From: Elias Rohrer Date: Thu, 1 Dec 2022 14:17:57 +0000 (+0100) Subject: Clean up docs in `keysinterface.rs` X-Git-Tag: v0.0.113~5^2 X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=03de0598afd032e9fd5dbbaca0aabc6a367ce4f5;p=rust-lightning Clean up docs in `keysinterface.rs` --- diff --git a/lightning/src/chain/keysinterface.rs b/lightning/src/chain/keysinterface.rs index f2d198bb..1426ff5c 100644 --- a/lightning/src/chain/keysinterface.rs +++ b/lightning/src/chain/keysinterface.rs @@ -7,9 +7,10 @@ // 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. +//! Provides keys to LDK and defines some useful objects describing spendable on-chain outputs. +//! +//! The provided output descriptors follow a custom LDK data format and are currently not fully +//! compatible with Bitcoin Core output descriptors. use bitcoin::blockdata::transaction::{Transaction, TxOut, TxIn, EcdsaSighashType}; use bitcoin::blockdata::script::{Script, Builder}; @@ -52,29 +53,30 @@ use crate::util::invoice::construct_invoice_preimage; /// Used as initial key material, to be expanded into multiple secret keys (but not to be used /// directly). This is used within LDK to encrypt/decrypt inbound payment data. -/// (C-not exported) as we just use [u8; 32] directly +/// +/// (C-not exported) as we just use `[u8; 32]` directly #[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)] pub struct KeyMaterial(pub [u8; 32]); -/// Information about a spendable output to a P2WSH script. See -/// SpendableOutputDescriptor::DelayedPaymentOutput for more details on how to spend this. +/// Information about a spendable output to a P2WSH script. +/// +/// See [`SpendableOutputDescriptor::DelayedPaymentOutput`] for more details on how to spend this. #[derive(Clone, Debug, PartialEq, Eq)] pub struct DelayedPaymentOutputDescriptor { - /// The outpoint which is spendable + /// The outpoint which is spendable. pub outpoint: OutPoint, - /// Per commitment point to derive delayed_payment_key by key holder + /// Per commitment point to derive the 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 `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 + /// 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. + /// Arbitrary identification information returned by a call to [`BaseSign::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, @@ -96,17 +98,17 @@ impl_writeable_tlv_based!(DelayedPaymentOutputDescriptor, { (12, channel_value_satoshis, required), }); -/// Information about a spendable output to our "payment key". See -/// SpendableOutputDescriptor::StaticPaymentOutput for more details on how to spend this. +/// Information about a spendable output to our "payment key". +/// +/// See [`SpendableOutputDescriptor::StaticPaymentOutput`] for more details on how to spend this. #[derive(Clone, Debug, PartialEq, Eq)] pub struct StaticPaymentOutputDescriptor { - /// The outpoint which is spendable + /// The outpoint which is spendable. pub outpoint: OutPoint, - /// The output which is referenced by the given 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. + /// Arbitrary identification information returned by a call to [`BaseSign::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, @@ -124,57 +126,76 @@ impl_writeable_tlv_based!(StaticPaymentOutputDescriptor, { (6, channel_value_satoshis, required), }); -/// 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. +/// Describes the necessary information to spend a spendable output. +/// +/// When on-chain outputs are created by LDK (which our counterparty is not able to claim at any +/// point in the future) a [`SpendableOutputs`] 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. +/// +/// [`SpendableOutputs`]: crate::util::events::Event::SpendableOutputs #[derive(Clone, Debug, PartialEq, Eq)] pub enum SpendableOutputDescriptor { - /// An output to a script which was provided via KeysInterface directly, either from - /// `get_destination_script()` or `get_shutdown_scriptpubkey()`, thus you should already know - /// how to spend it. No secret keys are provided as rust-lightning was never given any key. + /// An output to a script which was provided via [`KeysInterface`] directly, either from + /// [`get_destination_script`] or [`get_shutdown_scriptpubkey`], thus you should already + /// know how to spend it. No secret keys are provided as LDK 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. + /// + /// [`get_shutdown_scriptpubkey`]: KeysInterface::get_shutdown_scriptpubkey + /// [`get_destination_script`]: KeysInterface::get_shutdown_scriptpubkey StaticOutput { - /// The outpoint which is spendable + /// The outpoint which is spendable. outpoint: OutPoint, /// The output which is referenced by the