let mut sha = self.derive_unique_start(); + + let child_ix = self.rand_bytes_child_index.fetch_add(1, Ordering::AcqRel); + let child_privkey = self.rand_bytes_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted"); sha.input(&child_privkey.private_key.key[..]); + sha.input(b"Unique Secure Random Bytes Salt"); Sha256::from_engine(sha).into_inner() } + + fn read_chan_signer(&self, reader: &[u8]) -> Result { + InMemorySigner::read(&mut std::io::Cursor::new(reader)) + } }