given outpoint. output: TxOut, }, - /// An output to a P2WSH script which can be spent with a single signature after a CSV delay. + /// An output to a P2WSH script which can be spent with a single signature after an `OP_CSV` + /// delay. /// /// The witness in the spending input should be: + /// ```bitcoin /// (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). + /// Note that the `nSequence` field in the spending input must be set to + /// [`DelayedPaymentOutputDescriptor::to_self_delay`] (which means the transaction is not + /// broadcastable until at least [`DelayedPaymentOutputDescriptor::to_self_delay`] blocks after + /// the outpoint confirms, see [BIP + /// 68](https://github.com/bitcoin/bips/blob/master/bip-0068.mediawiki)). Also note that LDK + /// won't generate a [`SpendableOutputDescriptor`] until the corresponding block height + /// is reached. /// /// These are generally the result of a "revocable" output to us, spendable only by us unless /// 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::provide_channel_parameters) 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. + /// To derive the delayed payment key which is used to sign this input, you must pass the + /// holder [`InMemorySigner::delayed_payment_base_key`] (i.e., the private key which corresponds to the + /// [`ChannelPublicKeys::delayed_payment_basepoint`] in [`BaseSign::pubkeys`]) and the provided + /// [`DelayedPaymentOutputDescriptor::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 + /// [`ChannelPublicKeys::delayed_payment_basepoint`] which appears in [`BaseSign::pubkeys`]. + /// + /// To derive the [`DelayedPaymentOutputDescriptor::revocation_pubkey`] provided here (which is + /// used in the witness script generation), you must pass the counterparty + /// [`ChannelPublicKeys::revocation_basepoint`] (which appears in the call to + /// [`BaseSign::provide_channel_parameters`]) and the provided + /// [`DelayedPaymentOutputDescriptor::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 [`DelayedPaymentOutputDescriptor::revocation_pubkey`] (derived + /// as explained above), our delayed payment pubkey (derived as explained above), and the + /// [`DelayedPaymentOutputDescriptor::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: + /// An output to a P2WPKH, spendable exclusively by our payment key (i.e., the private key + /// which corresponds to the `payment_point` in [`BaseSign::pubkeys`]). The witness + /// in the spending input is, thus, simply: + /// ```bitcoin /// + /// ``` /// /// These are generally the result of our counterparty having broadcast the current state, /// allowing us to claim the non-HTLC-encumbered outputs immediately. @@ -191,29 +212,17 @@ impl_writeable_tlv_based_enum!(SpendableOutputDescriptor, (2, StaticPaymentOutput), ); -/// 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 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 -/// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys. +/// A trait to sign Lightning channel transactions as described in +/// [BOLT 3](https://github.com/lightning/bolts/blob/master/03-transactions.md). /// -/// A more secure iteration would be to use hashlock (or payment points) to pair -/// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager -/// at the price of more state and computation on the hardware wallet side. In the future, -/// we are looking forward to design such interface. -/// -/// 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. -// 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. +/// Signing services could be implemented on a hardware wallet and should implement signing +/// policies in order to be secure. Please refer to the [VLS Policy +/// Controls](https://gitlab.com/lightning-signer/validating-lightning-signer/-/blob/main/docs/policy-controls.md) +/// for an example of such policies. pub trait BaseSign { /// Gets the per-commitment point for a specific commitment number /// - /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards. + /// 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 /// @@ -222,7 +231,7 @@ pub trait BaseSign { /// /// May be called more than once for the same index. /// - /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards. + /// 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]; /// Validate the counterparty's signatures on the holder commitment transaction and HTLCs. @@ -236,16 +245,16 @@ pub trait BaseSign { /// A validating signer should ensure that an HTLC output is removed only when the matching /// preimage is provided, or when the value to holder is restored. /// - /// NOTE: all the relevant preimages will be provided, but there may also be additional + /// Note that all the relevant preimages will be provided, but there may also be additional /// irrelevant or duplicate preimages. - fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, preimages: Vec) -> Result<(), ()>; - /// Gets the holder's channel public keys and basepoints + fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, + preimages: Vec) -> Result<(), ()>; + /// Returns 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. + /// Returns 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 + /// [`BaseSign`] 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. @@ -257,40 +266,43 @@ pub trait BaseSign { /// A validating signer should ensure that an HTLC output is removed only when the matching /// preimage is provided, or when the value to holder is restored. /// - /// NOTE: all the relevant preimages will be provided, but there may also be additional + /// Note that all the relevant preimages will be provided, but there may also be additional /// irrelevant or duplicate preimages. // // TODO: Document the things someone using this interface should enforce before signing. - fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, preimages: Vec, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()>; + fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, + preimages: Vec, secp_ctx: &Secp256k1 + ) -> Result<(Signature, Vec), ()>; /// Validate the counterparty's revocation. /// /// This is required in order for the signer to make sure that the state has moved /// forward and it is safe to sign the next counterparty commitment. fn validate_counterparty_revocation(&self, idx: u64, secret: &SecretKey) -> Result<(), ()>; - - /// 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. + /// Creates a signature for a holder's commitment transaction and its claiming HTLC transactions. + /// + /// This will be called + /// - with a non-revoked `commitment_tx`. + /// - with the latest `commitment_tx` when we initiate a force-close. + /// - with the previous `commitment_tx`, just to get claiming HTLC + /// signatures, if we are reacting to a [`ChannelMonitor`] + /// [replica](https://github.com/lightningdevkit/rust-lightning/blob/main/GLOSSARY.md#monitor-replicas) + /// that decided to broadcast before it had been updated to the latest `commitment_tx`. + /// /// This may be called multiple times for the same transaction. /// /// An external signer implementation should check that the commitment has not been revoked. /// - /// May return Err if key derivation fails. Callers, such as ChannelMonitor, will panic in such a case. - // + /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor // TODO: Document the things someone using this interface should enforce before signing. - // 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_holder_commitment, but exists only for tests to get access to holder commitment - /// transactions which will be broadcasted later, after the channel has moved on to a newer - /// state. Thus, needs its own method as sign_holder_commitment may enforce that we only ever - /// get called once. + fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, + secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()>; + /// Same as [`sign_holder_commitment_and_htlcs`], but exists only for tests to get access to + /// holder commitment transactions which will be broadcasted later, after the channel has moved + /// on to a newer state. Thus, needs its own method as [`sign_holder_commitment_and_htlcs`] may + /// enforce that we only ever get called once. #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))] - fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()>; - + fn unsafe_sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, + secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()>; /// Create a signature for the given input in a transaction spending an HTLC transaction output /// or a commitment transaction `to_local` output when our counterparty broadcasts an old state. /// @@ -301,12 +313,13 @@ pub trait BaseSign { /// /// 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 + /// `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 + /// not allow the spending of any funds by itself (you need our holder `revocation_secret` to do /// so). - fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1) -> Result; - + fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, + per_commitment_key: &SecretKey, secp_ctx: &Secp256k1 + ) -> Result; /// Create a signature for the given input in a transaction spending a commitment transaction /// HTLC output when our counterparty broadcasts an old state. /// @@ -315,30 +328,30 @@ pub trait BaseSign { /// It may be called multiple times for same output(s) if a fee-bump is needed with regards /// to an upcoming timelock expiration. /// - /// Amount is value of the output spent by this input, committed to in the BIP 143 signature. + /// `amount` is the 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 + /// `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), thus changing the format of the witness script + /// `htlc` holds HTLC elements (hash, timelock), thus changing the format of the witness script /// (which is committed to in the BIP 143 signatures). - fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1) -> Result; - + fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, + per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, + secp_ctx: &Secp256k1) -> Result; #[cfg(anchors)] /// Computes the signature for a commitment transaction's HTLC output used as an input within - /// `htlc_tx`, which spends the commitment transaction, at index `input`. The signature returned + /// `htlc_tx`, which spends the commitment transaction at index `input`. The signature returned /// must be be computed using [`EcdsaSighashType::All`]. Note that this should only be used to /// sign HTLC transactions from channels supporting anchor outputs after all additional /// inputs/outputs have been added to the transaction. /// /// [`EcdsaSighashType::All`]: bitcoin::blockdata::transaction::EcdsaSighashType::All - fn sign_holder_htlc_transaction( - &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor, - secp_ctx: &Secp256k1 + fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, + htlc_descriptor: &HTLCDescriptor, 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. /// @@ -347,29 +360,29 @@ pub trait BaseSign { /// 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 + /// `witness_script` is either an 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. + /// `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 + /// `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; - + 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. /// /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have /// chosen to forgo their output as dust. - fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1) -> Result; - + fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, + secp_ctx: &Secp256k1) -> Result; /// Computes the signature for a commitment transaction's anchor output used as an /// input within `anchor_tx`, which spends the commitment transaction, at index `input`. fn sign_holder_anchor_input( &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1, ) -> Result; - /// Signs a channel announcement message with our funding key and our node secret key (aka /// node_id or network_key), proving it comes from one of the channel participants. /// @@ -381,11 +394,10 @@ pub trait BaseSign { /// protocol. fn sign_channel_announcement(&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1) -> Result<(Signature, Signature), ()>; - /// Set the counterparty static channel data, including basepoints, - /// counterparty_selected/holder_selected_contest_delay and funding outpoint. Since these are - /// static channel data, they MUST NOT be allowed to change to different values once set, as LDK - /// may call this method more than once. + /// `counterparty_selected`/`holder_selected_contest_delay` and funding outpoint. Since these + /// are static channel data, they MUST NOT be allowed to change to different values once set, + /// as LDK may call this method more than once. /// /// channel_parameters.is_populated() MUST be true. fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters); @@ -398,11 +410,12 @@ pub trait BaseSign { /// /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor -pub trait Sign: BaseSign + Writeable { -} +pub trait Sign: BaseSign + Writeable {} -/// Specifies the recipient of an invoice, to indicate to [`KeysInterface::sign_invoice`] what node -/// secret key should be used to sign the invoice. +/// Specifies the recipient of an invoice. +/// +/// This indicates to [`KeysInterface::sign_invoice`] what node secret key should be used to sign +/// the invoice. pub enum Recipient { /// The invoice should be signed with the local node secret key. Node, @@ -415,27 +428,26 @@ pub enum Recipient { /// A trait to describe an object which can get user secrets and key material. pub trait KeysInterface { - /// A type which implements Sign which will be returned by derive_channel_signer. + /// A type which implements [`Sign`] which will be returned by [`Self::derive_channel_signer`]. type Signer : Sign; - /// Get node secret key based on the provided [`Recipient`]. /// - /// The node_id/network_key is the public key that corresponds to this secret key. + /// The `node_id`/`network_key` is the public key that corresponds to this secret key. /// - /// This method must return the same value each time it is called with a given `Recipient` + /// This method must return the same value each time it is called with a given [`Recipient`] /// parameter. /// - /// Errors if the `Recipient` variant is not supported by the implementation. + /// Errors if the [`Recipient`] variant is not supported by the implementation. fn get_node_secret(&self, recipient: Recipient) -> Result; /// Get node id based on the provided [`Recipient`]. This public key corresponds to the secret in /// [`get_node_secret`]. /// - /// This method must return the same value each time it is called with a given `Recipient` + /// This method must return the same value each time it is called with a given [`Recipient`] /// parameter. /// - /// Errors if the `Recipient` variant is not supported by the implementation. + /// Errors if the [`Recipient`] variant is not supported by the implementation. /// - /// [`get_node_secret`]: KeysInterface::get_node_secret + /// [`get_node_secret`]: Self::get_node_secret fn get_node_id(&self, recipient: Recipient) -> Result { let secp_ctx = Secp256k1::signing_only(); Ok(PublicKey::from_secret_key(&secp_ctx, &self.get_node_secret(recipient)?)) @@ -444,7 +456,7 @@ pub trait KeysInterface { /// one is provided. Note that this tweak can be applied to `other_key` instead of our node /// secret, though this is less efficient. /// - /// Errors if the `Recipient` variant is not supported by the implementation. + /// Errors if the [`Recipient`] variant is not supported by the implementation. /// /// [`node secret`]: Self::get_node_secret fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result; @@ -458,10 +470,8 @@ pub trait KeysInterface { /// 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_scriptpubkey(&self) -> ShutdownScript; - /// Generates a unique `channel_keys_id` that can be used to obtain a `Signer` through - /// [`KeysInterface::derive_channel_signer`]. The `user_channel_id` is provided to allow - /// implementations of `KeysInterface` to maintain a mapping between it and the generated - /// `channel_keys_id`. + /// 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 generate_channel_keys_id(&self, inbound: bool, channel_value_satoshis: u64, user_channel_id: u128) -> [u8; 32]; @@ -478,37 +488,38 @@ pub trait KeysInterface { /// /// 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. + /// 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). + /// [`Sign`]-implementing objects (i.e., [`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. /// /// This method is slowly being phased out -- it will only be called when reading objects /// written by LDK versions prior to 0.0.113. + /// + /// [`Signer`]: Self::Signer + /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor + /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager fn read_chan_signer(&self, reader: &[u8]) -> Result; - /// Sign an invoice. /// By parameterizing by the raw invoice bytes instead of the hash, we allow implementors of /// this trait to parse the invoice and make sure they're signing what they expect, rather than /// blindly signing the hash. - /// The hrp is ascii bytes, while the invoice data is base32. + /// The `hrp` is ASCII bytes, while the invoice data is base32-encoded. /// /// The secret key used to sign the invoice is dependent on the [`Recipient`]. /// - /// Errors if the `Recipient` variant is not supported by the implementation. + /// Errors if the [`Recipient`] variant is not supported by the implementation. fn sign_invoice(&self, hrp_bytes: &[u8], invoice_data: &[u5], receipient: Recipient) -> Result; - /// Get secret key material as bytes for use in encrypting and decrypting inbound payment data. /// /// If the implementor of this trait supports [phantom node payments], then every node that is /// intended to be included in the phantom invoice route hints must return the same value from /// this method. - // This is because LDK avoids storing inbound payment data by encrypting payment data in the - // payment hash and/or payment secret, therefore for a payment to be receivable by multiple - // nodes, they must share the key that encrypts this payment data. + // This is because LDK avoids storing inbound payment data by encrypting payment data in the + // payment hash and/or payment secret, therefore for a payment to be receivable by multiple + // nodes, they must share the key that encrypts this payment data. /// /// This method must return the same value each time it is called. /// @@ -517,37 +528,38 @@ pub trait KeysInterface { } #[derive(Clone)] -/// A simple implementation of Sign that just keeps the private keys in memory. +/// 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 + /// Holder secret key in the 2-of-2 multisig script of a channel. This key also backs the + /// holder's anchor output in a commitment transaction, if one is present. pub funding_key: SecretKey, - /// Holder secret key for blinded revocation pubkey + /// Holder secret key for blinded revocation pubkey. pub revocation_base_key: SecretKey, - /// Holder secret key used for our balance in counterparty-broadcasted commitment transactions + /// Holder secret key used for our balance in counterparty-broadcasted commitment transactions. pub payment_key: SecretKey, - /// Holder secret key used in HTLC tx + /// Holder secret key used in an HTLC transaction. pub delayed_payment_base_key: SecretKey, - /// Holder htlc secret key used in commitment tx htlc outputs + /// Holder HTLC secret key used in commitment transaction HTLC outputs. pub htlc_base_key: SecretKey, - /// Commitment seed + /// Commitment seed. pub commitment_seed: [u8; 32], - /// Holder public keys and basepoints + /// Holder public keys and basepoints. pub(crate) holder_channel_pubkeys: ChannelPublicKeys, - /// Private key of our node secret, used for signing channel announcements + /// Private key of our node secret, used for signing channel announcements. node_secret: SecretKey, - /// Counterparty public keys and counterparty/holder selected_contest_delay, populated on channel acceptance + /// Counterparty public keys and counterparty/holder `selected_contest_delay`, populated on channel acceptance. channel_parameters: Option, - /// The total value of this channel + /// The total value of this channel. channel_value_satoshis: u64, - /// Key derivation parameters + /// Key derivation parameters. channel_keys_id: [u8; 32], } impl InMemorySigner { - /// Create a new InMemorySigner + /// Creates a new [`InMemorySigner`]. pub fn new( secp_ctx: &Secp256k1, node_secret: SecretKey, @@ -562,8 +574,8 @@ impl InMemorySigner { ) -> 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); + &payment_key, &delayed_payment_base_key, + &htlc_base_key); InMemorySigner { funding_key, revocation_base_key, @@ -580,11 +592,11 @@ impl InMemorySigner { } fn make_holder_keys(secp_ctx: &Secp256k1, - funding_key: &SecretKey, - revocation_base_key: &SecretKey, - payment_key: &SecretKey, - delayed_payment_base_key: &SecretKey, - htlc_base_key: &SecretKey) -> ChannelPublicKeys { + funding_key: &SecretKey, + revocation_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), @@ -595,50 +607,51 @@ impl InMemorySigner { } } - /// Counterparty pubkeys. - /// Will panic if provide_channel_parameters wasn't called. + /// Returns the counterparty's pubkeys. + /// + /// Will panic if [`BaseSign::provide_channel_parameters`] has not been called before. 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 + /// Returns the `contest_delay` value specified by our counterparty and applied on holder-broadcastable + /// transactions, i.e., the amount of time that we have to wait to recover our funds if we /// broadcast a transaction. - /// Will panic if provide_channel_parameters wasn't called. + /// + /// Will panic if [`BaseSign::provide_channel_parameters`] has not been called before. 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 + /// Returns the `contest_delay` value specified by us and applied on transactions broadcastable + /// by our counterparty, i.e., the amount of time that they have to wait to recover their funds /// if they broadcast a transaction. - /// Will panic if provide_channel_parameters wasn't called. + /// + /// Will panic if [`BaseSign::provide_channel_parameters`] has not been called before. 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 provide_channel_parameters wasn't called. + /// Returns whether the holder is the initiator. + /// + /// Will panic if [`BaseSign::provide_channel_parameters`] has not been called before. pub fn is_outbound(&self) -> bool { self.get_channel_parameters().is_outbound_from_holder } - /// Funding outpoint - /// Will panic if provide_channel_parameters wasn't called. + /// + /// Will panic if [`BaseSign::provide_channel_parameters`] has not been called before. 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 + /// Returns a [`ChannelTransactionParameters`] for this channel, to be used when verifying or /// building transactions. /// - /// Will panic if provide_channel_parameters wasn't called. + /// Will panic if [`BaseSign::provide_channel_parameters`] has not been called before. pub fn get_channel_parameters(&self) -> &ChannelTransactionParameters { self.channel_parameters.as_ref().unwrap() } - - /// Whether anchors should be used. - /// Will panic if provide_channel_parameters wasn't called. + /// Returns whether anchors should be used. + /// + /// Will panic if [`BaseSign::provide_channel_parameters`] has not been called before. pub fn opt_anchors(&self) -> bool { self.get_channel_parameters().opt_anchors.is_some() } - - /// 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. + /// 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 error 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 if an output descriptor `script_pubkey` does not match the one we can spend. /// - /// 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 if an output descriptor script_pubkey does not match the one we can spend. + /// [`descriptor.outpoint`]: StaticPaymentOutputDescriptor::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 @@ -654,7 +667,7 @@ impl InMemorySigner { let remotesig = sign(secp_ctx, &sighash, &self.payment_key); let payment_script = bitcoin::Address::p2wpkh(&::bitcoin::PublicKey{compressed: true, inner: remotepubkey}, Network::Bitcoin).unwrap().script_pubkey(); - if payment_script != descriptor.output.script_pubkey { return Err(()); } + if payment_script != descriptor.output.script_pubkey { return Err(()); } let mut witness = Vec::with_capacity(2); witness.push(remotesig.serialize_der().to_vec()); @@ -663,13 +676,16 @@ impl InMemorySigner { 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. + /// 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`, does not have a - /// sequence set to `descriptor.to_self_delay`, or if an output descriptor - /// script_pubkey does not match the one we can spend. + /// Returns an error if the input at `input_idx` does not exist, has a non-empty `script_sig`, + /// is not spending the outpoint described by [`descriptor.outpoint`], does not have a + /// sequence set to [`descriptor.to_self_delay`], or if an output descriptor + /// `script_pubkey` does not match the one we can spend. + /// + /// [`descriptor.outpoint`]: DelayedPaymentOutputDescriptor::outpoint + /// [`descriptor.to_self_delay`]: DelayedPaymentOutputDescriptor::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 @@ -713,6 +729,7 @@ impl BaseSign for InMemorySigner { } 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, _preimages: Vec, secp_ctx: &Secp256k1) -> Result<(Signature, Vec), ()> { @@ -855,6 +872,7 @@ impl BaseSign for InMemorySigner { } const SERIALIZATION_VERSION: u8 = 1; + const MIN_SERIALIZATION_VERSION: u8 = 1; impl Sign for InMemorySigner {} @@ -894,8 +912,7 @@ impl ReadableArgs for InMemorySigner { let secp_ctx = Secp256k1::signing_only(); let holder_channel_pubkeys = InMemorySigner::make_holder_keys(&secp_ctx, &funding_key, &revocation_base_key, - &payment_key, &delayed_payment_base_key, - &htlc_base_key); + &payment_key, &delayed_payment_base_key, &htlc_base_key); let keys_id = Readable::read(reader)?; read_tlv_fields!(reader, {}); @@ -916,12 +933,12 @@ impl ReadableArgs for InMemorySigner { } } -/// Simple KeysInterface implementor that takes a 32-byte seed for use as a BIP 32 extended key -/// and derives keys from that. +/// Simple [`KeysInterface`] implementation that takes a 32-byte seed for use as a BIP 32 extended +/// key and derives keys from that. /// -/// Your node_id is seed/0' -/// ChannelMonitor closes may use seed/1' -/// Cooperative closes may use seed/2' +/// Your `node_id` is seed/0'. +/// Unilateral closes may use seed/1'. +/// Cooperative closes may use seed/2'. /// The two close keys may be needed to claim on-chain funds! /// /// This struct cannot be used for nodes that wish to support receiving phantom payments; @@ -949,25 +966,23 @@ pub struct KeysManager { } impl KeysManager { - /// Constructs a KeysManager from a 32-byte seed. If the seed is in some way biased (eg your - /// 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, + /// Constructs a [`KeysManager`] from a 32-byte seed. If the seed is in some way biased (e.g., + /// your 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 - /// simply use the current time (with very high precision). + /// `seed`, `starting_time` must be unique to each run. Thus, the easiest way to achieve this + /// is to simply use the current time (with very high precision). /// - /// The seed MUST be backed up safely prior to use so that the keys can be re-created, however, - /// obviously, starting_time should be unique every time you reload the library - it is only + /// The `seed` MUST be backed up safely prior to use so that the keys can be re-created, however, + /// obviously, `starting_time` should be unique every time you reload the library - it is only /// used to generate new ephemeral key data (which will be stored by the individual channel if /// necessary). /// /// Note that the seed is required to recover certain on-chain funds independent of - /// ChannelMonitor data, though a current copy of ChannelMonitor data is also required for any - /// channel, and some on-chain during-closing funds. + /// [`ChannelMonitor`] data, though a current copy of [`ChannelMonitor`] data is also required + /// for any channel, and some on-chain during-closing funds. /// - /// 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. + /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor pub fn new(seed: &[u8; 32], starting_time_secs: u64, starting_time_nanos: u32) -> Self { let secp_ctx = Secp256k1::new(); // Note that when we aren't serializing the key, network doesn't matter @@ -979,8 +994,8 @@ impl KeysManager { Ok(destination_key) => { let wpubkey_hash = WPubkeyHash::hash(&ExtendedPubKey::from_priv(&secp_ctx, &destination_key).to_pub().to_bytes()); Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0) - .push_slice(&wpubkey_hash.into_inner()) - .into_script() + .push_slice(&wpubkey_hash.into_inner()) + .into_script() }, Err(_) => panic!("Your RNG is busted"), }; @@ -1026,7 +1041,7 @@ impl KeysManager { Err(_) => panic!("Your rng is busted"), } } - /// Derive an old Sign containing per-channel secrets based on a key derivation parameters. + /// Derive an old [`Sign`] containing per-channel secrets based on a key derivation parameters. pub fn derive_channel_keys(&self, channel_value_satoshis: u64, params: &[u8; 32]) -> InMemorySigner { let chan_id = u64::from_be_bytes(params[0..8].try_into().unwrap()); let mut unique_start = Sha256::engine(); @@ -1076,7 +1091,7 @@ impl KeysManager { ) } - /// Creates a Transaction which spends the given descriptors to the given outputs, plus an + /// 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. /// @@ -1086,8 +1101,8 @@ impl KeysManager { /// /// 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. + /// 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; @@ -1297,11 +1312,11 @@ impl KeysInterface for KeysManager { /// nodes in the case that one node goes down. /// /// Note that multi-path payments are not supported in phantom invoices for security reasons. -// In the hypothetical case that we did support MPP phantom payments, there would be no way for -// nodes to know when the full payment has been received (and the preimage can be released) without -// significantly compromising on our safety guarantees. I.e., if we expose the ability for the user -// to tell LDK when the preimage can be released, we open ourselves to attacks where the preimage -// is released too early. +// In the hypothetical case that we did support MPP phantom payments, there would be no way for +// nodes to know when the full payment has been received (and the preimage can be released) without +// significantly compromising on our safety guarantees. I.e., if we expose the ability for the user +// to tell LDK when the preimage can be released, we open ourselves to attacks where the preimage +// is released too early. // /// Switching between this struct and [`KeysManager`] will invalidate any previously issued /// invoices and attempts to pay previous invoices will fail. @@ -1373,8 +1388,9 @@ impl KeysInterface for PhantomKeysManager { } impl PhantomKeysManager { - /// Constructs a `PhantomKeysManager` given a 32-byte seed and an additional `cross_node_seed` - /// that is shared across all nodes that intend to participate in [phantom node payments] together. + /// Constructs a [`PhantomKeysManager`] given a 32-byte seed and an additional `cross_node_seed` + /// that is shared across all nodes that intend to participate in [phantom node payments] + /// together. /// /// See [`KeysManager::new`] for more information on `seed`, `starting_time_secs`, and /// `starting_time_nanos`. diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs index 79c85e75..28719f2d 100644 --- a/lightning/src/ln/functional_tests.rs +++ b/lightning/src/ln/functional_tests.rs @@ -5258,9 +5258,10 @@ fn test_dynamic_spendable_outputs_local_htlc_timeout_tx() { #[test] fn test_key_derivation_params() { - // This test is a copy of test_dynamic_spendable_outputs_local_htlc_timeout_tx, with - // a key manager rotation to test that key_derivation_params returned in DynamicOutputP2WSH - // let us re-derive the channel key set to then derive a delayed_payment_key. + // This test is a copy of test_dynamic_spendable_outputs_local_htlc_timeout_tx, with a key + // manager rotation to test that `channel_keys_id` returned in + // [`SpendableOutputDescriptor::DelayedPaymentOutput`] let us re-derive the channel key set to + // then derive a `delayed_payment_key`. let chanmon_cfgs = create_chanmon_cfgs(3);